Method for manufacturing separator, method for manufacturing electrode body, and method for manufacturing battery

Abstract

The present disclosure relates to a method for manufacturing a separator having excellent electrolyte permeability, a method for manufacturing an electrode body, and a method for manufacturing a battery. A method for manufacturing a separator disposed between a positive electrode and a negative electrode, the method comprising: a step for immersing the separator in a liquid containing a surfactant; and a step for drying the separator taken out from the liquid.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a separator, a method for manufacturing an electrode body, and a method for manufacturing a battery. Background Art

[0002] In the manufacturing process of a battery using an electrolytic solution obtained by dissolving an electrolyte in an organic solvent, a liquid injection operation is performed to supply the electrolytic solution into an outer casing that houses an electrode body and to allow the electrolytic solution to permeate the electrode body.

[0003] The battery electrodes are sometimes pressed at high pressure to increase the energy density. When the electrode is pressed to increase the packing density of the electrode active material in the electrode, the permeability of the electrolyte decreases. The decrease in the permeability of the electrolyte becomes a cause of the decrease in the efficiency of the injection operation.

[0004] Japanese Patent Application Laid-Open No. 9-306501 describes an organic electrolyte battery in which electrodes are prepared using an electrode mixture to which a surfactant having an affinity for an organic electrolyte is added, thereby shortening the time for the electrolyte to impregnate the electrodes.

[0005] The invention recorded in Japanese Patent Publication No. 9-306501 takes improving the impregnation property of the electrolyte relative to the electrode as a subject, but does not take improving the impregnation property of the electrolyte relative to the separator disposed between the electrodes as a subject. In addition, the method of adding a surfactant to the electrode mixture may affect the performance of the electrode. Summary of the invention

[0006] In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a method for producing a separator having excellent permeability to an electrolyte solution, a method for producing an electrode body using the separator, and a method for producing a battery using the separator.

[0007] Means for solving the above-mentioned problems include the following embodiments.

[0008] <1> A method for manufacturing a separator, wherein the separator is disposed between a positive electrode and a negative electrode, and the method for manufacturing the separator comprises:

[0009] a step of immersing the separator in a liquid containing a surfactant; and

[0010] A step of drying the separator taken out from the liquid.

[0011] <2> according to <1> The manufacturing method of the separator,

[0012] The method for manufacturing the separator further includes a step of selecting the type of the surfactant.

[0013] The selecting includes comparing the permeability of the separator to the electrolyte before being immersed in the liquid containing the surfactant and the permeability of the separator to the electrolyte after being immersed in the liquid containing the surfactant.

[0014] <3> A method for manufacturing an electrode body, comprising:

[0015] pass <1> or <2> The process of manufacturing a separator by the method described above; and

[0016] A step of disposing the separator between the positive electrode and the negative electrode.

[0017] <4> A method for manufacturing a battery, comprising:

[0018] pass <3> The process of manufacturing an electrode body by the method described above; and

[0019] A step of impregnating the electrode body with an electrolyte solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram schematically showing an example of the structure of a stacked body included in an electrode body.

[0021] Figure 2 This is a diagram schematically showing an example of application of a battery module to an electric vehicle.

[0022] Figure 3 This is a diagram schematically showing an example of the configuration of a battery module.

[0023] Figure 4 This is a diagram schematically showing an example of the configuration of a battery module.

[0024] Figure 5 This is a diagram schematically showing an example of the configuration of battery cells included in a battery module. DETAILED DESCRIPTION

[0025] In the present disclosure, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as a minimum value and a maximum value, respectively.

[0026] In the numerical range recorded in stages in the present disclosure, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the upper limit or lower limit of other numerical ranges recorded in stages. In the numerical range recorded in the present disclosure, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the value shown in the embodiment.

[0027] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved.

[0028] In the present disclosure, when an embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the sizes of components in each figure are conceptual, and the relative relationship between the sizes of the components is not limited to this.

[0029] <Method for manufacturing separator>

[0030] The manufacturing method of the separator disclosed in the present invention is a manufacturing method of the separator disposed between the positive electrode and the negative electrode, and the manufacturing method of the separator comprises:

[0031] a step of immersing the separator in a liquid containing a surfactant; and

[0032] A step of drying the separator taken out from the liquid.

[0033] In a general method for manufacturing a battery, an electrolyte solution obtained by dissolving an electrolyte in an organic solvent is supplied to an outer casing containing an electrode body. Then, the operation is stopped and the battery is kept on standby until the electrolyte solution supplied to the outer casing permeates the electrode body. This standby time may be the main reason for reducing the efficiency of the injection operation.

[0034] The electrode assembly housed in the outer casing includes a stacked body composed of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.

[0035] The present inventors' research results revealed that the use of a separator produced by the above method can shorten the time for impregnation of the electrode body with the electrolyte solution, thereby improving the efficiency of the injection work. The reasons for this are, for example, considered to be as follows.

[0036] The electrolyte mainly permeates from the end face of the electrode body exposed from the cross section of the electrode. The separator manufactured by the method disclosed in the present invention has a surfactant inside, so that the permeability of the electrolyte to the separator is improved. As a result, it is presumed that: in addition to the cross section of the electrode exposed from the end face of the electrode body, the amount of electrolyte permeating from the cross section of the separator also increases, and in conjunction with this, the amount of electrolyte permeating from the separator to the adjacent electrode also increases.

[0037] The separator produced by the method of the present disclosure has a greater effect of shortening the impregnation time of the electrolyte solution than a separator whose surface is only treated with a surfactant.

[0038] The type of separator used in the method of the present disclosure is not particularly limited.

[0039] Specific examples of the material of the separator include polyolefins such as polyethylene and polypropylene, polyamide, polyimide, polyamideimide, polyester, etc. Among them, polyolefins are preferred.

[0040] Specific examples of the form of the separator include nonwoven fabric, cloth, and a microporous film.

[0041] The separator may have a single-layer structure or a multi-layer structure.

[0042] The thickness of the separator is not particularly limited and can be selected from common thicknesses. For example, the thickness of the separator can be selected from a range of 10 μm to 150 μm.

[0043] The type of surfactant used in the method of the present disclosure is not particularly limited and can be selected according to the types of the separator and the electrolyte.

[0044] The selection of the surfactant used in the method of the present invention can, for example, be performed by comparing the permeability of the separator to the electrolyte before being immersed in the liquid containing the surfactant and the permeability of the separator to the electrolyte after being immersed in the liquid containing the surfactant, and determining whether the permeability of the former is better than that of the latter.

[0045] The electrolyte solution may be one prepared for evaluating permeability, or may be one actually used in a battery including a separator produced by the method of the present disclosure.

[0046] That is, the manufacturing method of the separator disclosed in the present invention may also include a process of selecting the type of surfactant, and the selection includes: comparing the permeability of the separator to the electrolyte before being immersed in the liquid containing the surfactant and the permeability of the separator to the electrolyte after being immersed in the liquid containing the surfactant.

[0047] As the liquid containing a surfactant, for example, an aqueous solution of a surfactant can be used.

[0048] The separator taken out from the liquid containing the surfactant may be dried using a dryer or by natural drying.

[0049] <Method for Manufacturing Electrode Body>

[0050] The manufacturing method of the electrode body disclosed in the present invention comprises:

[0051] A process of manufacturing a separator by the above-mentioned method for manufacturing a separator; and

[0052] A step of disposing the separator between the positive electrode and the negative electrode.

[0053] In the present disclosure, the electrode body refers to a structure including a stacked body composed of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.

[0054] Examples of the form of the electrode body including a stacked body composed of a positive electrode, a negative electrode, and a separator disposed therebetween include a stacked state of a plurality of stacked bodies cut into predetermined sizes, and a wound state of a long stacked body.

[0055] All of the separators included in the electrode body may be separators produced by the above method, or part of the separators included in the electrode body may be separators produced by the above method.

[0056] The positive electrode and the negative electrode included in the electrode body contain a positive electrode active material or a negative electrode active material as an electrode active material, respectively.

[0057] Hereinafter, the positive electrode and the negative electrode included in the electrode body may be collectively referred to as “electrode”.

[0058] When the battery is a lithium ion secondary battery, the positive electrode active material may be, specifically, a composite oxide composed of lithium and a transition metal, and other metals that may be arbitrarily contained (hereinafter also referred to as a lithium transition metal composite oxide). As transition metals and other metals, Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, etc. may be cited.

[0059] Examples of the lithium transition metal composite oxide include layered lithium transition metal composite oxides, spinel lithium transition metal composite oxides, and olivine lithium transition metal composite oxides.

[0060] Examples of layered lithium transition metal composite oxides include lithium transition metal composite oxides containing at least one transition metal selected from Ni, Co, and Mn. Specifically, examples include LiNi a Co b Mn c A compound represented by the structural formula O2 (a, b, c are numbers greater than 0 and less than 1, respectively, and a+b+c=1), and a compound to which one or more elements selected from Al, Mg, La, Ti, Zn, B, W, Fe, Cr, V, Ru, Cu, Cd, Ag, Y, Sc, Ga, In, As, Sb, Pt, Au, Si, etc. are added.

[0061] Specific examples of spinel-type lithium transition metal composite oxides include LiMn 2 O 4 .

[0062] Specific examples of the olivine-type lithium transition metal composite oxide include LiMPO 4 (M: Fe, Co, Ni, or Mn).

[0063] The positive electrode active material contained in the electrode may be used alone or in combination of two or more.

[0064] When the battery is a lithium ion secondary battery, specific examples of the negative electrode active material include carbon materials such as graphite, hard carbon, soft carbon, and activated carbon, silicon, metallic lithium, lithium alloys, and lithium titanate (LTO).

[0065] The negative electrode active material contained in the electrode may be used alone or in combination of two or more.

[0066] The electrodes may comprise a conductive material.

[0067] Specific examples of the conductive material include carbon materials such as carbon black (acetylene black, thermal black, furnace black, etc.), carbon nanotubes, and graphite.

[0068] The conductive material contained in the electrode may be used alone or in combination of two or more.

[0069] The electrodes may include a binder.

[0070] Specific examples of the binder include polyvinylidene fluoride (PVdF), polyethylene, polypropylene, polyethylene terephthalate, cellulose, nitrocellulose, carboxymethyl cellulose, polyethylene oxide, polyepichlorohydrin, polyacrylonitrile, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), polyacrylate, polymethacrylate, polytetrafluoroethylene (PTFE), and the like.

[0071] The binder contained in the electrode may be used alone or in combination of two or more.

[0072] The electrode included in the electrode body may include a current collector and an electrode layer disposed in contact with one surface or both surfaces of the current collector.

[0073] The thickness of the electrode layer is not particularly limited and can be selected from the thickness of common electrode layers. For example, the thickness of the electrode layer can be selected from the range of 10 μm to 200 μm.

[0074] Examples of the material of the current collector constituting the positive electrode include aluminum, aluminum alloys, nickel, titanium, stainless steel, etc. Examples of the shape of the current collector include foil and mesh.

[0075] Examples of the material of the current collector constituting the negative electrode include copper, copper alloys, nickel, titanium, stainless steel, etc. Examples of the shape of the current collector include foil and mesh.

[0076] Figure 1 An example of the structure of a stacked body included in the electrode body is schematically shown in FIG.

[0077] Figure 1 The laminate 100 shown is composed of a positive electrode 10, a negative electrode 20, and a separator 30 disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10 is composed of a positive electrode layer 10A and a positive electrode collector 10B. The negative electrode 20 is composed of a negative electrode layer 20A and a negative electrode collector 20B.

[0078] <Battery Manufacturing Method>

[0079] The manufacturing method of the battery disclosed herein comprises:

[0080] A step of manufacturing an electrode body by the above-mentioned method for manufacturing an electrode body; and

[0081] A step of impregnating the electrode body with an electrolyte solution.

[0082] The method for carrying out the step of impregnating the electrode body with the electrolyte solution is not particularly limited and can be selected from known methods.

[0083] The penetration of the electrolyte solution is performed, for example, by supplying the electrolyte solution into the interior of the outer casing that houses the electrode assembly.

[0084] The step of allowing the electrolyte to penetrate may include reducing the pressure inside the outer casing that houses the electrode body. By reducing the pressure inside the outer casing that houses the electrode body, the penetration of the electrolyte into the electrode body can be promoted.

[0085] The type of the outer casing that houses the electrode assembly is not particularly limited and can be selected according to the type of battery.

[0086] In one embodiment, a sheet-shaped outer casing may be used.

[0087] As a sheet-like outer casing, an outer casing containing metal can be cited. Specifically, a laminate having a metal layer containing a metal such as aluminum and a heat-sealing layer containing a resin melted by heating (so-called laminated film) can be cited. That is, the battery manufactured by the method of the present disclosure can be a battery using a laminated film as an outer casing (so-called laminated battery).

[0088] The outer casing may be one member or may be composed of two or more members. For example, when the outer casing is a sheet-like object, the outer casing may be composed of one sheet-like object or two sheet-like objects.

[0089] If necessary, a recessed portion for accommodating the electrode body may be formed in the sheet-like outer casing by embossing.

[0090] As a method of housing the electrode assembly in an outer casing using a sheet-like outer casing, for example, the following method 1 and method 2 can be cited.

[0091] Method 1: A method of joining the outer casing around the electrode body while placing the electrode body between one outer casing folded in half or between two overlapping outer casings

[0092] Method 2: A method of placing the electrode body in a bag made by joining the periphery of a folded outer casing or two overlapped outer casings.

[0093] The type of the electrolyte solution that permeates the electrode body is not particularly limited, and a solution prepared by dissolving a solute used in a known electrolyte solution in a solvent can be used.

[0094] Specific examples of the solute of the electrolyte include LiPF6 and LiFSi.

[0095] The solute of the electrolyte solution may be used alone or in combination of two or more.

[0096] As the solvent of the electrolyte, specifically, cyclic or chain carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) can be listed. The solvent can be a mixture of two or more solvents, or a mixture comprising cyclic carbonates and chain carbonates.

[0097] The solvent may contain additives such as vinylene carbonate (VC).

[0098] (Battery types and application examples)

[0099] The type of battery produced by the method of the present disclosure is not particularly limited.

[0100] Specific examples of the battery include secondary batteries such as lithium ion secondary batteries, lead storage batteries, nickel-metal hydride storage batteries, nickel-cadmium storage batteries, nickel-iron storage batteries, nickel-zinc storage batteries, silver oxide-zinc storage batteries, and cobalt-titanium-lithium secondary batteries.

[0101] From the viewpoint of energy density, versatility, etc., the battery may be a lithium ion secondary battery.

[0102] The battery of the present disclosure can be mounted on an electric vehicle. Hereinafter, an example in which the battery of the present disclosure is applied to an electric vehicle will be described with reference to the accompanying drawings. In the following description, the "battery unit 20" corresponds to the battery of the present disclosure.

[0103] Figure 2 1 is a schematic plan view showing the main parts of a vehicle 100 to which the battery pack 10 according to the embodiment is applied. Figure 2As shown, the vehicle 100 is an electric vehicle (BEV) equipped with a battery pack 10 under the floor. In addition, the arrows UP, FR, and LH in each figure respectively indicate the upper side in the vehicle vertical direction, the front side in the vehicle front-back direction, and the left side in the vehicle width direction. When the front-back, left-right, up-down and down directions are used for description, unless otherwise specified, they indicate the front-back in the vehicle front-back direction, the left-right in the vehicle width direction, and the up-down in the vehicle vertical direction.

[0104] As an example, the vehicle 100 of the present embodiment is provided with a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 at a position closer to the front side of the vehicle than the battery pack 10. In addition, a motor 108, a gear box 110, an inverter 112, and a charger 114 are provided at a position closer to the rear side of the vehicle than the battery pack 10.

[0105] The DC current output from battery pack 10 is regulated in voltage by DC / DC converter 102 and then supplied to electric compressor 104, PTC heater 106, inverter 112, etc. In addition, by supplying power to motor 108 via inverter 112, the rear wheels rotate and vehicle 100 travels.

[0106] A charging port 116 is provided at the right side of the rear portion of the vehicle 100. By connecting a charging plug of an external charging device (not shown) to the charging port 116, electric power can be stored in the battery pack 10 via the charger 114.

[0107] The configuration and structure of each component constituting the vehicle 100 are not limited to the above-mentioned configuration. For example, it can also be applied to a hybrid vehicle (HV: Hybrid Vehicle) or a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle) equipped with an engine. In addition, in the present embodiment, the motor 108 is mounted on the rear of the vehicle and is a rear-wheel drive vehicle, but it is not limited to this. The motor 108 may be mounted on the front of the vehicle and is a front-wheel drive vehicle, or a pair of motors 108 may be mounted on the front and rear of the vehicle. In addition, it may be a vehicle with an in-wheel motor on each wheel.

[0108] The battery pack 10 is configured to include a plurality of battery modules 11. In the present embodiment, as an example, 10 battery modules 11 are provided. Specifically, on the right side of the vehicle 100, five battery modules 11 are arranged along the front-rear direction of the vehicle, and on the left side of the vehicle 100, five battery modules 11 are arranged along the front-rear direction of the vehicle. In addition, each battery module 11 is electrically connected.

[0109] Figure 3 1 is a schematic three-dimensional diagram of the battery module 11. Figure 3 As shown, the battery module 11 is formed into a substantially rectangular parallelepiped shape with the vehicle width direction as the length direction. In addition, the outer shell of the battery module 11 is formed of an aluminum alloy. For example, the outer shell of the battery module 11 is formed by joining the two ends of an aluminum die casting and an aluminum alloy extrusion by laser welding or the like.

[0110] A pair of voltage terminals 12 and a connector 14 are provided at both ends of the battery module 11 in the vehicle width direction. A flexible printed circuit board 21 described later is connected to the connector 14. Bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0111] The battery module 11 has a length MW in the vehicle width direction of, for example, 350 mm to 600 mm, a length ML in the vehicle front-rear direction of, for example, 150 mm to 250 mm, and a height MH in the vehicle vertical direction of, for example, 80 mm to 110 mm.

[0112] Figure 4 1 is a plan view of the battery module 11 with the upper cover removed. Figure 4 As shown, a plurality of battery cells 20 are accommodated in an aligned state inside the battery module 11. In the present embodiment, as an example, 24 battery cells 20 are aligned in the vehicle front-rear direction and bonded to each other.

[0113] A flexible printed circuit (FPC) 21 is provided on the battery cell 20. The flexible printed circuit 21 is formed in a strip shape with the vehicle width direction as the longitudinal direction, and a thermistor 23 is provided at both ends of the flexible printed circuit 21. The thermistor 23 is not bonded to the battery cell 20 but is pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0114] In addition, one or more buffers (not shown) are accommodated inside the battery module 11. For example, the buffer is a thin plate-shaped member that can be elastically deformed, and is arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, buffers are arranged at both ends and the center of the battery module 11 in the longitudinal direction.

[0115] Figure 5 This is a schematic diagram of the battery cell 20 housed in the battery module 11 as viewed from the thickness direction. Figure 5As shown, the battery cell 20 is formed in a substantially rectangular plate shape, and an electrode body (not shown) is accommodated therein. The electrode body is formed by stacking a positive electrode, a negative electrode, and a separator, and is sealed by a laminate film 22 .

[0116] In this embodiment, as an example, the electrode body receiving portion is formed by folding and laminating the embossed sheet-shaped laminate film 22. The laminate film 22 can adopt any one of a single-cup embossing structure with one embossing and a double-cup embossing structure with two embossings. The laminate film 22 in one embodiment is a single-cup embossing structure with a drawing depth of about 8 mm to 10 mm.

[0117] The upper ends of the battery cell 20 at both ends in the longitudinal direction are bent, and the corners become the outer shape. In addition, the upper end of the battery cell 20 is bent, and the fixing band 24 is wound around the upper end of the battery cell 20 along the longitudinal direction.

[0118] Terminals (tabs) 26 are provided at both ends of the battery cell 20 in the longitudinal direction. In the present embodiment, as an example, the terminals 26 are provided at positions offset downward from the vertical center of the battery cell 20. The terminals 26 are joined to bus bars (not shown) by laser welding or the like.

[0119] For example, the length CW1 of the battery cell 20 in the vehicle width direction is 530mm~600mm, 600mm~700mm, 700mm~800mm, 800~900mm or more than 1000mm, the length CW2 of the area accommodating the electrode body is 500mm~520mm, 600mm~700mm, 700mm~800mm, 800~900mm or more than 1000mm, the height CH is 80mm~110mm or 110mm~140mm, the thickness is 5.0mm~7.0mm, 7.0mm~9.0mm or 9.0mm~11.0mm, and the height TH of the terminal 26 is 40mm~50mm, 50mm~60mm or 60mm~70mm.

Claims

1. A method for manufacturing a separator, wherein the separator is disposed between a positive electrode and a negative electrode, and the method for manufacturing the separator comprises: A step of immersing the separator in a liquid containing a surfactant; as well as A step of drying the separator taken out from the liquid.

2. The method for manufacturing a separator according to claim 1, The method for manufacturing the separator further includes a step of selecting the type of the surfactant. The options include: The permeability of the separator to the electrolyte before being immersed in the liquid containing the surfactant was compared with the permeability of the separator to the electrolyte after being immersed in the liquid containing the surfactant.

3. A method for manufacturing an electrode body, comprising: A process for manufacturing a separator by the method according to claim 1 or 2; as well as A step of disposing the separator between the positive electrode and the negative electrode.

4. A method for manufacturing a battery, comprising: The process of manufacturing an electrode body by the method according to claim 3; as well as A step of impregnating the electrode body with an electrolyte solution.

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