JP6051038B2 - Foil for positive electrode current collector of lithium ion secondary battery, method for producing the same, and lithium ion secondary battery - Google Patents

Description

The present invention relates to a foil for a positive electrode current collector of a lithium ion secondary battery, a method for producing the same , and a lithium ion secondary battery, and relates to a lithium ion secondary battery excellent in high rate characteristics.

Lithium ion secondary batteries are currently widely used in applications such as mobile phones, notebook personal computers, and video cameras because of their high energy density. In general, lithium ion secondary batteries for these applications use lithium cobaltate (LiCoO ₂ ) and lithium manganate (LiMn ₂ O ₄ ) as a positive electrode active material and graphite as a negative electrode.
When such a high-performance secondary battery is applied to a field requiring a larger amount of electric power, such as an automobile, a rapid charge / discharge characteristic capable of quickly discharging and charging is required.
However, it is necessary to increase the current value in order to perform rapid charge / discharge. However, in current lithium ion secondary batteries, when charging / discharging is performed at a large current (high rate), the battery capacity (initial battery capacity maintenance rate) decreases remarkably as the battery voltage rapidly decreases.

Therefore, Patent Document 1 proposes a positive electrode current collector structure in which lithium ion conductivity is shared by a compound having ion permeability and electronic conductivity is shared by electron conductive carbon fine particles.
Patent Document 2 describes that perforation processing is performed on a positive electrode current collector foil (hereinafter also referred to as positive electrode foil) to reduce electrode resistance and enable rapid charge / discharge at a high rate.

JP 2007-226969 A JP 2008-31171 A

However, the proposal of Patent Document 1 requires that a film having an ion permeability and carbon fine particles be applied to form a film on the positive electrode current collector, which increases the manufacturing cost of the lithium ion secondary battery. In addition, when the positive foil is perforated as in Patent Document 2, the strength of the foil is remarkably reduced, and thus the positive foil may be broken during battery production.
The present invention has been made based on such a problem, and is capable of improving the rapid charge / discharge characteristics while suppressing an increase in cost and a decrease in the strength of the positive electrode current collector, and is capable of improving the productivity. It aims at providing the foil for positive electrode collectors of a secondary battery.
Moreover, an object of this invention is to provide the lithium ion secondary battery which is excellent in a quick charge / discharge characteristic by providing the said foil for positive electrode collectors.

As described above, in the lithium ion secondary battery, the higher the charge / discharge rate (higher rate), the faster the battery voltage decreases and the battery capacity decreases. This is understood to be mainly caused by the internal resistance of the battery. Therefore, the present inventor studied to lower the electrical resistance between the positive electrode active material and the positive electrode current collector. As a result, as the positive electrode current collector, if an aluminum alloy foil having pits for accommodating the active material particles is formed on the surface in contact with the positive electrode active material, a decrease in voltage can be suppressed even when high rate discharge is performed. A high capacity retention rate can be obtained, and if an appropriate amount of Zn is contained in the aluminum alloy foil, the etching process for forming the pits can be performed efficiently, and the production of a positive electrode current collector is achieved. It was found that the performance is improved.
According to the present invention, it is not clear why the voltage drop is suppressed even when high-rate discharge is performed and a high capacity retention rate is obtained. However, by roughening the surface of the positive electrode foil, the contact area between the positive electrode active material and the positive electrode foil increases, the interface contact resistance between the positive electrode active material and the positive electrode current collector decreases, and the internal resistance of the battery decreases. The inventor speculates that this is the reason.
This invention is made | formed based on the above knowledge, and has the following structures.

The foil for the positive electrode current collector of the lithium ion secondary battery of the present invention has 0.1 to 1.5% by mass of Zn, 0.03 to 0.07% by mass of Si, and 0.08 to 0.11 of Fe. It is made of an aluminum alloy foil having a thickness of 10 to 50 μm, the balance being inevitable impurities and Al. The lithium iron phosphate having a particle size of 0.3 to 3 μm, the lithium manganate having a particle size of 3 to 20 μm, and a particle size of 3 Crater-like etching pits for accommodating a positive electrode active material in the form of one or more of lithium cobaltate having a particle size of ˜30 μm and cobalt acid / manganese acid / lithium nickelate having a particle size of 10 to 15 μm on the surface The etching pits are formed with a diameter of 0.3 to 3 μm and present at a density of 10 ³ pieces / mm ² or more and 10 ⁵ pieces / mm ² or less, and the density of the etching pits exceeding 3 μm in diameter is 10 It is characterized by being not more than pieces / mm ² .
In the present invention, the etching pit in which the particulate positive electrode active material is accommodated is formed on the surface of the foil because the contact area between the positive electrode active material and the positive electrode foil can be further increased. The term “accommodation” here does not require that the positive electrode active material be accommodated in all of the formed etching pits, and it is sufficient that the positive electrode active material is accommodated in some of the etching pits. Further, the present invention includes the case where the entire particulate positive electrode active material does not need to be accommodated in the etching pits and the positive electrode active material is partially accommodated in the etching pits.

The manufacturing method of the foil for positive electrode collectors of the lithium ion secondary battery which concerns on this invention is 0.1-1.5 mass% of Zn, 0.03-0.07 mass% of Si, and 0.08 of Fe. By subjecting an aluminum alloy foil having a thickness of 10 to 50 μm, which contains 0.11% by mass and the remainder of inevitable impurities and Al, to a surface treatment with an alkaline solution, lithium iron phosphate having a particle size of 0.3 to 3 μm, Particulate positive electrode active material comprising one or more of lithium manganate having a particle size of 3 to 20 μm, lithium cobaltate having a particle size of 3 to 30 μm, and cobalt acid, manganate and lithium nickelate having a particle size of 10 to 15 μm A method for producing an aluminum alloy foil for a positive electrode current collector of a lithium ion secondary battery, in which crater-like etching pits for containing the aluminum alloy foil are formed on the surface of the aluminum alloy foil, By applying a surface treatment to the solution, the etching pits having a diameter of 0.3 to 3 μm are present at a density of 10 ³ pieces / mm ² or more and 10 ⁵ pieces / mm ² or less, and the pits having a diameter exceeding 3 μm. The density is 10 pieces / mm ² or less.

The lithium ion secondary battery excellent in high rate discharge characteristics of the present invention includes a positive electrode current collector, a positive electrode active material , a conductive material, a binder , a positive electrode having a diluent , a negative electrode current collector, a negative electrode active material , a conductive material, and a binder. The positive electrode current collector is made of the foil for positive electrode current collector according to claim 1.
In the lithium ion secondary battery excellent in high rate discharge characteristics of the present invention, the positive electrode active material is lithium iron phosphate, the conductive material is acetylene black, the binder is polyvinylidene fluoride, and the diluent Is N-methyl-2-pyrrolidone, the negative electrode current collector is preferably a copper foil, and the negative electrode active material is preferably mesocarbon microbeads.

According to the present invention , etching pits are present on the surface with a size of 0.3 to 3 μm and a density of 10 ³ pieces / mm ² or more and 10 ⁵ pieces / mm ² or less, and the density of etching pits exceeding 3 μm in diameter is increased. By configuring the positive electrode current collector with a zinc-containing aluminum alloy foil specified to 10 pieces / mm ² or less , rapid charge / discharge characteristics can be improved while suppressing an increase in cost and a decrease in strength of the positive electrode current collector.
In addition, since aluminum alloy foil contains zinc, when pits are formed by surface etching treatment using an alkaline solution on aluminum alloy foil, the etching rate during this surface treatment is increased, and positive electrode current collectors are produced. Can significantly improve the performance.
This is presumably because zinc dissolved in the etching solution from the aluminum alloy foil reprecipitates on the foil surface and promotes nucleation of etching pits.

It is a figure which shows typically one Embodiment of the lithium ion secondary battery which concerns on this invention. It is a figure which shows the positive electrode in the embodiment typically, FIG. 2 (a) is sectional drawing which shows the positive electrode electrical power collector in which the pit was formed, FIG.2 (b) is positive electrode current collection with which the positive electrode active material was apply | coated. It is sectional drawing which shows a body. FIG. 3A schematically shows a positive electrode in the embodiment, FIG. 3A is a cross-sectional view showing a positive electrode current collector on which a crater is formed, and FIG. 3B shows a positive electrode current collector on which a positive electrode active material is laminated. It is sectional drawing.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
As shown in FIG. 1, the lithium ion secondary battery 10 of this embodiment includes an electrode group 4 formed by laminating a positive electrode 1 and a negative electrode 2 with a separator 3 interposed therebetween. In addition to the stacked type, the electrode group 4 may have a configuration in which the positive electrode 1 and the negative electrode 2 are wound through a separator 3.

<Positive electrode>
The positive electrode 1 includes a positive electrode current collector (positive electrode current collector foil) 1a and a positive electrode mixture layer 1b.
The positive electrode current collector 1a is made of an aluminum alloy foil containing zinc (zinc-containing aluminum alloy foil), and a large number of pits 1d are formed on the surface thereof as shown in FIG.
Since the positive electrode current collector 1a is composed of a zinc-containing aluminum alloy foil, the surface etching treatment using an alkaline solution is performed on the alloy foil to form the pit 1d, so that the etching rate during the surface treatment is increased. The productivity of the positive electrode current collector 1a can be significantly improved.

The zinc-containing aluminum alloy foil preferably has a Zn content of 0.1 to 1.5% by mass, and the balance is composed of Al and inevitable impurities.
When the zinc content of the zinc-containing aluminum alloy foil is less than 0.1% by mass, the effect of improving the etching rate cannot be sufficiently obtained. On the other hand, if the zinc content exceeds 1.5% by mass, there are too many etching pit nucleation sites, and the density of pits 1d increases, but the pit diameter decreases. As a result, as described later, the positive electrode active material 1c cannot be sufficiently accommodated in the pits 1d. For this reason, it is preferable that zinc content of a zinc containing aluminum alloy foil is 0.1 to 1.5 mass%.

  The thickness of the zinc-containing aluminum alloy foil is preferably in the range of 10 to 50 μm. If the thickness is less than 10 μm, the strength may be insufficient, and the alloy foil may be broken by etching surface treatment of an alkaline solution described later. If the thickness exceeds 50 μm, the positive electrode current collector occupies the volume inside the battery This is because the proportion of the body 1a increases and the battery capacity decreases. More preferably, the zinc-containing aluminum alloy foil has a thickness in the range of 12 to 30 μm. In addition, the positive electrode 1 has a thickness of about 50 to 300 μm including the positive electrode current collector 1a and the positive electrode mixture layers 1b on both sides thereof.

  The surface of the positive electrode current collector 1a is roughened by etching surface treatment of an alkaline solution or the like. The reason for roughening the surface is to reduce the interface contact resistance with the positive electrode active material contained in the positive electrode mixture layer 1b. The content of the roughening is determined in view of the purpose of increasing the contact area with the positive electrode active material in consideration of the positive electrode active material. That is, since the positive electrode active material has a different particle size depending on the type, the surface may be roughened according to the type (particle size). As shown in FIG. 2B, forming a plurality of pits 1d that can accommodate the particulate positive electrode active material 1c is listed as an example of roughening. In the case of FIG. 2B, ideally, the contact area between the positive electrode current collector 1a and the positive electrode active material 1c is increased because the entire positive electrode active material 1c is accommodated in the pits 1d without any gap. The interface contact resistance between the two can be reduced. However, as described above, the present invention requires that the positive electrode active material is accommodated in all formed pits, and that the entire particulate positive electrode active material is accommodated in the pits. It is not a thing.

  This embodiment is not applicable when the particle diameter of the positive electrode active material 1c is considerably larger than the thickness of the positive electrode current collector 1a, but when lithium iron phosphate having a particle diameter of about several μm is used as the positive electrode active material. Is valid. In this case, the pit 1d is preferably produced according to the following.

Pit diameter (diameter): 0.3 to 3 μm
If the pit diameter is less than 0.3 μm, the pit diameter is too small with respect to the particle diameter of the positive electrode active material 1c, so that the positive electrode active material 1c cannot be accommodated in the pit 1d. Become. Therefore, the internal resistance of the battery does not decrease and the high rate discharge characteristics of the battery are hardly improved.
If the pit diameter exceeds 3 μm, the thickness is locally thinner than the surrounding area, resulting in a low strength portion, which may reduce the strength of the aluminum foil and cause breakage.

Pit density (diameter: 0.3 to ³ μm): 10 ³ pieces / mm ² to 10 ⁵ pieces / mm ²
When the pit density is less than 10 ³ pieces / mm ² , the increase in the contact area between the positive electrode current collector 1a and the positive electrode active material 1c is reduced, and the decrease in the interface contact resistance is reduced. Therefore, the internal resistance of the battery does not decrease and the high rate discharge characteristics of the battery are hardly improved.
If the pit density exceeds 10 ⁵ pieces / mm ² , the adjacent pits 1d overlap, and as a result, the foil surface may become smooth.
Density of pits 1d exceeding 3 μm in diameter: 10 pieces / mm ² or less This defines the allowable density of coarse pits 1d (defects) formed by etching. If the defects exceed this density, the high rate discharge characteristics may be adversely affected.

Since the pit 1d is only one form of the roughening process, the roughening process for obtaining the pit of the present invention is not limited to the process for forming the pit 1d as shown in FIG. For example, as shown in FIG. 3, the process of forming the crater-like pit 1e on the surface of the positive electrode current collector 1a may be a roughening process.
The crater-like pit 1e is suitable for the positive electrode active material 1c having a large diameter. That is, part of the surface of the positive electrode active material 1c is accommodated in contact with the inner surface of the crater 1e, so that the contact area between the positive electrode current collector 1a and the positive electrode active material 1c can be increased. This form can be adapted to the positive electrode active material 1c having a particle diameter larger than that of lithium phosphate such as lithium cobaltate (LiCoO ₂ ) and lithium manganate (LiMn ₂ O ₄ ).

Since the zinc-containing aluminum alloy foil is usually produced by rolling, the as-prepared zinc-containing aluminum alloy foil has a flat surface. In this embodiment, the zinc-containing aluminum alloy foil having a flat surface is subjected to surface etching treatment using an alkaline solution to be roughened. Thereby, pits 1d can be efficiently formed on the alloy foil with the above-mentioned appropriate pit diameter and pit density, and the positive electrode current collector 1a can be manufactured with high productivity.
As an example of the alkaline solution for forming pits on the surface of the aluminum alloy foil, a 20% aqueous sodium hydroxide solution can be used. Pits can be formed by performing an etching process under the conditions of the alkaline solution temperature of, for example, 35 ° C. and an immersion time of 2 minutes. In addition, you may change suitably the liquid temperature and immersion time of an alkaline solution.

Next, the positive electrode mixture layer 1b is formed by kneading a conductive material, a binder, and a diluent into the positive electrode active material 1c, which is the main component, to form a paste, and applying it to both the front and back surfaces of the positive electrode current collector 1a. Can do.
As the positive electrode active material 1c, a known material such as a lithium-containing metal oxide, a lithium-containing metal phosphate compound, or a lithium-containing compound can be used. As the lithium-containing metal _{oxide, LiCoO 2, Li (Co x} Mn y Ni z) O 2, Li 2 MnO 4 , and examples of the lithium-containing metal phosphate _{compound, LiFePO 4, LiMnPO 4, LiFe} 1-x Mn _x PO _{4 and} LiCoPO ₄ are exemplified, and examples of the lithium-containing compound include LiTi ₂ (PO ₄ ) ₃ and LiFeO ₂ . Among them, LiFePO ₄ (lithium iron phosphate), Li ₂ MnO ₄ (lithium manganate), LiCoO ₂ (lithium cobaltate), Li (Co _{x M} n _y Ni _z ) in terms of electrochemical characteristics, safety and cost. It is preferable to use one or more of O ₂ (cobalt acid / manganate / lithium nickelate). The particle diameters of these preferable positive electrode active materials 1c are generally as follows. The roughening treatment of the positive electrode current collector 1a is performed with the following particle size in mind.

Lithium iron phosphate: 0.3-3 μm
Lithium manganate: 3 to 20 μm
Lithium cobaltate: 3-30 μm
Cobalt acid / manganate / lithium nickelate: 10-15 μm
A known material may be used for the binder and the diluent.

<Negative electrode>
The negative electrode 2 includes a negative electrode current collector 2a and a negative electrode mixture layer 2b.
As the negative electrode current collector 2a, a copper foil is used in view of electrochemical properties, processability to a foil shape, and cost. However, the present invention does not prevent the use of a metal foil made of another material for the negative electrode current collector 2a. Further, even when the Li 4 _Ti 5 _O 12 _(lithium titanate) as the negative electrode, it is possible to use a positive electrode current collector foil of the present invention.
The thickness of the negative electrode current collector 2a may be 10 to 50 μm, which is the same as that of the positive electrode current collector 1a. Moreover, the thickness of the negative electrode 2 including the negative electrode current collector 2a and the negative electrode mixture layer 2b on both surfaces thereof may be 50 to 300 μm, which is the same as the positive electrode 1.

Next, the negative electrode mixture layer 2b can be formed by kneading a conductive material, a binder, and a diluent together with a negative electrode active material as a main component into a paste and applying the paste to both surfaces of the negative electrode current collector 2a. .
As the negative electrode active material, a known material capable of occluding and releasing lithium ions, for example, a carbon material, lithium titanate, lithium-aluminum alloy, silicon-based or tin-based lithium alloy can be used. Among these, it is preferable to use a carbon material having a large amount of occlusion / release of lithium ions and a small irreversible capacity. As the carbon material, acetylene black, ketjen black, vapor grown carbon fiber, and graphite (graphite) can be suitably used.

<Separator>
The separator 3 provided between the positive electrode 1 and the negative electrode 2 is made of, for example, a polypropylene or polyethylene resin film having countless fine holes and electrically insulates the positive electrode 1 and the negative electrode 2 from each other. Li ⁺ can pass freely.

<Electrolyte>
As an electrolytic solution in which the electrode group 4 including the positive electrode 1, the negative electrode 2, and the separator 3 is immersed, it is preferable to use a nonaqueous electrolytic solution or an ion conductive polymer containing a lithium salt.
Examples of the nonaqueous solvent for the nonaqueous electrolyte in the nonaqueous electrolyte containing a lithium salt include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). Can be mentioned.
Examples of the lithium salt that can be dissolved in the non-aqueous solvent include lithium hexafluorophosphate (LiPF ₆ ), lithium borotetrafluoride (LiBF ₄ ), and lithium trifluoromethanesulfonate (LiSO ₃ CF ₄ ).

  The electrode group 4 having the above configuration is immersed in an electrolyte solution inside a battery case to be sealed (both are not shown), and the positive electrode 1 and the negative electrode 2 are electrically connected to terminals, respectively. The secondary battery 10 is configured.

Hereinafter, the present invention will be described based on more specific examples.
<Examination of etching rate of aluminum alloy foil>
Various zinc-containing aluminum alloy foils (Experimental Examples 1 to 4) having the compositions shown in Table 1 were prepared. These alloy foils were immersed in an etching solution (trade name “MEC ALMAT AR-1210”, manufactured by MEC Co., Ltd.) at 35 ° C. for 150 seconds to perform surface etching treatment, thereby roughening the surface. The etching rate during this surface etching treatment was evaluated by measuring the weight loss per unit area before and after roughening. The results are shown in Table 1.

As shown in Table 1, the aluminum alloy foil containing zinc (Experimental Examples 1, 2, and 4) has an etching rate higher than that of the aluminum alloy foil having less zinc content (Experimental Example 3). With the aluminum alloy foil of Example 3, a longer processing time is required to obtain the same etching amount as other aluminum alloy foils (Experimental Examples 1, 2, and 4). From this, it was found that the productivity of the positive electrode current collector can be greatly improved by using the aluminum alloy foil containing zinc as compared with the case of using the alloy foil not containing zinc.
Here, the diameter of the pits formed in the aluminum alloy foil becomes a small diameter depending on the zinc content of the aluminum alloy foil, and the aluminum alloy foil (Experimental Example 4) having a zinc content exceeding 1.5 mass%. The pit diameter formed seems to be smaller than the diameter (1 μm) of the lithium iron phosphate particles.

<Examination of battery discharge capacity>
A positive electrode was prepared using the positive electrode foil obtained by roughening the zinc-containing aluminum alloy foil of Experimental Examples 1 to 4, and a negative electrode was prepared. The method for producing the positive electrode and the negative electrode is as follows.
[Positive electrode]
A positive electrode slurry composed of a positive electrode active material, a conductive material, a binder, and a diluent shown below was applied on the positive electrode foil so as to have a thickness of 50 μm to obtain a positive electrode.
Positive electrode active material Lithium iron phosphate (average particle size: 1 μm)
Conductive material Acetylene Black (AB)
Binder Polyvinylidene fluoride (PVDF)
Diluent N-methyl-2-pyrrolidone (NMP)
Mixing ratio of each component (weight ratio) Positive electrode active material: AB: PVDF = 85: 8: 7

[Negative electrode]
A negative electrode slurry composed of the following negative electrode active material and the same conductive material, binder and diluent as the positive electrode was applied onto a copper foil (thickness 10 μm) to a thickness of 40 μm to obtain a negative electrode.
Negative electrode active material Mesocarbon microbeads (MCMB)
Compounding ratio (mass ratio) of each component MCMB: AB: PVDF = 93: 2: 5
The positive electrode and the negative electrode produced as described above were assembled together with a separator, and impregnated with an electrolytic solution to produce lithium ion secondary batteries (Experimental Battery 1 to Experimental Battery 4).

High-rate discharge load characteristics were measured using the produced lithium ion secondary battery.
The measurement conditions are as follows. Then, assuming that the discharge capacity of the experimental example battery 3 when discharged at each current was 1, the discharge capacities of the other batteries (experimental example batteries 1, 2, 4) were obtained. The results are shown in Table 2.

Charging CC-CV: 0.2C-4.0V 8hr.
Discharge CC: 0.2C, 1C, 5C, 10C, 15C (E.V = 2.0V)
Definition of C: Calculated from the rated capacity value of the battery, 1C indicates a current value at which discharge is completed in one hour when a battery having a certain capacity is discharged at a constant current. For example, 15C means a current value 15 times that of 1C.
CC (Constant Current): Indicates that charging / discharging is performed at a constant current.
CC-CV (Constant Current-Constant Voltage): Used when charging the battery. A method of charging with a constant current first, and after reaching a specified voltage, charging while lowering the current value to maintain that voltage. "0.2C-4.0V 8hr." Starts charging at 0.2C first, gradually decreases the current value from the point when the voltage reaches 4.0V, and charging 8 hours after the start of charging Indicates that you want to complete.

As shown in Table 2, experimental batteries 1 and 2 having a positive electrode foil with a zinc content of 0.1 to 1.5% by mass are an experimental battery 3 with a positive electrode foil having a zinc content of less than 0.1% by mass. Compared to the above, the etching rate at the time of the roughening treatment is characterized by a high etching speed, and at the same time, the discharge capacity is equivalent or higher.
In Experimental Examples Batteries 1 to 3, pits having substantially the same size as the lithium iron phosphate particles (positive electrode active material) are formed on the surface of the positive electrode current collector. Therefore, as shown in FIG. It is presumed that the lithium iron oxide particles are accommodated and the contact area of the positive electrode current collector with the lithium iron phosphate particles is increased. Therefore, it is understood that the interface contact resistance between the positive electrode active material and the positive electrode current collector is reduced, the voltage drop is suppressed even during high-rate discharge, and a high discharge capacity can be maintained.

On the other hand, the experimental battery 4 in which the zinc content of the positive electrode current collector exceeds 1.5% by mass has a smaller discharge capacity than the experimental batteries 1 to 3, and in particular, the larger the current, the higher the discharge capacity. Is significantly below.
This is thought to be because the pits formed on the surface of the positive electrode current collector are smaller in diameter than the lithium iron phosphate particles, so that the lithium iron phosphate particles are not sufficiently accommodated in the pits. It is done.
From the above results, it was found that the zinc content of the positive electrode current collector is preferably in the range of 0.1 to 1.5% by mass.

  DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 1a ... Positive electrode collector (foil for positive electrode collectors), 1b ... Positive electrode mixture layer, 1c ... Positive electrode active material, 1d ... Pit, 1e ... Crater-like pit, 2 ... Negative electrode, 2a ... Negative electrode collector Electrical body, 2b ... negative electrode mixture layer, 3 ... separator, 4 ... electrode group, 10 ... lithium ion secondary battery.

Claims (4)

Thickness of 10 to 50 μm containing 0.1 to 1.5% by mass of Zn, 0.03 to 0.07% by mass of Si, 0.08 to 0.11% by mass of Fe, and the balance of inevitable impurities and Al Made of aluminum alloy foil,
1 of lithium iron phosphate having a particle size of 0.3 to 3 μm, lithium manganate having a particle size of 3 to 20 μm, lithium cobaltate having a particle size of 3 to 30 μm, cobalt acid / manganese acid / lithium nickelate having a particle size of 10 to 15 μm A crater-like etching pit for accommodating a particulate positive electrode active material composed of seeds or two or more kinds is formed on the surface, and the etching pit has a diameter of 0.3 to ³ μm and is 10 ³ / mm ^2. The foil for a positive electrode current collector of a lithium ion secondary battery, characterized in that the density of the etching pits present at a density of 10 ⁵ pieces / mm ² or less and a diameter exceeding 3 μm is 10 pieces / mm ² or less. . Thickness of 10 to 50 μm containing 0.1 to 1.5% by mass of Zn, 0.03 to 0.07% by mass of Si, 0.08 to 0.11% by mass of Fe, and the balance of inevitable impurities and Al By subjecting the aluminum alloy foil to a surface treatment with an alkaline solution,
1 of lithium iron phosphate having a particle size of 0.3 to 3 μm, lithium manganate having a particle size of 3 to 20 μm, lithium cobaltate having a particle size of 3 to 30 μm, cobalt acid / manganese acid / lithium nickelate having a particle size of 10 to 15 μm Method for producing aluminum alloy foil for positive electrode current collector of lithium ion secondary battery, wherein crater-like etching pits for accommodating particulate or two or more kinds of particulate positive electrode active materials are formed on the surface of said aluminum alloy foil Because
By performing a surface treatment of the alkaline solution, the etching pits have a diameter of 0.3 to 3 μm and a size of 10 ³ Piece / mm ² 10 or more ⁵ Piece / mm ² The density of the etching pit exceeding 3 μm in diameter is 10 / mm. ² The manufacturing method of the foil for positive electrode collectors of a lithium ion secondary battery characterized by the following. A positive electrode current collector, a positive electrode active material , a conductive material , a positive electrode having a binder, and a diluent ; a negative electrode current collector, a negative electrode active material , a conductive material, and a negative electrode having a binder; and the positive electrode current collector comprises: A lithium ion secondary battery excellent in high- rate discharge characteristics, comprising the positive electrode current collector foil according to Item 1. The positive electrode active material is lithium iron phosphate, the conductive material is acetylene black, the binder is polyvinylidene fluoride, the diluent is N-methyl-2-pyrrolidone, and the negative electrode current collector The lithium ion secondary battery excellent in high-rate discharge characteristics according to claim 3, wherein is a copper foil and the negative electrode active material is mesocarbon microbeads.

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