JP2018206490A - Secondary battery and manufacturing method thereof - Google Patents

Abstract

To provide a secondary battery including an electrode assembly capable of suitably restraining occurrence of warpage stress in the outermost layer electrode provided with an electrode material layer on one principal surface of a collector in the cross-sectional view.SOLUTION: In a secondary battery comprising an electrode assembly of plane laminated structure and an exterior body for housing the electrode assembly, the electrode assembly has a partial electrode assembly, and a long-sized electrode of curvature form surrounding the partial electrode assembly along the cross-sectional contour thereof. The long-sized electrode includes a collector, an electrode material layer provided entirely on one principal surface of the collector, and an electrode material provided locally in both end regions of the other principal surface of the collector.SELECTED DRAWING: Figure 1

Description

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

  Secondary batteries that can be repeatedly charged and discharged have been used for various purposes. For example, the secondary battery is used as a power source for electronic devices such as smartphones and notebook computers.

  In recent years, with the demand for thinner and smaller electronic devices, there is a demand for secondary batteries that are thinner, smaller, and have higher capacity. In order to meet such demand, Patent Document 1 discloses that an electrode assembly that is a constituent element of a secondary battery has 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 a sectional view. Is disclosed. A positive electrode and a negative electrode of the electrode assembly, that is, an electrode of the electrode assembly includes a current collector and an electrode material layer coated with an active material on a main surface of the current collector in a cross-sectional view.

JP, 2014-120456, A

  Here, the outermost layer electrode of the plurality of electrodes provided along the stacking direction may be provided with an electrode material layer only on one main surface of the current collector. Specifically, the electrode material layer of the outermost layer electrode can be provided only between one main surface of the current collector of the outermost layer electrode and the separator. In other words, the electrode material layer of the outermost layer electrode is not provided on the other main surface of the current collector of the outermost layer electrode. This is because when the electrode material layer is provided on the other main surface of the current collector, lithium ions do not easily move to the electrode material layer of the opposite electrode, so that the current is provided on the other main surface of the current collector. This is because the electrode material layer is difficult to function suitably as a component of the secondary battery.

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

  As shown in FIG. 10, an electrode assembly 100 ′ having a planar laminated structure (for example, an electrode assembly 100X ′ having a rectangular shape in plan view) has a positive electrode 10A ′ and a negative electrode with a separator 50 ′ sandwiched in the laminating direction. 10B ′ are alternately arranged, and then hot pressing (also referred to as hot pressing) is performed to connect the layers. Each of the plurality of electrodes 10 ′ provided along the stacking direction is subjected to a pressure treatment for obtaining a desired density after applying and drying the electrode material layer 12 ′ on at least one main surface of the current collector 11 ′. It is obtained by doing. Specifically, the electrode 10 ′ located in the inner region of the electrode assembly 100 ′ is used to obtain a desired density after applying and drying the electrode material layer 12 ′ on both main surfaces of the current collector 11 ′. It is obtained by performing a pressure treatment. On the other hand, the electrode 10 ′ located in the outermost layer region of the electrode assembly 100 ′ is used to obtain a desired density after applying and drying the electrode material layer 12 ′ only on one main surface of the current collector 11 ′. It is obtained by performing a 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 includes an active material and a binder (polymer compound). That is, the current collector 11 ′ and the electrode material layer 12 ′ are different from each other in the types of constituent materials.

  The difference in material type between the current collector 11 ′ and the electrode material layer 12 ′ is that when the pressure treatment for obtaining each electrode 10 ′ having a desired density is performed, the current collector 11 ′ and the electrode material This can lead to a difference in the degree of stretching of the layer 12 '. Specifically, due to the difference in the degree of extension, the electrode material layer 12 ′ is more relative to the current collector 11 ′ during the pressure treatment for obtaining the electrode 10 ′ (corresponding to a single-sided electrode) positioned in the outermost layer. Tend to stretch greatly. In particular, in the electrode 10 ′ (corresponding to a single-sided electrode) positioned in 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. Generation | occurrence | production of this curvature stress can lead to the curvature of electrode 10 '(equivalent to a single-sided electrode) located in the outermost layer (refer the lower left part of FIG. 10).

  The warpage of the electrode 10 ′ positioned at the outermost layer (corresponding to a single-sided electrode) is caused by the separator 50 ′ positioned between the electrode 10 ′ in the inner region (corresponding to a double-sided electrode) when the electrode assembly 100 ′ is configured. It may not be possible to favorably bond the electrode 10 'to be positioned as a whole. Therefore, there is a possibility that the outermost electrode 10 'may not function 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 exhibit desired battery characteristics.

  The present invention has been devised in view of such circumstances. Specifically, the present invention provides an electrode assembly in which the electrode material layer is provided with an electrode assembly that can suitably suppress the occurrence of warping stress of the outermost layer electrode provided on one main surface of the current collector in a cross-sectional view. It is an object of the present invention to provide a secondary battery and a manufacturing method thereof.

To achieve the above object, in one embodiment of the present invention,
A secondary battery comprising an electrode assembly having a planar laminated structure and an exterior body for housing the electrode assembly,
The electrode assembly includes a partial electrode assembly, and a long electrode in a bent form surrounding the partial electrode assembly along a cross-sectional contour of the partial electrode assembly,
A long electrode is a current collector, an electrode material layer provided entirely on one main surface of the current collector, and an electrode locally provided on both end regions of the other main surface of the current collector A secondary battery comprising a material part is provided.

To achieve the above object, in one embodiment of the present invention,
A method for manufacturing a secondary battery comprising an electrode assembly having a planar laminated structure and an exterior body for housing the electrode assembly,
Forming a partial electrode assembly;
Enclosing the partial electrode assembly with an elongated electrode along a cross-sectional profile of the partial electrode assembly,
A long electrode is formed by providing an electrode material layer entirely on one main surface of the current collector and locally providing electrode material portions on both end regions of the other main surface of the current collector. A method for manufacturing a battery is provided.

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

FIG. 1 is a schematic cross-sectional view of an electrode assembly of a secondary battery according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of an electrode assembly of a secondary battery according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of an electrode assembly of a secondary battery according to still another embodiment of the present invention. FIG. 4 is a schematic view of an electrode assembly of a secondary battery according to still another embodiment of the present invention. FIG. 5 is a schematic view of an electrode assembly of a secondary battery according to still another embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a method for manufacturing an electrode assembly of a secondary battery according to an embodiment of the present invention. FIG. 7A is a schematic cross-sectional view of a process of a method for manufacturing an electrode assembly of a secondary battery according to one embodiment of the present invention. FIG. 7B is a schematic cross-sectional view of the process of the method for manufacturing the electrode assembly of the secondary battery according to the embodiment of the present invention. FIG. 7C is a schematic cross-sectional view of the process of the method for manufacturing the electrode assembly of the secondary battery according to the embodiment of the present invention. FIG. 7D is a schematic cross-sectional view of a process of a method for manufacturing an electrode assembly of a secondary battery according to one embodiment of the present invention. FIG. 7E is a schematic cross-sectional view of a process of a method for manufacturing an electrode assembly of a secondary battery according to an embodiment of the present invention. FIG. 7F is a schematic cross-sectional view of a process of a method for manufacturing an electrode assembly of a secondary battery according to an embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of a process of a method for manufacturing an electrode assembly of a secondary battery according to another embodiment of the present invention. FIG. 9 is a cross-sectional view schematically showing the basic configuration of the electrode configuration layer. FIG. 10 is a schematic diagram showing a technical problem found by the inventor of the present application.

  Before describing a method for manufacturing a secondary battery according to an embodiment of the present invention, a basic configuration of the secondary battery will be described. The term “secondary battery” in this specification refers to a battery that can be repeatedly charged and discharged. The “secondary battery” is not excessively bound by the name, and may include, for example, “electric storage device”. The “plan view” in the present specification refers to a 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. In addition, the “cross-sectional view” as used in the present specification refers to 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]
In the present invention, a secondary battery is provided. The “secondary battery” in the present specification refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery of the present invention is not excessively bound by its name, and for example, “electric storage device” can also be included in the subject of the present invention. The secondary battery has a structure in which an electrode assembly and an electrolyte are accommodated and enclosed in an exterior body. In the present invention, it is assumed that the electrode assembly has a planar laminated structure in which a plurality of electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. Further, the exterior body 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 (such as a pouch), each of the plurality of positive electrodes is connected to the positive electrode external terminal via the positive electrode current collecting lead. The external terminal for positive electrode is fixed to the exterior body by a seal portion, and the seal portion prevents electrolyte leakage. Similarly, each of the plurality of negative electrodes is connected to a negative electrode external terminal via a negative electrode current collecting lead. The external terminal for negative electrode is fixed to the exterior body by a seal portion, and the seal portion prevents electrolyte leakage. However, the present invention is not limited thereto, and the positive electrode current collector lead connected to each of the plurality of positive electrodes may have the function of a positive electrode external terminal, and the negative electrode current collector connected to each of the plurality of negative electrodes. The lead may have a function of an external terminal for negative electrode. When the form of the exterior body is a conductive hard case, each of the plurality of positive electrodes is connected to a positive electrode external terminal via a positive electrode current collecting lead. The external terminal for positive electrode is fixed to the exterior body by a seal portion, and the seal portion prevents electrolyte leakage.

  The positive electrode 10A includes at least a positive electrode current collector 11A and a positive electrode material layer 12A (see FIG. 9), and a positive electrode material layer 12A is provided on at least one surface of the positive electrode current collector 11A. In the positive electrode current collector 11A, a positive electrode side extraction tab is positioned at a position where the positive electrode material layer 12A is not provided, that is, at an end 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 includes at least a negative electrode current collector 11B and a negative electrode material layer 12B (see FIG. 9), and a negative electrode material layer 12B is provided on at least one surface of the negative electrode current collector 11B. A negative electrode side extraction tab is positioned at a portion of the negative electrode current collector 11B where the negative electrode material layer 12B is not provided, that is, at an end 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 materials directly involved in the transfer of electrons in the secondary battery, and are the main positive and negative electrodes responsible for charge / discharge, that is, the battery reaction. It is a substance. More specifically, ions are brought into 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 these ions are converted into the positive electrode 10A and the negative electrode. 10B is transferred to and delivered from 10B, and charging / discharging is performed. The positive electrode material layer 12A and the negative electrode material layer 12B are particularly preferably layers that can occlude and release lithium ions. That is, a secondary battery in which lithium ions move between the positive electrode 10A and the negative electrode 10B through the electrolyte and the battery is charged and discharged is preferable. When lithium ions are involved in charging / 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 a “binder”) is included in the positive electrode material layer 12A in order to sufficiently contact the particles and maintain the shape. It is preferable. Further, a conductive additive may be included in the positive electrode material layer 12A in order to facilitate the transmission of electrons that promote the battery reaction. Similarly, the negative electrode active material of the negative electrode material layer 12B is made of, for example, a granular material, and it is preferable that a binder is included for sufficient contact and shape retention between the particles, which facilitates the transfer of electrons that promote the battery reaction. In order to do so, a conductive additive may be included in the negative electrode material layer 12B. Thus, because of the form in which a plurality of components are contained, the positive electrode material layer 12A and the negative electrode material layer 12B can also be referred to as “positive electrode mixture layer” and “negative electrode mixture layer”, respectively.

  The positive electrode active material is preferably a material that contributes to 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, such a lithium transition metal composite oxide is preferably included as a positive electrode active material in the positive electrode material layer 12A of the secondary battery. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a part of those transition metals replaced with another metal. Although such a positive electrode active material may be included as a single species, two or more types may be included in combination. In a more preferred embodiment, the positive electrode active material contained in the positive electrode material layer 12A is lithium cobalt oxide.

  The binder that can be included in the positive electrode material layer 12A is not particularly limited, but poly (vinylidene fluoride), vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-tetrafluoroethylene copolymer. And at least one selected from the group consisting of polytetrafluoroethylene and the like. The conductive aid that can be included in the positive electrode material layer 12A is not particularly limited, but carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, graphite, carbon nanotube, and gas phase There may be mentioned at least one selected from carbon fibers such as grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. 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 additive of the positive electrode material layer 12A is carbon black. In a more preferred embodiment, the binder and conductive additive 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 occlusion and release of lithium ions. From this point of view, the negative electrode active material is preferably, for example, various carbon materials, oxides, or lithium alloys.

  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 because 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 in its structural form. This is because deterioration due to non-uniformity such as crystal grain boundaries or defects is less likely to be caused. In a more preferred embodiment, the negative electrode active material of the negative electrode material layer 12B is artificial graphite.

  The binder that can be included in the negative electrode material layer 12B is not particularly limited, but is at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin, and polyamideimide resin. Species can be mentioned. In a more preferred embodiment, the binder contained in the negative electrode material layer 12B is styrene butadiene rubber. The conductive auxiliary agent that can be included in the negative electrode material layer 12B is not particularly limited, but carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, graphite, carbon nanotube, and gas phase There may be mentioned at least one selected from carbon fibers such as grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. The negative electrode material layer 12B may contain a component resulting from a thickener component (for example, carboxymethyl cellulose) used during battery manufacture.

  In a more 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 and 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 a metal foil, a punching metal, a net or an expanded metal. 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 in 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, a copper foil.

  The separator 50 is a member provided from the viewpoints of preventing a short circuit due to contact between the positive and negative electrodes and holding the electrolyte. In other words, the separator 50 can be said to be a member that allows ions to pass through while preventing 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 film form due to its small thickness. Although only illustrative, a polyolefin microporous film may be used as the separator. In this regard, the microporous film used as the separator 50 may include, for example, only polyethylene (PE) or only polypropylene (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. The surface of the separator may have adhesiveness.

  In addition, it is preferable that the separator 50 and the electrode (positive electrode 10A / negative electrode 10B) are bonded from the viewpoint of further improving the handling of the electrode. The separator 50 is bonded to the electrode by using an adhesive separator as the separator 50, applying an adhesive binder on the electrode material layer (positive electrode material layer 12A / negative electrode material layer 12B) and / or thermocompression bonding, or the like. Can be done. Examples of the adhesive that provides adhesiveness to the separator 50 or the electrode material layer include polyvinylidene fluoride and an acrylic adhesive.

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

As a specific non-aqueous electrolyte solvent, a solvent containing at least carbonate is preferable. Such carbonates may be cyclic carbonates and / or chain carbonates. Although not particularly limited, examples of 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). In a preferred embodiment, a combination of cyclic carbonates and chain carbonates is used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and diethyl carbonate. Further, as a specific nonaqueous electrolyte solute, for example, a Li salt such as LiPF ₆ or LiBF ₄ is preferably used. Further, as a specific nonaqueous electrolyte solute, for example, a Li salt such as LiPF ₆ or LiBF ₄ is preferably used.

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

  Any external terminal used in the field of secondary batteries can be used as the external terminal. Such an external terminal may be made of a material capable of achieving electron movement, and is usually made of a conductive material such as aluminum, nickel, iron, copper, and stainless steel. The external terminal 5 may be electrically and directly connected to the substrate, or may be electrically and indirectly connected to the substrate via another device. However, the present invention is not limited to this, and the positive electrode current collector lead connected to each of the plurality of positive electrodes may have the function of the positive electrode external terminal, and the negative electrode current collector connected to each of the plurality of negative electrodes. The lead may have a function of an external terminal for negative electrode.

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

  The conductive hard case includes a main body portion and a lid portion. A main-body part consists of the bottom part and side part which comprise the bottom face of the said exterior body. The main body and the lid are sealed after the electrode assembly, the electrolyte, the current collecting lead, and the external terminal are accommodated. The sealing method is not particularly limited, and examples thereof include a laser irradiation method. As a material constituting the main body part and the lid part, any material capable of constituting a hard case type exterior body in the field of secondary batteries can be used. Such a material may be any material that can achieve electron transfer, and examples thereof include conductive materials such as aluminum, nickel, iron, copper, and stainless steel. The dimensions of the main body and the lid are mainly determined according to the dimensions of the electrode assembly. For example, when the electrode assembly is accommodated, the dimensions are such that the electrode assembly is prevented from moving (displacement) within the exterior body. It is preferable to have. By preventing the movement of the electrode assembly, the electrode assembly is prevented from being destroyed, and the safety of the secondary battery is improved.

  The flexible case is composed of a soft sheet. The soft sheet only needs to have a degree of softness that can achieve bending of the seal portion, and is preferably a plastic sheet. The plastic sheet is a sheet having a characteristic that the deformation due to the external force is maintained when the external sheet is applied and then removed. For example, a so-called laminate film can be used. A flexible pouch made of a laminate film can be produced, for example, by laminating two laminate films and heat-sealing the peripheral edge. As the laminate film, a film obtained by laminating a metal foil and a polymer film is generally used. Specifically, a film having a three-layer structure including an outer layer polymer film / metal foil / inner layer polymer film is exemplified. The outer layer polymer film is for preventing damage to the metal foil due to permeation and contact of moisture and the like, and polymers such as polyamide and polyester can be suitably used. The metal foil is for preventing the permeation of moisture and gas, and a foil of copper, aluminum, stainless steel or the like can be suitably used. The inner layer polymer film is for protecting the metal foil from the electrolyte accommodated therein, and for melting and sealing at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used.

[Secondary battery of the present invention]
Considering the basic configuration of the secondary battery according to the embodiment of the present invention, the characteristic part of the secondary battery according to the embodiment of the present invention will be described below.

  The inventor of the present application diligently studied countermeasures for suppressing the warping stress of the outermost electrode provided on one main surface of the current collector in a cross-sectional view. As a result, the present invention has been devised.

  Prior to describing the features of the present invention, terms used in this specification are defined below. The “partial electrode assembly” in the present specification is, in a broad sense, a stage before an electrode assembly (finished product) is finally obtained by providing an outermost layer electrode, and is used as a precursor of the electrode assembly. Refers to the equivalent. The term “partial electrode assembly” as used in the present specification, in a narrow sense, includes an electrode having electrode material layers entirely provided on both main surfaces of a current collector in a cross-sectional view, and is long. Forms parts other than the scale electrode. The “cross-sectional contour of the partial electrode assembly” referred to in this specification refers to the contour shape of the partial electrode assembly in a cross-sectional view. The term “electrode material portion” as used herein refers to a member in which an electrode material is provided locally (or limitedly or partially) on the main surface of the current collector. The “electrode material layer” in the present specification refers to a member in which an electrode material is provided in a layered manner on the main surface of a current collector.

The present invention has been devised from a different viewpoint from the conventional electrode assembly having a planar laminated structure in which a plurality of electrode constituent layers in which separators are arranged between electrodes are laminated. Specifically, the present invention has been devised based on the technical idea of winding the long electrode 10 (single-sided electrode) around the partial electrode assembly 90. In order to realize such technical idea, the present invention has both the following first and second features. Specifically, according to the present invention, first, the electrode assembly 100 includes a partial electrode assembly 90 and a long electrode having a bent shape that surrounds the partial electrode assembly 90 along a sectional outline of the partial electrode assembly 90. 10 (see FIG. 1). In addition, according to the present invention, secondly, the long electrode 10 has a current collector 11, an electrode material layer 11 </ b> X provided on one main surface 11 </ b> X of the current collector 11, and a current collector. 11 is provided with electrode material portions 13 locally provided at both end regions 11Y ₁ and 11Y ₂ of the other main surface 11Y (see FIG. 1). The material composition of the electrode material portion 13 is substantially the same as the material composition of the electrode material layer 12 provided on one main surface 11X of the current collector 11. Such a feature of the present invention is structurally significant in that it is not an extension of the conventional technical knowledge of those skilled in the art of laminating a planar outermost layer electrode in the planar laminated structure type electrode assembly 100. Have a difference.

  According to the first feature of the present invention described above, the elongated electrode 10 in the bent form surrounds the partial electrode assembly 90 along the sectional outline of the partial electrode assembly 90. That is, the long electrode 10 in the bent form is wound around the partial electrode assembly 90 along the cross-sectional contour of the partial electrode assembly 90. In this state, due to the winding of the long electrode 10 along the cross-sectional contour of the partial electrode assembly 90, tensile stress is easily applied to the long electrode 10. That is, a predetermined tension can be applied to the long electrode 10. Such tension can suppress warping stress that may occur in the long electrode 10. In other words, such tension can lead to the bending of the long electrode 10. In particular, when a tension that is relatively greater than the warping stress that can occur in the long electrode 10 is applied to the long electrode 10, the warping stress that can occur in the long electrode 10 can be more suitably suppressed.

According to the above-mentioned second feature of the present invention, the two end regions 11Y ₁ and 11Y ₂ of the other main surface 11Y opposite to the one main surface 11X of the current collector 11 on which the electrode material layer 11X is provided, The electrode material part 13 is provided locally. That is, the electrode material layer 12 provided on one main surface 11X and the electrode material portion 13 provided on the other main surface 11Y face each other across the current collector 11 in a cross-sectional view. In such a portion facing each other, an electrode provided with the material composition of the electrode material portion 13 on one main surface 11X of the current collector 11 when the long electrode 10 is manufactured (specifically, during pressure treatment). Due to the fact that the material composition of the material layer 12 is substantially the same, the electrode material layer 12 and the electrode material part 13 may have substantially the same degree of elongation. Therefore, in the mutually opposing portions, the electrode material layer 12 provided to one main surface 11X of the current collector 11 and the other main surface 11Y of the current collector during the pressurizing process of the long electrode 10 The electrode material portion 13 provided for the above can be extended to the same extent.

  Specifically, the degree of expansion of the electrode material layer 12 during the pressure treatment is relatively greater than the degree of elongation of the current collector 11 during the pressure treatment. In the laminated body, warping stress may be generated such that the electrode material layer 12 becomes an outer curved surface and the current collector 11 becomes an inner curved surface. On the other hand, the degree of expansion of the electrode material part 13 during the pressure treatment is relatively larger than the degree of elongation of the current collector 11 during the pressure treatment, and thus the electrode material part 13 and the current collector 11 are. In such a laminate, warping stress may occur such that the electrode material portion 13 becomes an outer curved surface and the current collector 11 becomes an inner curved surface. That is, in one embodiment of the present invention, at the portion where the electrode material layer 12 and the electrode material portion 13 face each other, “the electrode material layer 12 and the current collector provided on one main surface 11X of the current collector 11”. 11 ”and“ direction in which warpage stress of the electrode material portion 13 provided on the other main surface 11Y of the current collector 11 and the current collector 11 can occur ”. They can be in opposite relations.

In this regard, as shown in FIG. 10, in the conventional outermost layer electrode 10 ′ (single-sided electrode), the outermost layer electrode 10 ′ (single-sided electrode) is caused by the difference in the degree of expansion between the current collector 11 ′ and the electrode material layer 12 ′ during the pressure treatment. The end regions of the outer layer electrode 10 ′ may tend to be more warped than the center region. Considering this tendency, in the present invention, the electrode material portion 13 is locally provided in both end regions 11Y ₁ and 11Y ₂ of the other main surface 11Y of the current collector. That is, portions where the electrode material layer 12 and the electrode material portion 13 face each other are formed in both end regions of the long electrode 10. Thereby, in the both end regions of the long electrode 10, the “direction in which the warp stress of the laminate of the electrode material layer 12 and the current collector 11 can occur” and “the laminate of the electrode material portion 13 and the current collector 11 are formed. The direction in which the warp stress can occur can be reversed.

  Therefore, in the portion where the electrode material layer 12 and the electrode material portion 13 face each other, the directions of the warping stresses are opposite to each other, indicating that “the warpage of the laminate of the electrode material layer 12 and the current collector 11”. The “stress” can be substantially offset by “the warping stress of the laminate of the electrode material portion 13 and the current collector 11”. Such offset can suppress the warping stress that can occur in the long electrode 10 during the pressurizing process, in particular, the warping stress that can occur in both end regions of the long electrode 10.

  In particular, the present invention has both the first feature and the second feature as described above, and both the first feature and the second feature of the present invention are warped of the long electrode 10. The technical effect of suppressing stress can be achieved. From the above, in one embodiment of the present invention, it is possible to suitably suppress the warping stress of the long electrode 10 due to having both the first feature and the second feature. It is. That is, as compared with the case where the electrode material layer 12 is provided only on one main surface of the current collector 11, the warpage of the long electrode 10 can be suitably suppressed as a whole.

  Due to this, as shown in FIG. 1, such warpage can be suitably adhered to the long electrode 10 in a bent form on the separator 50 positioned between the electrode assembly 100 and the partial electrode assembly 90 when the electrode assembly 100 is configured. Will lead to Therefore, the long electrode 10 having a bent shape 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.

  In addition, since the warp stress that may occur in the long electrode 10 can be suppressed as described above, it is not necessary to take the following warp stress suppression measures that have become common technical knowledge for those skilled in the art.

  Specifically, since the warping stress can be generated by a pressurizing process for obtaining a desired density at the time of forming the outermost layer electrode 10 ′, in order to suppress the warping stress according to the common general knowledge of those skilled in the art so far. The thickness of the current collector 11 ′ of the outermost layer electrode 10 ′ is relative to the thickness of the current collector 11 ′ of the double-sided electrode provided for the inner region (corresponding to the partial electrode assembly) of the electrode assembly 100 ′. May need to be large (see FIG. 10). Therefore, the energy density of the battery can be reduced due to the increase in the thickness of the current collector 11 ′ of the outermost layer electrode 10 ′.

  In this regard, in one embodiment of the present invention, it is possible to suppress the warping stress that may occur in the long electrode 10 by another means as described above, and therefore, compared with a double-sided electrode that can be provided to the partial electrode assembly 90. It is not necessary to relatively increase the thickness of the current collector 11 of the long electrode 10. Therefore, the difference between the thickness of the current collector 11 of the long electrode 10 and the thickness of the current collector of the other double-sided electrode can be reduced, that is, substantially the same.

  Further, according to the conventional technical knowledge of those skilled in the art, in order to suppress the warping stress, it is necessary to relatively reduce the pressure (pressing force) applied to the outermost layer electrode 10 '. Therefore, the energy density of the battery can be reduced due to the relatively small pressure applied to the outermost layer electrode 10 '(see FIG. 10).

  In this regard, in one embodiment of the present invention, the warping stress that can occur in the long electrode 10 can be suppressed by another means as described above. Compared with the applied pressure, it is not necessary to relatively reduce the applied pressure when forming the long electrode 10 (single-sided electrode). That is, it is possible to reduce the difference between the pressure applied when forming the double-sided electrode provided to the partial electrode assembly 90 and the pressure applied when forming the long electrode 10 (single-sided electrode). Therefore, the difference between the density of the double-sided electrodes provided to the partial electrode assembly 90 obtained by the pressure treatment and the density of the long electrodes 10 can be reduced, that is, substantially the same. From the above, one embodiment of the present invention does not require an increase in the thickness of the current collector 11 of the long electrode 10 and / or a reduction in the pressure applied to the long electrode 10. It is also advantageous in that it is possible to suppress a decrease in energy density.

  The secondary battery according to one embodiment of the present invention preferably adopts the following aspects.

  In one embodiment, the electrode assembly 100α includes two partial electrode assemblies 90 that are spaced apart from each other along the stacking direction, and a single continuous long electrode 10 is formed on the outer peripheral surface of the electrode assembly 100. It is preferable to surround each of the two partial electrode assemblies 90 so that the electrode material portion 13 does not exist in 100P (see FIG. 2).

  The aspect shown in FIG. 2 has the following features compared to FIG. First, the embodiment shown in FIG. 2 uses two partial electrode assemblies 90 that are separated from each other in the stacking direction as compared with FIG. 1, and the long electrode 10 in a bent form has the two partial electrode assemblies. The three-dimensional body 90 is characterized by surrounding each of the partial electrode assemblies 90 along the sectional outline. 2ndly, the aspect shown in FIG. 2 has the characteristic that the electrode material part 13 of the elongate electrode 10 which comprises a bending form compared with FIG. 1 does not exist in the outer peripheral surface 100P of the electrode assembly 100. FIG.

  According to the first feature, the elongated electrode 10 in the bent form surrounds the two partial electrode assemblies 90 along the cross-sectional outline of each partial electrode assembly 90. Therefore, the long electrode 10 is wound around the two partial electrode assemblies 90 along the cross-sectional contours in a cross-sectional view as compared with the aspect shown in FIG. Therefore, the number of bent portions of the long electrode 10 formed due to the winding around the two partial electrode assemblies 90 is increased in comparison with the embodiment shown in FIG. Specifically, in the embodiment shown in FIG. 1, the number of bent portions of the long electrode 10 is three in a sectional view, whereas in the embodiment shown in FIG. 2, the elongated electrode 10 is bent in a sectional view. The number of parts is six. Due to the increase in the number of the bent portions, a tensile stress is more easily applied to the long electrode 10. That is, it is possible to provide a relatively large tension to the long electrode 10 as compared with the embodiment shown in FIG. With such a relatively large tension, it is possible to more suitably suppress the warping stress that may occur in the long electrode 10.

  According to the second feature, the electrode material portion 13 of the long electrode 10 having a bent shape does not exist on the outer peripheral surface 100 </ b> P of the electrode assembly 100. In this regard, when the electrode material portion 13 can be present on the outer peripheral surface 100P of the electrode assembly 100, lithium ions are unlikely to move to the electrode material layer of the opposite electrode through the electrolytic solution, thereby existing on the outer peripheral surface 100P. There is a problem that the electrode material portion 13 that can be used does not suitably function as a component of the electrode assembly 100, that is, the secondary battery. However, according to the second feature of this aspect, since the electrode material portion 13 does not exist on the outer peripheral surface 100P of the electrode assembly 100, occurrence of such a problem can be suitably avoided. Therefore, it is possible to avoid a reduction in energy density of the secondary battery due to the avoidance of such a problem.

  In one aspect, it is preferable that one electrode material portion 13a and the other electrode material portion 13b of the long electrode 10 face each other along the stacking direction (see FIG. 2).

  The embodiment shown in FIG. 2 is characterized in that in addition to the above embodiment, one electrode material portion 13a and the other electrode material portion 13b of the long electrode 10 face each other along the stacking direction. When the electrode material portion 13 of the elongated electrode 10 having a bent shape is not present on the outer peripheral surface 100 </ b> P of the electrode assembly 100, the electrode material portion 13 may be present in the inner region of the electrode assembly 100. In particular, when one electrode material portion 13a and the other electrode material portion 13b of the long electrode 10 are present in the inner region of the electrode assembly 100 so as to face each other along the stacking direction, the following effects are exhibited. obtain. Specifically, when the opposite electrode 10α having an electrode material layer having a polarity different from those of the electrode material portions 13a and 13b exists between the electrode material portions 13a and 13b, lithium ions are extracted from the electrode material portions of the opposite electrode. It can be suitably moved to the electrode material layer. Therefore, these electrode material portions 13 can be suitably functioned as the electrode assembly 100, that is, a constituent element of the secondary battery. As a result, a decrease in the energy density of the secondary battery can be suitably avoided by the suitable function of the electrode material portion 13.

  In addition, it is not limited to this, At least 1 partial electrode assembly 90 may further be provided between both electrode material part 13a, 13b (refer FIG. 3). In this case, the electrode material layer adjacent to each of the two electrode material portions 13a and 13b via the separator (the component of the further partial electrode assembly 90) is opposite to the electrode material portions 13a and 13b having different polarities. Note that it must be a component of the electrode.

  In one aspect, the separator 50 with an adhesive layer that is in contact with the long electrode 10 and the partial electrode assembly 90 is positioned between the long electrode 10 and the partial electrode assembly 90 in a sectional view. Preferred (see FIGS. 1 and 2).

  This aspect is characterized in that a separator 50 with an adhesive layer is positioned between the long electrode 10 and the partial electrode assembly 90 in a sectional view. The separator 50 is positioned between the electrode 10 and the partial electrode assembly 90 from the viewpoint of preventing a short circuit due to contact between the positive and negative electrodes. Specifically, the separator 50 is provided so as to be in contact with both the outermost layer electrode 10 and the partial electrode assembly 90, and the separator 50 is provided with an adhesive layer having an adhesive function on both main surfaces thereof. (Not shown). That is, the separator 50 is “the separator 50 with an adhesive layer”. Specifically, the adhesive layer provided on one main surface of the separator 50 is bonded to the electrode material layer 12 of the long electrode 10. On the other hand, the adhesive layer provided on the other main surface of the separator 50 is bonded to the partial electrode assembly 90. As described above, the long electrode 10 and the partial electrode assembly 90 can be suitably integrated through the “separator 50 with an adhesive layer”.

  In one aspect, it is preferable that the long electrode further includes an electrode material portion provided locally between both end regions of the other main surface of the current collector (not shown).

As described above, in the conventional outermost layer electrode (single-sided electrode), the both end regions may tend to be more warped than the central region. Considering such a tendency, the electrode material portion 13 is locally provided in both end regions 11Y ₁ and 11Y ₂ of the other main surface 11Y of the current collector (see FIG. 1). That is, portions where the electrode material layer 12 and the electrode material portion 13 face each other are formed in both end regions of the long electrode 10. Thereby, in both end regions of the long electrode 10, “the direction in which the warp stress of the laminate of the electrode material layer 12 and the current collector 11 can occur” and “the warp of the laminate of the electrode material portion 13 and the current collector 11. It is possible to make the opposite relationship to “the direction in which stress can occur”. Thereby, as described above, it is possible to suppress the warping stress that may occur particularly in the both end regions of the long electrode. In this embodiment, in addition to this, the electrode material portion is provided not only locally but also between the both end regions of the other main surface of the current collector. Since the electrode material part has a function of suppressing the warping stress that can occur in the long electrode, by increasing the number of the electrode material part, the warping stress that can occur in the long electrode can be suppressed more appropriately. Can be possible.

  In one aspect, the current collector 11 of the long electrode 10 is positioned on the inner side of the tabs 20 (the positive electrode tab 20A and the negative electrode tab 20B) provided for the double-sided electrodes of the partial electrode assembly 90 in plan view. It is preferable (see FIG. 4).

  In this aspect, the current collector 11 of the long electrode 10 is positioned on the inner side of the tab 20 provided to the partial electrode assembly 90 in plan view. Specifically, the end portion 11α of the current collector 11 of the long electrode 10 is positioned inside the end portion 20α of the extraction tab 20 provided to the partial electrode assembly 90 in plan view. Due to this arrangement of the long electrode 10 inside the current collector 11, the end of the current collector 11 is substantially the same as the end of the extraction tab 20 provided to the partial electrode assembly 90 in plan view. Compared with the case of being on the same plane, the extraction tab 20 provided in the partial electrode assembly 90 can be more easily exposed. Therefore, a part of the current collector 11 exposed at the end of the long electrode 10 can be suitably welded to the extraction tab 20. Specifically, a part of the current collector 11 exposed at the end of the long electrode 10 can be easily welded to the extraction tab 20. Such suitable welding can contribute to suitable electrical connection between the lead portion (welded portion) and the external terminal via the leads. Taking the case where a negative electrode is used as the long electrode 10 as an example, the positive electrode of the partial electrode assembly 90 from the viewpoint of preventing a short circuit caused by a part of the negative electrode current collector facing the positive electrode tab in plan view. The tab 20A is preferably protected with a tape.

  In one aspect, it is preferable that the long electrode 10 has a tab, and only the tab of the long electrode 10 is positioned so as to locally overlap the tab of the partial electrode assembly 90 in a plan view ( (See FIG. 5).

Taking the case where the negative electrode is used as the long electrode, for example, in the state where the long electrode 10 is wound around the partial electrode assembly 90, the positive electrode tab 20A of the partial electrode assembly 90 and the negative electrode side current collector are viewed in plan view. A short circuit may occur due to the fact that some of them face each other. Therefore, in the present embodiment, taking the case of using the negative electrode as elongated electrode as an example, in view of the short-circuit prevention, the negative electrode tab 20B ₁ provided elongated electrode 10, only the negative electrode tab 20B ₁ is viewed in plane it is preferable to be positioned to overlap the negative electrode tab 20B ₂ and the local portion the electrode assembly 90. Thereby, after winding, it can be avoided that the positive electrode tab 20A of the partial electrode assembly 90 and a part of the negative electrode side current collector face each other in plan view. By avoiding such mutual facing, it is possible to avoid occurrence of a short circuit due to the positive electrode tab 20A of the partial electrode assembly 90 and a part of the negative electrode side current collector facing each other in plan view. Therefore, the safety of the battery can be improved as a result of avoiding the occurrence of such a short circuit.

  In one embodiment, the long electrode 10 at the portion facing the side surface 90β of the partial electrode assembly 90 has a single-sided electrode structure in cross-sectional view, and the long electrode 10 is preferably a negative electrode (see FIG. 1). ).

  In this embodiment, since the portion of the long electrode 10 facing the side surface 90β of the partial electrode assembly 90 has a single-sided electrode structure in a sectional view, the electrode material is also applied to the portion facing the side surface 90β of the partial electrode assembly 90. Layer 11 will be positioned. When a negative electrode is used as the long electrode 10, specifically, when a negative electrode material layer is used as the electrode material layer 11, the negative electrode material layer can function as a layer capable of receiving lithium ions. Lithium ions that can move in 90 side regions can be suitably received. Therefore, it is possible to suitably suppress lithium deposition on the negative electrode end portion of the partial electrode assembly 90 due to lithium ion movement. Therefore, as a result of suppressing lithium precipitation, the safety of the battery can be improved.

  In addition, it is not limited to this, In one aspect | mode, the elongate electrode of the part which opposes the side surface of a partial electrode assembly may have only a collector in sectional view (not shown).

  In this case, the electrode material layer does not exist in the long electrode of the portion facing the side surface of the partial electrode assembly. Therefore, the width dimension of the electrode assembly finally obtained due to the absence of the electrode material layer can be relatively reduced as compared with the case where the long electrode has the electrode material layer. Therefore, the size of the secondary battery including the electrode assembly can be relatively reduced.

  When the long electrode is used as a positive electrode, the positive electrode material layer does not substantially function as a layer capable of accepting lithium ions, so the partial electrode originates from lithium ions that can move in the side region of the partial electrode assembly. It is difficult to suppress lithium deposition on the negative electrode end of the assembly. Therefore, when the long electrode is used as a positive electrode, it is preferable that the portion of the long electrode facing the side surface of the partial electrode assembly has only a current collector in a sectional view.

  In one aspect, a part of the current collector 11 of the long electrode 10 is exposed, and a part of the exposed current collector 11 is positioned outside the separator 50 and the electrode material layer 12 in a plan view. It is preferable (see FIG. 1).

  The present invention is characterized in that the long electrode 10 surrounds the partial electrode assembly 90 in a cross-sectional view (see FIG. 1), but both the long electrode 10 and the partial electrode assembly 90 are the electrode assembly 100. It is a component. Therefore, in order for the electrode assembly 100 to function suitably as a whole, the tab of the double-sided electrode in the partial electrode assembly 90 and a part of the current collector 11 of the long electrode 10 can be electrically connected. It needs to be in a state. That is, it is necessary to arrange the tabs of the double-sided electrodes in the partial electrode assembly 90 and a part of the current collector 11 of the long electrode 10 so as to face each other in plan view. Therefore, it is necessary to expose a part of the current collector 11 of the long electrode 10 in plan view. In view of this point, in this aspect, it is preferable that a part of the exposed current collector 11 is positioned outside the separator 50 and the electrode material layer 12 in a plan view. Accordingly, a part of the current collector 11 can be preferably opposed to the tab of the double-sided electrode in the partial electrode assembly 90 in plan view. Therefore, the tab of the double-sided electrode in the partial electrode assembly 90 and a part of the current collector 11 where the long electrode 10 is exposed can be electrically connected suitably. As a result, the electrode assembly 100 as a whole can be connected. It becomes possible to make it function suitably.

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

  The manufacturing method of the present invention has been devised from a viewpoint different from the conventional method of forming an electrode assembly having a planar laminated structure by laminating a plurality of electrode constituent layers obtained by arranging separators between electrodes. . Specifically, the present invention includes a step of forming a partial electrode assembly and a step of surrounding the partial electrode assembly by the elongated electrodes along the cross-sectional contour of the partial electrode assembly. An electrode material layer is provided entirely on one main surface of the electric body, and an electrode material portion is locally provided on both end regions of the other main surface of the current collector. That is, the feature of the manufacturing method of the present invention is different in that it is not on the extension of the technical common sense of those skilled in the art that an electrode assembly is obtained by laminating each electrode including the outermost layer electrode.

In the manufacturing method of the present invention, as described above, the long electrode 10 is provided with the electrode material layer 12 entirely on one main surface 11X of the current collector 11, and both ends of the other main surface 11Y of the current collector 11 are provided. formed by locally providing the electrode material portions 13 in the region _11Y 1, _{11Y 2.} That is, portions where the electrode material layer 12 and the electrode material portion 13 face each other are formed in both end regions of the long electrode 10. Thereby, in both end regions of the long electrode 10, “the direction in which the warp stress of the laminate of the electrode material layer 12 and the current collector 11 can occur” and “the warp of the laminate of the electrode material portion 13 and the current collector 11. It is possible to make the opposite relationship to “the direction in which stress can occur”.

  Therefore, in the portion where the electrode material layer 12 and the electrode material portion 13 face each other, the directions of the warping stresses are opposite to each other, indicating that “the warpage of the laminate of the electrode material layer 12 and the current collector 11”. The “stress” can be substantially offset by “the warping stress of the laminate of the electrode material portion 13 and the current collector 11”. Such offset can suppress the warping stress that can occur in the long electrode 10 during the pressurizing process, in particular, the warping stress that can occur in both end regions of the long electrode 10.

  In the manufacturing method of the present invention, the long electrode 10 is used to surround the partial electrode assembly 90 along the cross-sectional contour of the partial electrode assembly 90. That is, the long electrode 10 is wound around the partial electrode assembly 90 along the sectional outline of the partial electrode assembly 90. Due to such winding, the long electrode 10 is bent in a cross-sectional view, whereby a tensile stress is easily applied to the long electrode 10. That is, a predetermined tension can be applied to the long electrode 10. Such tension can suppress warping stress that may occur in the long electrode 10.

  In the manufacturing method of the present invention, as described above, warping stress that can be generated in the long electrode 10 is suppressed both when the long electrode 10 is formed and when the long electrode 10 is wound around the partial electrode assembly 90. It is possible. Therefore, in one embodiment of the present invention, it is possible to suitably suppress the warpage of the long electrode 10 as a whole as compared with the conventional mode in which the electrode material layer 12 is provided only on one main surface of the current collector 11. . Due to this, as shown in FIG. 6, the warpage can be suppressed by suitably bonding the long electrode 10 in a bent form to the separator 50 positioned between the electrode assembly 100 and the partial electrode assembly 90 when the electrode assembly 100 is configured. Will lead to Therefore, the long electrode 10 having a bent shape 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.

  In addition, it is preferable that the manufacturing method of this invention takes the following aspects.

  In one embodiment, a separator 50 with an adhesive layer is provided on one main surface 11X of the current collector 11 of the long electrode 10 and before the partial electrode assembly 90 is surrounded, the separator 50 with an adhesive layer is interposed. The partial electrode assembly 90 is preferably fixed to one end region of the long electrode 10 (see FIG. 6).

  This aspect is characterized by the aspect before forming the long electrode 10 and winding the long electrode 10 around the partial electrode assembly 90. Specifically, the partial electrode assembly 90 can be fixed to the long electrode 10 via the separator 50 due to the adhesiveness of the adhesive layer provided to the separator 50. In particular, fixing the partial electrode assembly 90 to the one end region of the long electrode 10 enables effective use of the long electrode 10 other than the fixed portion, and the partial electrode assembly 90 of the long electrode 10. This is advantageous in that it can be reliably wound around. Further, due to the adhesiveness of the adhesive layer provided to the separator 50, it is provided to one side of the separator 50 after the long electrode 10 is wound around the partial electrode assembly 90 via the separator 50. The adhesive material layer adheres to the electrode material layer 12 of the long electrode 10. On the other hand, the adhesive layer provided on the other side of the separator 50 adheres to the partial electrode assembly 90. As described above, the long electrode 10 and the partial electrode assembly 90 can be suitably integrated through the “separator 50 with an adhesive layer”.

  In one aspect, two partial electrode assemblies 90 are used, the electrode material portion 13 is absent on the outer peripheral surface, and one partial electrode assembly 90 and the other partial electrode assembly 90 are mutually connected along the stacking direction. It is preferable that a single continuous long electrode 13 is bent so that the partial electrode assembly is surrounded by the long electrode 13 (see FIGS. 7A to 7F).

  This will be specifically described with reference to FIGS. 7A to 7F.

First, as shown in FIG. 7A, the long electrode 10 is provided with the electrode material layer 12 on the entire main surface 11 </ b> X of the current collector 11, and both end regions 11 </ b> Y of the other main surface 11 </ b> Y of the current collector 11. ₁ , 11Y ₂ is formed by locally providing the electrode material portion 13 and then applying pressure treatment. Next, the separator 50 with an adhesive layer is provided over the entire main surface of the electrode material layer 12. Specifically, the adhesive layer is provided on both main surfaces of the separator 50.

  Next, as shown in FIG. 7B, the partial electrode assembly 90 having substantially the same width as the electrode material portion 13 in a cross-sectional view is opposed to the one electrode material portion 13 and the other electrode material portion 13. It positions on the separator 50 with an adhesive layer.

  Next, as illustrated in FIGS. 7C and 7D, the stacked body in the mode illustrated in FIG. 7B is bent inward so that both electrode material portions 13 face upward in a cross-sectional view.

  Next, as shown in FIGS. 7E and 7F, the two electrode member portions 13 are opposed to each other in a cross-sectional view, and the two partial electrode assemblies 90 are spaced apart from each other along the stacking direction. The laminate of the aspect shown in 7D is further bent inward.

  Next, as shown in FIG. 7F, a long electrode 10 and a partial electrode are provided by providing opposite electrodes having different polarities in a space region formed between one electrode material portion 13 and the other electrode material portion 13. An electrode assembly precursor integrated with the assembly 90 is formed.

  Next, heat and pressure are applied to the precursor of the electrode assembly. Since the interlaminar connectivity (adhesion) can be improved by applying heat and pressure to the precursor of the electrode assembly obtained by integration, the long electrode 10 and the partial electrode assembly 90 can be improved by the heat and pressure. It becomes possible to perform more suitable integration.

  Thus, a desired electrode assembly (100) can be obtained.

  Also from the above thing, in this aspect, the two partial electrode assemblies 90 are each surrounded along the cross-sectional outline of each partial electrode assembly 90 by the elongate electrode 10 of a bending form. Therefore, the long electrode 10 is in a state of being wound around the two partial electrode assemblies 90 along each cross-sectional contour in a cross-sectional view. Therefore, the number of bent portions of the long electrode 10 formed due to the winding around the two partial electrode assemblies 90 is increased as compared with the embodiment shown in FIG. Specifically, in the embodiment shown in FIG. 6, the number of bent portions of the long electrode 10 is three in a sectional view, whereas in the embodiment shown in FIG. 7F, the elongated electrode 10 is bent in a sectional view. The number of parts is six. Due to the increase in the number of the bent portions, a tensile stress is more easily applied to the long electrode 10. That is, it is possible to provide a relatively large tension to the long electrode 10 as compared with the aspect shown in FIG. With such a relatively large tension, it is possible to more suitably suppress the warping stress that may occur in the long electrode 10.

  In this aspect, the electrode material portion 13 of the long electrode 10 having a bent shape is not positioned on the outer peripheral surface 100P of the electrode assembly 100. When the electrode material portion 13 is positioned on the outer peripheral surface 100P of the electrode assembly 100, lithium ions are unlikely to move to the electrode material layer of the opposite electrode via the electrolytic solution, whereby the electrode material portion 13 positioned on the outer peripheral surface 100P is It is possible to suitably avoid the occurrence of a problem that the assembly 100 does not function properly. Therefore, it is possible to avoid a reduction in energy density of the secondary battery due to the avoidance of such a problem.

  In order to make one electrode material part 13a and the other electrode material part 13b of the elongate electrode 10 oppose each other along the laminating direction, as shown in FIG. 7F, these electrode material parts 13a and 13b are interposed between both electrode material parts 13a and 13b. When the opposite electrode 10α provided with an electrode material layer having a polarity different from that of the electrode material portion is provided, it becomes possible to suitably move lithium ions from these electrode material portions to the electrode material layer of the opposite electrode. Therefore, these electrode material portions 13 can be suitably functioned as the electrode assembly 100. As a result, a decrease in the energy density of the secondary battery can be suitably avoided by the suitable function of the electrode material portion 13.

  Further, as described above, when the precursor of the electrode assembly is subjected to heat and pressure, the predetermined shape (shape) of the long electrode 10 is maintained by the predetermined tension provided to the electrode 10 due to this. It can be “continuous” or “continuous”. By maintaining the shape of the long electrode 10 that is “continuous” or “continuous”, the main surface of the electrode material layer 12 can be an outer curved surface in the long electrode 10, and the main surface of the current collector 11 can be an inner curved surface. It is possible to more suitably suppress the occurrence of warping stress.

  In one embodiment, at least one partial electrode assembly 90 may be further provided between both electrode material portions 13a and 13b (see FIG. 8).

In this case, as described above, first, the long electrode 10 is provided with the electrode material layer 12 entirely on one main surface 11X of the current collector 11, and both end regions of the other main surface 11Y of the current collector 11 are provided. It is formed by locally providing the electrode material portion 13 on 11Y ₁ and 11Y ₂ . Next, the separator 50 with an adhesive layer is provided over the entire main surface of the electrode material layer 12. Next, the partial electrode assembly 90 having substantially the same width dimension as that of the electrode material portion 13 in a cross-sectional view is placed on the separator 50 with an adhesive layer so as to face the one electrode material portion 13 and the other electrode material portion 13 respectively. Position.

  Here, although not particularly limited, in this embodiment, the partial electrode assembly 90 in which the separators 50 with the adhesive layer are provided on both main surfaces is provided on one electrode material portion 13.

  Then, finally, the laminated body shown in the upper part of FIG. 8 so that both electrode material portions 13 face each other in a cross-sectional view and the three partial electrode assemblies 90 are arranged along the laminating direction. Is bent inward a predetermined number of times. In addition, it is not limited to this, After bending a laminated body so that a space area may be formed between one electrode material part 13 and the other electrode material part 13, a separator with an adhesive layer on both main surfaces At least one partial electrode assembly 90 provided with 50 may be provided. In this case, as compared with the embodiment shown in the upper part of FIG. 8, the step of providing the partial electrode assembly 90 provided with the separator 50 with the adhesive layer on both main surfaces on one electrode material portion 13 is excluded. pay attention to.

  As described above, a desired electrode assembly 100 can be obtained.

  When at least one partial electrode assembly 90 provided with the separator 50 with the adhesive layer on both main surfaces is further provided, the further partial electrode assembly 90 is adjacent to both the electrode material portions 13a and 13b. If there are counter electrodes provided with electrode material layers having polarities different from those of the electrode material portions, lithium ions can be suitably moved from these electrode material portions to the electrode material layers of the opposite electrodes. Therefore, these electrode material portions 13 can be suitably functioned as components of the electrode assembly 100. As a result, a decrease in the energy density of the secondary battery can be suitably avoided by the suitable function of the electrode material portion 13.

  In one aspect, it is preferable to use a long electrode that further includes an electrode material portion locally provided between both end regions of the other main surface of the current collector (not shown).

As described above, in the conventional outermost layer electrode (single-sided electrode), both end regions may tend to be more warped than the central region, and therefore both end regions 11Y ₁ of the other main surface 11Y of the current collector. , 11Y ₂ is provided with the electrode material portion 13 locally (see FIG. 6). Thereby, in both end regions of the long electrode 10, “the direction in which the warp stress of the laminate of the electrode material layer 12 and the current collector 11 can occur” and “the warp of the laminate of the electrode material portion 13 and the current collector 11. It is possible to make the opposite relationship to “the direction in which stress can occur”. Thereby, as described above, it is possible to suppress the warping stress that may occur particularly in the both end regions of the long electrode. In this embodiment, in addition to this, the electrode material portion is further provided locally not only between the both end regions of the other main surface of the current collector but also between the both end regions. Since the electrode material portion has a function of suppressing the warping stress that can occur in the long electrode, it is possible to more suitably suppress the warping stress that can be generated in the long electrode by increasing the number of the electrode material portions. Could be possible.

  In one aspect, the current collector 11 of the long electrode 10 is preferably positioned on the inner side of the tab used for the double-sided electrode of the partial electrode assembly 90 in plan view (see FIG. 4).

  In this embodiment, the current collector 11 of the long electrode 10 is positioned on the inner side of the tab 20 provided to the partial electrode assembly 90 in plan view. Due to the inner arrangement of the current collector 11 of the long electrode 10, the end of the current collector 11 is substantially the same as the end of the extraction tab 20 provided to the partial electrode assembly 90 in plan view. Compared with the case of being on the same plane, the extraction tab 20 provided to the long electrode assembly 90 can be more easily exposed. Therefore, a part of the current collector 11 exposed at the end of the long electrode 10 can be easily welded to the extraction tab 20.

  In one aspect, it is preferable that only the tab provided for the long electrode 10 is locally overlapped with the tab of the partial electrode assembly 90 in a plan view (see FIG. 5).

  In this embodiment, for example, in the case of using a negative electrode as the long electrode, from the viewpoint of preventing the short circuit, the long electrode 10 is provided with a negative electrode tab, and only the negative electrode tab of the partial electrode assembly 90 is viewed in plan view. It is preferable to overlap locally with the negative electrode tab. Thereby, after winding, it can avoid that the positive electrode tab of the partial electrode assembly 90 and a part of negative electrode side current collector mutually oppose by planar view. Also from the above, by avoiding such mutual facing, it is possible to avoid occurrence of a short circuit due to the positive electrode tab of the partial electrode assembly 90 and a part of the negative electrode side current collector facing each other in plan view. it can. Therefore, the safety of the battery can be improved.

  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 an embodiment of the present invention, particularly the non-aqueous electrolyte secondary battery, is merely an example, and the electric / information / communication field (for example, a mobile phone, a smart phone, a notebook) Mobile devices such as personal computers and digital cameras), home / small industrial applications (eg, power tools, golf carts, home / care / industrial robots), large industrial applications (eg, forklifts, elevators, bay ports) Crane field), transportation system field (for example, hybrid vehicle, electric vehicle, bus, train, electric assist bicycle, electric motorcycle, etc.), power system application (for example, various power generation, road conditioner, smart grid, general home installation) Field), as well as space and deep sea applications (eg space probes) It can be used in the field), such as diving research vessel.

10 long electrode 11 current collector 11X collector main surface _11Y 1 one other main surface 11Y collector of, 11Y ₂ current collector other across region 12 electrode material layer 13 electrode material of the main surface of the 20 Tab 20A Positive electrode tab
20B Negative electrode tab 50 Separator 90 Partial electrode assembly 90β Side surface of partial electrode assembly 100 Electrode assembly

Claims (20)

A secondary battery comprising an electrode assembly having a planar laminated structure and an exterior body for housing the electrode assembly,
The electrode assembly includes a partial electrode assembly, and a long electrode having a bent shape surrounding the partial electrode assembly along a cross-sectional contour of the partial electrode assembly.
The long electrode is locally provided on a current collector, an electrode material layer provided entirely on one main surface of the current collector, and both end regions of the other main surface of the current collector. And a secondary battery. The electrode assembly includes two partial electrode assemblies spaced apart from each other along a stacking direction;
2. The two according to claim 1, wherein the single continuous long electrode surrounds each of the two partial electrode assemblies such that the electrode material portion is absent on the outer peripheral surface of the electrode assembly. Next battery.   The secondary battery according to claim 2, wherein the one electrode material portion of the long electrode and the other electrode material portion are opposed to each other along the stacking direction.   The secondary battery according to claim 2, wherein an opposite electrode having a different polarity is provided between the one electrode material portion and the other electrode material portion.   5. The secondary battery according to claim 2, wherein at least one partial electrode assembly is further provided between the one electrode material portion and the other electrode material portion.   The separator with an adhesive layer in contact with the outermost layer electrode and the partial electrode assembly is positioned between the elongated electrode and the partial electrode assembly in a cross-sectional view. A secondary battery according to any one of the above.   The said elongate electrode further has the said electrode material part provided locally between the said both end area | regions of the said other main surface of the said collector. Secondary battery.   The partial electrode assembly includes an electrode in which an electrode material layer is entirely provided on both main surfaces of a current collector in a cross-sectional view, and forms a portion other than the long electrode. The secondary battery in any one of 1-7.   The secondary according to any one of claims 1 to 8, wherein the current collector of the long electrode is positioned inside a tab provided for the electrode of the partial electrode assembly in a plan view. battery.   The long electrode has a tab, and only the tab of the long electrode is positioned so as to locally overlap the tab of the partial electrode assembly in a plan view. The secondary battery in any one of.   The secondary battery according to claim 1, wherein the long electrode and the electrode of the partial electrode assembly have a layer capable of inserting and extracting lithium ions. A method of manufacturing a secondary battery comprising an electrode assembly having a planar laminated structure and an exterior body for housing the electrode assembly,
Forming a partial electrode assembly;
Surrounding the partial electrode assembly with an elongated electrode along a cross-sectional profile of the partial electrode assembly,
The long electrode is formed by providing an electrode material layer entirely on one main surface of the current collector and locally providing electrode material portions on both end regions of the other main surface of the current collector. Production method. A separator with an adhesive layer is provided on the one main surface of the current collector of the long electrode,
The manufacturing method according to claim 12, wherein the partial electrode assembly is fixed to one end region of the long electrode via the separator with the adhesive layer before surrounding the partial electrode assembly. . Using two said partial electrode assemblies,
The single continuous elongate so that the electrode material portion is absent on the outer peripheral surface, and one of the partial electrode assemblies and the other partial electrode assembly are separated from each other along the stacking direction. The manufacturing method according to claim 12 or 13, wherein an electrode is bent and the partial electrode assembly is surrounded by the long electrode.   The manufacturing method according to claim 14, wherein the one electrode material part of the long electrode and the other electrode material part are opposed to each other along the stacking direction.   The manufacturing method according to claim 14 or 15, wherein an opposite electrode having a different polarity is provided between the one electrode material portion and the other electrode material portion.   The manufacturing method according to claim 14, wherein at least one partial electrode assembly is further provided between the one electrode material portion and the other electrode material portion.   18. The electrode according to claim 12, wherein the electrode material portion is further provided locally between the both end regions of the other main surface of the current collector as the long electrode. Production method.   The manufacturing method according to any one of claims 12 to 18, wherein the current collector of the long electrode is positioned inside a tab provided for an electrode of the partial electrode assembly in a plan view.   The long electrode comprises a tab, and only the tab of the long electrode is positioned so as to locally overlap the tab of the partial electrode assembly in plan view. The manufacturing method as described in.

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