Battery and method for manufacturing the same

Abstract

To provide a battery with excellent suppression of positional variation in electrode stacks and a method for manufacturing the same. [Solution] The battery comprises an electrode stack 1, an outer casing 2 that houses the electrode stack 1, and a heat-conducting resin member 3 disposed between the electrode stack 1 and the outer casing 2, wherein the length of the surface of the heat-conducting resin member 3 that contacts the electrode stack 1 is longer than the length of the surface of the electrode stack 1 that contacts the heat-conducting resin member 3.

Description

Technical Field

[0001] The present disclosure relates to a battery and a method for manufacturing the same.

Background Art

[0002] As a all-solid-state battery in which an electrode laminate is enclosed in an exterior body and a heat transfer material is disposed inside the exterior body so as to contact the electrode laminate, for example, the one described in Patent Document 1 can be mentioned. Patent Document 1 discloses a all-solid-state battery cell in which an electrode laminate is enclosed in an exterior material, the electrode laminate includes a current collecting tab extending from an end portion, the current collecting tab is connected to a terminal led out from an end portion of the all-solid-state battery cell, and a first heat transfer material is disposed inside the exterior material so as to contact the electrode laminate and the exterior material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional battery in which a heat transfer material is disposed, when the heat transfer material is disposed inside the exterior body, there is a problem that the position of the electrode laminate varies.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a battery and a method for manufacturing the same that are excellent in suppressing variation in the position of an electrode laminate.

Means for Solving the Problems

[0006] Means for solving the above problems include the following aspects. <1> A battery comprising an electrode stack, an outer casing housing the electrode stack, and a thermal conductive resin member disposed between the electrode stack and the outer casing, wherein the length of the surface of the thermal conductive resin member that contacts the electrode stack is longer than the length of the surface of the electrode stack that contacts the thermal conductive resin member. <2> The heat-conducting resin member is positioned to cover the surface of the electrode laminate that contacts the heat-conducting resin member and a portion of the two surfaces of the electrode laminate that are in contact with that surface. <1> The battery listed. <3> The electrode stack further has a current-collecting tab on the short side surface. <1> or <2> The battery listed. <4> It is a solid-state battery. <1> ~ <3> The battery listed in one of the following items. <5> The aforementioned exterior body has a can-shaped exterior body. <1> ~ <4> The battery listed in one of the following items. <6> The process includes a step of pressing together the electrode laminate and the heat-conducting resin member. <1> ~ <5> A method for manufacturing a battery as described in any one of the following. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a battery that exhibits excellent suppression of positional variations in electrode stacks and a method for manufacturing the same. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of a conventional battery before the electrode laminate and the thermal conductive resin member are pressed together during manufacturing. [Figure 2] This is a schematic cross-sectional view showing an example of a conventional battery. [Figure 3] This is a schematic cross-sectional view of an example of a battery according to this disclosure, before the electrode laminate and the thermal conductive resin member are pressed together during the manufacturing process. [Figure 4] This is a schematic cross-sectional view showing an example of a battery related to this disclosure. [Modes for carrying out the invention]

[0009] The battery and its manufacturing method described herein will be explained in detail below with reference to drawings. The following figures are schematic representations, and the size and shape of each part have been exaggerated as appropriate for ease of understanding.

[0010] (battery) The battery according to this disclosure comprises an electrode stack, an outer casing housing the electrode stack, and a thermal conductive resin member disposed between the electrode stack and the outer casing, wherein the length of the surface of the thermal conductive resin member that contacts the electrode stack is longer than the length of the surface of the electrode stack that contacts the thermal conductive resin member. Furthermore, the battery relating to this disclosure is preferably a solid-state battery, and more preferably an all-solid-state battery. The solid-state battery includes an all-solid-state battery having a solid electrolyte as an electrolyte between electrodes, and the solid electrolyte may contain less than 10% by mass of electrolyte relative to the total amount of electrolyte.

[0011] The method for manufacturing a battery according to the embodiment of this disclosure will be explained below with reference to the figures.

[0012] Figure 1 is a schematic cross-sectional view of a conventional battery before the electrode stack 1 and the thermal conductive resin member 3 are pressed together during manufacturing. Figure 2 is a schematic cross-sectional view showing an example of a conventional battery. Figure 1 shows the state before the electrode laminate 1 is pressed into place, with the heat-conducting resin member 3 placed inside the outer casing 2. In Figure 2, the thermal conductive resin member 3 and the electrode laminate 1 in Figure 1 are pressed together. Furthermore, in Figures 1 and 2, the length of the surface of the thermal conductive resin member 3 that contacts the electrode stack 1 is shorter than the length of the surface of the electrode stack 1 that contacts the thermal conductive resin member 3. In this configuration, when the heat-conducting resin member 3 and the electrode laminate 1 are pressed together, misalignment of the electrode laminate 1 is likely to occur, particularly in the longitudinal direction of the surface of the electrode laminate 1 that is in contact with the heat-conducting resin member 3, resulting in variations in the position of the electrode laminate 1.

[0013] On the one hand, FIG. 3 is a schematic cross-sectional view before crimping the electrode laminate 1 and the heat-conductive resin member 3 during the production of an example of the battery according to the present disclosure. Further, FIG. 4 is a schematic cross-sectional view showing an example of the battery according to the present disclosure. In FIG. 3, the heat-conductive resin member 3 is disposed inside the exterior body 2, showing the state before the electrode laminate 1 is crimped. In FIG. 4, the heat-conductive resin member 3 and the electrode laminate 1 in FIG. 3 are crimped. Also, in FIGS. 3 and 4, the length of the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is longer than the length of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3. With such a battery according to the present disclosure, when the heat-conductive resin member 3 and the electrode laminate 1 are crimped, the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is compressed into the shape of the electrode laminate 1. At the end of the electrode laminate 1, the portion of the heat-conductive resin member 3 that contacts the end of the electrode laminate 1 presses against the end of the electrode laminate 1, thereby suppressing displacement of the electrode laminate 1, particularly in the longitudinal direction of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3, and suppressing variation in the position of the electrode laminate 1.

[0014] Actually, in the embodiments shown in FIGS. 3 and 4, when the length of the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is 2.5 mm longer than the length of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3, the displacement (position shift) in the longitudinal direction of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3 was analyzed, and it was 1.48×10 -4 mm. On the other hand, in the embodiments shown in FIGS. 1 and 2, when the length of the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is 3.0 mm shorter than the length of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3, the displacement (position shift) in the longitudinal direction of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3 was analyzed, and it was 1.71×10 -4 mm. Thus, with the battery according to the present disclosure, variation in the position of the electrode laminate is suppressed.

[0015] In addition, in FIGS. 3 and 4, only the vicinity of one end of the heat-conductive resin member 3 and the electrode laminate 1 is shown. However, similarly, at the other end on the opposite side of the heat-conductive resin member 3 and the electrode laminate 1, it is preferable that the length of the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is longer than the length of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3.

[0016] From the viewpoint of suppressing the displacement of the electrode laminate 1, the length of the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is preferably 0.2 mm or more longer than the length of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3, more preferably 1 mm or more longer, still more preferably 2 mm or more longer, and particularly preferably 4 mm or more and 20 mm or less longer. In addition, from the viewpoint of suppressing the displacement of the electrode laminate 1, at both ends in the longitudinal direction of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3, the length of the surface of the heat-conductive resin member 3 that contacts the electrode laminate 1 is preferably 0.1 mm or more longer than the length of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3, more preferably 0.5 mm or more longer, still more preferably 1 mm or more longer, and particularly preferably 2 mm or more and 10 mm or less longer.

[0017] From the viewpoint of suppressing the displacement of the electrode laminate 1, the heat-conductive resin member 3 is preferably arranged so as to cover a part of the two surfaces of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3 and the electrode laminate 1 that contacts the said surface. Further, the two surfaces are preferably two surfaces that face each other and are perpendicular to the longitudinal direction of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3. In addition, regarding the amount covered by the heat-conductive resin member 3 on the two surfaces, there is no particular limitation, but it is preferable that a region at a distance of 0.1 mm or more from the end of the surface of the electrode laminate 1 that contacts the heat-conductive resin member 3 is covered, more preferably a region at a distance of 0.5 mm or more is covered, and particularly preferably a region at a distance of 1 mm or more and 100 mm or less is covered.

[0018] The battery according to this disclosure preferably further has current-collecting tabs on the short-side surface of the electrode stack 1. Furthermore, it is preferable that the short-side surface is perpendicular to the longitudinal direction of the surface in contact with the heat-conducting resin member 3 in the electrode stack 1. Moreover, it is preferable that the current-collecting tabs extend from the current collector in the electrode stack 1. When the current collection tab is in the above configuration, the connection with the external terminal can be made stable.

[0019] The electrode laminate 1 preferably comprises at least a current collector, a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer. A specific configuration of the electrode stack 1 is, for example, a stack made by stacking unit electrode stacks. The unit electrode laminate can be any known form, but examples include current collector / positive electrode active material layer / electrolyte layer / negative electrode active material layer / current collector, current collector / positive electrode active material layer / electrolyte layer / negative electrode active material layer / current collector / negative electrode active material layer / electrolyte layer / positive electrode active material layer / current collector, etc.

[0020] The material, shape, and size of the outer casing 2 are not particularly limited and can be appropriately selected as desired, and known forms can also be used. In particular, the outer casing 2 is preferably a can-shaped outer casing, more preferably a can-shaped metal outer casing, and even more preferably a rectangular can-shaped metal outer casing.

[0021] The material of the heat-conducting resin member 3 is not particularly limited; any resin material capable of conducting heat generated in the electrode laminate 1 is acceptable, and known resin materials can be used. Furthermore, the material of the thermal conductive resin member 3 is preferably insulating. As the material of the thermal conductive resin member, a known thermal conductive resin can be used, and a mixture of resin and metal filler is also preferably used. The heat-conducting resin member 3 is not particularly limited and may be in the form of a sheet or a paste.

[0022] Furthermore, as shown in Figure 4, the battery according to this disclosure preferably has an internal void, and the thermal conductive resin member 3 is in contact with the void. By the thermal conductive resin member 3 being in contact with the void, the heat dissipation efficiency is improved, and the cooling efficiency of the electrode stack 1 is improved.

[0023] The battery manufacturing method according to this disclosure preferably includes a step of pressing together the electrode stack 1 and the thermal conductive resin member 3. This embodiment allows for greater realization of the effects of this disclosure. The pressure and temperature during the crimping process are not particularly limited and can be appropriately selected depending on the materials of the electrode laminate 1 and the heat-conducting resin member 3 used.

[0024] Furthermore, the battery according to this disclosure may have a bipolar electrode having a positive electrode active material layer on one side of the current collector and a negative electrode active material layer on the side opposite to the current collector foil, and a laminate sheet that covers the side members (e.g., terminals) and is heat-welded to the side members.

[0025] <Components that make up a battery> For example, aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil can be used as the current collector. The thickness of the current collector may be, for example, 1 μm to 100 μm.

[0026] Here, the thickness of each layer, such as the current collector, positive electrode active material layer, and negative electrode active material layer, is the average value of measurements taken at 10 arbitrarily selected locations.

[0027] The positive electrode active material layer contains a positive electrode active material capable of intercalating and releasing charge carriers such as lithium ions. The positive electrode active material can be any material usable as a positive electrode active material for lithium-ion secondary batteries, such as a lithium composite metal oxide having a layered rock salt structure, a metal oxide with a spinel structure, or a polyanionic compound. Furthermore, two or more positive electrode active materials may be used in combination. In this embodiment, the positive electrode active material layer contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0028] The negative electrode active material layer can be any element, alloy, or compound capable of intercalating and releasing charge carriers such as lithium ions, and is not particularly limited. For example, the negative electrode active material can be Li, or carbon, metal compounds, elements or compounds thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, or hard carbon (difficult-to-graphitize carbon) or soft carbon (easily graphitized carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon and tin. In this embodiment, the negative electrode active material layer contains graphite as a carbon-based material.

[0029] The positive electrode active material layer and the negative electrode active material layer may further contain conductive additives, binders, electrolytes (polymer matrix, ion-conducting polymer, electrolyte solution, etc.) to enhance electrical conductivity, and electrolyte-supporting salts (lithium salts) to enhance ionic conductivity. The components contained in the positive electrode active material layer and the negative electrode active material layer, or the mixing ratio of such components, and the thickness of the positive electrode active material layer and the negative electrode active material layer are not particularly limited, and conventionally known knowledge regarding lithium-ion secondary batteries may be referenced as appropriate. The thickness of the positive electrode active material layer and the negative electrode active material layer is, for example, 2 μm to 150 μm. Conventionally known methods such as the roll-coating method may be used to form the positive electrode active material layer or the negative electrode active material layer on the surface of the current collector. To improve the thermal stability of the positive electrode active material layer or the negative electrode active material layer, a heat-resistant layer may be provided on the surface of the current collector (one side or both sides), or on the surface of the positive electrode active material layer or the negative electrode active material layer. The heat-resistant layer may, for example, contain inorganic particles and a binder, and may also contain additives such as thickeners.

[0030] Conductive additives are added to enhance the conductivity of the positive electrode active material layer or the negative electrode active material layer. Examples of conductive additives include acetylene black, carbon black, and graphite.

[0031] Examples of binders include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins such as poly(meth)acrylic acid; styrene-butadiene rubber (SBR); alginates such as carboxymethylcellulose, sodium alginate, and ammonium alginate; water-soluble cellulose ester crosslinks; and starch-acrylic acid graft polymers. These binders can be used individually or in combination. Examples of solvents include water and N-methyl-2-pyrrolidone (NMP).

[0032] The electrolyte layer (separator) is a component placed between the positive electrode active material layer and the negative electrode active material layer to isolate them, preventing short circuits caused by contact between the two electrodes, while allowing charge carriers such as lithium ions to pass through. The electrolyte layer prevents short circuits between adjacent bipolar electrodes when bipolar electrodes are stacked.

[0033] The electrolyte layer may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains electrolytes. Examples of materials constituting the electrolyte layer include polypropylene, polyethylene, polyolefin, and polyester. The electrolyte layer may have a single-layer structure or a multilayer structure. The multilayer structure may include, for example, an adhesive layer, a ceramic layer as a heat-resistant layer, and so on. The electrolyte layer may be impregnated with an electrolyte, or the electrolyte layer itself may be composed of an electrolyte such as a polymer electrolyte or an inorganic electrolyte.

[0034] Examples of electrolytes impregnated into the electrolyte layer include liquid electrolytes (electrolyte solutions) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, or polymer gel electrolytes containing an electrolyte held in a polymer matrix.

[0035] When the electrolyte layer is impregnated with an electrolyte solution, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 can be used as the electrolyte salt. Furthermore, known solvents such as cyclic carbonates, cyclic esters, linear carbonates, linear esters, and ethers can be used as the non-aqueous solvent. Two or more of these known solvent materials may also be used in combination.

[0036] Examples of side members include current-collecting side members. A current-collecting side member is a side member having a current-collecting section in at least a part of it. The current-collecting section is electrically connected, for example, to a tab in the battery. The current-collecting side member may be entirely a current-collecting section, or only partially a current-collecting section. Examples of materials for the side member include metals such as stainless steel (SUS). The shape of the side member is not particularly limited, but may be, for example, a rectangular parallelepiped.

[0037] The laminate sheet preferably has at least a metal layer, and further has a welding resin layer on the side of the metal layer facing the side member. The laminate sheet may also have a protective layer on the side of the metal layer opposite to the side member. Examples of materials for the welding resin layer include olefin resins such as polypropylene (PP) and polyethylene (PE). Examples of materials for the metal layer include aluminum, aluminum alloys, and stainless steel. Examples of materials for the protective layer include polyethylene terephthalate (PET) and nylon. The thickness of the welded resin layer is, for example, 40 μm to 100 μm. The thickness of the metal layer is, for example, 30 μm to 60 μm. The thickness of the protective layer is, for example, 20 μm to 60 μm. The overall thickness of the laminate sheet is, for example, 70 μm to 220 μm.

[0038] The battery has a resin layer (e.g., a tab film) disposed on the surface of a pair of sides of the side member. The resin layer covers a portion of the surface of the side member and is interposed between the side member and the laminate sheet. Examples of materials for the resin layer include olefin resins such as polypropylene (PP) and polyethylene (PE). The thickness of the resin layer is, for example, 40 μm to 100 μm.

[0039] The battery relating to this disclosure is typically a lithium-ion secondary battery. Applications of the battery include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. It is particularly preferable for the battery to be used as a power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Furthermore, the battery relating to this disclosure may be used as a power source for mobile devices other than vehicles (e.g., railways, ships, aircraft), or as a power source for electrical products such as information processing devices.

[0040] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Explanation of symbols]

[0041] 1: Electrode laminate, 2: Outer casing, 3: Thermal conductive resin component

Claims

1. Electrode stack and, An outer casing that houses the electrode stack, The assembly comprises a heat-conducting resin member disposed between the electrode laminate and the outer casing, The length of the surface of the thermal conductive resin member that contacts the electrode stack is longer than the length of the surface of the electrode stack that contacts the thermal conductive resin member. battery.

2. The battery according to claim 1, wherein the heat-conducting resin member is arranged to cover a surface of the electrode laminate that is in contact with the heat-conducting resin member and a portion of two surfaces of the electrode laminate that are in contact with the surface.

3. The battery according to claim 1, further comprising a current-collecting tab on the short-side surface of the electrode stack.

4. The battery according to claim 1, which is a solid-state battery.

5. The battery according to claim 1, wherein the outer casing is a can-shaped outer casing.

6. A method for manufacturing a battery according to any one of claims 1 to 5, comprising the step of pressing together an electrode laminate and a heat-conducting resin member.

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