JP6926910B2 - Rechargeable battery - Google Patents

Description

The present invention relates to a secondary battery. In particular, the present invention relates to a secondary battery including an electrode stacking unit.

Since the secondary battery is a so-called storage battery, it can be repeatedly charged and discharged, and is used for various purposes. For example, secondary batteries are used in mobile devices such as mobile phones, smartphones and notebook computers.

The secondary battery is composed of at least a positive electrode, a negative electrode, and a separator between them. The positive electrode is composed of a positive electrode material layer and a positive electrode current collector, and the negative electrode is composed of a negative electrode material layer and a negative electrode current collector. In a general secondary battery electrode assembly, a plurality of such positive electrodes and negative electrodes are laminated via a separator, and the electrode assembly having such a laminated body form is housed in an exterior body.

JP-A-2002-042855 Japanese Unexamined Patent Publication No. 2014-167938

The inventor of the present application noticed that there is a problem to be overcome with the conventional secondary battery, and found that it is necessary to take measures for that purpose. Specifically, the inventor of the present application has found that there are the following problems.

The separator used in the secondary battery secures the ionic conductivity between the positive electrode and the negative electrode while separating the positive electrode and the negative electrode. Although many polyolefin-based separators (particularly polyolefin-based microporous membranes) have been used conventionally, it is also conceivable to use a ceramic separator as a separator for a secondary battery.

The inventor of the present application states that the ceramic separator is excellent in thermal stability in a high temperature environment, and although a secondary battery with improved safety can be expected in that respect, there is still a problem in terms of electrical stability. Found.

Specifically, the ceramic separator is positioned between the positive electrode and the negative electrode, and if it is exposed to greater stress during battery fabrication and / or when the battery is used, it may cause short-circuit defects. I found that there is.

The present invention has been made in view of such a problem. That is, a main object of the present invention is to provide a secondary battery having further improved electrical stability from the viewpoint of a separator.

The inventor of the present application has attempted to solve the above problems by dealing with it in a new direction, rather than dealing with it as an extension of the prior art. As a result, they have invented a technology for manufacturing a secondary battery that has achieved the above-mentioned main purpose.

The present invention is a secondary battery comprising an electrode stacking unit including a positive electrode, a negative electrode, and an interelectrode separator between the positive electrode and the negative electrode.
A battery in which one of the positive electrode and the negative electrode current collector forms both outermost layers of the electrode laminated unit, but extends from both outermost layers and covers the side surface of the unit corresponding to a part of the side surface of the electrode laminated unit. It forms a side part and
A side separator is provided between the side surface of the unit and the side surface of the battery, and the side separator is a ceramic separator.
A secondary battery is provided in which a current collector forming both outermost layers and a side separator are in close contact with each other on the side surface of the battery.

In the present invention, the electrical stability is further improved from the viewpoint of the separator. Therefore, it becomes easy to obtain a desired secondary battery.

In particular, in the present invention, the occurrence of short-circuit defects can be suppressed even when a ceramic separator is used. That is, according to the present invention, the secondary battery provided with the ceramic separator more preferably avoids the occurrence of an inconvenient short circuit even if it receives greater stress during its manufacture and / or use, and is electrically operated. It is a better battery in terms of stability.

Schematic cross-sectional view showing the configuration of the secondary battery of the present invention. Schematic cross-sectional view for explaining an integrated separator (an integrated structure of a lateral separator and an inter-electrode separator). Schematic cross-sectional view for explaining the specific thickness-dimensional relationship and density relationship between the side separator and the electrode-to-electrode separator. Schematic cross-sectional view for explaining the mode in which the polar material layer extends between the side surface of the unit and the side surface of the battery. Schematic process cross-sectional view illustrating the manufacturing process of the secondary battery of the present invention. Schematic cross-sectional view to illustrate a side separator positioned only with respect to a single battery side. Schematic cross-sectional view for explaining an electrode assembly having a two-dimensional laminated structure. Schematic perspective view for explaining the first test (confirmation test regarding the adhesion characteristics of the ceramic separator). 2nd test (effect confirmation test of ceramic separator thickness on the side surface of the folded battery), 3rd test (effect confirmation test of ceramic separator density on the side surface of the folded battery) and 4th test (pole material of the side surface of the folded battery) Schematic cross-sectional view for explaining the effect confirmation test of the layer)

Hereinafter, the "secondary battery" according to the embodiment of the present invention will be described in more detail. Although explanations will be given with reference to the drawings as necessary, the various elements in the drawings are merely schematically and exemplified for the understanding of the present invention, and the appearance, dimensional ratio, etc. may differ from the actual ones. ..

The “cross-sectional view (or cross-sectional view)” described directly or indirectly in the present specification is two along the stacking direction (thickness direction of the battery or the electrode material layer) of the electrode material layers constituting the secondary battery. It is based on a virtual cross section of the next battery.

Further, the vertical direction and the horizontal direction, which are used directly or indirectly in the present specification, correspond to the vertical direction and the horizontal direction in the drawings, respectively. Unless otherwise specified, the same code or symbol shall indicate the same member or the same meaning.

[General / basic configuration of secondary battery]
The term "secondary battery" as used herein refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery obtained by the manufacturing method of the present invention is not excessively bound by the name, and for example, a power storage device and the like can be included in the subject.

General or basic matters related to the electrode lamination unit included in the secondary battery of the present invention will be described. The secondary battery includes an electrode stacking unit in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. FIG. 7 schematically illustrates an electrode lamination unit of a general secondary battery. As shown in the figure, in a general secondary battery, a positive electrode and a negative electrode are stacked via a separator to form an electrode constituent layer, and at least one or more such electrode constituent layers are laminated to form an electrode lamination unit. Is configured. In a general secondary battery, such an electrode lamination unit is enclosed in an exterior body together with an electrolyte (for example, a non-aqueous electrolyte).

The positive electrode is composed of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, a positive electrode material layer is provided on at least one surface of the positive electrode current collector, and the positive electrode material layer contains a positive electrode active material as an electrode active material. For example, the positive electrode in the electrode stacking unit may be provided with positive electrode material layers on both sides of the positive electrode current collector, or may be provided with positive electrode material layers on only one side of the positive electrode current collector.

The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, a negative electrode material layer is provided on at least one surface of the negative electrode current collector, and the negative electrode material layer contains a negative electrode active material as an electrode active material. For example, the negative electrode in the electrode stacking unit may be provided with negative electrode material layers on both sides of the negative electrode current collector, or may be provided with negative electrode material layers on only one side of the negative electrode current collector.

The electrode active materials contained in the positive electrode and the negative electrode, that is, the positive electrode active material and the negative electrode active material are substances that are directly involved in the transfer of electrons in the secondary battery, and are the main substances of the positive and negative electrodes that are responsible for charge / discharge, that is, the battery reaction. be. More specifically, ions are brought to the electrolyte due to the "positive electrode active material contained in the positive electrode material layer" and the "negative electrode active material contained in the negative electrode material layer", and such ions are transferred between the positive electrode and the negative electrode. The electrons are transferred and charged / discharged. The positive electrode material layer and the negative electrode material layer are particularly preferably layers capable of occluding and releasing lithium ions. That is, it is preferable that the non-aqueous electrolyte secondary battery is a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via the non-aqueous electrolyte to charge and discharge the battery. When lithium ions are involved in charging / discharging, the secondary battery corresponds to a so-called lithium ion battery, and the positive electrode and the negative electrode have layers capable of occluding and discharging lithium ions.

When the positive electrode active material of the positive electrode material layer is made of, for example, granules, it is preferable that the positive electrode material layer contains a binder for sufficient contact between particles and shape retention. Further, a conductive auxiliary agent may be contained in the positive electrode material layer in order to facilitate the transfer of electrons that promote the battery reaction. Similarly, when the negative electrode active material of the negative electrode material layer is composed of particles, for example, it is preferable that the negative electrode active material contains a binder for sufficient contact between particles and shape retention, and facilitates the transfer of electrons that promote the battery reaction. A conductive auxiliary agent may be contained in the negative electrode material layer. As described above, since the form is composed of a plurality of components, the positive electrode material layer and the negative electrode material layer can also be referred to as a positive electrode mixture layer and a negative electrode mixture layer, respectively.

The positive electrode active material is preferably a substance that contributes to the occlusion and release of lithium ions. From this point of view, the positive electrode active material is preferably, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material is preferably a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese and iron. That is, in the positive electrode material layer of the secondary battery obtained by the production method of the present invention, such a lithium transition metal composite oxide is preferably contained as the positive electrode active material. For example, the positive electrode active material may be lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, or a part of the transition metal thereof replaced with another metal. Such a positive electrode active material may be contained as a single species, but may be contained in combination of two or more species. Although it is merely an example, in the secondary battery obtained by the production method of the present invention, the positive electrode active material contained in the positive electrode material layer may be lithium cobalt oxide.

The binder that can be contained in the positive electrode material layer is not particularly limited, but is limited to, but is not limited to, a polyvinylidene fluoride, a vinylidene fluoride-hexafluoropropylene copolymer, a bilinidene fluoride-tetrafluoroethylene copolymer, and the like. At least one selected from the group consisting of polytetrafluoroethylene and the like can be mentioned. The conductive auxiliary agent that can be contained in the positive electrode material layer is not particularly limited, but is limited to carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes, and vapor phase growth. At least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned. For example, the binder of the positive electrode material layer may be polyvinylidene fluoride, and the conductive auxiliary agent of the positive electrode material layer may be carbon black. Although only an example, the binder and the conductive auxiliary agent of the positive electrode material layer may be a combination of polyvinylidene fluoride and carbon black.

The negative electrode active material is preferably a substance that contributes to the occlusion and release of lithium ions. From this point of view, the negative electrode active material is preferably, for example, various carbon materials, oxides, lithium alloys, or the like.

Examples of various carbon materials for the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, and diamond-like carbon. In particular, graphite is preferable because it has high electron conductivity and excellent adhesion to a negative electrode current collector. Examples of the oxide of the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide and the like. The lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium, for example, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of a metal such as La and lithium. It is preferable that such an oxide is amorphous as its structural form. This is because deterioration due to non-uniformity such as grain boundaries or defects is less likely to occur. Although it is merely an example, in the secondary battery obtained by the manufacturing method of the present invention, the negative electrode active material of the negative electrode material layer may be artificial graphite.

The binder that can be contained in the negative electrode material layer is not particularly limited, but is at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide-based resin, and polyamide-imide-based resin. Can be mentioned. For example, the binder contained in the negative electrode material layer may be styrene-butadiene rubber. The conductive auxiliary agent that can be contained in the negative electrode material layer is not particularly limited, but is limited to carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes, and vapor phase growth. At least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned. The negative electrode material layer may contain a component derived from a thickener component (for example, carboxylmethyl cellulose) used at the time of manufacturing the battery.

Although only an example, the negative electrode active material and the binder in the negative electrode material layer may be a combination of artificial graphite and styrene-butadiene rubber.

The positive electrode current collector and the negative electrode current collector used for the positive electrode and the negative electrode are members that contribute to collecting and supplying electrons generated by the active material due to the battery reaction. Such a current collector may be a sheet-shaped metal member and may have a perforated or perforated form. For example, the current collector may be a metal leaf, a punching metal, a net, an expanded metal, or the like. The positive electrode current collector used for the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel and the like, and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector used for the negative electrode is preferably one made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel and the like, and may be, for example, a copper foil.

The separator used for the positive electrode and the negative electrode is a member provided from the viewpoint of preventing a short circuit due to contact between the positive and negative electrodes and retaining an electrolyte. In other words, the separator can be said to be a member through which ions pass while preventing electronic contact between the positive electrode and the negative electrode. Preferably, the separator is a porous or microporous insulating member and has a film morphology due to its small thickness. Although only an example, a microporous polyolefin membrane may be used as the separator. In this regard, the microporous membrane used as the separator may contain, for example, only polyethylene (PE) or polypropylene (PP) as the polyolefin. Furthermore, the separator may be a laminate composed of a "microporous membrane made of PE" and a "microporous membrane made of PP".

In a general secondary battery, an electrode stacking unit including a positive electrode, a negative electrode, and a separator is enclosed in the exterior together with an electrolyte. When the positive electrode and the negative electrode have a layer capable of occluding and releasing lithium ions, the electrolyte is preferably a "non-aqueous" electrolyte such as an organic electrolyte or an organic solvent (that is, the electrolyte is a non-aqueous electrolyte). preferable). In the electrolyte, metal ions emitted from the electrodes (positive electrode / negative electrode) are present, and therefore, the electrolyte assists the movement of the metal ions in the battery reaction.

A non-aqueous electrolyte is an electrolyte containing a solvent and a solute. As a specific solvent for the non-aqueous electrolyte, a solvent containing at least carbonate is preferable. Such carbonates may be cyclic carbonates and / or chain carbonates. Although not particularly limited, the cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC). be able to. Examples of the chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC). Although only an example, a combination of cyclic carbonates and chain carbonates may be used as the non-aqueous electrolyte, and for example, a mixture of ethylene carbonate and diethyl carbonate is used. Further, as a specific non-aqueous electrolyte solute, for example, a Li salt such as _{LiPF 6} and / or LiBF _{4 is preferably used.} The electrolyte of the secondary battery may be classified as a polymer electrolyte.

The exterior body of a general secondary battery encloses an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated, but may be in the form of a hard case or in the form of a soft case. There may be. Specifically, the exterior body may be a hard case type corresponding to a so-called metal can, or a soft case type corresponding to a pouch made of a so-called laminated film.

[Secondary battery of the present invention]
The secondary battery of the present invention is characterized by an overall battery structure related to an electrode current collector and a separator related thereto. In particular, the secondary battery of the present invention is characterized by the extending form of the electrode current collector that determines the overall structure of the battery, and is also characterized by the separator related to the extending form.

Specifically, in the secondary battery 1 of the present invention, in the electrode lamination unit 100 provided with the positive electrode, the negative electrode and the inter-electrode separator 10 between them, the current collector 20 of either the positive electrode or the negative electrode is an electrode. While forming both outermost layers 120 of the laminated unit 100, it forms a battery side surface portion 160 extending from both outermost layers 120 and covering a unit side surface 150 corresponding to a part side surface of the electrode laminated unit 100 (. (See FIG. 1). That is, as shown in FIG. 1, the secondary battery 1 of the present invention has a structure in which the current collector 20 constituting the electrode stacking unit 100 is largely folded back. In other words, the current collector 20 integrally forms the top wall and the bottom wall of the electrode stacking unit 100 as a whole, and also forms a side wall (specifically, a part of the side wall) of the electrode stacking unit 100. ..

In the present specification, the "electrode laminated unit" refers to an electrode laminated portion in which a positive electrode and a negative electrode are stacked on each other via a separator, and in a narrow sense, a positive electrode and a negative electrode are interposed via a separator. It refers to an electrode laminated portion formed by stacking one of them so as to be sandwiched between the other. Further, in the present specification, the "both outermost layers of the electrode lamination unit" refers to a layer located on the outermost side in the electrode lamination portion of the positive electrode and the negative electrode via a separator, and in a narrow sense. Refers to the two outermost layers (the uppermost layer and the lowest layer facing each other in the electrode stacking direction) of the electrode laminated portions stacked so that one of the positive electrode and the negative electrode is sandwiched by the other via the separator. Further, in the present specification, the "partial side surface of the electrode stacking unit" refers to at least a part of the side surface of the electrode stacking unit in a broad sense, and in a narrow sense, the current collection of the "both outermost layers". It refers to a part of the side area of the electrode stacking unit captured excluding the body.

In the secondary battery of the present invention, as an overall structure, the outer current collector 20 constituting the electrode lamination unit 100 is extended so as to be largely folded back. In combination with the extending form of the electrode current collector, the secondary battery of the present invention has a peculiar installation form of the separator. Specifically, a side separator 15 is provided between the unit side surface 150 and the battery side surface portion 160. As can be seen with reference to FIG. 1, a side separator 15 is provided between the "electrode laminating unit side surface 150" and the "current collector 20 having a folded form as a whole and forming the battery side surface 160". It can be said that it has been done. As described above, in the secondary battery of the present invention, in addition to the separator of the component of the electrode lamination unit (that is, the separator between the electrodes 10 between the positive electrode and the negative electrode), the side which becomes the non-electrode lamination element of the electrode lamination unit. It has a square separator 15.

As can be seen from the form shown in FIG. 1, the side separator 15 provided in the secondary battery is positioned at the folded-back portion of the current collectors 20 in both outermost layers. In the secondary battery of the present invention, such a side separator is a ceramic separator. That is, the side separator 15 is a separator made of a material different from the conventionally used polyolefin-based separator. The term "ceramic separator" as used herein means a separator in which the proportion of the ceramic component accounts for the majority of all the components constituting the separator. For example, the content of the ceramic component is 60 volumes based on the total volume. % Or more, preferably 65% by volume or more. Also, preferably, the ceramic separator in the present invention does not have the pore structure or fibrous structure usually used in polyolefins, and is therefore a substantially solid separator.

The ceramic component in the ceramic separator can correspond to, for example, an oxide component and / or a nitride component. Specifically, the ceramic component may be at least one component selected from the group consisting of alumina, silica, titania, magnesia, barium titanate, silicon nitride and aluminum nitride.

The ceramic separator may be provided as a granular body composed of granular ceramic components. In such cases, a binder component may be included for better contact between the particles and shape retention. As such a binder component, at least one selected from the group consisting of polyvinylidene fluoride (PVDF), phenoxy resin, epoxy resin, polyvinyl butyrate resin, polyvinyl alcohol resin, urethane resin, acrylic resin, ethyl cellulose, methyl cellulose and carboxymethyl cellulose. It may be an organic material of.

The ceramic separator itself used in the present invention can be formed by applying a ceramic raw material consisting of at least a mixture of a ceramic component and an organic material. More preferably, it can be obtained by applying a ceramic raw material slurry containing a ceramic component, an organic material and an organic solvent, and then drying the slurry. Examples of the organic solvent used in this raw material slurry include N-methylpyrrolidone (NMP), methylethylketone (MEK), isopropyl alcohol (IPA), ethanol, acetone, acetonitrile, ethyl acetate, butyl acetate, toluene, tetrahydrofuran (THF), N, At least one selected from the group consisting of N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) can be mentioned. Typically, the coating layer obtained by applying the ceramic raw material slurry can be dried to vaporize the organic solvent in the slurry and remove it from the coating layer, whereby the ceramic separator. You may get.

In the secondary battery of the present invention, the side separator has a structure in which it is in close contact with other layers. Specifically, the current collector 20 forming both outermost layers and the side separator 15 are in close contact with each other at the battery side surface portion 160. As can be seen from the form shown in FIG. 1, this means that at least two layers constituting the folded portion of the secondary battery of the present invention are substantially in close contact with each other. With such a close contact structure, the structural strength of the "folded portion" is increased, and a higher structural strength can be provided in the secondary battery. More specifically, in the structure of the secondary battery, the folded portion is composed of a single layer of a separator layer and a current collector, respectively. Therefore, it is usually considered that the folded-back portion has a lower structural strength than the electrode laminated portion of the electrode stacking unit, but in the present invention, the reduced structural strength can be compensated for by forming a close contact layer structure. It can, and thus, higher structural strength can be provided to the secondary battery.

Even though the secondary battery of the present invention contains a ceramic separator, as can be seen from Examples described later, the occurrence of short-circuit defects is further suppressed. That is, conventionally, although ceramic separators are excellent in thermal stability in a high temperature environment, it has been considered that there is a problem in electrical stability. In the secondary battery of the present invention, a battery having a ceramic separator and improved characteristics in terms of electrical stability has been realized. More specifically, according to the present invention, a secondary battery provided with a ceramic separator more preferably avoids an inconvenient short circuit even if it is subjected to greater stress during its manufacture and / or use. , It is a better battery in terms of electrical stability.

In one preferred embodiment, the lateral separator 15 and the interelectrode separator 10 are integrated with each other (see FIG. 2). That is, the separator 15 between the unit side surface 150 and the battery side surface portion 160 has a form integrated with the separator 10 included in the electrode laminated portion of the electrode laminated unit 100. This means that the separator of the component of the electrode laminated unit and the separator of the non-electrode laminated element of the electrode laminated unit are in a continuous form with each other. As can be seen from the illustrated aspect, at least one separator of the secondary battery of the present invention constitutes the electrode laminated portion of the electrode laminated unit, but extends outward from the electrode laminated portion and is folded back. There is. When the side separator and the inter-electrode separator are integrated with each other, these separators can be provided collectively, which contributes to a simple manufacturing process. Further, since the side separator and the inter-electrode separator integrated with each other can exert the separator function as a whole, short-circuit prevention and the like can be further promoted.

Preferably, the interelectrode separator 10 as well as the lateral separator 15 also forms a ceramic separator. That is, it is preferable that both the "separator 15 between the unit side surface 150 and the battery side surface portion 160" and the "separator 10 included in the electrode laminated portion of the electrode laminated unit" are ceramic separators. More preferably, the side separator 15 integrated with each other and the inter-electrode separator 10 form a ceramic separator. In the secondary battery of the present invention having such characteristics, although the electrode laminated portion of the electrode laminated unit is formed, the separator extending outward from the electrode laminated portion and folded back as a whole is called a ceramic separator. It can be said that it has become. When both the side separator and the inter-electrode separator are ceramic separators, it is not necessary to change the raw material between them, which can be a simple manufacturing process. Further, when the side separator and the inter-electrode separator are made of the same ceramic material, the material anisotropy of the secondary battery separator as a whole is further reduced, and the battery design can be facilitated.

In the secondary battery of the present invention, the lateral separator and the inter-electrode separator may have a thickness-dimensional relationship peculiar to each other. In one preferred embodiment, the thickness dimension of the lateral separator is greater than the thickness dimension of the interelectrode separator. For example, if the average thickness dimension of the side separator 15 is T1 and the average thickness dimension of the interelectrode separator 10 on one side is T2, it is preferable that T1> T2. To give a concrete example of this, for example, 1.2 × T2 <T1 <5 × T2 (more specifically, 1.25 × T2 ≦ T1 ≦ 4 × T2) may be used. With such a thickness-dimensional relationship, the occurrence of short-circuit defects can be suppressed more effectively. That is, the secondary battery of the present invention satisfying the relationship of T1> T2 more preferably avoids the occurrence of an inconvenient short circuit even if it receives a larger stress during production and / or use. It is superior in terms of electrical stability. The "average thickness dimension T1" of the side separator referred to here is within a predetermined range corresponding to the thickness width of the electrode body that is not "folded back" in the cross-sectional view as shown in FIG. Substantially means the average thickness of. Simply, in the cross-sectional view as shown in FIG. 3, when the uppermost surface level of the electrode body not attached to the "folding back" is virtually extended in the lateral direction, it becomes the side separator 15. The thickness at the upper point where it intersects, the thickness at the lower point where it intersects the lateral separator 15 when the lowermost level of the electrode body is virtually extended in the lateral direction, and the current collector level of the electrode body. The arithmetic mean of the intermediate point thickness at the point where it intersects the lateral separator 15 when virtually extended laterally may be adopted (if there are multiple collectors 45, at each level). An arithmetic mean that takes into account the thickness of the intersection may be used). On the other hand, the "one-sided average thickness dimension T2" of the inter-electrode separator substantially means the overall average thickness of a single inter-electrode separator. Simply, the "one-sided average thickness" of the inter-electrode separator is defined as the electrode layer 48 (that is, electrode lamination) that is in contact with the target inter-electrode separator 10 on the inside in a cross-sectional view as shown in FIG. The arithmetic mean of the thicknesses at the two edge points of the electrode layer located relatively inward when viewed along the stacking direction of the portions) may be adopted.

The suitable thickness difference between the lateral separator and the electrode-to-electrode separator as described above can be obtained by locally changing the thickness of the separator raw material layer or by pressing the separator raw material layer at least partially. This may be achieved (see FIG. 5 below).

As can be seen from the fact that the thickness (thickness dimension) of the side separator is referred to as "average thickness dimension" above, it is not always necessary that the thickness is constant as a whole, and the thickness is locally. It may have changed. For example, the thickness of the side separator 15 increases from the inside to the outside relatively along the stacking direction of the electrode laminated portions (that is, from the central portion to the upper side or the lower side when viewed in a cross-sectional view as shown in FIG. 3). Its thickness may increase (as it goes toward). As described above, even if the lateral separator has a local difference in its thickness, the "average thickness dimension" T1 as described above is within a certain range (for example, the electrode as described above). Current collector and / or electrode material in the electrode body that is not "folded back", 1.2 x T2 <T1 <5 x T2 in relation to the thickness T2 of the inter-separator) Shorts with layers can be suppressed more effectively.

Further, in the secondary battery of the present invention, the lateral separator and the inter-electrode separator may have a specific density relationship with each other. In one preferred embodiment, the density of the lateral separator is greater than the density of the interelectrode separator. For example, when the average density of the side separator 15 is D1 and the average density of the interelectrode separator 10 is D2 (see FIG. 3), it is preferable that D1> D2. To give a concrete example of this, for example, D1 may have a density increased by about 2% to 15% as compared with D2 (that is, 1.02 × D2 ≦ D1 ≦ 1.15 × D2). More specifically, the density may be increased by about 4% to 10% from D2 (that is, 1.04 × D2 ≦ D1 ≦ 1.10 × D2). Having such a density relationship, the occurrence of short-circuit defects can be suppressed more effectively. That is, the secondary battery of the present invention satisfying the relationship of D1> D2 more preferably avoids the occurrence of an inconvenient short circuit even if it receives a larger stress during production and / or use, and is electrically operated. Better in terms of stability. The "average density D1" of the side separator referred to here is within a predetermined range corresponding to the thickness width of the electrode body that is not "folded back" in the cross-sectional view as shown in FIG. It effectively means the average density. Simply, in the cross-sectional view as shown in FIG. 3, when the uppermost surface level of the electrode body not attached to the "folding back" is virtually extended in the lateral direction, it becomes the side separator 15. The density at the upper point where it intersects, the density at the lower point where it intersects the lateral separator 15 when the bottom surface level of the electrode body is virtually extended in the lateral direction, and the current collector level of the electrode body. The arithmetic mean of the intermediate point densities at the points where it intersects the lateral separator 15 when virtually extended laterally may be adopted (if there are multiple collectors 45, the intersection at each level). An arithmetic mean that takes into account the density of points may be used). On the other hand, the "average density D2" of the inter-electrode separator substantially means the overall average density of the single inter-electrode separator of interest. Simply, the "average density" of the inter-electrode separator is defined as the electrode material layer 48 (that is, the laminating direction of the electrode laminated portion) that is in contact with the inter-electrode separator 10 inside in a cross-sectional view as shown in FIG. The arithmetic mean of the densities at the two edge points of the electrode layer located relatively inward when viewed along the above may be adopted.

Such a suitable density difference between the lateral separator and the inter-electrode separator can be achieved, for example, by changing the ceramic raw material slurry between the lateral separator and the inter-electrode separator. A suitable density difference between the lateral separator and the inter-electrode separator can also be achieved by at least partially pressing the separator raw material layer. Furthermore, the density difference of the ceramic separator can be achieved by changing the ceramic component concentration (volume concentration) in the ceramic raw material slurry corresponding to so-called PVC in addition to or instead of such a pressing process.

Inclusive of the features described above, when comparing the lateral separator and the interelectrode separator in the secondary battery of the present invention according to a certain preferred embodiment, at least one of the thickness and density of the former is higher than that of the latter. Is also getting bigger. That is, the lateral separator has a larger thickness than the inter-electrode separator, and / or the lateral separator has a higher density than the inter-electrode separator. In a secondary battery having the characteristics of such a side separator and an electrode-to-electrode separator, the occurrence of short-circuit defects can be suppressed more effectively.

In the secondary battery of the present invention, one of the positive electrode layer and the negative electrode layer may extend from the electrode lamination unit and be provided between the unit side surface 150 and the battery side surface portion 160 (FIG. 4). reference). That is, as shown in the figure, the unit electrode material layer included in the electrode laminated portion of the electrode laminated unit and the lateral electrode material layer extending outward from the electrode laminated portion and extending to the side of the electrode laminated unit. It is preferable that they are integrated with each other. In other words, although a part of the electrode material layer of the secondary battery of the present invention constitutes the electrode laminated portion of the electrode laminated unit, it extends outward from the electrode laminated portion and is folded back as a whole. It can be said that there is. When there is a lateral electrode material layer having a form extending on the side of the electrode lamination unit as described above, the battery capacity can be additionally formed on the side as well. That is, in addition to the capacity formation in the stacking direction of the electrode stacking unit, the capacity can be formed in the lateral direction orthogonal to the capacity formation, so that the capacity of the secondary battery as a whole can be further improved.

The lateral electrode layer preferably has a structure in close contact with other layers. Specifically, it is preferable that the electrode material layer is in close contact with the side separator 15 at least on the side surface of the battery. As can be seen from the form shown in FIG. 4, this means that at least two layers constituting the folded portion of the secondary battery of the present invention are substantially in close contact with each other. With such a close contact structure, the structural strength of the "folded portion" is increased, and the secondary battery provides high structural strength. In particular, in addition to the current collectors forming the outermost layers of the battery and the side separators being in close contact with each other on the side surface of the battery, the electrode material layer is in close contact with the side separators, so that the "folded portion" is formed. The structural strength will be particularly increased. That is, the folded portion of the secondary battery of the present invention has a configuration in which the current collector forming both outermost layers, the side separator, and the side electrode material layer are in close contact with each other. Has higher structural strength. The term "at least on the side surface of the battery" here means that the electrode layer is not only in close contact with the side separator, but may also be in close contact with the inter-electrode separator. There is.

The secondary battery of the present invention can be obtained by various manufacturing processes. With reference to FIGS. 5 (a) to 5 (e), a certain manufacturing process mode will be described exemplarily. First, as shown in FIG. 5A, a metal layer member 20'which serves as an electrode current collector is prepared. The metal layer member 20'is not particularly limited as long as it is used as an electrode current collector. When the current collectors of the "both outermost layers" are the positive electrode current collectors, the metal layer member 20'is made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel and the like. It's okay. On the other hand, when the current collectors of the "both outermost layers" are the negative electrode current collectors, the metal layer member 20'is made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel and the like. It may consist of.

Next, as shown in FIG. 5B, the electrode material layer 30'of either the positive electrode material layer or the negative electrode material layer is formed on the metal layer member 20'. Specifically, a polar material layer raw material containing at least an active material (positive electrode active material or negative electrode active material) and a binder is applied to form a polar material layer 30'. As shown, it is preferable to form two subpolar material layers 30A and 30B that are separated from each other.

Next, as shown in FIG. 5C, a separator layer 10'which is a base for the interelectrode separator and the lateral separator is formed. Specifically, the separator layer 10'is formed on the two sub-pole material layers 30A and 30B separated on the metal layer member 20' so as to straddle both of them. The separator raw material is entirely coated on the metal layer member 20'to form the separator raw material, but the upper surface of the separator raw material layer after coating is non-uniform (a partially recessed separator raw material layer 10'as shown). For example, a screen printing method may be used to obtain the above. From the above, it is possible to obtain the precursor member 40'for folding back, which is to be subjected to folding back bending later.

Next, as shown in FIG. 5D, the precursor member 40'for folding back is bent so as to be folded back with the electrode material layer member 50'that is the other of the positive electrode material layer and the negative electrode material layer interposed therebetween. More specifically, while the polar material layer member 50'is sandwiched by the folding precursor member 40', the polar material layer 30'and the separator layer 10'of the precursor member 40'are on the inside. The precursor member 40'is bent so as to be totally folded back. By going through at least the above steps, the secondary battery 1 of the present invention can be obtained.

The secondary battery of the present invention can be embodied in various aspects. It will be described in detail below.

(Aspect of single side installation of side separator)
In the secondary battery of this aspect, the side separator is arranged only on a part of the side surface of the electrode lamination unit (see FIG. 6). In particular, due to the fact that the current collector 20 constituting the electrode stacking unit has an overall structure that is folded back as a whole, the side separator 15 is a plurality of unit side surfaces (more specifically, more specifically) in the electrode stacking unit. , For example, four sides located at the same height level) may be positioned only on a single side. In such an embodiment, the side separator can be more easily provided in the manufacturing process as shown in FIG. 5, which contributes to the realization of a secondary battery which is also preferable in terms of manufacturing efficiency.

Insulation sealing portions may be provided on the side surfaces of other units that are not provided with the side separator. That is, the insulation sealing portion is provided on the side surface other than the single side surface provided with the side separator 15 among the plurality of unit side surfaces (more specifically, for example, four side surfaces located at the same height level). It may be (see FIG. 1). As shown in the figure, where the current collectors forming the top wall and bottom wall of the electrode lamination unit extend so as to project in a cross-sectional view, the space between the extending portions of the opposing current collectors is filled. It is preferable that the insulation sealing portion is provided as described above. The "insulation sealing portion" as used herein refers to a member that "insulates" the electrode constituent layer of the electrode lamination unit from the outside and "seals" the electrode constituent layer from the external environment. The material of the insulating sealing portion is not particularly limited as long as it provides "insulating property" and "sealing property". For example, the material of the insulating sealing portion may be a resin material, and may be a resin material containing polypropylene, which is merely an example.

When the insulation sealing portion is provided, an electrolyte may be provided inside the insulating sealing portion. That is, the electrolyte may be sealed inside the folded-back portion and the insulating sealing portion of the secondary battery. Since such an embodiment does not particularly require the installation of an exterior body, it leads to the realization of a more compact secondary battery.

(Aspect of the outermost negative electrode layer of the electrode lamination unit)
In the secondary battery of this aspect, the outermost side of the electrode lamination unit forms the negative electrode. That is, in the electrode lamination unit, the negative electrode is the outermost electrode, and the positive electrode is provided between the negative electrodes. In this case, the negative electrode forming the outermost electrode preferably corresponds to a so-called “single-sided electrode”. That is, it is preferable that the electrodes positioned on the top wall portion and the bottom wall portion of the electrode lamination unit are single-sided negative electrodes.

In this aspect, the current collector forming both outermost layers is the negative electrode current collector. That is, the negative electrode current collector integrally forms the top wall and the bottom wall of the electrode stacking unit as a whole, and also forms the side wall of the electrode stacking unit. For example, as the negative electrode current collector, a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel, etc. forms the top wall and bottom wall of the electrode lamination unit and also the side wall of the electrode lamination unit. It is made up. As can be seen from the illustrated form, such a negative electrode current collector is largely folded back while forming an electrode lamination unit. From the viewpoint of more preferably exhibiting such folded structure resistance, the negative electrode current collector may be made of stainless steel and / or nickel or the like.

When both outermost electrodes of the electrode lamination unit form a negative electrode, the positive electrode is provided so as to be sandwiched between the two outermost negative electrodes. Such a positive electrode is preferably a double-sided electrode in which positive electrode material layers are provided on both main surfaces of the positive electrode current collector. This is because the battery capacity of the electrode lamination unit can be more suitable.

Although the embodiments of the present invention have been described above, they merely exemplify typical examples. Therefore, those skilled in the art will easily understand that the present invention is not limited to this, and various aspects are conceivable.

For example, as one of the above aspects, a secondary battery without an exterior body has been mentioned, but the present invention is not particularly limited thereto. For example, in the secondary battery of the present invention, the exterior body may be additionally provided so that the electrode laminated unit formed by folding back the current collectors of both outermost layers is wrapped in the exterior body as a whole.

Various tests were conducted to confirm the effect of the secondary battery of the present invention.

[First test: Confirmation test for adhesion characteristics of ceramic separator]
A test was conducted to confirm the adhesion characteristics of the ceramic separator attached to the folded bend. In particular, the adhesion characteristics between the "ceramic separator" and the "current collectors that are the outermost layers of both" and the adhesion characteristics between the "ceramic separator" and the "polar material layer" were confirmed.

A peeling test was conducted using a laminated test piece that imitated the lamination of a secondary battery. The layers used for such a laminated test piece are as follows.

-Current collector: Electrolytic copper foil (manufactured by Nippon Foil Co., Ltd., thickness 10 μm)

-Ceramic separator layer: A layer formed by applying the raw material slurry of the ceramic separator used in the following tests 2 to 4 to a current collector or an electrode material layer and drying it.

-Double-sided tape: Made by 3M Japan, (Product name) Scotch Super strong double-sided tape Premium Gold Versatile, 15 mm width

・ Auxiliary substrate: PET material, thickness 100 μm)

-Polar material layer: A layer formed by applying the electrode material raw material slurry of the negative electrode material used in the following 2nd to 4th tests to ceramic and drying it.

As shown in FIG. 8, two types of laminated test specimens were prepared. As the laminated test body A, a laminated body in which an auxiliary substrate 240, a double-sided tape 230, a ceramic separator layer 220, and a current collector 210 were laminated in this order from the bottom was used. On the other hand, as the laminated test body B, a laminated body in which the auxiliary substrate 240, the double-sided tape 230, the ceramic separator layer 220, the electrode material layer 250, and the current collector 210 were laminated in this order from the bottom was used. An external peeling force was applied to each laminated test piece, and it was investigated which part was destroyed or peeled off. More specifically, the adhesion per unit width was confirmed by measuring the load when the product was pulled at a tensile speed of 500 mm / sec using a testing machine (manufactured by A & D Co., Ltd., model TENSILON RTF1210).

The results are shown in Table 1.

As can be seen from Table 1, it was found that the ceramic separator layer and the metal foil have high adhesion to each other. Therefore, it was found that there is a high possibility that the state of close contact with each other is maintained even if the integrated products are bent so as to be folded back.

Next, the second to fourth tests performed in connection with the secondary battery of the present invention will be described. The battery test specimens used in the second to fourth tests were prepared based on the methods described below.

(Polar material slurry of positive electrode material)
88 g of lithium cobalt oxide, 2 g of graphite (manufactured by Timcal, KS-6), and 6 g of graphite (Super P Li, manufactured by Timcal) were weighed.

Each of the weighed materials was placed in a 1000 mL pot, and PSZ pulverized media having a diameter of 1.0 mm and 200 g of N-methylpyrrolidone (hereinafter referred to as "NMP") as a solvent were added. Then, using a rolling ball mill, the mixture was mixed at 150 rpm for 24 hours and dispersed. As a result, the secondary particles of lithium cobalt oxide were crushed, and the average particle size D ₅₀ became 2.1 μm.

To the solution in which each material is dispersed as described above, 40 g of a 10 mass% NMP solution of polyvinylidene fluoride (Kureha Corporation, # 7208) is added, and further mixed at 150 rpm for 4 hours using a rolling ball mill. Then, a positive electrode raw material slurry was obtained.

(Polar material slurry of negative electrode material)
Graphite (manufactured by Mitsubishi Chemical Corporation, GTR7, average particle size D ₅₀ = 11.0 μm) 85 g, conductive aid (manufactured by Hitachi Chemical Co., Ltd., SMSC10-4V3) 15 g, NMP 100 g, polyvinylidene fluoride (Kureha Corporation) , # 7305), 53 g of 10 mass% NMP solution was weighed and stirred with a planetary mixer to obtain a graphite raw material slurry for the negative electrode.

(Ceramic separator raw material slurry)
80 g of spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size D ₅₀ = 0.3 μm) and 75 g of NMP as a solvent were put into a 500 mL pot. Further, a PSZ pulverized medium having a diameter of 5 mm was added, and the mixture was mixed at 150 rpm for 16 hours using a rolling ball mill and subjected to dispersion.

Next, 155 g of a binder solution (solution containing 10% by mass of PVDF-HFP, 67.5% by mass of NMP, and 22.5% by mass of MEK) of PVDF-HFP (SOLEF20216 HFP substitution amount 12 mol% manufactured by SOLVAY) was added, and a rolling ball mill was used. Mixing was carried out at 150 rpm for 4 hours to obtain a raw material slurry of a ceramic separator. In such an embodiment, a raw material slurry having a ceramic component concentration (corresponding to so-called pigment volume concentration PVC) of 70% was obtained.

(Making both outermost layers)
"Both outermost layers" to be attached to the fold were prepared. First, the above-mentioned negative electrode electrode material slurry is applied onto a negative electrode current collector foil made of electrolytic copper foil (manufactured by Nippon Foil Co., Ltd., thickness 10 μm), dried, and then pressed to separate them from each other. Two sub-negative electrode material layers were formed (see FIGS. 5 (a) and 5 (b)). Next, the raw material slurry of the above-mentioned ceramic separator was coated on both of the two separating sub-negative electrode material layers on the electrolytic copper foil to form a ceramic separator layer (FIG. 5). (C). More specifically, the raw material slurry of the above ceramic separator is applied by an appropriate coating method (screen printing method, doctor blade method, etc.), dried, and pressed as necessary (depending on the test content). To form a ceramic separator layer.

(Preparation of electrode laminated part)
An electrode laminated portion was prepared so as to be interposed between the folded "both outermost layer portions". In particular, an electrode laminated portion in which positive electrode material layers were formed on both main surfaces of the positive electrode current collector foil as shown in FIG. 5 (d) was produced. Specifically, the positive electrode slurry is applied onto a positive electrode current collector foil made of aluminum foil (manufactured by Tokai Toyo Aluminum Sales Co., Ltd., thickness 15 μm), dried, and then pressed to obtain a positive electrode. The electrode laminated portion of the above was prepared.

(Preparation of battery test piece)
A battery test piece was obtained by folding back both outermost layer portions with the electrode laminated portion interposed therebetween (see FIG. 5D). In particular, a battery test piece was produced by sandwiching the electrode laminated portion inside both outermost layer portions that are folded back so as to bend and pressing the entire portion. In the battery test piece thus obtained, the "current collector forming the outermost layer" and the "side ceramic separator" were in close contact with each other on the side surface of the folded battery. Similarly, the "polar material layer" and the "side ceramic separator" were also in close contact with each other.

[Second test: Test to confirm the effect of the thickness of the ceramic separator on the side surface of the folded battery]
A test was conducted to confirm the effect of the thickness of the ceramic separator on the side surface of the folded battery. Specifically, the thickness of the ceramic separator was changed variously, and "cracking at the side surface portion (folded portion) of the battery" and "occurrence of short circuit defect" were confirmed (see Table 2 and FIG. 9 (A) below). ). The thickness of the ceramic separator was changed by changing the coating thickness of screen printing using the raw material slurry of the ceramic separator. Here, specifically, "cracking at the side surface portion (folded portion) of the battery" is obtained by SEM observation of a state obtained by bending the battery before applying the electrolytic solution, hardening the battery with a resin and a curing agent, and polishing the cross section. I confirmed that. In addition, "occurrence of short circuit failure" was specifically confirmed by the presence or absence of charge / discharge abnormality at the time of initial charging.

The results are shown in Table 2.

In the second test, it was found that when the thickness a2 of the separator on the side surface portion (folded portion) of the battery is larger than the thickness a1 of the separator on the non-side surface portion, it is particularly preferable in terms of suppressing the occurrence of short circuit defects. According to the results in Table 2, it is preferable that the ceramic separator on the side surface portion (folded portion) of the battery has a thickness of 1.25 times or more and 4 times or less the thickness of the ceramic separator on the non-side surface portion. Can be seen. Therefore, in the present invention, it has been found that when the thickness dimension of the side separator is larger than the thickness dimension of the inter-electrode separator, the secondary battery is particularly preferable.

[Third test: Confirmation test of the influence of ceramic separator density on the side surface of the folded battery]
A test was conducted to confirm the effect of the ceramic separator density on the side surface of the folded battery. Specifically, the density of the ceramic separator was locally changed, and "cracking at the side surface (folded back) of the battery" and "occurrence of short circuit defects" were confirmed (see Table 3 and FIG. 9 (A) below). .. The density of the ceramic separator was changed by pressing the coated layer of the ceramic separator to reduce the apparent volume. The “cracking at the side surface portion (folded portion) of the battery” and the “occurrence of short circuit defect” are the same as in the second test.

The results are shown in Table 3.

In the third test, it was found that when the density of the ceramic separator on the side surface portion (folded portion) of the battery is higher than the density of the ceramic separator on the non-side surface portion, it is particularly preferable in terms of suppressing the occurrence of short circuit defects. According to the results in Table 3, the density of the ceramic separator on the side surface (folded portion) of the battery is 4% to 10% higher than the density of the ceramic separator on the non-side surface portion (that is, the density of the ceramic separator on the non-side surface portion). Such a favorable trend can be seen (with an increase of 4% to 10%). Therefore, in the present invention, it was found that when the density of the side separator is larger than the density of the inter-electrode separator, the secondary battery is particularly preferable (note that the third test corresponds to so-called PVC). Similar results could be obtained even in the case of a ceramic separator having a lower possible ceramic component concentration).

In the above test, the ceramic separator density was adjusted by pressing the raw material coating layer. However, since the density can be changed by the difference in the concentration of the raw material slurry, a supplementary confirmation test was conducted on it. Specifically, raw material slurries having different ceramic component concentrations that can correspond to PVC (pigment volume concentration) (more specifically, raw material slurries in which the ceramic component concentrations in the dry coating layer are different from each other) are used. To form a ceramic separator layer. The results are shown in Tables 4 and 5. As can be seen from such a table, it was confirmed that the ceramic separator density can be changed by changing the ceramic component concentration in addition to or instead of the pressing treatment.

[Fourth test: Impact confirmation test of the electrode material layer on the side surface of the folded battery]
A test was conducted to confirm the influence of the polar material layer on the side surface of the folded battery. Specifically, a polar material layer was provided on the side surface of the folded battery, and the thickness thereof was changed to confirm "cracking on the side surface (folded) of the battery" and "occurrence of short circuit defects" (Table 6 and below). (See FIG. 9B). The electrode material layer on the side surface of the folded battery was provided by continuously and integrally forming the negative electrode material layer as a sub-layer when both outermost layer portions were manufactured. "Cracks on the side surface (folded back) of the battery" and "occurrence of short circuit defects" are the same as in the above confirmation test.

The results are shown in Table 6.

In the fourth test, even if the electrode material layer is provided on the side surface portion (folded portion) of the battery, if the thickness is not excessive, the points of "cracking on the side surface portion (folded portion) of the battery" and "occurrence of short circuit defect". It turned out that there was no particular problem.

The secondary battery according to the present invention can be used in various fields where storage is expected. Although only an example, secondary batteries are used in the fields of electricity, information, and communication where mobile devices are used (for example, the fields of mobile devices such as mobile phones, smart watches, smartphones, laptop computers, and digital cameras), homes, and so on. Small industrial applications (eg, power tools, golf carts, home / nursing / industrial robots), large industrial applications (eg, forklifts, elevators, bay port cranes), transportation systems (eg, hybrid vehicles) , Electric vehicles, buses, trains, electric assisted bicycles, electric two-wheeled vehicles, etc.), power system applications (for example, various power generation, road conditioners, smart grids, general household installation type power storage systems, etc.), and space / deep sea It can be used for various purposes (for example, in the fields of space explorers, submersible research vessels, etc.).

1 Rechargeable battery 10 Electrode-to-electrode separator 15 Side separator 20 Current collector (one of the current collectors)
45 Current collector (the other current collector)
48 Electrode layer 100 Electrode lamination unit 120 Both outermost layers 150 Unit side surface 160 Battery side surface

Claims (10)

A secondary battery comprising an electrode stacking unit including a positive electrode, a negative electrode, and an interelectrode separator between the positive electrode and the negative electrode.
A unit in which a current collector of either the positive electrode or the negative electrode forms both outermost layers of the electrode laminated unit, but extends from both outermost layers and corresponds to a part of a side surface of the electrode laminated unit. It forms the side surface of the battery that covers the side surface.
A side separator is provided between the side surface of the unit and the side surface of the battery, and the side separator is a ceramic separator.
The current collector forming both outermost layers and the side separator are in close contact with each other on the side surface of the battery .
Along with the lateral separator, the interelectrode separator also forms a ceramic separator.
A secondary battery in which the thickness dimension of the side separator is larger than the thickness dimension of the inter-electrode separator. A secondary battery comprising an electrode stacking unit including a positive electrode, a negative electrode, and an interelectrode separator between the positive electrode and the negative electrode.
A unit in which a current collector of either the positive electrode or the negative electrode forms both outermost layers of the electrode laminated unit, but extends from both outermost layers and corresponds to a part of a side surface of the electrode laminated unit. It forms the side surface of the battery that covers the side surface.
Side separator is provided between the unit side and the battery side portion, Ri Oh said side lateral separator ceramic separator,
Before SL positive electrode and one of the electrode material layer of the negative electrode, are also provided between said unit side extending from the electrode laminate unit battery side portion, said forming the two outermost The current collector, the side separator, and the electrode material layer are in close contact with each other on the side surface of the battery.
Along with the lateral separator, the interelectrode separator also forms a ceramic separator.
A secondary battery in which the thickness dimension of the side separator is larger than the thickness dimension of the inter-electrode separator. The secondary battery according to claim 1 or 2, wherein the side separator and the interelectrode separator are integrated with each other. The secondary battery according to any one of claims 1 to 3, wherein the density of the side separator is larger than the density of the interelectrode separator. The secondary battery according to any one of claims 1 to 4, wherein the side separator is positioned only with respect to a single side surface of the plurality of side surfaces of the electrode laminated unit. The secondary battery according to claim 5, wherein an insulating sealing portion is provided on a side surface other than the single side surface among the plurality of side surfaces of the unit. The secondary battery according to any one of claims 1 to 6, wherein in the electrode lamination unit, the negative electrode is the outermost electrode, and the positive electrode is provided between the negative electrodes. The secondary battery according to claim 7, wherein the current collector forming both outermost layers is a negative electrode current collector. The secondary battery according to claim 7 or 8, wherein the positive electrode is a double-sided electrode in which positive electrode material layers are provided on both main surfaces of a positive electrode current collector. The secondary battery according to any one of claims 1 to 9, wherein the positive electrode and the negative electrode are electrodes capable of occluding and releasing lithium ions.

Images