Battery manufacturing method

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 Art

[0002] In a manufacturing process of a battery using an electrolytic solution obtained by dissolving an electrolyte in an organic solvent, a liquid injection operation is performed, in which the electrolytic solution is supplied into an exterior body that accommodates an electrode assembly, and the electrolytic solution is permeated into the electrode assembly. A battery electrode may be pressed at a high pressure in some cases to increase energy density. When the packing density of the electrode active material in the electrode is increased by pressing the electrode, the permeability of the electrolytic solution decreases. A decrease in the permeability of the electrolytic solution is a cause of reducing the efficiency of the liquid injection operation.

[0003] Patent Document 1 describes a method for manufacturing a battery, which is characterized by dispensing two types of electrolytic solutions having different compositions. Specifically, by injecting the electrolytic solutions into a battery case in order from the one having a lower electrolyte concentration and a lower viscosity, the permeation rate of the electrolytic solution into the electrode assembly is increased.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

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 electrolytic solutions having different electrolyte concentrations are prepared, and injection of these electrolytic solutions is performed in a plurality of separate steps, so there is room for improvement in the efficiency of the liquid injection operation. An object of an embodiment of the present disclosure is to provide a novel method for manufacturing a battery that improves the efficiency of an electrolytic solution injection operation.

Means for Solving the Problem

[0006] The following embodiments are included as means for solving the above problems. <1> A first step of manufacturing an electrode body comprising an electrode containing an electrode active material and a solute of an electrolyte, A method for manufacturing a battery, comprising a second step of permeating the electrode body with the solvent of an electrolyte solution. <2> The solvent that permeates the electrode body in the second step does not contain the solute of the electrolyte. <1> The battery manufacturing method described above. <3> The second step includes reducing the pressure inside the outer casing that houses the electrode body. <1> or <2> The battery manufacturing method described above. <4> The second step includes heating at least one of the electrode body or the solvent. <1> ~ <3> A method for manufacturing a battery as described in any one of the items. <5> The second step includes applying ultrasonic vibrations to the electrode body. <1> ~ <4> A method for manufacturing a battery as described in any one of the items. [Effects of the Invention]

[0007] According to one embodiment of the present disclosure, a novel method for manufacturing a battery is provided in which the efficiency of the electrolyte injection process is improved. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows an example of the configuration of the laminate contained in the electrode body. [Figure 2] This diagram schematically illustrates an example of the application of a battery module to an electric vehicle. [Figure 3] This diagram schematically shows an example of a battery module configuration. [Figure 4] This diagram schematically shows an example of a battery module configuration. [Figure 5] This diagram schematically shows an example of the configuration of a battery cell included in a battery module. [Modes for carrying out the invention]

[0009] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers written before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto.

[0010] The battery manufacturing method disclosed herein is A first step of manufacturing an electrode body comprising an electrode containing an electrode active material and a solute of an electrolyte, The method includes a second step of permeating the electrode body with the solvent of the electrolyte.

[0011] In typical battery manufacturing methods, an electrolyte, obtained by dissolving a solute such as a lithium salt in a solvent, is supplied to an casing that houses the electrodes. Work is then paused and a waiting period is observed until the electrolyte has permeated the electrodes. This waiting time can reduce the efficiency of the electrolyte injection process.

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

[0013] Furthermore, when the size of the battery is large (for example, the area of the main surface is 10,000 cm 2 2), the flow behavior of the electrolyte solution when permeating into the electrode assembly will not be uniform, which may cause uneven distribution of the solute after the injection operation. In the method of the present disclosure, since the solute of the electrolyte solution can be arranged at any position of the electrode assembly before the solvent is permeated, the uneven distribution of the solute after the injection operation can be effectively suppressed.

[0014] (First Step) In the first step, an electrode assembly including an electrode containing an electrode active material and a solute of an electrolyte solution is produced. In the present disclosure, the electrode assembly refers to a structure including a laminate composed of a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode. Examples of the form of the electrode assembly including a laminate composed of a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode include a state where a plurality of laminates cut into predetermined dimensions are stacked, and a state where a long laminate is wound.

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

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

[0017] Specific examples of solutes used when the battery is a lithium-ion secondary battery include LiPF6 and LiFSi. The solute contained in the electrode may be one type alone or two or more types.

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

[0019] Specific examples of negative electrode active materials for lithium-ion secondary batteries include carbon materials such as graphite, hard carbon, soft carbon, and activated carbon, as well as silicon, metallic lithium, lithium alloys, and lithium titanate (LTO). The negative electrode active material contained in the electrode may be a single type or two or more types.

[0020] The electrodes may contain a conductive material. Examples of conductive materials 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 one type alone or two or more types.

[0021] The electrodes may contain a binder. Examples of binders include polyvinylidene fluoride (PVdF), polyethylene, polypropylene, polyethylene terephthalate, cellulose, nitrocellulose, carboxymethylcellulose, 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 a single type or two or more types.

[0022] The electrodes included in the electrode body may comprise a current collector and an electrode layer arranged 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 common electrode layer thicknesses. For example, the electrode layer thickness can be selected from a range of 10 μm to 200 μm.

[0023] The materials used to construct the positive electrode current collector include aluminum, aluminum alloy, nickel, titanium, and stainless steel. The shape of the current collector can include foil, mesh, etc. The materials used to construct the negative electrode current collector include copper, copper alloys, nickel, titanium, and stainless steel. The shape of the current collector can include foil, mesh, etc.

[0024] Examples of separators included in the electrode body include nonwoven fabrics, cloths, and microporous films mainly composed of polyolefins such as polyethylene and polypropylene.

[0025] Figure 1 schematically shows an example of the configuration of the laminate contained in the electrode body. The laminate 100 shown in Figure 1 consists of a positive electrode 10, a negative electrode 20, and a separator 30 placed between the positive electrode 10 and the negative electrode 20. The positive electrode 10 consists of a positive electrode layer 10A and a positive electrode current collector 10B. The negative electrode 20 consists of a negative electrode layer 20A and a negative electrode current collector 20B.

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

[0027] The type of solvent used in the second step is not particularly restricted and can be selected from solvents commonly used as components of electrolytes. Specific examples of solvents include cyclic or linear carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). The solvent may be a mixture of two or more solvents, or a mixture containing both cyclic and linear carbonates. The solvent may contain additives such as vinylene carbonate (VC).

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

[0029] The second step may include reducing the pressure inside the outer casing that houses the electrodes. Reducing the pressure inside the outer casing that houses the electrodes can promote the penetration of the solvent into the electrodes.

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

[0031] The second step may include applying ultrasonic vibrations to the electrode body. Applying ultrasonic vibrations to the electrode body can promote the dissolution of the solute into the solvent within the electrode body. When applying ultrasonic vibrations to an electrode, the frequency of the ultrasonic vibrations is not particularly limited.

[0032] The electrode body may be subjected to ultrasonic vibrations of different frequencies in multiple separate applications. Alternatively, ultrasonic vibrations may be applied to different regions of the electrode body in multiple separate applications. In one embodiment, the steps of applying ultrasonic vibration X to a region X of the electrode body and applying ultrasonic vibration Y to a region Y different from region X of the electrode body may be performed in this order. Here, the frequency of ultrasonic vibration X is smaller than the frequency of ultrasonic vibration Y.

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

[0034] In step Y, ultrasonic vibration Y is applied to a region Y of the electrode body that is different from region X, thereby eliminating bubbles contained in region Y of the electrode body. Eliminating bubbles in region Y promotes the penetration of the solvent into region Y. Bubbles may also be eliminated by dissolving the gas in the bubbles into the solvent. The frequency of the ultrasonic vibration Y applied to the electrode body in process Y is selected from a frequency that causes bubbles to disappear (for example, above 100 kHz).

[0035] There are no particular restrictions on the type of casing that houses the electrodes; it can be selected according to the type of battery. In one embodiment, a sheet-like outer covering may be used. Examples of sheet-like outer casings include those containing metal. Specifically, examples include laminates (so-called laminate films) having a metal layer containing a metal such as aluminum and a heat-seal layer containing a resin that melts when heated. In other words, a battery manufactured by the method of this disclosure may be a battery that uses a laminate film as its outer casing (so-called laminate battery).

[0036] The exterior may consist of one component or two or more components. For example, if the exterior is a sheet, it may consist of one sheet or two sheets. If necessary, the sheet-like outer casing may have recesses for housing the electrode bodies formed by embossing.

[0037] Methods for housing electrode bodies in a sheet-like outer covering include, for example, the following methods 1 and 2. Method 1: A method in which the electrode body is placed between two folded outer casings or between two overlapping outer casings, and the outer casings surrounding the electrode body are joined together. Method 2: A method of placing the electrode into a bag made by joining the edges of one outer casing folded in half or two outer casings placed on top of each other.

[0038] (Types of batteries and application examples) The types of batteries manufactured by the method of this disclosure are not particularly limited. Specific examples of batteries include lithium-ion 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 batteries. From the standpoint of energy density, versatility, etc., the battery may be a lithium-ion secondary battery.

[0039] The battery of this disclosure may be installed in an electric vehicle. An example of applying the battery of this disclosure 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 this disclosure.

[0040] Figure 2 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. As shown in Figure 2, the vehicle 100 is a battery electric vehicle (BEV) with the battery pack 10 mounted under the floor. In each figure, the arrows UP, FR, and LH indicate the upper side in the vertical direction of the vehicle, the front side in the longitudinal direction of the vehicle, and the left side in the width direction of the vehicle, respectively. When describing the directions of front, rear, left, right, up, and down, unless otherwise specified, they refer to the front and rear in the longitudinal direction of the vehicle, the left and right in the width direction of the vehicle, and the up and down in the vertical direction of the vehicle.

[0041] In this embodiment, the vehicle 100, as an example, has a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 positioned in front of the battery pack 10. The motor 108, gearbox 110, inverter 112, and charger 114 are positioned behind the battery pack 10.

[0042] The DC current output from the battery pack 10 is voltage-adjusted by the DC / DC converter 102 and then supplied to the electric compressor 104, PTC heater 106, inverter 112, etc. Power is also supplied to the motor 108 via the inverter 112, causing the rear wheels to rotate and the vehicle 100 to move.

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

[0044] The arrangement and structure of the components constituting the vehicle 100 are not limited to the configuration described above. For example, it may be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. In this embodiment, the motor 108 is mounted at the rear of the vehicle and it is a rear-wheel drive vehicle, but it is not limited to this, and it may be a front-wheel drive vehicle with the motor 108 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, it may be a vehicle equipped with in-wheel motors for each wheel.

[0045] The battery pack 10 is composed of multiple battery modules 11. In this embodiment, as an example, 10 battery modules 11 are provided. Specifically, 5 battery modules 11 are arranged in the longitudinal direction of the vehicle on the right side of the vehicle 100, and 5 battery modules 11 are arranged in the longitudinal direction of the vehicle on the left side of the vehicle 100. Furthermore, each battery module 11 is electrically connected.

[0046] Figure 3 is a schematic perspective view of the battery module 11. As shown in Figure 3, the battery module 11 is formed in a roughly rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. The outer shell of the battery module 11 is made of aluminum alloy. For example, the outer shell of the battery module 11 is formed by joining aluminum die-cast parts to both ends of an aluminum alloy extruded 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, busbars (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 longitudinal direction is, for example, 150 mm to 250 mm, and the height MH in the vehicle vertical direction is, for example, 80 mm to 110 mm.

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

[0050] A flexible printed circuit board (FPC) 21 is placed on top of the battery cell 20. The flexible printed circuit board 21 is formed in a strip shape with the vehicle width direction as its longitudinal direction, and thermistors 23 are provided at both ends of the flexible printed circuit board 21. The thermistors 23 are not bonded to the battery cell 20, but are pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0051] Furthermore, one or more cushioning materials (not shown) are housed inside the battery module 11. For example, the cushioning material is a thin, elastically deformable plate-like member, 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, cushioning material is arranged at both ends in the longitudinal direction and in the longitudinal center of the battery module 11.

[0052] Figure 5 is a schematic view of a battery cell 20 housed in a battery module 11, viewed from the thickness direction. As shown in Figure 5, the battery cell 20 is formed in a roughly rectangular plate shape, and an electrode body (not shown) is housed inside. The electrode body is composed of a positive electrode, a negative electrode, and a separator stacked together, and is sealed with a laminate film 22.

[0053] In this embodiment, as an example, the electrode housing is formed by folding and bonding an embossed sheet-like laminate film 22. While both a single-cup embossed structure (with one embossed area) and a double-cup embossed structure (with two embossed areas) can be employed, this embodiment uses a single-cup embossed structure with a fold depth of approximately 8mm to 10mm.

[0054] The upper ends of both longitudinal ends of the battery cell 20 are bent, and the corners form the outer shape. In addition, the upper end of the battery cell 20 is bent, and a fixing tape 24 is wrapped around the upper end of the battery cell 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 a position offset below the vertical center of the battery cell 20. The terminals 26 are joined to a busbar (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, 530mm~600mm, 600mm~700mm, 700mm~800mm, 800~900mm, and 1000mm or more. The length CW2 of the area where the electrode body is housed is, for example, 500mm~520mm, 600mm~700mm, 700mm~800mm, 800~900mm, and 1000mm or more. The height CH of the battery cell 20 is, for example, 80mm~110mm and 110mm~140mm. The thickness of the battery cell 20 is 5.0mm~7.0mm, 7.0mm~9.0mm, and 9.0mm~11.0mm. The height TH of the terminal 26 is 40mm~50mm, 50mm~60mm, and 60mm~70mm. [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 manufacturing an electrode body comprising an electrode containing an electrode active material, a binder, and a solute of an electrolyte, A method for manufacturing a battery, comprising a second step of permeating the electrode body with the solvent of an electrolyte, wherein the solvent permeating the electrode body in the second step does not contain the solute of the electrolyte.

2. The method for manufacturing a battery according to Claim 1, wherein the area of ​​the main surface of the battery exceeds 10,000 cm².

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

4. The method for manufacturing 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 vibrations to the electrode body.

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