Method of manufacturing battery

Abstract

To provide a new method of manufacturing a battery, in which efficiency of an electrolytic solution injection operation is improved.SOLUTION: A method of manufacturing a battery includes: a first step of producing an electrode body with an electrode including an electrode active material and a solute of an electrolytic solution; and a second step of impregnating the electrode body with a solvent of the electrolytic solution.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a battery. [Background technology]

[0002] In the manufacturing process of a battery that uses an electrolytic solution obtained by dissolving an electrolyte in an organic solvent, a liquid injection operation is carried out in which the electrolytic solution is supplied to the inside of an exterior body that houses an electrode assembly and the electrolytic solution is allowed to permeate the electrode assembly. In order to increase the energy density of battery electrodes, they are sometimes subjected to a high-pressure pressing process. When the packing density of the electrode active material in the electrode is increased by pressing the electrode, the permeability of the electrolyte decreases. The decrease in the permeability of the electrolyte reduces the efficiency of the electrolyte injection process.

[0003] Patent Document 1 describes a method for manufacturing a battery, which is characterized by dispensing two types of electrolyte solutions with different compositions. Specifically, the electrolyte solution with the lowest electrolyte concentration and viscosity is injected into the battery case in order, thereby accelerating the permeation rate of the electrolyte solution into the electrode body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-165549 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the method described in Patent Document 1, a plurality of types of electrolyte solutions with different electrolyte concentrations are prepared, and these electrolyte solutions are injected in a plurality of times, so there is room for improvement in the efficiency of the injection operation. An object of one embodiment of the present disclosure is to provide a novel battery manufacturing method that improves the efficiency of the electrolyte injection operation. [Means for solving the problem]

[0006] Means for solving the above problems include the following embodiments. <1> A first step of preparing an electrode assembly including an electrode containing an electrode active material and a solute of an electrolyte; A second step of permeating the electrode body with a solvent for an electrolytic solution. <2> The solvent that is permeated into the electrode body in the second step does not contain any solutes of the electrolyte. <1> A method for manufacturing the battery according to claim 1. <3> The second step includes reducing the pressure inside the exterior body that houses the electrode assembly. <1> or <2> A method for manufacturing the battery according to claim 1. <4> The second step includes heating at least one of the electrode body or the solvent; <1> ~ <3> 13. A method for producing the battery according to claim 12. <5> The second step includes subjecting the electrode body to ultrasonic vibrations; <1> ~ <4> 13. A method for producing the battery according to claim 12. Effect of the Invention

[0007] According to one embodiment of the present disclosure, a novel battery manufacturing method is provided that improves the efficiency of the electrolyte injection operation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating an example of a configuration of a laminate included in an electrode assembly. [Diagram 2] FIG. 1 is a diagram illustrating an example of application of a battery module to an electric vehicle. [Diagram 3] FIG. 2 is a diagram illustrating an example of a configuration of a battery module. [Figure 4] FIG. 2 is a diagram illustrating an example of a configuration of a battery module. [Diagram 5] 2 is a diagram illustrating an example of a configuration of a battery cell included in a battery module. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the present disclosure, a numerical range indicated using "~" means a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in the present disclosure. In the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. When an embodiment of the present disclosure 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 size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0010] The method for manufacturing a battery according to the present disclosure includes: A first step of preparing an electrode assembly including an electrode containing an electrode active material and a solute of an electrolyte; and a second step of permeating the electrode body with a solvent for an electrolyte.

[0011] In a typical battery manufacturing method, an electrolyte solution obtained by dissolving a solute such as a lithium salt in a solvent is supplied to an exterior body that contains an electrode assembly. Then, the operation is stopped and a standby state is set up until the electrolyte solution supplied to the exterior body permeates the electrolyte body. This standby period can be a factor in reducing the efficiency of the electrolyte injection operation.

[0012] In the method of the present disclosure, an electrode body including electrodes containing an electrode active material and a solute of the electrolyte is first prepared, and then the solvent of the electrolyte is permeated into the electrode body. The solvent permeated into the electrode body has a lower viscosity than when the solute is included, and therefore permeates the electrode body in a shorter time than when the solute is included. The solvent permeated into the electrode body dissolves the solute contained in the electrodes that constitute the electrode body. In other words, the method of the present disclosure can create a state in which the electrolyte has permeated the electrode body in a shorter time than conventional methods.

[0013] Furthermore, the size of the battery is large (for example, the area of ​​the main surface is 10,000 cm 2 If the thickness of the electrode body is more than 1 mm, the flow behavior of the electrolyte will not be uniform when it penetrates the electrode body, and there is a risk of uneven distribution of the solute after the liquid injection operation. In the method disclosed herein, the solute of the electrolyte can be disposed at any part of the electrode body before the solvent is penetrated, so that uneven distribution of the solute after the liquid injection operation can be effectively suppressed.

[0014] (1st step) In the first step, an electrode assembly is prepared that includes electrodes containing an electrode active material and a solute of an electrolyte. In the present disclosure, an electrode assembly refers to a structure including a laminate made of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. Examples of the form of an electrode body including a laminate consisting of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode include a state in which a plurality of laminates cut to a predetermined size are stacked, and a state in which a long laminate is wound.

[0015] All of the electrodes included in the electrode assembly may contain a solute of the electrolyte, or only some of the electrodes included in the electrode assembly may contain a solute of the electrolyte. For example, when either the negative electrode or the positive electrode included in the electrode assembly contains a solute of the electrolyte, the other may or may not contain a solute of the electrolyte. Generally, the negative electrode has more voids between active material particles and is more permeable to the electrolyte than the positive electrode, so the negative electrode may contain a solute of the electrolyte.

[0016] The method for preparing an electrode containing an electrode active material and a solute of an electrolyte is not particularly limited. For example, the method may be a method for preparing an electrode using a composition containing an electrode active material and a solute of an electrolyte, or a method for disposing a solute of an electrolyte on the surface of an electrode prepared using a composition containing an electrode active material. The types of electrode active material contained in the electrode and the solute of the electrolyte are not particularly limited, and can be selected from commonly used materials.

[0017] When the battery is a lithium ion secondary battery, specific examples of the solute include LiPF6 and LiFSi. The solute contained in the electrode may be of one type alone or of two or more types.

[0018] When the battery is a lithium ion secondary battery, the positive electrode active material may be a composite oxide of lithium and a transition metal (hereinafter, also referred to as a lithium transition metal composite oxide). Examples of the transition metal include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, etc. Examples of the lithium transition metal composite oxide include layered lithium transition metal composite oxides, spinel type lithium transition metal composite oxides, and olivine type lithium transition metal composite oxides. The layered lithium transition metal composite oxide includes those containing at least one transition metal selected from Ni, Co, and Mn. Specifically, LiNi a Co b Mn c Examples of such compounds include compounds represented by the structural formula O2 (where a, b, and c are each a number between 0 and 1, and a+b+c=1), and compounds in 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 to the above compounds. A specific example of the spinel-type lithium transition metal composite oxide is LiMn2O4. A specific example of the olivine-type lithium transition metal composite oxide is LiMPO4 (M: Fe, Co, Ni, or Mn). The electrode may contain one type of positive electrode active material alone or two or more types.

[0019] 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). The negative electrode active material contained in the electrode may be one type alone or two or more types.

[0020] The electrodes may include a conductive material. Specific examples of the conductive material include carbon materials such as carbon black (acetylene black, thermal black, furnace black, etc.), carbon nanotubes, and graphite. The conductive material contained in the electrode may be of one type alone or of two or more types.

[0021] The electrode may include a binder. Specific examples of binders 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, and polytetrafluoroethylene (PTFE). The binder contained in the electrode may be of one type alone or two or more types.

[0022] The electrode included in the electrode assembly may include a current collector and an electrode layer disposed so as to be in contact with one or both sides of the current collector. The thickness of the electrode layer is not particularly limited and can be selected from the thicknesses of general electrode layers, for example, the thickness of the electrode layer can be selected in the range of 10 μm to 200 μm.

[0023] Examples of materials constituting the current collector of the positive electrode include aluminum, aluminum alloys, nickel, titanium, stainless steel, etc. Examples of the shape of the current collector include foil, mesh, etc. Examples of materials constituting the current collector of the negative electrode include copper, copper alloys, nickel, titanium, stainless steel, etc. Examples of the shape of the current collector include foil, mesh, etc.

[0024] The separator contained in the electrode assembly may be a nonwoven fabric, cloth, or microporous film mainly composed of a polyolefin such as polyethylene or polypropylene.

[0025] An example of the configuration of the laminate included in the electrode assembly is shown diagrammatically in FIG. 1 comprises 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 comprises a positive electrode layer 10A and a positive electrode current collector 10B. The negative electrode 20 comprises a negative electrode layer 20A and a negative electrode current collector 20B.

[0026] (2nd process) In the second step, the electrode body produced in the first step is permeated with a solvent for the electrolyte. From the viewpoint of maintaining a low viscosity, it is preferable that the solvent to be permeated into the electrode assembly does not contain a solute of the electrolyte.

[0027] The type of solvent used in the second step is not particularly limited, and can be selected from solvents that are commonly used as components of electrolyte solutions. Specific examples of the solvent include cyclic or chain carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc. The solvent may be a mixture of two or more solvents, or may be a mixture containing a cyclic carbonate and a chain carbonate. The solvent may contain an additive such as vinylene carbonate (VC).

[0028] In the second step, for example, the solvent is supplied to the inside of an exterior body that houses the electrode body, thereby allowing the solvent to permeate the electrode body. The method for supplying the solvent into the exterior body is not particularly limited, and can be selected from known methods. The solvent may be supplied to the inside of the exterior body once or multiple times. The total amount of the solvent supplied to the inside of the exterior body may be set so that the concentration of the solute contained in the electrode body dissolved in the solvent is within the range of 1% by mass to 15% by mass.

[0029] The second step may include reducing the pressure inside the exterior body that houses the electrode assembly. By reducing the pressure inside the exterior body that houses the electrode assembly, it is possible to promote the permeation of the solvent into the electrode assembly.

[0030] The second step may include heating at least one of the electrode body or the solvent. By heating at least one of the electrode body or the solvent, dissolution of the solute into the solvent in the electrode body can be promoted. The temperature of the electrode body or the solvent in a heated state can be selected, for example, from the range of room temperature to the boiling point of the solvent.

[0031] The second step may include applying ultrasonic vibration to the electrode body. By applying ultrasonic vibration to the electrode body, dissolution of the solute into the solvent in the electrode body can be promoted. When ultrasonic vibration is applied to the electrode body, the frequency of the ultrasonic vibration is not particularly limited.

[0032] The electrode body may be subjected to ultrasonic vibrations having different frequencies in a number of separate waves, or the electrode body may be subjected to ultrasonic vibrations in a number of separate waves to different regions thereof. In one embodiment, a step X of applying ultrasonic vibrations X to a region X of the electrode body and a step Y of applying ultrasonic vibrations Y to a region Y different from the region X of the electrode body may be carried out in this order, where the frequency of the ultrasonic vibrations X is lower than the frequency of the ultrasonic vibrations Y.

[0033] In step X, ultrasonic vibrations X are applied to region X of the electrode body to move air bubbles contained in region X of the electrode body to region Y. When the solvent is permeated into the electrode body, air bubbles may be generated. By moving these air bubbles to region Y without eliminating them, the permeation of the solvent into region X is promoted. The frequency of the ultrasonic vibration X applied to the electrode body in the step X is selected from frequencies (for example, 20 kHz to 100 kHz) that do not cause the air bubbles to disappear.

[0034] In step Y, ultrasonic vibration Y is applied to a region Y of the electrode body that is different from the region X, thereby eliminating air bubbles contained in the region Y of the electrode body. By eliminating the air bubbles contained in the region Y, the penetration of the solvent into the region Y is promoted. The elimination of the air bubbles may be performed by dissolving the gas in the air bubbles in the solvent. The frequency of the ultrasonic vibration Y applied to the electrode body in the step Y is selected from frequencies at which the air bubbles disappear (for example, greater than 100 kHz).

[0035] The type of exterior body in which the electrode assembly is housed is not particularly limited, and can be selected according to the type of battery. In some embodiments, a sheet-like outer casing may be used. The sheet-like exterior body may include a body containing a metal. Specifically, a laminate (so-called laminate film) having a metal layer containing a metal such as aluminum and a heat seal layer containing a resin that melts by heating may be included. That is, the battery manufactured by the method of the present disclosure may be a battery that uses a laminate film as an exterior body (so-called laminate battery).

[0036] The exterior body may be made of one member or two or more members. For example, when the exterior body is a sheet-like material, the exterior body may be made of one sheet-like material or two sheet-like materials. If necessary, the sheet-like exterior body may have recesses for accommodating the electrode assembly formed by embossing.

[0037] Examples of a method for housing the electrode assembly in an exterior body using a sheet-like exterior body include the following method 1 and method 2. Method 1: A method in which the electrode body is placed between one exterior body folded in half or between two overlapping exterior bodies, and then the exterior body around the electrode body is joined. Method 2: The electrode assembly is placed in a bag made by joining the periphery of one exterior body folded in half or two overlapping exterior bodies.

[0038] (Battery types and application examples) The type of battery produced by the method of the present disclosure is not particularly limited. Specific examples of batteries include secondary batteries such as lithium-ion secondary batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, and cobalt-titanium lithium secondary batteries. From the standpoint of energy density, versatility, and the like, the battery may be a lithium ion secondary battery.

[0039] The battery of the present disclosure may be installed in an electric vehicle. An example in which the battery of the present disclosure is applied to an electric vehicle will be described below with reference to the drawings. In the following description, "battery cell 20" corresponds to the battery of the present disclosure.

[0040] Fig. 2 is a schematic plan view showing a main part of a vehicle 100 to which a battery pack 10 according to an embodiment is applied. As shown in Fig. 2, the vehicle 100 is an electric vehicle (BEV: Battery Electric Vehicle) in which the battery pack 10 is mounted under the floor. Note that the arrows UP, FR, and LH in each figure indicate the upper side in the vehicle vertical direction, the front side in the vehicle longitudinal direction, and the left side in the vehicle width direction, respectively. When describing using the front-rear, left-right, up-down directions, they refer to the front-rear in the vehicle longitudinal direction, the left-right in the vehicle width direction, and the up-down in the vehicle vertical direction, unless otherwise specified.

[0041] As an example, in the vehicle 100 of this embodiment, a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 are disposed on the vehicle front side of the battery pack 10. In addition, a motor 108, a gear box 110, an inverter 112, and a charger 114 are disposed on the vehicle rear side of the battery pack 10.

[0042] The direct current output from the battery pack 10 has its voltage adjusted by a DC / DC converter 102, and is then supplied to an electric compressor 104, a PTC heater 106, an inverter 112, etc. In addition, power is supplied to a motor 108 via the inverter 112, causing the rear wheels to rotate and causing the vehicle 100 to run.

[0043] A charging port 116 is provided on the right side at the rear of the vehicle 100, and by connecting a charging plug of an external charging device (not shown) to the charging port 116, power can be stored in the battery pack 10 via the on-board charger 114.

[0044] The arrangement and structure of each component constituting the vehicle 100 are not limited to the above-mentioned configuration. For example, the present invention may be applied to a hybrid vehicle (HV: Hybrid Vehicle) equipped with an engine or a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle). In addition, in the present embodiment, the vehicle is a rear-wheel drive vehicle in which the motor 108 is mounted at the rear of the vehicle, but the present invention is not limited to this. The vehicle may be a front-wheel drive vehicle in which the motor 108 is mounted at the front of the vehicle, or a pair of motors 108 may be mounted at the front and rear of the vehicle. Furthermore, the vehicle may be equipped with an in-wheel motor on each wheel.

[0045] The battery pack 10 includes a plurality of battery modules 11. In the present embodiment, as an example, ten battery modules 11 are provided. Specifically, five battery modules 11 are arranged on the right side of the vehicle 100 in the vehicle longitudinal direction, and five battery modules 11 are arranged on the left side of the vehicle 100 in the vehicle longitudinal direction. In addition, the respective battery modules 11 are electrically connected to each other.

[0046] Fig. 3 is a schematic perspective view of the battery module 11. As shown in Fig. 3, the battery module 11 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. 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 aluminum die castings to both ends of an aluminum alloy extrusion material by laser welding or the like.

[0047] 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, which will be described later, is connected to the connector 14. In addition, bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0048] The length MW of the battery module 11 in the vehicle width direction is, for example, 350 mm to 600 mm, the length ML in the vehicle front-rear direction is, for example, 150 mm to 250 mm, and the height MH in the vehicle up-down direction is, for example, 80 mm to 110 mm.

[0049] Fig. 4 is a plan view of the battery module 11 with the top cover removed. As shown in Fig. 4, a plurality of battery cells 20 are housed in an arranged state inside the battery module 11. In this embodiment, as an example, 24 battery cells 20 are arranged in the front-rear direction of the vehicle and bonded to one another.

[0050] A flexible printed circuit (FPC) 21 is disposed on the battery cells 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 on each of both ends of the flexible printed circuit 21. The thermistor 23 is not bonded to the battery cells 20, and is configured to be pressed towards the battery cells 20 by the upper lid of the battery module 11.

[0051] One or more cushioning materials (not shown) are housed inside the battery module 11. For example, the cushioning materials are elastically deformable thin plate-like members, and are arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 being the thickness direction. As an example in this embodiment, cushioning materials are arranged at both ends of the battery module 11 in the longitudinal direction and in the central portion in the longitudinal direction.

[0052] Fig. 5 is a schematic diagram of a battery cell 20 housed in a battery module 11, viewed from the thickness direction. As shown in Fig. 5, the battery cell 20 is formed in a substantially rectangular plate shape, and houses an electrode body (not shown) inside. The electrode body is configured by laminating a positive electrode, a negative electrode, and a separator, and is sealed with a laminate film 22.

[0053] In this embodiment, as an example, the housing portion for the electrode body is formed by folding and pasting an embossed sheet-like laminate film 22. Note that, although both a single cup embossed structure in which embossing is performed at one place and a double cup embossed structure in which embossing is performed at two places can be adopted, the present embodiment adopts a single cup embossed structure with a drawing depth of about 8 mm to 10 mm.

[0054] The upper ends of the battery cells 20 at both ends in the longitudinal direction are bent to form corners. The upper end of the battery cells 20 is also bent, and a fixing tape 24 is wound around the upper end of the battery cells 20 along the longitudinal direction.

[0055] Here, terminals (tabs) 26 are provided at both longitudinal ends of the battery cell 20. In this 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 a bus bar (not shown) by laser welding or the like.

[0056] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, 1000 mm or more, the length CW2 of the region in which the electrode body is housed is, for example, 500 mm to 520 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, 1000 mm or more, and the height CH of the battery cell 20 is, for example, 80 mm to 110 mm, 110 mm to 140 mm. The thickness of the battery cell 20 is 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, 9.0 mm to 11.0 mm, and the height TH of the terminal 26 is 40 mm to 50 mm, 50 mm to 60 mm, 60 mm to 70 mm. [Explanation of symbols]

[0057] 10: Positive electrode 10A: Positive electrode layer 10B: Positive electrode current collector 20: Negative electrode 20A:Negative electrode layer 20B: Negative electrode current collector 30: Separator 100: Laminate

Claims

1. A first step of preparing an electrode assembly including an electrode containing an electrode active material and a solute of an electrolyte; a second step of permeating the electrode body with a solvent for an electrolytic solution.

2. The method for producing a battery according to claim 1 , wherein the solvent impregnated into the electrode body in the second step does not contain a solute of the electrolyte.

3. The method for producing a battery according to claim 1 , wherein the second step includes reducing the pressure inside the exterior body that houses the electrode assembly.

4. The method for producing a battery according to claim 1 , wherein the second step includes heating at least one of the electrode body or the solvent.

5. The method for manufacturing a battery according to claim 1 , wherein the second step includes applying ultrasonic vibration to the electrode body.

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