JP2018181705A - Secondary battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery including an electrode assembly that is capable of suppressing warpage stress of an outermost layer electrode from occurring, the outermost layer electrode including an electrode material layer provided to one main surface of a collector in cross-section view.SOLUTION: A secondary battery includes an electrode assembly of a planar laminated structure in which a plurality of electrode constituting layers each including a positive electrode 10A, a negative electrode 10B and a separator are laminated. At least one of the positive electrode 10A and the negative electrode 10B of the outermost layer comprises a collector 11 and an electrode material layer 12 provided to one main surface of the collector 11, and a heterogeneous composition layer 13 having a composition different from that of the electrode material layer 12 is further provided to another main surface of the collector 11, the heterogeneous composition layer 13 comprising at least an inorganic body 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a secondary battery and a method of manufacturing the same.

  From the past, secondary batteries capable of repeating charge and discharge have been used for various applications. For example, secondary batteries are used as power sources of electronic devices such as smartphones and notebook computers.

  In recent years, with the increasing demand for thinner and smaller electronic devices, there has been a demand for thinner, smaller and higher capacity secondary batteries. In order to meet such a demand, Patent Document 1 discloses that the electrode assembly which is a component of a secondary battery has a planar laminated structure in which a plurality of electrode configuration layers including a positive electrode, a negative electrode and a separator are stacked in cross section. Is disclosed. The positive electrode and the negative electrode of the electrode assembly, that is, the electrode of the electrode assembly, each include a current collector and an electrode material layer in which an active material is coated on the main surface of the current collector in a cross sectional view. According to Patent Document 1, in the electrode of the outermost layer among the plurality of electrodes provided along the stacking direction, it is indicated that the electrode material layer is provided only on one main surface of the current collector in a cross sectional view. It is disclosed.

JP 2007-149349 A

  Here, the inventor of the present application has found that the following problems may occur when the electrode material layer is provided only on one main surface of the current collector in a cross-sectional view in the electrode of the outermost layer.

  As shown in FIG. 7, the electrode assembly 100 ′ having a planar laminated structure (the electrode assembly 100 X ′ having a rectangular shape in plan view and the electrode assembly 100 Y ′ having a non-rectangular shape) has separators 50 ′ along the laminating direction. After alternately arranging the positive electrodes 10A ′ and the negative electrodes 10B ′ with the two electrodes interposed therebetween, the layers are obtained by applying heat and pressure (also referred to as a hot press) to connect the layers. After applying and drying the electrode material layer 12 ′ on at least one main surface of the current collector 11 ′, each of the plurality of electrodes 10 ′ provided along the stacking direction is subjected to pressure treatment to obtain a desired density. It is obtained by doing. Specifically, the electrode 10 'located in the inner region of the electrode assembly 100' is for obtaining a desired density after applying and drying the electrode material layer 12 'on both main surfaces of the current collector 11'. It can be obtained by pressure treatment. On the other hand, the electrode 10 'located in the outermost layer region of the electrode assembly 100' is for obtaining a desired density after applying and drying the electrode material layer 12 'only on one main surface of the current collector 11'. It can be obtained by pressure treatment. The current collector 11 'is mainly composed of a metal foil, that is, a metal member, while the electrode material layer 12' mainly contains an active material and a binder (polymer compound). That is, in the current collector 11 ′ and the electrode material layer 12 ′, the types of constituent materials are different from each other.

  The difference in the type of material between the current collector 11 'and the electrode material layer 12' is that the current collector 11 'and the electrode material are subjected to pressure treatment for obtaining each electrode 10' having a desired density. This can lead to differences in the degree of stretching of the layer 12 '. Specifically, due to the difference in the degree of elongation, the electrode material 12 'is relatively more precise than the current collector 11' at the time of pressure treatment for obtaining the electrode 10 '(corresponding to a single-sided electrode) positioned in the outermost layer. Tend to stretch significantly. In particular, in the electrode 10 '(corresponding to a single-sided electrode) positioned as the outermost layer, the electrode material layer 12' is provided only on one side of the main surface of the current collector 11 '. Warpage stress is likely to occur in the electrode 10 '(corresponding to a single-sided electrode) positioned in the outermost layer. The occurrence of such warpage stress can lead to warpage of the electrode 10 '(corresponding to a single-sided electrode) positioned in the outermost layer (see the lower left part of FIG. 7).

  The warp of the electrode 10 '(corresponding to a single-sided electrode) positioned in the outermost layer is the outermost layer in the separator 50' positioned between the electrode 10 '(corresponding to a double-sided electrode) in the inner region when configuring the electrode assembly 100'. The positioning electrode 10 'as a whole may not be able to adhere well. Therefore, the outermost electrode 10 ′ may not function properly as a component of the electrode assembly 100 ′. As a result, the secondary battery including the electrode assembly 100 'as a whole may not be able to preferably exhibit desired battery characteristics.

  The present invention has been made in view of such circumstances. Specifically, the present invention is a secondary provided with an electrode assembly capable of suppressing the occurrence of the warpage stress of the outermost layer electrode provided on one main surface of the current collector in the electrode material layer in a cross sectional view. It aims at providing a battery and its manufacturing method.

In order to achieve the above object, in one embodiment of the present invention:
A secondary battery comprising an electrode assembly having a planar laminated structure in which a plurality of electrode constituent layers including a positive electrode, a negative electrode and a separator are laminated,
At least one of the outermost positive electrode and the negative electrode has an electrode material layer provided on one of the main surfaces of the current collector and the current collector, and on the other main surface of the current collector, the electrode material layer There is further provided a heterogeneous composition layer having a composition different from that of the secondary battery, wherein the heterogeneous composition layer comprises at least an inorganic material.

In order to achieve the above object, in one embodiment of the present invention:
A method of manufacturing a secondary battery comprising an electrode assembly having a planar laminated structure in which a plurality of electrode constituent layers including a positive electrode, a negative electrode and a separator are laminated,
In the step of forming at least one of the outermost layer positive electrode and the negative electrode, the step includes forming a composition different from the electrode material layer on the other main surface opposite to one main surface of the current collector on which the electrode material layer is provided. There is provided a manufacturing method comprising providing a heterogeneous composition layer having at least an inorganic material.

  According to one embodiment of the present invention, it is possible to suppress the occurrence of the warpage stress of the outermost layer electrode in which the electrode material layer is provided on one main surface of the current collector in a cross sectional view.

FIG. 1 is a cross-sectional view schematically showing an outermost layer electrode of a secondary battery according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an electrode assembly of a secondary battery according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a different composition layer including a thermoplastic resin body and an inorganic body provided in contact with each other in the thermoplastic resin body. FIG. 4 is a cross-sectional view schematically showing an aspect in which pressure treatment is performed on the outermost layer electrode of the secondary battery according to the embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing an aspect of applying heat and pressure to an electrode assembly of a secondary battery according to an embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing a basic configuration of the electrode configuration layer. FIG. 7 is a schematic view showing a technical problem found by the inventor of the present invention.

  Before describing a method of manufacturing a secondary battery according to an embodiment of the present invention, the basic configuration of the secondary battery will be described. The term "secondary battery" as used herein refers to a battery that can be repeatedly charged and discharged. The "secondary battery" is not excessively limited by its name, and may include, for example, an "electric storage device" and the like. The “plan view” in the present specification refers to the state when the object is viewed from the upper side or the lower side along the thickness direction based on the stacking direction of the electrode materials constituting the secondary battery. Further, the “cross-sectional view” as referred to in the present specification is a state when viewed from a direction substantially perpendicular to the thickness direction based on the stacking direction of the electrode materials constituting the secondary battery.

[Basic configuration of secondary battery]
The present invention provides a secondary battery. The term "secondary battery" as used herein refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery of the present invention is not excessively limited by the name, and for example, "power storage device" and the like may be included in the subject matter of the present invention. The secondary battery has a structure in which an electrode assembly and an electrolyte are housed and sealed inside an outer package. In the present invention, it is premised that the electrode assembly has a planar laminated structure in which a plurality of electrode configuration layers including a positive electrode, a negative electrode, and a separator are stacked. Also, the outer package may take the form of a conductive hard case or a flexible case (such as a pouch). When the form of the exterior body is a flexible case (a pouch or the like), each of the plurality of positive electrodes is connected to the positive electrode external terminal through the positive electrode current collection lead. The positive electrode external terminal is fixed to the exterior body by the seal portion, and the seal portion prevents the electrolyte from leaking. Similarly, each of the plurality of negative electrodes is connected to the negative electrode external terminal through the negative electrode current collection lead. The negative electrode external terminal is fixed to the outer package by the seal portion, and the seal portion prevents the electrolyte from leaking. In addition, it is not limited to this, the current collection lead for positive electrodes connected with each of a plurality of positive electrodes may be provided with the function of the external terminal for positive electrodes, and the current collection for negative electrodes connected with each of a plurality of negative electrodes The lead may have the function of the negative electrode external terminal. When the form of the exterior body is a conductive hard case, each of the plurality of positive electrodes is connected to the positive electrode external terminal through the positive electrode current collection lead. The positive electrode external terminal is fixed to the exterior body by the seal portion, and the seal portion prevents the electrolyte from leaking.

  The positive electrode 10A includes at least a positive electrode current collector 11A and a positive electrode material layer 12A (see FIG. 6), and the positive electrode material layer 12A is provided on at least one side of the positive electrode current collector 11A. The positive electrode side extraction tab is positioned at a portion where the positive electrode material layer 12A is not provided in the positive electrode current collector 11A, that is, an end portion of the positive electrode current collector 11A. The positive electrode material layer 12A contains a positive electrode active material as an electrode active material. The negative electrode 10B is composed of at least a negative electrode current collector 11B and a negative electrode material layer 12B (see FIG. 6), and the negative electrode material layer 12B is provided on at least one side of the negative electrode current collector 11B. The negative electrode side extraction tab is positioned at a portion where the negative electrode material layer 12B is not provided in the negative electrode current collector 11B, that is, an end portion of the negative electrode current collector 11B. The negative electrode material layer 12B contains a negative electrode active material as an electrode active material.

  The positive electrode active material contained in the positive electrode material layer 12A and the negative electrode active material contained in the negative electrode material layer 12B are substances directly involved in the delivery of electrons in the secondary battery, and are mainly responsible for charge and discharge, that is, the battery reaction. It is a substance. More specifically, ions are provided to the electrolyte due to "the positive electrode active material contained in the positive electrode material layer 12A" and the "negative electrode active material contained in the negative electrode material layer 12B", and such ions are the positive electrode 10A and the negative electrode It moves between 10B and transfers electrons to charge and discharge. The positive electrode material layer 12A and the negative electrode material layer 12B are particularly preferably layers capable of inserting and extracting lithium ions. That is, a secondary battery is preferable in which lithium ions move between the positive electrode 10A and the negative electrode 10B through the electrolyte to perform charge and discharge of the battery. When lithium ion is involved in charging and discharging, the secondary battery corresponds to a so-called "lithium ion battery".

  The positive electrode active material of the positive electrode material layer 12A is made of, for example, a granular material, and a binder (also referred to as "binding material") is contained in the positive electrode material layer 12A for sufficient contact between particles and shape retention. Is preferred. Furthermore, a conductive support agent may be included in the positive electrode material layer 12A in order to facilitate the transfer of electrons for promoting the cell reaction. Similarly, although the negative electrode active material of the negative electrode material layer 12B is made of, for example, a granular material, it is preferable that a binder be included for sufficient contact between particles and shape retention, facilitating electron transfer promoting battery reaction. A conductive support agent may be contained in the negative electrode material layer 12B for this purpose. As described above, since the plurality of components are contained, the positive electrode material layer 12A and the negative electrode material layer 12B 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 material that contributes to the storage and release of lithium ions. In this respect, 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 complex 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 12A of the secondary battery, such a lithium transition metal composite oxide is preferably contained as a positive electrode active material. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or some of their transition metals 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. In a more preferable aspect, the positive electrode active material contained in the positive electrode material layer 12A is lithium cobaltate.

  The binder to be contained in the positive electrode layer 12A is not particularly limited, but is not limited to polyfluorinated vinylidene, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluorotyrene copolymer And at least one selected from the group consisting of polytetrafluoroethylene and the like. The conductive aid which may be contained in the positive electrode layer 12A is not particularly limited, but may be thermal black, furnace black, channel black, carbon black such as ketjen black and acetylene black, graphite, carbon nanotubes and gas phase At least one selected from carbon fibers such as grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned. In a more preferred embodiment, the binder of the positive electrode material layer 12A is polyvinylidene fluoride, and in another more preferred embodiment, the conductive aid of the positive electrode material layer 12A is carbon black. In a further preferred embodiment, the binder and the conductive aid of the positive electrode material layer 12A are a combination of polyvinylidene fluoride and carbon black.

  The negative electrode active material is preferably a material that contributes to the storage and release of lithium ions. In this respect, the negative electrode active material is preferably, for example, various carbon materials, oxides, lithium alloys, or the like.

  Examples of various carbon materials of the negative electrode active material include graphite (natural graphite, artificial graphite), soft carbon, hard carbon, diamond-like carbon and the like. In particular, graphite is preferable in that it has high electron conductivity and excellent adhesion to the negative electrode current collector 11B. 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. Such an oxide is preferably amorphous as its structural form. This is because deterioration due to nonuniformity such as grain boundaries or defects is less likely to occur. In a more preferable aspect, the negative electrode active material of the negative electrode material layer 12B is artificial graphite.

  The binder which may be contained in the negative electrode material layer 12B is not particularly limited, but at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin and polyamideimide resin. I can mention the species. In a more preferable embodiment, the binder contained in the negative electrode material layer 12B is a styrene butadiene rubber. The conductive aid to be contained in the negative electrode layer 12B is not particularly limited, but may be thermal black, furnace black, channel black, carbon black such as ketjen black and acetylene black, graphite, carbon nanotubes and gas phase At least one selected from carbon fibers such as grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned. In addition, the component resulting from the thickener component (for example, carboxymethylcellulose) used at the time of battery manufacture may be contained in the negative electrode material layer 12B.

  In a further preferred embodiment, the negative electrode active material and the binder in the negative electrode material layer 12B are a combination of artificial graphite and styrene butadiene rubber.

  The positive electrode current collector 11A and the negative electrode current collector 11B used for the positive electrode 10A and the negative electrode 10B are members that contribute to collecting or supplying electrons generated in the active material due to the battery reaction. Such a current collector may be a sheet-like metal member, and may have a porous or perforated form. For example, the current collector may be metal foil, punching metal, netting, expanded metal or the like. The positive electrode current collector 11A used for the positive electrode 10A 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 11B used for the negative electrode 10B is preferably 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, copper foil.

  The separator 50 is a member provided from the viewpoint of short circuit prevention due to contact of positive and negative electrodes and electrolyte retention. In other words, it can be said that the separator 50 is a member that allows ions to pass while preventing the electronic contact between the positive electrode 10A and the negative electrode 10B. Preferably, the separator 50 is a porous or microporous insulating member and has a membrane form due to its small thickness. By way of example only, a microporous polyolefin membrane may be used as a separator. In this respect, the microporous film used as the separator 50 may be, for example, one containing only polyethylene (PE) or only polyethylene (PP) as the polyolefin. Furthermore, the separator 50 may be a laminate composed of “PE microporous membrane” and “PP microporous membrane”. The surface of the separator may be covered with an inorganic particle coat layer and / or an adhesive layer or the like. The surface of the separator may have adhesiveness.

  From the viewpoint of further improving the handling of the electrode, it is preferable that the separator 50 and the electrode (positive electrode 10A / negative electrode 10B) be adhered. The adhesion between the separator 50 and the electrode can be achieved by using an adhesive separator as the separator 50, applying and / or thermocompression bonding an adhesive binder on the electrode material layer (positive electrode material layer 12A / negative electrode material layer 12B), etc. It can be done. Examples of the adhesive that provides adhesiveness to the separator 50 or the electrode material layer include polyvinylidene fluoride, an acrylic adhesive, and the like.

  The electrolyte assists in the movement of metal ions released from the electrodes (positive electrode 10A and negative electrode 10B). The electrolyte may be an electrolyte comprising a "non-aqueous" solvent, such as an organic electrolyte and an organic solvent, and a solute, or an "aqueous" electrolyte comprising water. The secondary battery is preferably a non-aqueous electrolyte secondary battery in which a "non-aqueous" electrolyte is used as the electrolyte. The electrolyte may have a form such as liquid or gel (note that, in the present specification, "liquid" non-aqueous electrolyte is also referred to as "non-aqueous electrolyte").

As a specific non-aqueous electrolyte solvent, one comprising at least a carbonate is preferable. Such carbonates may be cyclic carbonates and / or linear carbonates. Although not particularly limited, 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. As linear carbonates, at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC) can be mentioned. In a preferred embodiment, a combination of cyclic carbonates and linear carbonates is used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and diethyl carbonate is used. Further, as a specific non-aqueous electrolyte solute, preferably, for example, a Li salt such as LiPF ₆ or LiBF ₄ is used. Further, as a specific non-aqueous electrolyte solute, preferably, for example, a Li salt such as LiPF ₆ or LiBF ₄ is used.

  As the positive electrode current collector lead and the negative electrode current collector lead, any current collector lead used in the field of secondary batteries can be used. Such current collection lead may be made of a material that can achieve the movement of electrons, for example, a conductive material such as aluminum, nickel, iron, copper, stainless steel and the like. The positive electrode current collector lead is preferably made of aluminum, and the negative electrode current collector lead is preferably made of nickel. The form of the positive electrode current collection lead and the negative electrode current collection lead is not particularly limited, and may be, for example, a wire or a plate.

  As the external terminal, any external terminal used in the field of secondary batteries can be used. Such an external terminal may be made of a material that can achieve electron transfer, and is usually made of a conductive material such as aluminum, nickel, iron, copper, stainless steel and the like. The external terminals 5 may be electrically and directly connected to the substrate, or may be electrically and indirectly connected to the substrate through other devices. In addition, it is not limited to this, the current collection lead for positive electrodes connected with each of a plurality of positive electrodes may be provided with the function of the external terminal for positive electrodes, and the current collection for negative electrodes connected with each of a plurality of negative electrodes The lead may have the function of the negative electrode external terminal.

  The outer package may have the form of a conductive hard case or a flexible case (such as a pouch) as described above.

  The conductive hard case is composed of a main body and a lid. The main body portion is composed of a bottom portion and a side portion which constitute the bottom surface of the exterior body. The main body portion and the lid portion are sealed after housing the electrode assembly, the electrolyte, the current collection lead and the external terminal. It does not specifically limit as a sealing method, For example, a laser irradiation method etc. are mentioned. As a material which comprises a main-body part and a lid part, all materials which can comprise a hard case type | mold exterior body in the field | area of a secondary battery can be used. Such material may be any material as long as electron transfer can be achieved, and examples thereof include conductive materials such as aluminum, nickel, iron, copper, stainless steel and the like. The dimensions of the main body portion and the lid portion are mainly determined in accordance with the dimensions of the electrode assembly. For example, when the electrode assembly is accommodated, the dimension to such an extent that movement (displacement) of the electrode assembly in the exterior body is prevented It is preferable to have. Preventing the movement of the electrode assembly prevents the breakage of the electrode assembly and improves the safety of the secondary battery.

  The flexible case is composed of a soft sheet. The soft sheet has only to be soft enough to achieve bending of the seal portion, and is preferably a plastic sheet. The plastic sheet is a sheet having a characteristic that deformation by external force is maintained when it is removed after applying external force, and a so-called laminate film can be used, for example. The flexible pouch made of a laminate film can be produced, for example, by laminating two sheets of laminate film and heat-sealing the peripheral portion. As the laminate film, a film obtained by laminating a metal foil and a polymer film is generally used, and specifically, one having a three-layer structure consisting of an outer layer polymer film / metal foil / inner layer polymer film is exemplified. The outer layer polymer film is for preventing permeation of moisture and the like and damage to the metal foil due to contact and the like, and polymers such as polyamide and polyester can be suitably used. The metal foil is for preventing permeation of moisture and gas, and foils of copper, aluminum, stainless steel, etc. can be suitably used. The inner layer polymer film is intended to protect the metal foil from the electrolyte contained inside and to melt and seal it at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used.

[Secondary battery of the present invention]
In consideration of the basic configuration of the secondary battery according to the embodiment of the present invention, the characterizing portion of the secondary battery according to the embodiment of the present invention will be described below.

  The inventor of the present application has keenly studied measures to suppress the warpage stress of the electrode of the outermost layer in which the electrode material layer is provided on one main surface of the current collector in a cross sectional view. As a result, it came to devise this invention.

  Hereinafter, prior to describing the features of the present invention, definition of terms used in the present specification will be made. The term "different composition layer (or may be referred to as a different composition layer)" as used herein refers to a layer having a composition different from that of the electrode material layer in a broad sense, and in a narrow sense compared with the constituent material of the electrode material layer It refers to layers having different compositions. The term "composition" as used herein refers to the proportion of the amount of elements constituting a compound or the like. In addition, Al etc. which are contained in an electrode material layer (specifically negative electrode material layer) are mentioned as an example of "a constituent material of an electrode material layer" here. Moreover, the "inorganic body" as used in this specification refers to what consists of inorganic substances, and, specifically, refers to what is relatively hard to deform | transform at the time of the pressurization of an electrode. The term "thermoplastic resin body" as used herein refers to one made of a thermoplastic resin, specifically, it melts due to the thermal energy by the pressure when the electrode is pressurized, and shrinks and hardens when it is dried and cooled. Refers to those having the properties of thermoplastic resins.

  As shown in FIG. 1, a current collector 11 ′ (positive electrode current collector 11A ′, negative electrode current collector 11B ′) and an electrode material layer 12 ′ provided on one principal surface 11α (only) of the current collector. Compared with the conventional outermost layer electrode 10 '(the outermost layer positive electrode 10A' and the outermost layer negative electrode 10B ') having (the positive electrode material layer 12A' and the negative electrode material layer 12B '), the present invention has the following features (FIG. See Figure 2).

  Specifically, in one embodiment of the present invention, the outermost layer electrode 10A includes the current collector 11 (positive electrode current collector 11A, negative electrode current collector 11B) and one main surface 11α of the current collector 11 (only In addition to having the electrode material layer 12 (positive electrode material layer 12A, negative electrode material layer 12B) provided in the above, the other main surface 11β of the current collector 11 has a composition different from that of the electrode material layer 12 It is characterized by further comprising a different composition layer 13 having the same. Further, one embodiment of the present invention is characterized in that the different composition layer 13 includes at least an inorganic body 14 (positive electrode side: 14A, negative electrode side: 14B).

  As described above, the electrode 10 'positioned in the outermost layer has a structure in which the electrode material layer 12' is provided only on one side of the main surface of the current collector 11 ', and the electrode 10 positioned in the outermost layer At the time of pressure treatment for obtaining ', warp stress is likely to occur in the electrode 10' positioned as the outermost layer due to the electrode material layer 12 'stretching relatively larger than the current collector 11'. The occurrence of such warpage stress can lead to the warpage of the electrode 10 'positioned in the outermost layer (see the lower left part of FIG. 7). In this regard, in the present invention, the electrode 10 positioned in the outermost layer of the electrode assembly further includes the different composition layer 13 having a composition different from that of the electrode material layer 12 on the other main surface 11β of the current collector 11 And the hetero-composition layer 13 includes at least the inorganic material 14, the following phenomenon occurs in the finally obtained outermost layer electrode.

  Specifically, in one embodiment of the present invention, the heterogeneous composition layer 13 provided on the other major surface 11 β of the current collector 11 includes at least the inorganic body 14, and as described above, the inorganic body 14 is It holds a relatively hard state without deforming its shape when the electrode is pressurized. Therefore, by such state retention, the different composition layer 13 including the inorganic body 14 may be able to form a relatively hard plate layer. The warpage stress which may occur during pressure treatment for obtaining the electrode 10 'positioned in the outermost layer mentioned above is specifically caused by the electrode material layer 12' stretching relatively larger than the current collector 11 '. The main surface of the electrode material layer 12 ′ is an outer curved surface, and the main surface of the current collector 11 ′ is an inner curved surface (see the lower left portion in FIG. 7). In this regard, in one embodiment of the present invention, (i) the different composition layer 13 is provided on the other main surface 11β opposite to the one main surface of the current collector 11 to which the electrode material layer 12 is provided. And (ii) the main surface of the electrode material layer 12 becomes an outer curved surface at the electrode 10 of the outermost layer due to the fact that the different composition layer 13 forms a relatively hard plate layer, and the current collection is performed. It is possible to preferably prevent the occurrence of warpage stress that can make the main surface of the body 11 an inner curved surface. That is, in the embodiment of the present invention, it is possible to preferably prevent the occurrence of warpage in the outermost electrode 10 due to the warpage stress.

  The suppression of the warpage stress makes it possible to preferably adhere the outermost layer electrode 10 to the separator 50 positioned between the electrode assembly 10 and the electrode 10 (corresponding to a double-sided electrode) in the construction of the electrode assembly. Connect (see Figure 2). Therefore, the outermost electrode 10 can be suitably functioned as a component of the electrode assembly 100. As a result, the secondary battery including the electrode assembly 100 as a whole can preferably exhibit desired battery characteristics.

(Material of inorganic body (component of different composition layer))
In one embodiment of the present invention, the inorganic body 15 contained at least in the dissimilar composition layer 13 may be selected from Al ₂ O ₃ , SiO _2, TiO ₂ or ZrO ₂ . The inorganic body 15 is preferably Al ₂ O ₃ .

  The secondary battery according to an embodiment of the present invention may adopt the following aspects.

  In one embodiment, the heterogeneous composition layer 13 comprises at least two inorganic bodies 14 and further comprises a thermoplastic resin body 15, and the at least two inorganic bodies 14 are in contact with each other in the thermoplastic resin body 15. It may be provided as shown in FIG.

  In this embodiment, the different composition layers 13 have at least two inorganic bodies 14 provided in contact with each other in the thermoplastic resin body 15. The mutual contact of at least two inorganic bodies 15 in the thermoplastic resin body 15 means that there is no void between the inorganic bodies 14. The absence of such a void substantially means that the inorganic body 14 is contained relatively more than the thermoplastic resin body 15 in the heterogeneous composition layer 13.

  When the inorganic body 14 is contained in a relatively large amount relative to the thermoplastic resin body 15 in the dissimilar composition layer 13, the inorganic body 14 maintains a relatively hard state without deforming its shape when the electrode is pressurized. Due to a certain point, the different composition layer 13 containing a relatively large amount of the inorganic body 14 can form a relatively hard plate layer. In this embodiment, the different composition layer 13 forming a relatively hard plate layer is provided on the other main surface 11β opposite to the one main surface of the current collector 11 (the surface to which the electrode material layer 12 is provided). Therefore, it is possible to prevent the generation of the warpage stress that the main surface of the electrode material layer 12 becomes the outer curved surface and the main surface of the current collector 11 becomes the inner curved surface in the electrode 10 of the outermost layer.

(Material of Thermoplastic Resin Body (Component of Heterogeneous Composition Layer))
In this embodiment, as the thermoplastic resin body 15 further contained in the different composition layer 13, when the outermost positive electrode is used as the outermost electrode, poly-fluorinated vinylidene, vinylidene fluoride-hexafluoropropylene copolymer, bililiden is used. Mention may be made of at least one member selected from the group consisting of nidenfluoride-tetrafluorotyrene copolymer and polytetrafluoroethylene.

  In the embodiment of the present invention, as the thermoplastic resin body 15 further contained in the dissimilar composition layer 13, when the outermost layer negative electrode is used as the outermost layer electrode, styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride And at least one selected from the group consisting of polyimide resins, polyamideimide resins, and carboxymethylcellulose.

  In any of the cases where the outermost positive electrode and / or the outermost negative electrode is used as the outermost electrode, the thermoplastic resin body 15 further contained in the dissimilar composition layer 13 is preferably polyvinylidene fluoride.

[Method of Manufacturing Secondary Battery of the Present Invention]
Hereinafter, a method of manufacturing a secondary battery according to an embodiment of the present invention will be described.

  The method of manufacturing a secondary battery according to an embodiment of the present invention is characterized in the step of forming the electrode of the outermost layer.

  In this step, the electrode material layer 12 is provided only on one main surface 11α of the current collector 11 to form a laminate (corresponding to the electrode of the outermost layer) including the current collector 11 and the electrode material layer 12. Forming and pressurizing the laminate (corresponding to the electrode of the outermost layer). The pressurization is carried out to provide the outermost electrode with the desired density. Here, one embodiment of the present invention has the following features. Specifically, after the electrode material layer 12 is provided only on one main surface 11α of the current collector 11, the other main surface 11β on the opposite side to the one main surface 11α of the current collector 11 is provided. The method further includes providing a dissimilar composition layer 13 having a composition different from that of the electrode material layer 12, and the heterogeneous composition layer 13 is characterized by using at least an inorganic body 14 (see FIG. 4).

  The inorganic body 14 holds a relatively hard state without deforming its shape when the electrode is pressurized. Therefore, the hetero-composition layer 13 including the inorganic body 14 can form a relatively hard plate layer by such state retention. As described above, when the pressure treatment for obtaining the electrode 10 'positioned in the outermost layer is performed, the electrode material layer 12' expands relatively more than the current collector 11 ', and thus the electrode material layer Warpage stress may occur in which the main surface of 12 'becomes the outer curved surface and the main surface of the current collector 11' becomes the inner curved surface (see the lower left part of FIG. 7). In this regard, in one embodiment of the present invention, the different composition layer 13 forming the relatively hard plate layer is the other main surface on the opposite side to one main surface 11α of the current collector 11 providing the electrode material layer 12. The main surface of the electrode material layer 12 becomes an outer curved surface when forming the electrode 10 of the outermost layer due to the fact that the different composition layer 13 forms a relatively hard plate layer in order to provide 11β, the main surface of the current collector 11 It is possible to preferably prevent the occurrence of warpage stress that may cause the surface to be an inner curved surface.

  In addition, after forming the electrode 10 (one-sided electrode) of the outermost layer, the lamination direction of the electrode 10 of the outermost layer and the electrodes (double-sided electrode) in which the electrode material layer 12 is provided on both main surfaces of the current collector 11 Along the separator 50 to form a precursor of the electrode assembly 100. Then, the electrode assembly 100 can be finally obtained by applying heat and pressure to the precursor (see FIG. 5). By providing the electrode assembly 100 with the electrolyte in the outer package, it is possible to finally obtain the secondary battery according to the embodiment of the present invention.

  As described above, in the embodiment of the present invention, since it is possible to preferably prevent the warpage stress that may occur when forming the outermost layer electrode 10, the inner region when the electrode assembly 100 is configured due to it. The electrode 10 of the outermost layer can be preferably adhered to the separator 50 positioned between the electrodes 10 (corresponding to double-sided electrodes) (see FIG. 5). Therefore, the outermost electrode 10 can be suitably functioned as a component of the electrode assembly 100. As a result, the secondary battery including the electrode assembly 100 as a whole can preferably exhibit desired battery characteristics.

  The manufacturing method according to an embodiment of the present invention may adopt the following aspect.

  In one embodiment, as the different composition layer 13, one further comprising a thermoplastic resin body 15 is used, and at least two inorganic bodies 14 are in contact with each other in the thermoplastic resin body 15 (see FIG. 3).

  In this embodiment, as the different composition layer 13, one having at least two inorganic bodies 14 provided so as to be in contact with each other in the thermoplastic resin body 15 is used. When at least two inorganic bodies 15 are in contact with each other in the thermoplastic resin body 15, no void is present between the inorganic bodies 14. The absence of such a void substantially means that the inorganic body 14 is contained relatively more than the thermoplastic resin body 15 in the heterogeneous composition layer 13.

  When the inorganic body 14 is contained relatively more than the thermoplastic resin body 15 in the dissimilar composition layer 13, as described above, the inorganic body 14 is in a relatively hard state without being deformed in shape when the electrode is pressurized. Due to holding, the different composition layer 13 containing a relatively large amount of the inorganic substance 14 may be able to form a hard plate layer. Therefore, when the different composition layer 13 can form a relatively hard plate layer, the main surface of the electrode material layer 12 becomes an outer curved surface and the main surface of the current collector 11 becomes the outer surface when forming the electrode 10 of the outermost layer. It is possible to preferably prevent the occurrence of warpage stress that can be an inner curved surface.

  The secondary battery according to an embodiment of the present invention can be used in various fields where power storage is assumed. The secondary battery according to one embodiment of the present invention, in particular, the non-aqueous electrolyte secondary battery is, by way of example only, in the field of electricity, information and communication in which mobile devices and the like are used (for example, mobile phones, smartphones, notebooks) Mobile devices such as personal computers and digital cameras), home / small industrial applications (for example, electric tools, golf carts, home / care / industrial robots), large industrial applications (for example, forklifts, elevators, harbors) Field of crane), field of traffic system (for example, field of hybrid car, electric car, bus, train, electric assist bicycle, electric motorcycle etc.), electric power system application (for example, various power generation, road conditioner, smart grid, general household installation) Storage systems, etc.) and space / deep sea applications (eg, spacecraft) It can be used in the field), such as diving research vessel.

100, 100 'electrode assembly 50, 50' separator 10, 10 'electrode 10A, 10A' positive electrode 10B, 10B 'negative electrode 11, 11' current collector 11α current collector one main surface 11β current collector another Principal surface 11A, 11A 'Positive electrode current collector 11B, 11B' Negative electrode current collector 12, 12 'Electrode material layer 12A, 12A' Positive electrode material layer 12B, 12B 'Negative electrode material layer 13, 13A, 13B Different composition layer 14, 14A , 14B Inorganic body 15 Thermoplastic resin body

Claims (10)

A secondary battery comprising an electrode assembly having a planar laminated structure in which a plurality of electrode constituent layers including a positive electrode, a negative electrode and a separator are laminated,
At least one of the outermost layer positive electrode and the negative electrode includes a current collector and an electrode material layer provided on one main surface of the current collector, and on the other main surface of the current collector A secondary battery further provided with a heterogeneous composition layer having a composition different from that of the electrode material layer, the heterogeneous composition layer comprising at least an inorganic material.   The secondary battery according to claim 1, wherein the different composition layer forms a plate layer. Said different composition layer comprises at least two of said inorganic bodies,
The heterogeneous composition layer further comprises a thermoplastic resin body,
The secondary battery according to claim 1, wherein the at least two inorganic bodies are provided in contact with each other in the thermoplastic resin body.   The secondary battery according to claim 3, wherein the dissimilar composition layer comprises relatively more of the inorganic body than the thermoplastic resin body. It said thermoplastic resin body is polyvinylidene fluoride, the inorganic body is, Al ₂ O _3, the secondary battery according to any one of claims 1 to 4. A method of manufacturing a secondary battery comprising an electrode assembly having a planar laminated structure in which a plurality of electrode constituent layers including a positive electrode, a negative electrode and a separator are laminated,
In the step of forming at least one of the outermost layer positive electrode and the negative electrode, the step is different from the electrode material layer on the other main surface opposite to one main surface of the current collector provided with the electrode material layer. A method of manufacturing, comprising providing a heterogeneous composition layer having a composition, the heterogeneous composition layer comprising at least an inorganic material.   The manufacturing method according to claim 6, wherein the heterogeneous composition layer further comprises a thermoplastic resin body, and the at least two inorganic bodies are in contact with each other in the thermoplastic resin body.   The manufacturing method according to claim 7, wherein a layer containing relatively more inorganic body than the thermoplastic resin body is used as the different composition layer. The manufacturing method according to claim 7 or 8, wherein polyvinylidene fluoride is used as the thermoplastic resin body and Al ₂ O ₃ is used as the inorganic body.   The secondary battery according to any one of claims 1 to 5, wherein the positive electrode and the negative electrode have a layer capable of inserting and extracting lithium ions.

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