JP2008077993A - Electrode and non-aqueous secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode capable of achieving stably and efficiently at low cost a non-aqueous electrolyte secondary battery of high performance with high discharge capacity, high charge and discharge efficiency, and excellent cycle characteristics. <P>SOLUTION: The electrode consists of a current collector, a conductive material layer installed on the current collector, and an active material layer installed on the conductive material layer. The electrode satisfies any one or both of the following requirements (1) and (2). The non-aqueous electrolyte secondary battery is provided with this electrode, a positive electrode, and an electrolyte. (1) The numerical aperture of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less and the active material layer contains an active material including at least an element allowing with lithium. (2) The roughness Ra of the joint surface of the conductive material layer in contact with the active material layer is 0.01 or more and 3.0 μm or less and the porosity of the conductive material layer is 15% or more and 50% or less, and the active material layer contains an active material including at least an element alloying with lithium. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a current collector, a conductive material layer provided on the current collector, an electrode comprising an active material layer provided on the conductive material layer, and a non-aqueous electrolyte secondary using the electrode. It relates to batteries. The present invention also relates to an electrode having high discharge capacity, high charge / discharge efficiency, excellent cycle characteristics, and low cost, and a non-aqueous electrolyte secondary battery using this electrode.

  In recent years, with the miniaturization of electronic devices, high-capacity secondary batteries have become necessary. In particular, non-aqueous solvent lithium secondary batteries with higher energy density have attracted attention as compared with nickel-cadmium and nickel-hydrogen batteries. Conventionally, high capacity of a lithium secondary battery has been widely studied, but in recent years, the performance required for the battery has been advanced, and further increase in capacity and cost reduction are required.

  As a negative electrode material for a lithium secondary battery, graphite and the like have been studied so far. Graphite has been used because of its excellent cycle characteristics, small electrode expansion, and low cost. However, the negative electrode material made of graphite has a limit of theoretical capacity of 372 mAh / g, and further increase in capacity cannot be expected. Therefore, in recent years, studies have been made on alloy-based negative electrodes such as Si, Sn, and Al that form an alloy with lithium having a large theoretical capacity instead of the graphite negative electrode. In particular, since Si has a high capacity, many attempts have been made to apply it as a negative electrode. However, the Si-based negative electrode has a drawback that it has a large volume expansion upon reaction with lithium, Si is pulverized, is easily peeled off from the current collector, is highly reactive with the electrolyte, and has poor cycle characteristics. For this reason, realization of a negative electrode which is excellent in cycle characteristics and inexpensive, in which the reactivity with the electrolytic solution is suppressed while utilizing the high capacity of the alloy-based negative electrode is demanded.

  Under these circumstances, Patent Document 1 provides a negative electrode for a lithium secondary battery having a large charge / discharge capacity and less deterioration due to repeated charge / discharge by having a porous layer made of a carbon layer and a Li alloy on the current collector. It is described.

  Patent Document 2 discloses an electrode in which a first active material layer made of carbon is provided on a current collector, and a second active material layer made of a metal or semiconductor alloyable with Li is provided thereon. It is described that, when used, the active material is prevented from being peeled off due to expansion and contraction during charge and discharge, and a lithium secondary battery having excellent cycle characteristics is obtained.

  Patent Document 3 maintains a high charge / discharge efficiency by having a second layer mainly composed of a film-like oxide material capable of occluding Li on a first layer mainly composed of carbon. It is described that a high-capacity battery having improved cycle characteristics is obtained.

Patent Document 4 describes that a lithium secondary battery having a large charge / discharge capacity and excellent cycle characteristics is obtained by depositing Si or the like on a roughened current collector.
JP 7-326342 A JP 2001-283833 A Japanese Patent No. 3520921 Japanese Patent No. 3733069

With the recent increase in the need for higher capacity for batteries, utilization of alloy-based negative electrodes having a high capacity is desired. However, alloy-based negative electrodes have the following problems.
(1) The irreversible capacity accompanying the reaction with the electrolytic solution increases, and lithium in the positive electrode active material is consumed, resulting in a decrease in battery capacity.
(2) The alloy is pulverized and exfoliated from the current collector due to expansion / contraction due to insertion / extraction of lithium, and cycle characteristics deteriorate.
(3) Due to the reaction with the electrolyte during the cycle, the amount of chargeable / dischargeable active material decreases, and the cycle characteristics deteriorate.
(4) In order to suppress peeling and pulverization from the current collector, various processes such as roughening of the current collector are performed, and thus it is difficult to reduce costs.

  Therefore, in the further increase in capacity of the lithium secondary battery, not only the capacity is increased by using an alloy-based active material, but also the reaction with the electrolyte is suppressed, the cycle characteristics are improved, and the inexpensive negative electrode There is a strong demand to obtain.

  However, in Patent Documents 1 to 3, a carbon layer on a current collector, a porous layer made of a Li alloy, a layer made of a metal or a semiconductor that can be alloyed with Li, or a film-like oxide material that can occlude Li Is not defined for the surface area of the carbon layer bonded to the active material layer, and / or the surface roughness R and the porosity of the carbon layer, Due to the expansion and contraction of the active material layer due to the insertion / extraction of lithium, there is a problem that the destruction of the carbon layer surface proceeds and the cycle characteristics deteriorate.

  Further, in Patent Document 4, since a roughened current collector is used, it is difficult to alleviate the problem that the cost of the current collector greatly increases and the expansion and contraction of the active material layer due to insertion / extraction of lithium. There is a problem that the cycle characteristics deteriorate.

  The present invention has been devised in view of the above-mentioned background, and its problems are a high discharge capacity, high charge / discharge efficiency, excellent cycle characteristics, and an inexpensive electrode, and a non-aqueous solution using this electrode. An object is to provide an electrolyte secondary battery.

As a result of intensive studies on the alloy-based electrode, the present inventors have found that the adhesion between the alloy and the current collector deteriorates due to the expansion and contraction of the alloy that accompanies charging and discharging during the cycle, and the current cannot be collected. It becomes clear that the deterioration proceeds, and an electrode comprising a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer, Opening degree of the bonding surface of the conductive material layer in contact (here, “opening degree of the bonding surface of the conductive material layer in contact with the active material layer” refers to the conductive material before the formation of the active material layer) (Referring to the degree of opening in the vicinity of the layer surface) is 5% or more and 50% or less, and / or the joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 0.01 or more. 0 μm or less and the porosity of the conductive material layer is 15% or more and 50% or less.
(I) Since the stress of expansion and contraction of the alloy accompanying charging and discharging can be relaxed by the deformation of the conductive material layer, an inexpensive current collector that is not roughened can be used,
(Ii) The porosity of the joint surface of the conductive material layer in contact with the active material layer is less than 50%, and / or the joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 3.0 μm. Because it is smaller and the porosity of the conductive material layer is smaller than 50%, it is difficult for the active material layer to enter the recesses on the surface of the conductive material layer during the formation of the active material layer. Since current collection can be ensured while suppressing destruction of the conductive material layer, high-performance electrodes and non-aqueous electrolyte secondary batteries with high discharge capacity, high charge / discharge efficiency, and excellent cycle characteristics can be obtained at low cost. The present invention has been completed by finding that it can be stably and efficiently realized.

That is, the gist of the present invention is that an electrode comprising a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer is ) And (b), or an electrode that satisfies the requirements of both (Claim 1).
(B) The porosity of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less, and the active material layer contains an active material containing at least an element alloying with lithium. .
(B) The joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 0.01 to 3.0 μm, and the porosity of the conductive material layer is 15% to 50%. And the active material layer contains an active material containing at least an element alloying with lithium.

  Another gist of the present invention resides in the electrode according to claim 1, wherein the conductive substance is a substance containing carbon as a main component (claim 2).

  Another gist of the present invention resides in the electrode according to any one of claims 1 to 2, wherein the active material layer is a substance containing Si. (Claim 3).

Further, another gist of the present invention is the electrode according to any one of claims 1 to 3, wherein the active material layer is a compound in a phase in which element Z is present in a non-equilibrium state in Si. the a active material whose main component, characterized in that said compound is represented by the general formula SiZ _x M _y (as in the formula Z, M, x, y are the following conditions (1) to (4)) (Claim 4).
(1) The element Z is an element composed of C and / or N.
(2) Element M is one or more elements selected from elements other than Si and element Z.
(3) x represents the formula Q (Z) = [x with respect to the Z concentration (p / (a + p)) of the compound SiaZp (where a and p are integers) that exist in equilibrium with the composition closest to Si. / (1 + x)] / [p / (a + p)] is a value at which the Z concentration ratio Q (Z) calculated from 0.10 to 0.95.
(4) y is a number in the range of 0 ≦ y ≦ 0.50.

  Another gist of the present invention resides in the electrode according to any one of claims 1 to 4, wherein the active material layer is a material produced by vapor phase growth. (Claim 5).

  Another gist of the present invention is a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte, wherein the negative electrode is any one of claims 1 to 5. A nonaqueous electrolyte secondary battery comprising the electrode according to claim 6.

  According to the present invention, a high-performance nonaqueous electrolyte secondary battery having a high discharge capacity and excellent cycle characteristics can be stably and efficiently provided at low cost.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[1] Electrode The electrode of the present invention is an electrode comprising a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer. It is an electrode characterized by satisfying either or both of the requirements (a) and (b).
(B) The porosity of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less, and the active material layer contains an active material containing at least an element alloying with lithium. .
(B) The joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 0.01 to 3.0 μm, and the porosity of the conductive material layer is 15% to 50%. And the active material layer contains an active material containing at least an element alloying with lithium.

Such an electrode of the present invention is extremely useful as a negative electrode in a non-aqueous electrolyte secondary battery such as a positive and negative electrodes capable of inserting and extracting lithium ions, and a lithium secondary battery including an electrolyte. For example, a non-aqueous electrolyte secondary battery that uses an electrode of the present invention and is configured by combining a metal chalcogenide-based positive electrode for a lithium secondary battery that is normally used and an organic electrolyte mainly composed of a carbonate-based solvent has a capacity. Large, low irreversible capacity observed in the initial cycle, excellent cycle characteristics, high battery storage and reliability when left at high temperatures, and extremely excellent high efficiency discharge characteristics and low temperature discharge characteristics. .
It is also excellent as an electrode for an electronic energy device such as a capacitor.

<Conductive material layer>
The conductive material layer according to the present invention satisfies either or both of the following requirements (A) and (B).
(A) The degree of opening of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less.
(B) The concavity and convexity Ra of the conductive material layer in contact with the active material layer is 0.01 or more and 3.0 μm or less, and the porosity of the conductive material layer is 15% or more and 50% or less. is there. Hereinafter, the conductive material layer will be described in more detail.

[element]
The element of the conductive material layer is not particularly limited, but an element selected from Ni, Cu, Fe, C and the like is a main component, and the conductive material is preferably formed as the element or a compound using the element. Is composed mainly of an element capable of forming a solid solution or the like with a current collector and / or active material, more preferably composed mainly of Ni, Cu, and C elements, more preferably composed mainly of C elements. .

Here, the reason why it is preferable to use C as a main component for the element of the conductive material is, for example, when the active material element is Si and the current collector element is Cu,
(I) Reacts with lithium and acts as an active material. (Ii) Reacts with lithium with little volume change. (Iii) Reacts with active material element Si and current collector element Cu to form a compound or diffusion layer. Because there is.

[Form]
The conductive material layer of the present invention has, for example, a form as shown in the schematic diagram of the electrode shown in FIGS. 1A and 1B, and exists between the current collector and the active material layer. Examples of the conductive material include particles, fibers, and porous bodies.
In addition, the conductive material layer may be directly bonded or bonded to the current collector and / or the active material layer, or may be bonded via a binder such as a polymer material.

[Weight ratio of conductive material layer to active material layer]
The proportion of the conductive material layer represented by the following formula is not particularly limited, but is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, and the upper limit is usually 99% by weight or less. Preferably it is 95 weight% or less, More preferably, it is 90 weight% or less.
Ratio of conductive material layer =
Weight of conductive material layer ÷ (weight of conductive material layer + weight of active material layer) × 100
If the ratio of the conductive material layer is within this range, it is preferable because the expansion and contraction stress of the active material layer can be easily relaxed and the discharge capacity can be further increased.
The ratio of the conductive material layer is, for example, the weight of the conductive material layer and the weight of the active material layer per unit area of the negative electrode, based on the change in weight before and after the formation of the conductive material layer and the change in weight before and after the formation of the active material layer. And can be calculated by the previous equation.

[Film thickness]
The thickness of the conductive material layer is not particularly limited, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and the upper limit is usually 150 μm or less, preferably 100 μm or less, more preferably 60 μm. It is as follows. If the film thickness of the conductive material layer is within this range, the effect of relieving the expansion / contraction stress of the active material layer is large and preferable.

[Volume-based average particle diameter when conductive material is in particulate form]
When the conductive material is in the form of particles, the volume-based average particle diameter is not particularly limited, but is usually 1 μm or more, preferably 10 μm or more, more preferably 13 μm or more, and the upper limit is usually 100 μm or less, preferably 50 μm or less. More preferably, it is 30 μm or less.
When the volume-based average particle diameter of the particles is within this range, it is preferable that the expansion and contraction stress of the active material layer is easily relaxed.

  As the volume-based average particle diameter, for example, a 2% by volume aqueous solution (about 1 ml) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, is mixed with a measurement target, and laser diffraction is performed using ion-exchanged water as a dispersion medium. A value obtained by measuring a volume-based average particle diameter (median diameter) with an expression particle size distribution meter (for example, “LA-920” manufactured by Horiba, Ltd.) can be used. In Examples described later, the volume-based average particle diameter was determined by this method.

[Tap density when conductive material is particulate and element C]
The tap density when the conductive material is particulate and the element is C is not particularly limited, but is usually 0.5 g / cm ³ or more, preferably 0.7 g / cm ³ or more, more preferably 1.0 g / cm. ^The upper limit is usually 1.5 g / cm ³ or less, preferably 1.3 g / cm ³ or less.
If the tap density of the particles is within this range, it is preferable to ensure conductivity.
As the tap density, for example, a sieve having an opening of 300 μm is used, and after the negative electrode material powder is dropped into a 20 cm ³ tapping cell to fill the cell, a powder density measuring device (for example, a tap manufactured by Seishin Enterprise Co., Ltd.) is used. A value obtained by performing tapping with a stroke length of 10 mm 1000 times using a denser and measuring the tapping density at that time can be used.

[Porosity]
The porosity of the joint surface of the conductive material layer in contact with the active material layer is usually 5% or more, preferably 15% or more, more preferably 20% or more, and the upper limit is usually 50% or less, preferably It is 45% or less, more preferably 40% or less.
Here, the opening degree of the bonding surface of the conductive material layer in contact with the active material layer refers to the opening degree in the vicinity of the surface of the conductive material layer before the active material layer is formed.
If the opening degree of the joint surface is below this range, the joining with the active material layer tends to be insufficient, and the active material layer may be peeled off due to expansion / contraction due to insertion / extraction of titanium. On the other hand, if it exceeds this range, the active material layer may enter the concave portion of the joint surface, and expansion and contraction due to lithium insertion / extraction may cause destruction of the conductive material layer and cycle deterioration.

As the degree of opening of the bonding surface of the conductive material layer, for example, an electrode composed of a current collector, a conductive material layer, and an active material layer (or a current collector and a conductive material layer before forming the active material layer) Electrode) using a sample cross-section processing method using an argon ion beam (for example, “SM-09010” manufactured by JEOL Ltd.), the cross-section of the conductive material layer and the active material layer (or the cross-section of the conductive material layer) ) And observed with a scanning electron microscope, the ratio of the area of the pore portion before the formation of the active material layer to the area of the conductive material layer (for example, length 100 μm × width 5 μm) can be obtained and used.
Opening degree = pore area / measurement area × 100
In Examples described later, the degree of opening of the conductive material layer was determined by this method.
In addition, when the thickness of the conductive material layer is less than 10 μm, for example, the area ratio of the pore portion is obtained for the half thickness of the conductive material layer and is set as the value of the degree of opening.

[Aperture diameter]
The opening diameter of the joint surface of the conductive material layer in contact with the active material layer is not particularly limited, but is usually 0.1 μm or more, preferably 1 μm or more, and the upper limit is 100 μm or less, preferably 50 μm or less, more preferably. Is 10 μm or less.
Here, the opening diameter of the joint surface of the conductive material layer in contact with the active material layer refers to the average value of the opening diameters on the surface of the conductive material layer before forming the active material layer.
If the opening diameter of the joint surface is less than this range, joining with the active material layer tends to be insufficient, and the active material layer may be easily peeled off due to expansion / contraction due to insertion / extraction of titanium. On the other hand, if it exceeds this range, the active material layer may enter the concave portion of the joint surface, and expansion and contraction due to insertion / extraction of lithium may cause destruction of the conductive material layer and cycle deterioration.

  As the hole diameter of the joint surface of the conductive material layer, for example, when obtaining the above-mentioned degree of opening, the length of the hole part is measured, and the average is obtained as the value of the hole diameter.

[Unevenness Ra of Bonding Surface]
The unevenness Ra of the joint surface of the conductive material layer in contact with the active material layer is usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.4 μm or more, and the upper limit is 3.0 μm or less, preferably Is 2.5 μm or less, more preferably 2.0 μm or less.
If the unevenness Ra of the joint surface is within this range, it is preferable because the joint with the active material layer is sufficient and peeling of the active material layer due to expansion and contraction can be suppressed.

  As the unevenness Ra of the bonding surface of the conductive material layer, for example, the average surface roughness measured by using a surface roughness meter (for example, “Color Laser Microscope VK-9500” manufactured by Keyence Corporation) on the surface of the conductive material layer. Ra value can be used.

[Porosity]
The porosity of the conductive material layer is usually 15% or more, preferably 20% or more, more preferably 25% or more, and the upper limit is 50% or less, preferably 45% or less, more preferably 43% or less.
When the porosity is within this range, it is preferable because the expansion and contraction stress of the active material layer can be easily relaxed and the electrolytic solution can be retained.

For example, the porosity of the conductive material layer is measured by measuring the total pore volume of the electrode sheet on which the conductive material layer is formed with a mercury porosimeter (for example, “Autopore 9220” manufactured by Micromeritex Corporation). The porosity can be calculated from the following formula.
Porosity = total pore volume (cm ³ / g) × bulk density of conductive material layer (g / cm ³ ) × 100
In Examples described later, the porosity of the conductive material layer was determined by this method.

[The bulk density]
The bulk density of the conductive material layer of the present invention is not particularly limited, but when the conductive material is mainly composed of element C, it is usually 1.1 g / cm ³ or more, preferably 1.2 g / cm ³ or more, further preferably 1.3 g / cm ³ or more and the upper limit is 1.95 g / cm ³ or less, preferably 1.85 g / cm ³ or less, further preferably 1.7 g / cm ³ or less.
When the conductive material contains the element Cu as a main component, it is usually 4.4 g / cm ³ or more, preferably 4.9 g / cm ³ or more, more preferably 5.0 g / cm ³ or more, and the upper limit is 7 .6g / cm ³ or less, preferably 7.5 g / cm ³ or less, further preferably 6.7 g / cm ³ or less.
If the bulk density is within this range, it is preferable because the expansion and contraction stress of the active material layer can be easily relaxed and the electrolytic solution can be retained.

The bulk density of the conductive material layer is obtained by, for example, cutting out the electrode sheet on which the conductive material layer is formed into a rectangle, measuring the length (area), thickness, and weight, and the thickness of the current collector used and By subtracting the weight in the same area, the volume and weight of the conductive material layer were calculated to obtain the bulk density.
Bulk density of conductive material layer =
Weight of conductive material layer (g) ÷ area (cm ² ) ÷ thickness of conductive material layer (cm)

<Active material layer>
The active material layer contains an active material containing at least an element that forms an alloy with lithium and has the ability to occlude and release lithium ions. Hereinafter, the active material layer will be described in more detail.

[Active material elements]
The element that can be alloyed with lithium is at least an element that can be alloyed with lithium, such as Si, Sn, Al, Zn, Ag, Ge, and Pb (hereinafter sometimes referred to as an “active material element”). Although not particularly limited, Si and Sn elements are preferable, and Si element is more preferable. The active material layer may contain two or more kinds of active material elements, and the active material layer may contain additive elements Z and M other than the active material element.

[Additive elements]
When the active material layer contains additive elements Z and M, the additive element Z is preferably C and / or N element. Further, as the additive element M, other than the active material element and additive element Z, periodic table group 2, group 4, group 5, group 8, group 8, group 11, group 13, group 14, group 15, group 15 and One or more elements selected from Group 16 are preferable, B, Ti, Zr, W, and O elements are more preferable, and the O element is still more preferable.

Here, the reason why it is preferable to use C and N elements as the additive element Z is, for example, when the active material element is Si,
(I) It can form a higher melting point compound than Si (ii) The covalent bond radius is smaller than Si (iii) The diffusion coefficient in Si is small (iv) The volume change is small even when reacted with lithium is there.
The details are as follows.

Reason (i): Specifically, the elements C and N can form an equilibrium compound having a higher melting point than Si, such as SiC and Si ₃ N ₄ . A high melting point compound is generally a stable compound having a large free energy of formation and a large amount. For this reason, these can reduce the activity of Si mentioned later effectively, and can control the reactivity with electrolyte solution.
Reason (ii): the elements C, N is smaller than the covalent atomic radius of Si, although details are unknown, it is difficult to form a compound that is present in equilibrium in SiZ _x M _y compound at a high concentration It is thought that it is effective to distribute the element Z more homogeneously, the activity of Si can be reduced more effectively, and the reactivity with the electrolytic solution can be suppressed.
Reason (iii): Since elements C and N have a small diffusion coefficient in Si, if elements C and N are dispersed in Si, aggregation and crystallization of Si accompanying charge and discharge are suppressed, and Si Micronization and reaction with the electrolyte can be suppressed.
Reason (iv): Since the elements C and N have little volume change even if they react with lithium, it is considered difficult to influence the disconnection of the conductive path of Si.

Here, the activity will be described.
In general, activity is a kind of thermodynamic concentration. For a multi-component system consisting of substance amounts n ₁ , n _2, ..., If the chemical potential of component i is μ _i and the chemical potential of a pure substance is μ _i ⁰ ,
μ _i −μ _i ⁰ = RTlog a _i
A _i defined by is called activity.
Also, the ratio γi between the activity ai and the concentration ci
ai / ci = γi
Is called the activity coefficient.

  For example, when a system consisting of a solvent and a solute is considered as a thermodynamic solution, the activity coefficient is the chemical potential of a component when the system is considered as an ideal solution, and when the system is considered as a real solution. This is an amount corresponding to the difference from the true chemical potential of a certain component. (1) In the case of a real solution in which a certain component i is a solute, when the concentration of the solute decreases, the system approaches an ideal solution in which the component i is a solute, and the activity coefficient approaches 1. Conversely, (2) in the case of a real solution in which a certain component i is a solvent, when the concentration of the solvent increases, the system approaches the ideal solution in which the component i is a solvent and the activity coefficient approaches 1. Further, when the chemical potential of the component i is more stable in the real solution than in the ideal solution, γi <1.

  When the active material element is Si, the component i is Si, and the element Z regarded as a solute is contained in the Si regarded as a solvent, whereby the activity ai of the solvent Si is reduced, and γi <1, and the element Z It is considered that the Si compound containing solid (solid solution: regarded as a real solution) is more stable than Si (considered as an ideal solution), and as a result, the reactivity with the electrolytic solution is further suppressed.

However, if the compound Si _a Z _p or the like in which Si and the element Z exist in an equilibrium is formed, the activity of Si cannot be reduced efficiently. Therefore, when the additive element Z is included, the element Z is contained in the Si. It is considered important to exist in a non-equilibrium state.

[composition]
The composition of the active material layer is not particularly limited, but the active material element content is usually 35 at% or more, preferably 50 at% or more, more preferably 60 at% or more, and the upper limit is usually 95 at% or less, preferably Is 90 at% or less, more preferably 80 at% or less.

  The composition of the active material layer is set such that, for example, an X-ray photoelectron spectrometer (for example, “ESCA” manufactured by ULVAC-PHI) is used to flatten the surface of the electrode made of the active material, as shown in Examples described later. It can be obtained by placing the sample on a sample stage, using the Kα ray of aluminum as an X-ray source, performing depth profile measurement while performing Ar sputtering, and calculating the atomic concentration of the active material element or the like in the active material layer.

[Composition of active material elements SiZ _x M _y compound Si]
If the active material which the active material layer is mainly composed of SiZ _x M _y compound phases element Z is present in a non-equilibrium in the Si, the composition of SiZ _x M _y, the x of SiZ _x M _y, Si For the Z concentration (p / (a + p)) of the compound SiaZp (where a and p are integers) that exist in equilibrium with the composition closest to the formula Q (Z) = [x / (1 + x)] / [ The Z concentration ratio Q (Z) calculated by [p / (a + p)] is not particularly limited, but is usually 0.10 or more, preferably 0.15 or more, more preferably 0.30 or more, and particularly preferably 0. The upper limit is usually 0.95 or less, preferably 0.85 or less, more preferably 0.75 or less, and particularly preferably 0.65 or less. The “compound that exists in equilibrium with the composition closest to Si” refers to a compound Si _a Z _p that exists in equilibrium with a minimum value of p / (a + p) in Si _a Z _p . .

The compound Si _a Z _p that exists in equilibrium with the composition closest to Si in the present invention is described in the phase diagram of Si and element Z (for example, “Desk Handbooks Phase Diagrams for Binary Alloys” published by ASM International). are, in the present invention, the numerical value of the Z concentration of the _{Si a Z p (p / (} a + p)), by setting the above-mentioned Z concentration ratio Q (Z), Z concentration ratio Q (Z) A range is used to limit the range of x.

As used herein, “a compound present in equilibrium” refers to a stoichiometric compound such as the compound Si _a Z _p (where a and p are integers) described as the top of the diagram in the phase diagram or the like. For example, when Z is C, SiC is known as a stable compound, and in the present invention, this compound is a compound that exists in an equilibrium state. Therefore, when Z is C, SiC corresponds to Si _a Z _p of the present invention.

For example, when Z is N, Si ₃ N ₄ is known as the most stable compound, but Si ₂ N ₃ and SiN are also known to exist as stoichiometric compounds. In the present invention, all these compounds are assumed to exist in equilibrium. Therefore, when Z is N, SiN corresponds to Si _a Z _p of the present invention.

  On the other hand, the “compound existing in a non-equilibrium” refers to a compound other than the compound existing in an equilibrium. In the case of a compound that exists in a non-equilibrium state, a specific stoichiometric compound is not formed, and Si atoms and Z atoms are uniformly dispersed when viewed macroscopically.

  If the Z concentration ratio Q (Z) is less than this range, the effect of lowering the Si activity is small, the reactivity with the electrolyte cannot be suppressed, the electrode expansion increases, and it may be difficult to obtain desirable cycle characteristics. . On the other hand, if it exceeds this range, a stable compound SiaZp that exists in equilibrium is formed, and even if the element Z is increased, the activity of Si does not decrease, and the reactivity with the electrolytic solution may not be suppressed. In addition, since SiaZp or the like has low conductivity, when such a compound is formed, the conductivity of the active material deteriorates, lithium doping and dedoping becomes difficult, and charging / discharging may not be possible. Furthermore, if it greatly exceeds this range, it is difficult to obtain the effect of increasing the capacity by containing Si, and it may be difficult to obtain preferable battery characteristics.

  Here, when the Z concentration ratio Q (Z) is 1, it means that Si is a stable compound SiaZp.

  When the elements Z and C are simultaneously used as the element Z, the Z concentration ratio Q (Z) is obtained with respect to the element Z concentration based on the SiaZp of each of the two elements, and the total value is calculated as the Z concentration ratio Q. Consider (Z).

_Y in SiZ _{x My} is a real number that satisfies 0 ≦ y ≦ 0.5. Compound comprises SiZ _x M _y in the element M, if the y ≠ 0, the ratio y of the element M in the compound _SiZ x _{M y} is not particularly limited, usually 0.08 or more, preferably be 0.1 The upper limit is usually 0.5 or less, preferably 0.4 or less, and more preferably 0.3 or less. When y exceeds this range, the Si content is decreased, and it may be difficult to increase the capacity.

  Further, when the element M is not substantially included, the ratio y of the element M indicates y = 0 or y≈0. In the present invention, y≈0 means a case where the element M is inevitably included (M is not substantially included) in the production process of the active material according to the present invention. Less than 08.

[Composition in which the active material element is Si, the additive element Z is C, and the additive element M is O]
In the active material element Si, the additive element Z is in C, and the additional element M is O, when the active material represented by the general formula _SiC x _{O y,} in the general formula _SiC x _{O y,} x particularly limited However, it is usually 0.053 or more, preferably 0.08 or more, more preferably 0.15 or more, particularly preferably 0.25 or more, and the upper limit is usually 0.9 or less, preferably 0.75 or less. More preferably, it is 0.6 or less, and particularly preferably 0.45 or less.

  Further, y is not particularly limited, but is usually 0.0 or more, preferably 0.08 or more, more preferably 0.1 or more, and the upper limit is usually 0.5 or less, preferably 0.4 or less, More preferably, it is 0.3 or less.

[Active material element Si, presence state of element Z in the active material]
The presence state of the element Z in the active material layer of the present invention is not particularly limited in the XIsz value in X-ray diffraction measurement, but when the element Z is C, it is preferably 1.2 or less, more preferably 0.7 or less. It is. When the element Z is N, it is preferably 1.1 or less, more preferably 1.0 or less. If the XIsz value is less than or equal to this range, it is preferable to define a phase in which the element Z is present in a non-equilibrium state in Si as a main component and a compound that exists in an equilibrium such as SiaZp is not a main component. When the XIsz value exceeds this range, that is, when the phase of an equilibrium compound such as SiaZp is the main component (silicon carbide when element Z is C, silicon nitride when N is element), Si In the case where the activity of the electrolyte is not reduced, the reactivity with the electrolytic solution cannot be suppressed and the cycle characteristics are deteriorated, or the conductivity of the thin film negative electrode material is deteriorated due to low conductivity such as SiaZp. In some cases, dedoping becomes difficult and charge / discharge becomes difficult, or the discharge capacity per unit mass of the active material becomes small. The lower limit value of the XIsz value is usually 0.0 or more.

[X-ray diffraction measurement method]
The XIsz value of the active material in the X-ray diffraction measurement is measured, for example, by setting the active material surface of the electrode of the present invention on the irradiation surface and using an X-ray diffractometer (for example, “X-ray diffractometer” manufactured by Rigaku Corporation). The measurement conditions are as shown in the examples described later.
The definition of the XIsz value is as follows.

(XIsz value when element Z is C)
A peak intensity Isz with 2θ of 35.7 degrees and a peak intensity Is of 28.4 degrees are measured, and an intensity ratio XIsz (XIsz = Isz / Is) is calculated and defined as XIsz of the active material.
Here, a peak at 2θ of 35.7 degrees is considered to be a peak derived from SiC, a peak at 28.4 degrees is considered to be a peak derived from silicon, and an XIsz value of 1.2 or less means that SiC is almost detected. Means not.

(XIsz value when element Z is N)
The peak intensity Isz with 2θ of 70.2 degrees and the peak intensity Is with 28.4 degrees are measured, and the intensity ratio XIsz (XIsz = Isz / Is) is calculated and defined as XIsz of the active material.
Here, 2 [Theta] 27.1 ° peak Si ₃ N ₄ from the peak, 28.4 ° peak is considered the peak derived from silicon, that XIsz value is 1.1 or less, Si ₃ This means that N ₄ is hardly detected.

[Distribution of element Z in active material with active material element Si and additive element Z]
The element Z in the active material element Si exists, for example, as an atom, molecule, or cluster at a level of 1 μm or less. In the case of a thin film active material, the distribution state of the element Z is not particularly limited, but is preferably uniform in the thickness direction and in-plane direction (direction perpendicular to the thickness direction) in the thin film active material. More preferably, it is uniformly distributed in the in-plane direction of the thin film active material. When the distribution of the element Z is uneven and the active material is present locally, the expansion and contraction accompanying the charge and discharge of Si occurs intensively in the Si portion where the element Z does not exist. In some cases, the conductivity is deteriorated. The dispersion state of the element Z can be confirmed by EPMA or the like.

[Distribution state of element M in active material of active element of additive element Z and M with active material element]
The element M in the active material element Si is not particularly limited in the distribution state, and may be either uniformly distributed or not uniformly distributed.

[Raman RC value, Raman RSC value, Raman RS value of active material with active material element Si and additive element C]
For the active material of which the active material element is Si and the additive element C, the Raman RC value measured by the Raman method is preferably 2.0 or less, more preferably 1.0 or less, and particularly preferably 0.5 or less. When the Raman RC value exceeds this range, it is difficult to obtain the effect of increasing the capacity due to the inclusion of Si, and it may be difficult to obtain preferable battery characteristics. The lower limit of the Raman RC value is usually 0.0 or more from the measurement relationship.

  The Raman RSC value measured by the Raman method is preferably 0.25 or less, more preferably 0.20 or less. When the Raman RSC value exceeds this range, the electrical conductivity deteriorates, and it may be difficult to dope and de-dope lithium, making it difficult to charge and discharge. The lower limit of the Raman RSC value is usually 0.0 or more from the measurement relationship.

  Moreover, the Raman RS value measured by the Raman method is preferably 0.4 or more, more preferably 0.5 or more, preferably 0.75 or less, more preferably 0.65 or less. If the Raman RS value is below this range, the cycle characteristics may be deteriorated. If the Raman RS value exceeds this range, charging / discharging may not be possible.

  In addition, the Raman RC value, the Raman RSC value, and the Raman RS value by the Raman spectrum analysis of the active material in this invention are calculated | required from the Raman spectrum analysis by the following Raman measuring methods, and are respectively defined as follows.

(Raman measurement method)
Using a Raman spectrometer (for example, “Raman spectrometer” manufactured by JASCO Corporation), set the electrode in the measurement cell so that the active material becomes the measurement surface, and rotate the sample to the sample surface in the cell with an argon ion laser Irradiate with light and measure. The Raman RC value, the RSC value, and the RS value are obtained by performing background correction of the measured Raman spectrum. The background correction is performed by connecting the peak start points with a straight line, obtaining the background, and subtracting the value from the peak intensity.
Here, the Raman measurement conditions are as follows, and the smoothing process is a simple average of 15 points of convolution.
Argon ion laser wavelength: 514.5nm
Laser power on the sample: 15-40mW
Resolution: 10-20cm ^-1
Measurement range: 200 cm ^{−1 to} 1900 cm ⁻¹
Exposure time: 30-300sec
Integration count: 3 times

(Definition)
Raman RC value 1300cm ^-1 ~1600cm ^-1 peak intensity of peak c appearing in the vicinity of Ic, and measuring the peak intensity Ias peaks as appearing near 300cm ^-1 ~500cm ^-1, the intensity ratio RC (RC = Ic / Ias) is calculated and defined as the Raman RC value of the active material.
Here, the peak c and the peak as are considered to be peaks derived from carbon and silicon, respectively. Therefore, the Raman RC value reflects the amount of carbon, and the Raman RC value is 2.0 or less. , Which means that almost no carbon is detected.

Raman RSC value 650cm ^-1 ~850cm ^-1 peak intensity of the peak sc appearing near Isc, and measuring the peak intensity Ias peaks as appearing near 300cm ^-1 ~500cm ^-1, the intensity ratio RSC (RSC = Isc / Ias) is calculated and defined as the Raman RSC value of the active material.
Here, the peak sc and the peak as are considered to be peaks derived from SiC and silicon, respectively. Therefore, the Raman RSC value reflects the amount of SiC, and the Raman RSC value is 0.25 or less. This means that almost no SiC is detected.

- intensity of the Raman RS value 520 cm ^-1 Is, and measuring the peak intensity Ias peaks as appearing near 300cm ^-1 ~500cm ^-1, to calculate the intensity ratio RS (RS = Is / Ias) , Raman active material It is defined as an RS value.
The Raman RS value reflects the state of Si.

[Form]
Examples of the structure of the active material of the present invention include a columnar structure, a layered structure, and a flat plate structure.

[Film thickness]
The thickness of the active material layer is not particularly limited, but is usually 1 μm or more, preferably 3 μm or more, and the upper limit is usually 30 μm or less, preferably 20 μm or less, more preferably 15 μm or less. If the thickness of the active material layer is less than this range, the capacity per electrode of the electrode of the present invention using the active material layer is small, and a large number of negative electrodes are required to obtain a large capacity battery. The total volume of the current collector of the positive electrode, separator, and negative electrode itself increases, and the amount of the negative electrode active material that can be filled per battery volume is substantially reduced, which may make it difficult to increase the battery capacity. On the other hand, if it exceeds this range, the active material may be remarkably easily separated from the current collector substrate due to expansion / contraction associated with charge / discharge, and the cycle characteristics may be deteriorated.

  The active material is preferably formed from a vapor phase as described in the production method described later.

<Current collector>
Hereinafter, the current collector will be described in detail.

[Material]
Examples of the material for the current collector include copper, nickel, and stainless steel. Among them, copper that is easy to process into a thin film and inexpensive is preferable. The copper foil includes a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method, both of which can be used as a current collector. When the thickness of the copper foil is less than 25 μm, a copper alloy (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) having higher strength than pure copper can also be used.

A current collector made of a copper foil produced by a rolling method is suitable for use in a small cylindrical battery because the copper crystals are arranged in the rolling direction so that the negative electrode is hard to crack even if it is rounded sharply or rounded at an acute angle. be able to. For example, an electrolytic copper foil is prepared by immersing a metal drum in an electrolytic solution in which copper ions are dissolved, and flowing current while rotating the copper drum, thereby depositing copper on the surface of the drum and peeling it off. It is obtained. Copper may be deposited on the surface of the rolled copper foil by an electrolytic method. One side or both sides of the copper foil may be subjected to a roughening treatment or a surface treatment (for example, a chromate treatment having a thickness of about several nm to 1 μm, a base treatment such as Ti).
Among the copper foils, it is preferable to use a rolled copper foil or an electrolytic copper foil that is not roughened from the viewpoint of cost.

[thickness]
The current collector made of copper foil or the like is preferable in that a thinner electrode can be manufactured, and a negative electrode having a larger surface area can be packed in a battery container having the same storage volume. In some cases, the copper foil may be cut due to a lack of strength and winding during battery production. For this reason, the current collector made of copper foil or the like is preferably about 5 to 70 μm thick. In the case of forming the active material on both sides of the copper foil, the copper foil is preferably thinner, but in this case, from the viewpoint of avoiding the occurrence of cracks in the copper foil due to the expansion / contraction of the active material accompanying charging / discharging, A more preferable thickness of the copper foil is 8 to 35 μm.

  When a metal foil other than copper foil is used as the current collector, one having a suitable thickness can be used depending on the metal foil, but the thickness is generally in the range of about 5 to 70 μm. Is within.

[Physical properties]
The following physical properties are desired for the current collector.
(1) Average surface roughness (Ra)
The average surface roughness (Ra) of the current collector defined by the method described in JIS B0601-1994 is not particularly limited, but is usually 0.001 μm or more, preferably 0.01 μm or more, particularly preferably 0.10 μm or more. In addition, the upper limit is usually 1.5 μm or less, preferably 1.3 μm or less, particularly preferably 1.0 μm or less.

  By setting the average surface roughness (Ra) of the current collector within the range between the lower limit and the upper limit described above, good charge / discharge cycle characteristics can be expected. By setting it to the above lower limit or more, the area of the interface with the conductive material layer is increased and the adhesion is improved. The upper limit of the average surface roughness (Ra) is not particularly limited, but those having an average surface roughness (Ra) exceeding 1.5 μm are generally difficult to obtain as foils having a practical thickness as a battery. 1.5 μm or less is preferable.

(2) Tensile strength The tensile strength of the current collector is not particularly limited, but is usually 100 N / mm ² or more, preferably 250 N / mm ² or more, more preferably 400 N / mm ² or more, and particularly preferably 500 N / mm ² or more. It is.

  The tensile strength is obtained by dividing the maximum tensile force required until the test piece breaks by the cross-sectional area of the test piece. The tensile strength in the present invention is measured by the same apparatus and method as the elongation rate. If the current collector has a high tensile strength, cracking of the current collector substrate due to expansion / contraction of the active material accompanying charging / discharging can be suppressed, and good cycle characteristics can be obtained in some cases.

(3) 0.2% proof stress of 0.2% proof stress current collector is not particularly limited, normally 30 N / mm ² or more, preferably 150 N / mm ² or more, particularly preferably 300N / mm ² or more.

  The 0.2% proof stress is the magnitude of the load necessary to give a plastic (permanent) strain of 0.2%. It means that The 0.2% proof stress in the present invention is measured by the same apparatus and method as the elongation rate. If the current collector has a high 0.2% proof stress, plastic deformation of the current collector due to expansion / contraction of the active material accompanying charging / discharging can be suppressed, and good cycle characteristics can be obtained. is there.

[2] Manufacturing Method The manufacturing method of the electrode of the present invention is not particularly limited as long as the electrode having the above characteristics can be manufactured. For example, the electrode can be manufactured by the following method.

<Method for forming conductive material layer on current collector surface>
[material]
As a raw material for the conductive material layer, the above-mentioned single raw material of the conductive element, a compound containing the element, or the like can be used. Examples of element C include natural graphite, spheroidized natural graphite, artificial graphite, carbon black, carbon fiber, vapor-grown carbon fiber, carbon nanofiber, amorphous carbon, and a composite of graphite and amorphous carbon. is there.
Cu and Ni elements include copper powder, copper fiber, copper porous body, nickel powder, nickel fiber, nickel porous body, and the like.
These may be used alone or in combination of two or more.

[Formation method]
A method of forming a conductive material layer on a current collector in an electrode comprising a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer As such, there are a direct bonding or bonding method, a bonding method such as a polymer material, and a bonding method.

[Method for directly bonding or bonding conductive material layers]
Methods for directly bonding or bonding the conductive material layers include: a. CVD method, b. Thermal spraying, c. Sintering method, d. An AD method or the like is used.

a. CVD Method In the CVD method, a conductive material is formed by depositing raw materials on the surface of a current collector by a gas phase chemical reaction. In general, the CVD method is characterized by the ability to synthesize various materials with high purity in order to control the compound gas in the reaction chamber by inflow of gas. Specific methods include thermal CVD, plasma CVD, optical Examples thereof include a CVD method and a cat-CVD method. In the thermal CVD method, a raw material gas of a halogen compound having a high vapor pressure is introduced into a reaction vessel heated to about 1000 ° C. together with a carrier gas and a reaction gas to cause a thermochemical reaction to form a conductive material. . The plasma CVD method is a method using plasma instead of thermal energy, and the photo CVD method is a method using light energy instead of thermal energy. The cat-CVD method is a catalytic chemical vapor deposition method, and forms a conductive substance by applying a catalytic decomposition reaction between a source gas and a heating catalyst.

  Among these, the cat-CVD method is preferable because a conductive material containing C element as a main component can be formed at a low temperature at a high speed. Examples of the element used as a catalyst include Fe, Ni, Co, rare earth metals, etc., preferably a Ni catalyst is used, and it is dissolved in a solvent such as alcohol or water as an acetate or nitrate, and is applied onto a current collector and dried. And further reducing to form a catalytic metal.

The catalytic cracking reaction temperature between the source gas of the cat-CVD method and the heating catalyst is not particularly limited, but is usually 450 ° C. or higher, preferably 500 ° C. or higher, more preferably 550 ° C. or higher, and the upper limit is usually 1100. C. or lower, preferably 900 C or lower, more preferably 800 C or lower.
If the catalytic cracking reaction temperature is below this range, the growth of element C may be slow. In addition, if it exceeds this range, there is a possibility that the reaction between the current collector and the catalytic metal proceeds or that the current collector is altered.

b. Thermal spraying In thermal spraying, the above-mentioned raw material that becomes a conductive substance is melted or softened by heating, accelerated into fine particles, and solidified and deposited on the current collector substrate. Specific examples of the method include flame spraying, arc spraying, direct current plasma spraying, RF plasma spraying, and laser spraying.

c. Sintering method In the sintering method, a conductive material and a sintering agent are formed on a current collector. Usually, a material obtained by dispersing and mixing a conductive material and a sinterable material is used as a current collector substrate. It is manufactured by thinly coating (or molding) and drying on top, followed by compaction pressing to a predetermined thickness and density, and sintering by a heat treatment process.

  As the sintering agent, precursors such as oxides, carbides and nitrides, and carbon precursors are used. For example, as an oxide precursor, an organic zirconium compound, an organic titanium compound or the like is used, and as a carbon precursor, petroleum pitch or coal tar pitch is heat-treated (oxidized) to adjust the softening point and volatile content (Osaka) Kasei TGP3500) and the like.

d. AD Method In the AD (Aerosol Deposition) method, a conductive material layer is formed on the current collector without a binder component, and usually a normal temperature impact is applied to the current collector substrate at high speed under vacuum on the current collector substrate. It is manufactured by a method of integrating with a current collector without a binder component by solidification or the like.

[Method of adhering the conductive material layer through a binder such as a polymer material]
As a method of adhering the conductive substance layer with a binder such as a polymer material interposed, a conductive substance and a slurry in which a binder is dispersed in a solvent are placed on a current collector substrate. It is manufactured by a process of thinly applying and drying, followed by a pressing process of compacting to a predetermined thickness and density.

  As the binder, a polymer that is stable against a liquid solvent described later is preferable. For example, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, and cellulose, rubbery polymers such as styrene / butadiene rubber, isoprene rubber, butadiene rubber or ethylene / propylene rubber, and styrene / butadiene / styrene blocks. Polymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers and thermoplastic elastomeric polymers such as hydrogenated products thereof, syndiotactic 1,2-polybutadiene , Ethylene / vinyl acetate copolymer, or soft resinous polymer such as propylene / α-olefin (carbon number 2 to 12) copolymer, polyvinylidene fluoride, polytetrafluoroethylene, or polytetrafluoroethylene / ethylene The fluoropolymer of the polymer or the like, and the like alkali metal ion (especially lithium ion) polymer composition having ion conductivity. These may be used alone or in combination of two or more.

  Examples of the polymer composition having ionic conductivity include, for example, polyether polymer compounds such as polyethylene oxide and polypropylene oxide, crosslinked polymers of polyether compounds, polyepichlorohydrin, polyphosphazene, polysiloxane, High polymer such as propylene carbonate, ethylene carbonate, γ-butyrolactone, etc., in which a polymer compound such as polyvinyl pyrrolidone, polyvinylidene carbonate, or polyacrylonitrile is combined with a lithium salt or an alkali metal salt mainly composed of lithium. A polymer containing an organic compound having a dielectric constant or an ion-dipole interaction force can be used.

  Specifically, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, polyimide, or cellulose and derivatives thereof (for example, carboxymethylcellulose), styrene / butadiene rubber, isoprene rubber, butadiene rubber, or ethylene are usually used. Rubbery polymers such as propylene rubber; Fluorine polymers such as polyvinylidene fluoride, polytetrafluoroethylene, or polytetrafluoroethylene / ethylene copolymer; Polyether polymer compounds such as polyethylene oxide and polypropylene oxide; Examples thereof include crosslinked polymers of polyether compounds, preferably polyethylene, polypropylene, polyimide, styrene / butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, or polyethylene. Ethylene oxide and the like, more preferably, polyethylene, styrene-butadiene, polyvinylidene fluoride, or polytetrafluoroethylene. These are currently used industrially and are suitable because they are easy to handle.

  An aqueous solvent or an organic solvent is used as a dispersion medium for preparing the slurry when the conductive substance and the binder are mixed and applied onto the current collector. As the aqueous solvent, water is usually used, and additives such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone may be added to water up to about 30% by weight or less. it can.

  As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic hydrocarbons such as anisole, toluene and xylene And alcohols such as butanol and cyclohexanol. Among them, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable.

<Method for forming active material layer on conductive material layer>
[material]
As the raw material for the active material layer, the above-mentioned active material elements alone, compounds, compositions, and mixtures can be used. Examples of the active material element include elements that can be alloyed with lithium, such as Si, Sn, Al, Zn, Ag, Ge, and Pb, and examples of the active material element include crystalline Si, amorphous Si, and metal. As a compound of Sn, Al, Zn, Ag, or the like, a silicon compound (sublimation compound such as SiC, Si ₃ N ₄ , SiS, or SiS ₂ ) or the like can be used.

The sublimable compound containing the active material element is as described above. However, it is preferable to use the sublimable compound because it is easy to suppress reaction with the container in the vapor deposition method described later and to easily control the composition of the active material. . In particular, SiC is preferable because oxygen mixed from the atmosphere reacts with carbon in SiC, so that the amount of oxygen contained in the active material can be reduced and the amount of carbon can be adjusted.
Further, when a sublimable compound is used for at least a part of the active material raw material, the ratio of the sublimable compound is usually 20% by weight or more, preferably 30% by weight or more, more preferably 40% by weight or more, The upper limit is usually 100% by weight or less, preferably 90% by weight or less, and more preferably 70% by weight or less. When the ratio of the sublimable compound is below this range, it may be difficult to obtain the effect using the above-described sublimable compound.

The kind of the additive element Z is as described above. Among the raw materials, for example, as the raw material for the C element, the reactive species with carbon such as natural graphite, artificial graphite and amorphous carbon, and carbon such as carbide As the N element raw material, nitride or the like can be used. In addition, when the raw material is a gas, the C element raw material is a gas containing C (CH ₄ , C ₂ H ₆ , C ₃ H _8, etc.) or a gas obtained by vaporizing C by graphite arc discharge or resistance heating. As a source of N element, a gas containing NH (NH ₃ , N _2, etc.) can be used.

  In the case of vapor phase growth by the vapor deposition method described later, it is most effective to increase the heating temperature of the active material raw material in order to increase the growth rate, but at the same time, oxygen mixed from the atmosphere easily reacts with the active material and is oxidized. Many substances may be formed, but when the additive element Z contains a C element, the reaction between oxygen and carbon in the atmosphere proceeds as the temperature rises, so the amount of oxygen contained in the active material can be reduced. preferable.

  In addition, for example, when the active material element is Si, the reaction between Si and carbon forms a compound composed of Si and C, which has a higher evaporation rate than Si alone, and evaporates. .

Moreover, a single compound combining the active material element and the additive elements Z and M may be used, or a plurality of compounds may be used.
The active material elements, the sublimable compounds containing the active material elements, and the raw materials of the additive elements Z and M are used as, for example, powder, granules, pellets, lumps, plates, and the like.

In the general formula SiZ _x M _y, if it contains an additional element M at y ≠ 0, the additional element M is other than the additive element Z as an active material element, periodic table Group 2, Group 4, Group 5, Group 6, Group 8 , Group 9, Group 13, Group 14, Group 14, Group 15 and Group 16 or more elements, more preferably B, Ti, Zr, W, O elements, Preferably, O element can be used.

  The active material layer can be formed by at least one of A: sputtering, B: vacuum deposition, C: CVD, and D: ion plating, which will be described in detail below. Moreover, you may form an active material combining these.

A. Sputtering Sputtering uses active plasma material generated from a target made of the above-mentioned raw material under reduced pressure to collide and deposit on the conductive material layer on the current collector surface to form a thin film or the like. According to sputtering, the interface state between the formed active material and the conductive material or current collector is good, and the adhesion of the active material to the conductive material or current collector is also high.

  As a method for applying the sputtering voltage to the target, either a DC voltage or an AC voltage can be used. At that time, it is possible to control the collision energy of ions from the plasma by applying a substantially negative bias voltage to the current collector.

  The ultimate vacuum in the chamber before starting the active material formation is usually 0.1 Pa or less in order to prevent impurities from being mixed.

As the sputtering gas, an inert gas such as Ne, Ar, Kr, or Xe is used. Among these, argon gas is preferably used in terms of sputtering efficiency. When the compound SiZ _x M element Z in _y is N, said to coexist as a small amount of nitrogen gas in the inert gas production preferable. Usually, the sputtering gas pressure is about 0.05 to 70 Pa.

  The current collector for forming the active material by sputtering can also be controlled in temperature by water cooling or a heater. The temperature range of the current collector is usually room temperature to 900 ° C, but preferably 150 ° C or less.

  The growth rate in forming an active material by sputtering is usually 0.01 to 0.5 μm / min.

  Before the formation of the active material, the conductive material layer and the current collector surface can be etched by pre-treatment such as reverse sputtering or other plasma treatment. Such pretreatment is effective for removing contaminants and oxide films on the conductive material layer and the current collector surface, and improving the adhesion of the active material.

B. Vacuum deposition In the vacuum deposition, the raw material that becomes the active material is melted and evaporated and deposited on the conductive material layer. Vacuum deposition can form a film at a higher growth rate than sputtering. Vacuum deposition can be advantageously used in terms of manufacturing cost from the viewpoint of shortening the time for forming an active material having a predetermined thickness as compared with sputtering. Specific examples of the method include an induction heating method, a resistance heating method, and an electron beam heating vapor deposition method. In the induction heating method, a vapor deposition crucible such as graphite is formed by inductive current, in the resistance heating method by an energized heating current such as a vapor deposition boat, and in electron beam heating vapor deposition, the vapor deposition material is heated and melted and evaporated by an electron beam.

As an atmosphere for vacuum deposition, a vacuum is generally used. When the compound SiZ _x M _y in the element Z is N, a small amount of nitrogen gas to a reduced pressure while introducing with an inert gas, it is possible to form simultaneously SiZ _x M _y in vacuo.

  The ultimate vacuum in the chamber before starting the active material formation is usually 0.1 Pa or less in order to prevent impurities from being mixed.

  The current collector for forming the active material by vacuum deposition can also be controlled in temperature by a heater or the like. The temperature range of the current collector is usually room temperature to 900 ° C, but preferably 150 ° C or less.

  The growth rate in forming an active material by vacuum deposition is usually about 0.1 to 500 μm / min.

  Similarly to the case of sputtering, before the active material is deposited on the conductive material layer, the conductive material layer or the current collector surface may be etched by ion irradiation with an ion gun or the like. Such etching treatment can further enhance the adhesion between the conductive material layer or the substrate and the active material. By forming ions to collide with the conductive material layer or the current collector during the formation of the active material, the adhesion of the active material to the conductive material or the current collector can be further improved.

C. CVD (Chemical Vapor Deposition)
In the CVD, the raw material that becomes an active material is deposited on a conductive material layer by a gas phase chemical reaction. In general, CVD has a feature that various materials with high purity can be synthesized in order to control a compound gas in a reaction chamber by gas inflow. Specific methods include thermal CVD, plasma CVD, photo CVD, cat -CVD etc. can be mentioned. In thermal CVD, a raw material gas of a halogen compound having a high vapor pressure is introduced together with a carrier gas and a reaction gas into a reaction vessel heated to around 1000 ° C., and a thermochemical reaction is caused to form an active material. Plasma CVD uses plasma instead of thermal energy. Photo CVD uses light energy instead of thermal energy. Cat-CVD is a catalytic chemical vapor deposition method, in which an active material is formed by applying a catalytic decomposition reaction between a source gas and a heating catalyst.

Si sources used in CVD are SiH ₄ , SiCl _4, etc., and Z sources are NH ₃ , N ₂ , CH ₄ , C ₂ H ₆ , C ₃ H _8, etc. These may be used alone or in combination of two or more.

D. Ion plating In ion plating, the raw material that is an active material is melted and evaporated, and the evaporated particles are ionized and excited under plasma to form a solid material on the conductive material layer. Specifically, examples of the method for melting and evaporating the raw material include an induction heating method, a resistance heating method, an electron beam heating vapor deposition method, and the like. Examples thereof include cathodic thermionic irradiation method, high frequency excitation method, HCD method, cluster ion beam method, and multi-arc method. Moreover, the method of evaporating the raw material and the method of ionization and excitation can be selected as appropriate and performed in combination.

  Utilizing the advantages of the high growth rate of the vapor deposition method and the strong adhesion of the sputtering to the conductive material layer and the current collector, for example, the first thin film layer is formed by sputtering, and then the vapor deposition method is used at high speed. By forming the second thin film layer, it is possible to form an interface region where the adhesion to the conductive material and the current collector is good, and to form the active material at a high growth rate. By such a hybrid combination method of growth methods, an electrode having a high charge / discharge capacity and excellent charge / discharge cycle characteristics can be efficiently produced.

  Forming the active material by combining sputtering and vapor deposition is preferably performed continuously while maintaining a reduced pressure atmosphere. This is because contamination of impurities can be prevented by continuously forming the first thin film layer and the second thin film layer without being exposed to the atmosphere. For example, it is preferable to use a thin film forming apparatus that sequentially performs sputtering and vapor deposition while moving the current collector in the same vacuum environment.

  When forming an active material on both surfaces of a current collector, forming an active material layer (which may be a combination of the first thin film layer and the second thin film layer) on one surface of the current collector; The formation of the active material layer (which may be a combination of the first thin film layer and the second thin film layer) on the other surface of the current collector is performed continuously while maintaining a reduced-pressure atmosphere. preferable.

[3] Non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of occluding and releasing lithium ions, and an electrolyte. Is used.

  There is no particular limitation on the selection of members other than the negative electrode necessary for the battery configuration such as the positive electrode and the electrolyte constituting the nonaqueous electrolyte secondary battery of the present invention. In the following, materials of members other than the negative electrode constituting the nonaqueous electrolyte secondary battery of the present invention will be exemplified, but usable materials are not limited to these specific examples.

<Positive electrode>
The positive electrode is formed by forming, on a current collector, an active material layer containing a positive electrode active material and an organic substance (binder) having a binding and thickening effect. The positive electrode is usually a slurry-like material in which an organic substance having a binding and thickening effect with the positive electrode active material is dispersed in water or an organic solvent. It is formed by a pressing process for compacting to a predetermined thickness and density.

The positive electrode active material is not particularly limited as long as it has a function capable of inserting and extracting lithium, but a metal chalcogenide-based positive electrode material is particularly preferable. Specifically, for example, lithium transition metal composite oxide materials such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide; transition metal oxide materials such as manganese dioxide; carbonaceous materials such as fluorinated graphite Can be used. Specifically, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and their non-stoichiometric compounds, MnO ₂ , TiS ₂ , FeS ₂ , Nb ₃ S ₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , P ₂ O ₅ , CrO ₃ , V ₃ O ₃ , TeO ₂ , GeO _{2 and the} like can be used. These may be used alone or in combination of two or more.

  A positive electrode conductive agent can be used for the positive electrode active material layer. The positive electrode conductive agent may be any electron conductive material that does not cause a chemical change at the charge / discharge potential of the positive electrode active material used. For example, natural graphite (such as flake graphite), graphite such as artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, metal fiber, etc. Conductive fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and organic conductive materials such as polyphenylene derivatives It can be included alone or as a mixture thereof. Among these conductive agents, artificial graphite and acetylene black are particularly preferable. Although the addition amount of a electrically conductive agent is not specifically limited, 1-50 weight% is preferable with respect to positive electrode active material material, and 1-30 weight% is especially preferable. In the case of carbon or graphite, 2 to 15% by weight is particularly preferable with respect to the positive electrode active material.

There is no restriction | limiting in particular as an organic substance which has a binding and thickening effect used for formation of a positive electrode active material layer, Any of a thermoplastic resin and a thermosetting resin may be sufficient. For example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene / butadiene rubber, tetrafluoroethylene / hexafluoroethylene copolymer, tetrafluoroethylene / hexafluoropropylene copolymer (FEP) , Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / chlorotrifluoroethylene copolymer, ethylene / tetrafluoroethylene copolymer (ETFE resin) ), Polychlorotrifluoroethylene (PCTFE), vinylidene fluoride / pentafluoropropylene copolymer, propylene / tetrafluoroethylene copolymer, ethylene-chlorotri Fluoroethylene copolymer (ECTFE), vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer, vinylidene fluoride / perfluoromethyl vinyl ether / tetrafluoroethylene copolymer, ethylene / acrylic acid copolymer or (Na ⁺ ) ion cross-linked body, ethylene / methacrylic acid copolymer or (Na ⁺ ) ion cross-linked body of the material, ethylene / methyl acrylate copolymer or (Na ⁺ ) ion cross-linked body of the material, ethylene / methacrylic acid Examples thereof include an acid methyl copolymer or a (Na ⁺ ) ion crosslinked product of the above materials, and these materials can be used alone or as a mixture. Among these materials, more preferable materials are polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

  In addition to the conductive agent described above, the positive electrode active material layer may further contain a filler, a dispersant, an ionic conductor, a pressure enhancer, and other various additives. Any filler can be used as long as it is a fibrous material that does not cause a chemical change in the constructed battery. Usually, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 weight% is preferable as content in an active material layer.

  In preparing the positive electrode active material slurry, an aqueous solvent or an organic solvent is used as a dispersion medium. As the aqueous solvent, water is usually used, and additives such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone may be added to water up to about 30% by weight or less. it can.

  As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic hydrocarbons such as anisole, toluene and xylene And alcohols such as butanol and cyclohexanol. Among them, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. These may be used alone or in combination of two or more.

  A positive electrode active material, a binder as a binder, an organic substance having a thickening effect, a positive electrode conductive agent blended as necessary, and other fillers are mixed in these solvents to prepare a positive electrode active material slurry, The positive electrode active material layer is formed by applying this to the positive electrode current collector substrate so as to have a predetermined thickness.

  The upper limit of the concentration of the positive electrode active material in the positive electrode active material slurry is usually 70% by weight or less, preferably 55% by weight or less, and the lower limit is usually 30% by weight or more, preferably 40% by weight or more. If the concentration of the positive electrode active material exceeds this upper limit, the positive electrode active material in the positive electrode active material slurry tends to aggregate, and if it falls below the lower limit, the positive electrode active material tends to settle during storage of the positive electrode active material slurry.

  The upper limit of the concentration of the binder in the positive electrode active material slurry is usually 30% by weight or less, preferably 10% by weight or less, and the lower limit is usually 0.1% by weight or more, preferably 0.5% or more. When the concentration of the binder exceeds the upper limit, the internal resistance of the positive electrode obtained is increased, and when the concentration is lower than the lower limit, the binding property of the positive electrode active material layer is deteriorated.

  For the positive electrode current collector substrate, it is preferable to use, for example, a valve metal or an alloy thereof that forms a passive film on the surface by anodic oxidation in an electrolytic solution. Examples of the valve metal include metals belonging to Groups 4, 5, and 13 of the periodic table and alloys thereof. Specifically, Al, Ti, Zr, Hf, Nb, Ta and alloys containing these metals can be exemplified, and Al, Ti, Ta and alloys containing these metals can be preferably used. . In particular, Al and its alloys are desirable because of their light weight and high energy density. The thickness of the positive electrode current collector substrate is not particularly limited, but is usually about 1 to 50 μm.

<Electrolyte>
Any electrolyte such as an electrolytic solution or a solid electrolyte can be used as the electrolyte. The electrolyte refers to all ionic conductors, and both the electrolytic solution and the solid electrolyte are included in the electrolyte.

As the electrolytic solution, for example, a solution obtained by dissolving a solute in a non-aqueous solvent can be used. As the solute, an alkali metal salt, a quaternary ammonium salt, or the like can be used. Specifically, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) _{3 and the} like are preferably used. One kind of these solutes may be selected and used, or two or more kinds may be mixed and used.
The content of these solutes in the electrolytic solution is preferably 0.2 mol / L or more, particularly 0.5 mol / L or more, and 2 mol / L or less, particularly 1.5 mol / L or less.

  Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; cyclic ester compounds such as γ-butyrolactone; chain ethers such as 1,2-dimethoxyethane; crown ethers, 2- Cyclic ethers such as methyltetrahydrofuran, 1,2-dimethyltetrahydrofuran, 1,3-dioxolane, and tetrahydrofuran; chain carbonates such as diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate can be used. Among these, a nonaqueous solvent containing a cyclic carbonate and a chain carbonate is preferable.

  One type of these solvents may be selected and used, or two or more types may be mixed and used.

  The nonaqueous electrolytic solution according to the present invention may contain various auxiliary agents such as a cyclic carbonate having an unsaturated bond in the molecule and conventionally known overcharge inhibitors, deoxidizers, and dehydrators.

  Examples of the cyclic carbonate having an unsaturated bond in the molecule include vinylene carbonate compounds, vinyl ethylene carbonate compounds, methylene ethylene carbonate compounds, and the like.

  Examples of the vinylene carbonate compounds include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, fluoro vinylene carbonate, trifluoromethyl vinylene carbonate, and the like.

  Examples of the vinyl ethylene carbonate compound include vinyl ethylene carbonate, 4-methyl-4-vinyl ethylene carbonate, 4-ethyl-4-vinyl ethylene carbonate, 4-n-propyl-4-vinyl ethylene carbonate, 5-methyl- Examples include 4-vinylethylene carbonate, 4,4-divinylethylene carbonate, 4,5-divinylethylene carbonate, and the like.

Examples of the methylene ethylene carbonate compound include methylene ethylene carbonate, 4,4-dimethyl-5-methylene ethylene carbonate, 4,4-diethyl-5-methylene ethylene carbonate, and the like.
Of these, vinylene carbonate and vinyl ethylene carbonate are preferable, and vinylene carbonate is particularly preferable.
These may be used alone or in combination of two or more.

  When the non-aqueous electrolyte contains a cyclic carbonate compound having an unsaturated bond in the molecule, the proportion in the non-aqueous electrolyte is usually 0.01% by weight or more, preferably 0.1% by weight or more, particularly Preferably it is 0.3 wt% or more, most preferably 0.5 wt% or more, and the upper limit is usually 8 wt% or less, preferably 4 wt% or less, particularly preferably 3 wt% or less.

  By including in the electrolyte a cyclic carbonate having an unsaturated bond in the molecule, the cycle characteristics of the battery can be improved. The reason is not clear, but it is presumed that a stable protective film can be formed on the surface of the negative electrode. However, when the content is small, this property is not sufficiently improved. However, if the content is too large, the gas generation amount tends to increase during high-temperature storage, so the content in the electrolyte is preferably in the above range.

Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorine-containing compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole and 2,6-difluoroanisole Anisole compounds and the like can be mentioned.
These may be used alone or in combination of two or more.

  The ratio of the overcharge inhibitor in the non-aqueous electrolyte is usually 0.1 to 5% by weight. By containing an overcharge preventing agent, rupture / ignition of the battery during overcharge or the like can be suppressed.

Other auxiliary agents include, for example, carbonate compounds such as fluoroethylene carbonate, trifluoropropylene carbonate, phenylethylene carbonate, erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, anhydrous glutar Carboxylic anhydrides such as acid, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; Ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone and tetramethylthiuram monosulfate Sulfur-containing compounds such as N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1 , 3-dimethyl-2-imidazolidinone and nitrogen-containing compounds such as N-methylsuccinimide; hydrocarbon compounds such as heptane, octane and cycloheptane; fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride, etc. And fluorine-containing aromatic compounds.
These may be used alone or in combination of two or more.

  The ratio of these auxiliaries in the nonaqueous electrolytic solution is usually 0.1 to 5% by weight. By containing these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved.

  The non-aqueous electrolyte solution may include an organic polymer compound in the electrolyte solution, and may be a gel, rubber, or solid sheet solid electrolyte. Specific examples of organic polymer compounds include polyether polymer compounds such as polyethylene oxide and polypropylene oxide; crosslinked polymers of polyether polymer compounds; vinyl alcohol polymer compounds such as polyvinyl alcohol and polyvinyl butyral; vinyl Insoluble matter of alcohol polymer compound; polyepichlorohydrin; polyphosphazene; polysiloxane; vinyl polymer compound such as polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), poly (ω -Methoxyoligooxyethylene methacrylate-co-methyl methacrylate) and the like.

<Battery configuration>
The nonaqueous electrolyte secondary battery of the present invention is composed of at least a positive electrode and a negative electrode, and an electrolyte, and may further include an outer can, a separator, a gasket, a sealing plate, a cell case, and the like as necessary.

  The material and shape of the separator are not particularly limited. The separator is separated so that the positive electrode and the negative electrode do not come into physical contact with each other, and preferably has high ion permeability and low electrical resistance. The separator is preferably selected from materials that are stable with respect to the electrolyte and excellent in liquid retention. Specific examples include porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene.

  The shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. For example, a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a pellet electrode and a separator It can be made into a laminated coin type or the like.

The method for producing the nonaqueous electrolyte secondary battery of the present invention having at least an electrolyte, a negative electrode, and a positive electrode is not particularly limited, and can be appropriately selected from commonly employed methods.
An example of the method for producing the nonaqueous electrolyte secondary battery of the present invention is as follows: a negative electrode is placed on an outer can, an electrolytic solution and a separator are provided thereon, a positive electrode is placed so as to face the negative electrode, and a gasket and A method of assembling the battery by caulking with a sealing plate is mentioned.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples, unless the summary is exceeded.

[Example 1]
<Formation of conductive material layer>
As a current collector, rolled copper having a smooth surface with an average surface roughness (Ra) of 0.05 μm, a tensile strength of 400 N / mm ² , a 0.2% proof stress of 380 N / mm ² and a thickness of 12 μm. Using foil, as a conductive substance, the crystal plane (002) spacing d ₀₀₂ = 0.336 nm, volume-based average particle size = 18.5 μm, tap density = 1.07 g / cm ³ , specific surface area = 5.2 m ² / g, Raman R value = 0.2, circularity = 0.92 particulate artificial graphite and 2% by weight of carboxymethyl cellulose (CMC) as a binder (when the conductive material is 100% by weight) And 1% by weight of styrene-butadiene rubber (SBR) were added and mixed in the form of an aqueous solution or a water suspension, respectively. The mixture thus obtained was applied onto the copper foil using a coating machine, pre-dried at 80 ° C. for 30 minutes, and pressed with a roll press to make the bulk density of the conductive material layer about 1.4 g / It adjusted to cm < ³ > (weighing about 4.3 mg / cm < ² >).

The obtained conductive material layer was cut into 4 cm square, the size, thickness and weight were measured, the current collector thickness and weight were subtracted, and the bulk density of the conductive material layer was determined to be 1.42 g / cm ^3. It was. The surface roughness Ra was measured according to the following method to be 1.5 μm. Moreover, when the total pore volume was measured with the mercury porosimeter according to the following method, it was 0.278 ml / g and the porosity corresponded to 39%.

<Formation of active material layer>
A current collector in which a conductive material layer made of the C element is formed as a current collector, a mixture of Si and C (Si: C = 1: 0.3 by atomic ratio) is used as a target material, and RF Film formation was performed with a sputtering apparatus (“CFS-4ES” manufactured by Tokuda Seisakusho Co., Ltd.) to obtain a negative electrode in which a conductive material layer and a thin film active material layer were formed on a current collector. At this time, the SUS substrate is attached to a water-cooled holder and maintained at about 25 ° C., and the chamber is evacuated to 2 × 10 ⁻³ Pa in advance, and then a high-purity argon gas is allowed to flow through the chamber to a pressure of 0.67 Pa. After forming the atmosphere, film formation was performed at a power density of 8.8 W / cm ² for 78 minutes. The oxygen concentration of this sputtering gas was about 0.001%.

About the obtained negative electrode, a cross section was produced by a sample cross section processing method using an argon ion beam (“SM-09010” manufactured by JEOL Ltd.), and a bonding portion between the conductive material layer and the active material layer was scanned with a scanning electron microscope ( SEM) was observed.
The degree of opening of the conductive material layer was determined by calculating the area ratio of the pore portion to the measurement area (length 100 μm × width 5 μm) in the field of view of the three joints, and calculating the average value using the following formula. The porosity was 38%.
Moreover, the cross section was similarly produced for the conductive material layer before the formation of the active material layer, and the degree of opening in the vicinity of the surface of the conductive material layer was calculated in the same manner. As a result, the degree of opening was 38%.
Opening degree = pore area / measurement area × 100
The pore diameter of the conductive material layer was 10 μm as determined from the above-mentioned field of view.
The thicknesses of the conductive material layer and the active material layer were 30 μm and 5.5 μm, respectively. Further, from the weight change before and after the formation of the conductive material layer and the weight change before and after the formation of the active material layer, the weight of the conductive material layer and the active material layer per unit area of the negative electrode are obtained. It was 75 weight% when the ratio with respect to was computed by the following formula.
Ratio of conductive material layer =
Weight of conductive material layer ÷ (weight of conductive material layer + weight of active material layer) × 100

  Moreover, when the composition analysis of the active material layer was performed by XPS according to the following method, the element C was contained in the Si thin film by 24 atomic%, and the C concentration ratio Q (C) with respect to the element C concentration in SiC was 0. .49. In terms of atomic concentration ratio, Si / C / O = 1.00 / 0.33 / 0.04. Further, when the Raman value of the active material layer was determined by Raman measurement according to the following method, RC = 0.05, RSC = sc peak was not detected, and RS = 0.55. Furthermore, when X-ray diffraction measurement of the active material layer was performed according to the following method, no clear peak of SiC was detected and XIsz = 0.38.

<Measurement of unevenness Ra of joint surface>
As the unevenness Ra of the bonding surface of the conductive material layer, the surface of the conductive material layer was measured with a surface roughness meter (“Color Laser Microscope VK-9500” manufactured by Keyence Corporation) on the electrode sheet 3 cm × 3 cm on which the conductive material layer was formed. )) And the average surface roughness Ra was used.

<Porosity measurement>
In order to measure the porosity of the conductive material layer, 20 cm ² of the electrode sheet on which the conductive material layer is formed is cut into strips, and in order to prevent the sheets from sticking to each other, put in a sample cell with a nickel mesh sandwiched between them. The total pore volume was measured with a porosimeter ("Autopore 9220" manufactured by Micromeritex Corporation), and the porosity was calculated from the following equation. The weight of the conductive material layer was used by subtracting the weight of the copper foil of the same area from the weight of the electrode sheet.
Porosity = total pore volume (cm ³ / g) × bulk density of conductive material layer (g / cm ³ ) × 100

<XPS measurement>
For the X-ray photoelectron spectroscopy measurement, an X-ray photoelectron spectrometer (“ESCA” manufactured by ULVAC-PHI) was used to place the active material layer on the sample stage so that the surface of the active material layer was flat, and the aluminum Kα ray was X-rayed. The depth profile was measured while performing Ar sputtering with the source. Spectra of Si2p (90 to 110 eV), C1s (280 to 300 eV), and O1s (525 to 545 eV) at a constant depth (for example, 200 nm) were obtained. The obtained C1s peak top was 284.5 eV, charge correction was performed, the peak areas of the Si2p, C1s, and O1s spectra were obtained, and the device sensitivity coefficient was multiplied to calculate the atomic concentrations of Si, C, and O, respectively. From the obtained atomic concentrations of Si, C, and O, a primitive concentration ratio Si / C / O (Si atomic concentration / C atomic concentration / O atomic concentration) is calculated, and the composition value Si / C / O of the active material layer is calculated. It is defined as

<Raman measurement>
For Raman measurement, a Raman spectrometer (“Raman spectrometer” manufactured by JASCO Corporation) is used, and the active material layer is set in the measurement cell so that it becomes the analysis surface. The measurement is performed by applying an argon ion laser beam to the sample surface in the cell. I went while irradiating.
The Raman measurement conditions here are as follows.
Argon ion laser wavelength: 514.5nm
Laser power on the sample: 15-40mW
Resolution: 10-20cm ^-1
Measurement range: 200 cm ^{−1 to} 1900 cm ⁻¹
Smoothing processing: simple average, 15 points of convolution

<X-ray diffraction measurement>
For X-ray diffraction measurement, “RINT2000PC” manufactured by Rigaku Corporation was used, the active material layer was set in the measurement cell so as to be the analysis surface, and measurement in the range of 2θ = 10 to 70 degrees by the Out-of-Plane method. Went. The background was corrected by connecting 2θ = 15-20 ° and 40-45 ° with straight lines.

  In the following Examples and Comparative Examples, the analysis and measurement methods of the obtained conductive material layer and active material layer are the same as in Example 1 unless otherwise specified.

  Using the negative electrode produced above, a lithium secondary battery was prepared according to the following method. The discharge capacity, charge / discharge efficiency, and cycle characteristics of this battery were evaluated by the following method. The results are shown in Table 2. . Moreover, the example of the SEM photograph used in order to obtain | require a hole opening degree in FIG. 2 was shown.

<Coin-type lithium secondary battery manufacturing method>
A negative electrode having a conductive material layer and an active material layer formed on one side of the current collector produced by the above method is punched out to 10 mmφ, vacuum-dried at 110 ° C., transferred to a glove box, and electrolyzed under an argon atmosphere. And a coin-type battery (lithium secondary battery) was produced using the separator and the counter electrode. As the electrolytic solution, a 1 mol / L-LiPF ₆ electrolytic solution using a mixed solution of ethylene carbonate (EC) / diethyl carbonate (DEC) = 3/7 (weight ratio) as a solvent was used. A polyethylene separator was used as the separator. A lithium metal counter electrode was used as the counter electrode.

<Evaluation of discharge capacity>
The battery is charged to 10 mV with respect to the lithium counter electrode at a current density of 0.25 mA / cm ² , and further charged to a current value of 0.02 mA at a constant voltage of 10 mV. A charge / discharge cycle of discharging to 1.5 V with respect to the lithium counter electrode at a current density of 25 mA / cm ² was repeated 5 times, and an average value of discharges in the first to third cycles was defined as a discharge capacity. Moreover, when setting it as the discharge capacity per area, it calculated | required by dividing by the negative electrode area, and calculated according to the following.
Discharge capacity (mAh / cm ² )
= Average discharge capacity (mAh) in the first to third cycles / negative electrode area (cm ² )

<Charge / discharge efficiency evaluation>
When measuring the discharge capacity, it was calculated according to the following.
Charging / discharging efficiency (%) = {initial discharge capacity (mAh) / initial charge capacity (mAh)} × 100

<Cycle characteristic evaluation>
This charge / discharge cycle was repeated 20 times according to the above-described discharge capacity measurement method, and the cycle retention rate was calculated by the following equation.
Cycle maintenance rate (%) =
{Discharge capacity after 20 cycles (mAh) / 1. Average discharge capacity after 1 to 3 cycles (mAh)} × 100

[Example 2]
<Formation of conductive material layer>
A conductive material layer was formed on the current collector in the same manner as in Example 1 except that the bulk density during pressing of the conductive material layer was about 1.8 g / cm ³ and the basis weight was 7.8 mg / cm ² .

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 1.77 g / cm ³ . The unevenness Ra on the surface of the conductive material layer was 0.7 μm. The total pore volume was 0.168 ml / g, and the porosity corresponded to 30%.

<Formation of active material layer>
An active material layer was formed on the conductive material layer in the same manner as in Example 1 except that the film formation time was 46 minutes.

According to the same method as in Example 1, the degree of opening of the obtained conductive material layer was calculated to be 25%, and the opening diameter was 5 μm. The thicknesses of the conductive material layer and the active material layer were 44 μm and 3.5 μm, respectively. Furthermore, when the ratio of the conductive material layer to the active material layer was calculated, it was 90% by weight.
Further, when the active material layer was analyzed by XPS, Raman measurement, and X-ray diffraction measurement, it was the same as in Example 1.
Using this negative electrode, coin batteries were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 3]
<Formation of conductive material layer>
As the conductive material, volume-based average particle diameter = 16.9 μm, tap density = 1.13 g / cm ³ , specific surface area = 3.1 m ² / g, Raman R value = 0.32, circularity = 0.93. Example 1 except that a particulate natural graphite-amorphous carbon composite was used, the bulk density of the conductive material layer during pressing was about 1.50 g / cm ³ , and the basis weight was 4.7 mg / cm ^2. Similarly to the above, a conductive material layer was formed on the current collector.

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 1.50 g / cm ³ . The unevenness Ra on the surface of the conductive material layer was 1.6 μm. The total pore volume was 0.263 ml / g, and the porosity corresponded to 39%.

<Formation of active material layer>
Using a current collector formed with a conductive material layer, using crushed Si as an active material raw material, and performing negative frequency deposition by high frequency induction heating type vacuum deposition using “MU-1700D high frequency induction heating apparatus” manufactured by Sekisui Medical Electronics Co., Ltd. Was made.
The current collector is attached to a water-cooled holder and maintained at about 25 ° C., and the inside of the chamber is evacuated to create an atmosphere of 1 × 10 ⁻³ Pa. It heated and vacuum-deposited for 80 seconds. Moreover, the temperature of the upper surface of the crucible at the time of vacuum deposition measured with the radiation thermometer at this time was 1650 degreeC.

According to the same method as in Example 1, the degree of opening of the obtained conductive material layer was calculated to be 30%, and the opening diameter was 9 μm. The thicknesses of the conductive material layer and the active material layer were 31 μm and 4 μm, respectively. Furthermore, when the ratio of the conductive material layer to the active material layer was calculated, it was 80% by weight.
Further, when the composition of the active material was analyzed by XPS in accordance with the same method as in Example 1, the additive element C mixed from the graphite crucible into the Si thin film was added at 11 atomic% from the atmosphere. The element O contained 11 atomic%, and the C concentration ratio Q (C) with respect to the element C concentration in SiC corresponded to 0.25. Moreover, it was Si / C / O = 1.00 / 0.14 / 0.14 in terms of atomic concentration ratio. Moreover, when the Raman value of the active material was determined by Raman measurement according to the same method as in Example 1, RC = peak was not detected, and RSC = 0.05 and RS = 0.57. Furthermore, when the X-ray diffraction measurement of the active material was performed according to the same method as in Example 1, no clear SiC peak was detected and XIsz = 0.12. Using this negative electrode, coin batteries were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 4]
<Formation of conductive material layer>
As the conductive material, particulate copper powder (made by Rare Metallic) having a purity of 99.9% and a volume-based average particle size = 10 μm was used, and CMC 0.5 wt% and SBR 0.25 wt% were used as binders. The conductive material layer was formed on the current collector in the same manner as in Example 1 except that the bulk density when the conductive material layer was pressed was about 5 g / cm ³ and the basis weight was 16 mg / cm ² .

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 4.91 g / cm ³ . The unevenness Ra on the surface of the conductive material layer was 1.2 μm. The total pore volume was 0.094 ml / g, and the porosity corresponded to 46%.

<Formation of active material layer>
In the same manner as in Example 1, an active material layer was formed on the conductive material layer.

According to the same method as in Example 1, the degree of opening of the obtained conductive material layer was calculated to be 43%, and the opening diameter was 6 μm. The thicknesses of the conductive material layer and the active material layer were 33 μm and 5.5 μm, respectively. The ratio of the conductive material layer to the active material layer was calculated to be 92% by weight.
Further, when the active material layer was analyzed by XPS, Raman measurement, and X-ray diffraction measurement, it was the same as in Example 1.
Using this negative electrode, coin batteries were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 5]
<Formation of conductive material layer>
As the conductive substance, the crystal plane (002) spacing d ₀₀₂ = 0.3358 nm, volume-based average particle size = 22.0 μm, tap density = 1.01 g / cm ³ , specific surface area = 5.3 m ² / g, Using granular natural graphite having a Raman R value = 0.26 and circularity = 0.92, the bulk density of the conductive material layer during pressing is about 1.5 g / cm ³ and the basis weight is 7.4 mg / cm ^2. A conductive material layer was formed on the current collector in the same manner as in Example 1 except that.

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 1.51 g / cm ³ . The surface roughness Ra of the conductive material layer was 1.0 μm. The total pore volume was 0.261 ml / g, and the porosity corresponded to 39%.

<Formation of active material layer>
Using Si as a target material, film formation was performed with an RF sputtering apparatus (“CFS-4ES” manufactured by Tokuda Manufacturing Co., Ltd.) to obtain a negative electrode in which a thin film active material layer was formed on a conductive material layer. At this time, the SUS substrate is attached to a water-cooled holder and maintained at about 25 ° C., and the chamber is evacuated to 2 × 10 ⁻³ Pa in advance, and then a high-purity argon gas is allowed to flow through the chamber to a pressure of 0.67 Pa. After forming the atmosphere, film formation was performed at a power density of 8.8 W / cm ² for 30 minutes. The oxygen concentration of this sputtering gas was about 0.001%.

According to the same method as in Example 1, the degree of opening of the obtained conductive material layer was calculated to be 30%, and the opening diameter was 9 μm. The thicknesses of the conductive material layer and the active material layer were 31 μm and 4 μm, respectively. The ratio of the conductive material layer to the active material layer was calculated to be 80% by weight.
Further, when this negative electrode was analyzed for the composition of the active material by XPS according to the same method as in Example 1, it was Si / O = 1.00 / 0.05 in terms of atomic concentration ratio.
Using this negative electrode, coin batteries were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Comparative Example 1]
<Formation of active material layer>
The active material layer was formed on the current collector in the same manner as in Example 1 except that the active material layer was directly formed on the surface of the copper foil without forming the conductive material layer on the current collector. Produced. In addition, the reverse sputtering was performed for the purpose of removing the oxide film etc. on the copper foil surface before film formation, and the substrate surface was etched.
From observation with a scanning electron microscope (SEM) of the cross section of the obtained thin film active material layer, the film thickness of the formed active material layer was about 5 μm. Moreover, although the active material layer was formed directly on the current collector surface, peeling from the current collector surface was also observed in part.

Further, when the active material layer was analyzed by XPS, Raman measurement, and X-ray diffraction measurement, it was the same as in Example 1.
Using this negative electrode, coin batteries were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Comparative Example 2]
<Formation of conductive material layer>
A conductive material layer was formed on the current collector in the same manner as in Example 2. Without forming an active material layer on the conductive material layer, the conductive material layer was used as a negative electrode as it was.

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 1.77 g / cm ³ . Further, the surface roughness Ra of the conductive material layer was 0.70 μm. The total pore volume was 0.168 ml / g, and the porosity corresponded to 30%.
Using this negative electrode, a coin battery was prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Comparative Example 3]
<Formation of conductive material layer>
After the conductive material layer was applied and dried, a conductive material layer was formed on the current collector in the same manner as in Example 1 except that it was not subjected to a roll press.

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 1.06 g / cm ³ . The unevenness Ra on the surface of the conductive material layer was 4.0 μm. The total pore volume was 0.565 ml / g, and the porosity corresponded to 60%.

<Formation of active material layer>
In the same manner as in Example 1, an active material layer was formed on the conductive material layer.

According to the same method as in Example 1, the degree of opening of the obtained conductive material layer was calculated to be 57%, and the opening diameter was 20 μm. The thicknesses of the conductive material layer and the active material layer were 110 μm and 5.5 μm, respectively. The ratio of the conductive material layer to the active material layer was calculated to be 89% by weight.
Using this negative electrode, coin batteries were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Comparative Example 4]
<Formation of conductive material layer>
As the conductive material, a fibrous vapor-grown carbon fiber (manufactured by Showa Denko) having a fiber diameter of 150 nm, a fiber length of about 20 μm, and a specific surface area of 13 m ² / g was used. As a binder, CMC 1% by weight, SBR4 It was coated on the current collector in the same manner as in Example 1 except that the weight density was applied and the bulk density at the time of pressing the conductive material layer was about 0.7 g / cm ³ and the basis weight was 1.1 mg / cm ^2. A conductive material layer was formed.

According to the same method as in Example 1, the bulk density of the obtained conductive material layer was determined to be 0.7 g / cm ³ . Further, the total pore volume of the conductive material layer was 0.632 ml / g, and the porosity corresponded to 67%.

<Formation of active material layer>
In the same manner as in Example 1, an active material layer was formed on the conductive material layer.

According to the same method as in Example 1, the degree of opening of the obtained conductive material layer was calculated to be 65%. The thicknesses of the conductive material layer and the active material layer were 15 μm and 5.5 μm, respectively. The ratio of the conductive material layer to the active material layer was calculated to be 45% by weight.
When a coin battery was produced using this negative electrode in the same manner as in Example 1, the active material layer peeled off during the production, and the coin battery could not be evaluated.

[Comparative Example 5]
<Formation of active material layer>
As a current collector, rolled copper having a smooth surface with an average surface roughness (Ra) of 0.05 μm, a tensile strength of 400 N / mm ² , a 0.2% proof stress of 380 N / mm ² and a thickness of 12 μm. Using foil, Si was used as a target material, and film formation was performed with an RF sputtering apparatus (“CFS-4ES” manufactured by Tokuda Manufacturing Co., Ltd.) to obtain a negative electrode in which a thin film active material layer was formed on a current collector. . At this time, the SUS substrate is attached to a water-cooled holder and maintained at about 25 ° C., and the chamber is evacuated to 2 × 10 ⁻³ Pa in advance, and then a high-purity argon gas is allowed to flow through the chamber to a pressure of 0.67 Pa. After forming the atmosphere, film formation was performed at a power density of 8.8 W / cm ² for 30 minutes. The oxygen concentration of this sputtering gas was about 0.001%. In addition, the reverse sputtering was performed for the purpose of removing the oxide film etc. on the copper foil surface before film formation, and the substrate surface was etched.

<Formation of conductive material layer>
A conductive material layer (an active material layer on a current collector and a conductive material layer on the active material layer) was used in the same manner as in Example 1 except that a negative electrode having an active material layer formed thereon was used instead of the current collector. Was formed).

The bulk density of the obtained conductive material layer obtained in the same manner as in Example 1 was 1.41 g / cm ³ . The surface roughness Ra of the conductive material layer was 1.5 μm. The total pore volume was 0.280 ml / g, and the porosity corresponded to 39%.

According to the same method as in Example 1, the thicknesses of the obtained active material layer and conductive material layer were 2 μm and 30 μm, respectively. The ratio of the conductive material layer to the active material layer was calculated to be 88% by weight.
Tables 1 and 2 collectively show analysis values and the like of the negative electrodes prepared in the above examples and comparative examples.

From Tables 1 and 2, the following can be understood.
The negative electrode of Comparative Example 1 has an active material layer directly formed on a rolled copper foil with a smooth surface, and is outside the specified range of the present invention because no conductive material layer is formed. As a result, good cycle characteristics Was not obtained.

  The negative electrode of Comparative Example 2 is formed of only a conductive material layer on a rolled copper foil having a smooth surface and is outside the specified range of the present invention because no active material layer is formed. As a result, a high discharge capacity Was not obtained.

  The negative electrode of Comparative Example 3 has a conductive material layer formed on a current collector and an active material layer formed on the conductive material layer, and satisfies a part of the requirements of the present invention. The porosity, Ra, and porosity of the joint surface of the conductive material layer in contact with the surface were outside the specified ranges of the present invention, and as a result, good cycle characteristics could not be obtained.

  The negative electrode of Comparative Example 4 has a conductive material layer formed on a current collector and an active material layer formed on the conductive material layer, and satisfies a part of the requirements of the present invention. The porosity and porosity of the joint surface of the conductive material layer in contact with the surface were outside the specified ranges of the present invention, and as a result, good cycle characteristics could not be obtained.

  In the negative electrode of Comparative Example 5, the active material layer is formed on the current collector, and the conductive material layer is formed on the active material layer, and the formation order of the conductive material layer and the active material layer is reversed. As a result, good cycle characteristics could not be obtained.

  On the other hand, the negative electrodes of the present invention of Examples 1 to 5 are a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer. The open area of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less, and the active material layer contains at least an active material element that is alloyed with lithium And / or the joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 0.01 or more and 3.0 μm or less, and the porosity of the conductive material layer is 15% or more, 50 %, And the active material layer contains an active material containing at least an element alloying with lithium, and all satisfy the specified range of the present invention. When such a negative electrode is used, a high-performance battery having high discharge capacity, high charge / discharge efficiency, and excellent cycle characteristics can be obtained.

In an electrode comprising a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer, one of the following (a) and (b) Alternatively, by using an electrode characterized by satisfying both requirements, it is possible to realize a non-aqueous electrolyte secondary battery with high discharge capacity, high charge / discharge efficiency, excellent cycle characteristics, and low cost. The electrode and non-aqueous electrolyte secondary battery of the present invention can be suitably used in various fields such as electronic devices to which the non-aqueous electrolyte secondary battery is applied.
(B) The porosity of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less, and the active material layer contains an active material containing at least an element alloying with lithium. .
(B) The joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 0.01 to 3.0 μm, and the porosity of the conductive material layer is 15% to 50%. And the active material layer contains an active material containing at least an element alloying with lithium.

It is a schematic diagram which shows the structure of the electrode of this invention. In this figure, (a) shows the conductive material in the form of particles, and (b) shows the conductive material in the form of a porous body. In Example 1, it is the SEM photograph used in order to obtain | require a hole opening degree.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive material layer 2 Active material layer 3 Conductive material 4 Pore 5 Current collector

Claims (6)

In an electrode comprising a current collector, a conductive material layer provided on the current collector, and an active material layer provided on the conductive material layer, one of the following (a) and (b) An electrode characterized by satisfying both requirements.
(B) The porosity of the joint surface of the conductive material layer in contact with the active material layer is 5% or more and 50% or less, and the active material layer contains an active material containing at least an element alloying with lithium. .
(B) The joint surface unevenness Ra of the conductive material layer in contact with the active material layer is 0.01 to 3.0 μm, and the porosity of the conductive material layer is 15% to 50%. And the active material layer contains an active material containing at least an element alloying with lithium.   The electrode according to claim 1, wherein the conductive substance is a substance containing carbon as a main component.   The electrode according to claim 1, wherein the active material is a material containing Si. The active material, a material element Z in Si as a main component a compound of a non-equilibrium exists and phase, said compound formula SiZ _x M _y (wherein Z, M, x, y are The electrode according to any one of claims 1 to 3, wherein the electrode is represented by the following conditions (1) to (4).
(1) The element Z is an element composed of C and / or N.
(2) Element M is one or more elements selected from elements other than Si and element Z.
(3) x represents the formula Q (Z) = [x with respect to the Z concentration (p / (a + p)) of the compound SiaZp (where a and p are integers) that exist in equilibrium with the composition closest to Si. / (1 + x)] / [p / (a + p)] is a value at which the Z concentration ratio Q (Z) calculated from 0.10 to 0.95.
(4) y is a number in the range of 0 ≦ y ≦ 0.50.   The electrode according to any one of claims 1 to 4, wherein the active material layer is a material produced by vapor phase growth.   A nonaqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte, wherein the negative electrode is the electrode according to any one of claims 1 to 5. Non-aqueous electrolyte secondary battery.