METHOD FOR MANUFACTURING A BATTERY

Abstract

Method for manufacturing a battery, comprising: a first step of manufacturing an electrode body containing an electrode containing an electrodeactive material and a solute of an electrolyte solution; and a second step of penetrating a solvent of the electrolyte solution into the electrode body.

Description

BACKGROUNDTechnical FieldThe present disclosure relates to a method for manufacturing a battery.Related ArtIn a method for manufacturing a battery using an electrolyte solution obtained by dissolving an electrolyte in an organic solvent, a liquid injection process is performed in which the electrolyte solution is supplied to the inside of an outer body accommodating an electrode body and the electrolyte solution is caused to penetrate into the electrode body.In some cases, a method is performed in which an electrode of the battery is pressed with high pressure to increase an energy density. When a packing density of an electrode active material inside the electrode is increased by pressing the electrode, the permeability of the electrolyte solution decreases. The decrease in the permeability of the electrolyte solution results in a decrease in the efficiency of the liquid injection operation.Japanese Patent Application JP 2000-195 549 A describes a method for manufacturing a battery, which is characterized in that two kinds of electrolyte solutions having different compositions are discharged. In particular, by injecting the electrolyte solutions into a battery case in the order of an electrolyte solution having a lower electrolyte concentration and a lower viscosity, the penetration speed of the electrolyte solution into the electrode body is increased.In the method described in JP 2000-195 549 A, since plural kinds of electrolyte solutions having different electrolyte concentrations are prepared and the injection of these electrolyte solutions is performed separately in time, there is room for improvement in the efficiency of a liquid injection operation.SUMMARYIn view of the above, an object of an embodiment of the present disclosure is to provide a novel method for manufacturing a battery in which the efficiency of a liquid injection process of an electrolyte solution is improved.The means for solving the above-described problem include the following embodiments. <1> A method for manufacturing a battery, comprising: a first step of manufacturing an electrode body including an electrode containing an electrode active material and a solute of an electrolyte solution; A second step for causing a solvent of the electrolyte solution to permeate into the electrode body. <2> The method for manufacturing a battery according to any one of <1> to <3>, wherein the solvent permeating into the electrode body in the second step does not contain the solute of the electrolyte solution. <3> The method for manufacturing a battery according to any one of <1> to <2>, wherein the second step comprises releasing pressure from an inside of an outer body accommodating the electrode body. <4> The method for manufacturing a battery according to any one of <1> to <3>, wherein the second step includes heating at least one of the electrode bodies or solvents. <5> The method for manufacturing a battery according to any one of <1> to <4>, wherein the second step includes applying ultrasonic vibration to the electrode body.BRIEF DESCRIPTION OF THE FIGURESEmbodiments of the present disclosure will be described in detail with reference to the following figures, wherein: FIG. 1 is a diagram schematically showing an example of the configuration of a laminated body in an electrode body; FIG. 2 is a diagram schematically showing an example of application of a battery module in an electric vehicle; FIG. 3 is a diagram schematically showing an example of a configuration of a battery module; FIG. 4 is a diagram schematically showing an example of a configuration of a battery module; and FIG. 5 is a diagram schematically showing an example of the configuration of a battery cell in a battery module.DETAILED DESCRIPTIONIn the present disclosure, a numerical range indicated by the use of "to" means a range in which the numerical values described before and after "to" are included as the minimum value and the maximum value, respectively. In numerical ranges described stepwise in the present disclosure, an upper limit value or a lower limit value described in a certain numerical range may be replaced with an upper limit value or a lower limit value of another numerical range described stepwise. In the numerical ranges described in this disclosure, an upper limit value or a lower limit value of a certain numerical range may be replaced with a value indicated in the examples. In the present disclosure, the term "step" includes not only independent steps, and even in a case where one step cannot be clearly distinguished from another step, it is included in this term as long as the intended purpose of the step is achieved. In a case where an embodiment in the present disclosure is explained with reference to the figures, the configuration of the embodiment is not limited to the configuration illustrated in the figures. Moreover, the sizes of the elements in the respective figures are conceptual, and the relative relationships between the sizes of the elements are not limited thereto.The method for manufacturing a battery of the present disclosure includes: a first step of manufacturing an electrode body including an electrode containing an electrode active material and a solute of an electrolyte solution; and a second step of causing a solvent of the electrolyte solution to permeate into the electrode body.In a general method of manufacturing a battery, an electrolyte solution obtained by dissolving a solute such as a lithium salt in a solvent is supplied to an outer body accommodating an electrode body. Then, the operation is stopped and put on standby until the electrolytic solution supplied to the outer body enters the electrode body. This waiting time may result in a decrease in the efficiency of liquid injection.In the method of the present disclosure, an electrode body including an electrode including an electrode active material and a solute of an electrolyte solution is first prepared, and then a solvent of the electrolyte solution is caused to penetrate into the electrode body. Since the viscosity of the solvent that permeates into the electrode body is lower than the viscosity of the solvent that contains the solute, the solvent permeates into the electrode body in a shorter time than in the case of containing the solute. The solvent that has penetrated into the electrode body dissolves the solute contained in the electrode configuring the electrode body. In other words, the method of the present disclosure can bring about a state in which the electrolyte solution enters the electrode body in a shorter time than in a conventional method.Moreover, in a case where the battery is large (e.g., an area of the main surface exceeds 10,000 cm 2), the flow behavior of the electrolyte solution when entering the electrode body may not be uniform, and there is a possibility that a deviation in the solute distribution is generated after the liquid injection process. In the method of the present disclosure, since the solute of the electrolyte solution can be disposed at any position of the electrode body before the solvent penetrates into the electrode body, it is possible to effectively suppress a deviation in the solute distribution after the liquid injection process.(First Step)In the first step, the electrode body containing the electrode having the electrode active material and the solute of the electrolyte solution is prepared. In the present disclosure, an electrode body refers to a structure including a laminated body made up of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. Examples of a shape of the electrode body including the laminate composed of the positive electrode, the negative electrode, and the separator disposed between the positive electrode and the negative electrode include a state in which a plurality of layers of laminated bodies cut to predetermined dimensions are superposed on each other, a state in which an elongated laminate body is wound, and the like.It is possible that all the electrodes included in the electrode body contain the solute of the electrolyte solution, or it is possible that some of the electrodes included in the electrode body contain the solute of the electrolyte solution. For example, in a case where either the negative electrode or the positive electrode of the electrode body contains the solute of the electrolyte solution, the other may or may not contain the solute of the electrolyte solution. Generally, a negative electrode has more voids between the particles of the active material than a positive electrode, and is superior in transmittance to the electrolyte solution. For this reason, the negative electrode may contain the solute of the electrolyte solution.A method for manufacturing the electrode containing the electrode active material and the solute of the electrolyte solution is not particularly limited. For example, a method of manufacturing the electrode using a composition containing the electrode active material and the solute of the electrolyte solution, a method of disposing the solute of the electrolyte solution on a surface of an electrode manufactured using a composition containing the electrode active material, and the like can be used. The types of the electrode active material and the solute of the electrolyte solution contained in the electrode are not particularly limited, and may be selected from commonly used substances. Specific examples of the solute in a case where the battery is a lithium ion secondary battery are LiPF 6, LiMHi, and the like. The solute contained in the electrode may be of a single species, but may be of two or more species.Specific examples of a positive electrode active material in a case where the battery is a lithium ion secondary battery include composite oxides formed of lithium and a transition metal and optionally other metals (hereinafter also referred to as lithium transition metal composite oxides). Examples of the transition metal and other metals are Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, and the like. Examples of lithium transition metal composite oxides include layered lithium transition metal composite oxides, spinel type lithium transition metal composite oxides, olivine type lithium transition metal composite oxides, and the like.Examples of layered lithium transition metal composite oxides include those containing at least one metal selected from Ni, Co or Mn as the transition metal. Specific examples thereof are compounds having the structural formula of LiNi a Co b Mn c O 2( wherein a, b and c are each a number of 0 or more and 1 or less, 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 or the like are added to the above compounds. Specific examples of spinel type lithium transition metal composite oxides include LiMn 2 O 4. Specific examples of olivine type lithium transition metal composite oxides are LiMPO 4( in which M is Fe, Co, Ni or Mn). The positive electrode active material contained in the electrode may be made of a single species, but may be made of two or more species thereof.Specific examples of a negative electrode active material in a case where the battery is a lithium ion secondary battery include carbon materials such as graphite, hard carbon, soft carbon, activated carbon, and the like, silicon, metallic lithium, lithium alloys, lithium titanate (LTO), and the like. The negative electrode active material contained in the electrode may be made of a single kind, but may be made of two or more kinds thereof.The electrode may include a conductive material. Specific examples of the conductive material include carbon materials such as carbon black (acetylene black, thermal black, furnace black or the like), carbon nanotubes, graphite and the like. The conductive material contained in the electrode may be made of a single kind, but may be made of two or more kinds thereof.The electrode may contain a binder. Specific examples of binders are polyvinylidene fluoride (PVdF), polyethylene, polypropylene, polyethylene terephthalate, cellulose, nitrocellulose, carboxymethylcellulose, polyethylene oxide, polyepichlorohydrin, polyacrylonitrile, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), polyacrylate, polymethacrylate, polytetrafluoroethylene (PTFE), and the like. The binders contained in the electrode can consist of a single species, but also of two or more species.The electrode included in the electrode body may include a current collector and an electrode layer disposed to contact one or both surfaces of the current collector. The thickness of the electrode layer is not particularly limited, and may be selected from general thicknesses of electrode layers. For example, the thickness of the electrode layer may be selected from a range of 10 μm to 200 μm.Examples of a material configuring a current collector of the positive electrode include aluminum, aluminum alloys, nickel, titanium, stainless steel, and the like. Examples of the shape of the current collector are a sheet, a mesh, and the like. Examples of a material constituting a current collector of the negative electrode include copper, copper alloys, nickel, titanium, stainless steel, and the like. Examples of the shape of the current collector are a sheet, a mesh, and the like.Examples of the separator contained in the electrode body include nonwoven fabrics, wipes, microporous films, and the like containing a polyolefin such as polyethylene, polypropylene, or the like as a main component.An example of a configuration of the laminated body included in the electrode body is schematically illustrated in FIG. 1. A laminated body 100 illustrated in FIG. 1 includes 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 includes a positive electrode layer 10A and a positive electrode current collector 10B. The negative electrode 20 includes a negative electrode layer 20A and a negative electrode current collector 20B.(Second Step)In the second step, the solvent of the electrolyte solution is caused to penetrate into the electrode body prepared in the first step. In order to keep the viscosity low, it is preferable that the solvent that permeates into the electrode body does not contain the solute of the electrolyte solution.The kind of the solvent used in the second step is not particularly limited, and may be selected from solvents usually used as constituents of electrolytic solutions. Specific examples of solvents include cyclic or linear carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), and the like. The solvent may be a mixture of two or more kinds of solvents, and may be a mixture containing a cyclic carbonate and a linear carbonate. The solvent may contain an additive such as vinylene carbonate (VC) or the like.In the second step, the solvent is supplied to, for example, the inside of the outer body accommodating the electrode body, thereby allowing the solvent to penetrate into the electrode body. A method for supplying the solvent to the inside of the outer body is not particularly limited, and may be selected from known methods. The number of times the solvent is supplied to the inside of the outer body may be one time or plural times. The total amount of the solvent supplied to the inside of the outer body may be adjusted so that the concentration of the solute in a state in which the solute contained in the electrode body has been dissolved in the solvent is in a range of 1 mass percent to 15 mass percent.The second step may include depressurizing the interior of the outer body accommodating the electrode body. By releasing the pressure from the interior of the outer body which accommodates the electrode body, the penetration of the solvent into the electrode body can be promoted.The second step may comprise heating at least one of the electrode bodies or the solvent. By heating at least one of the electrode bodies or the solvent, the dissolution of the dissolved substance in the solvent inside the electrode body can be promoted. The temperature of the electrode body or the solvent in the heated state can be selected, for example, from a range from room temperature to the boiling point of the solvent.The second step may include applying ultrasonic vibration to the electrode body. By applying ultrasonic vibration to the electrode body, dissolution of the solute in the solvent inside the electrode body can be promoted. In a case where ultrasonic vibration is applied to the electrode body, a frequency of the ultrasonic vibration is not particularly limited.Ultrasonic vibrations having different frequencies can be applied to the electrode body at a plurality of periods. Alternatively, the ultrasonic vibration may be applied to various regions of the electrode body divided into a plurality of timings. In certain embodiments, a step X of applying the ultrasonic vibration X to an area X of the electrode body and a step Y of applying the ultrasonic vibration Y to an area Y different from the area X of the electrode body may be performed in this order. Here, a frequency of the ultrasonic vibration X is lower than a frequency of the ultrasonic vibration Y.In step X, by applying the ultrasonic vibration X to the region X of the electrode body, the bubbles contained in the region X of the electrode body are moved to the region Y. When the solvent penetrates into the electrode body, bubbles may be generated in some cases. By displacing the bubbles into the region Y without removing them, the penetration of the solvent into the region X is promoted. The frequency of the ultrasonic vibration X applied to the electrode body in step X is selected from frequencies that do not eliminate the bubbles (e.g., 20 kHz to 100 kHz).In step Y, by applying the ultrasonic vibration Y to the region Y different from the region X of the electrode body, the bubbles contained in the region Y of the electrode body are eliminated. By eliminating the bubbles contained in the region Y, the penetration of the solvent into the region Y is promoted. Elimination of the bubbles can be accomplished by dissolving gas in the bubbles in the solvent. The frequency of the ultrasonic vibration Y applied to the electrode body in step Y is selected from frequencies that eliminate the bubbles (e.g., greater than 100 kHz).The type of the outer body in which the electrode body is accommodated is not particularly limited, and may be selected depending on the type of the battery. In certain embodiments, a sheet-shaped outer body may be used. Examples of the sheet-shaped outer bodies are those containing a metal. Specific examples are laminated bodies (so-called laminate films) having a metal layer containing a metal such as aluminum or the like and a heat-seal layer containing a resin which is melted by heating. That is, the battery manufactured by the method of the present disclosure may be a battery (so-called laminate battery) in which a laminate film is used as an outer body.The outer body may be a single element or consist of two or more elements. In a case where the outer body is a sheet-shaped object, the outer body may be, for example, a sheet-shaped object or two sheet-shaped objects. If necessary, a recess for receiving the electrode body can be formed on the sheet-shaped outer body by embossing.Examples of a method for accommodating the electrode body in the outer body using a sheet-shaped outer body are, for example, the following Methods 1 and Method 2: a method in which the electrode body is disposed between an outer body folded in half or between two outer bodies laid one above the other, the outer bodies being joined at an edge of the electrode body. Method 2: A method of inserting the electrode body into a pouch prepared by joining together the periphery of one half-folded outer body or two superposed outer bodies(Types of Battery and Application Examples)The type of the battery manufactured by the method of the present disclosure is not particularly limited. Specific examples of the battery include secondary batteries such as lithium ion secondary batteries, lead batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, cobalt-titanium-lithium secondary batteries, and the like. From the viewpoint of energy density, versatility, and the like, the battery may be a lithium ion secondary battery.The battery of the present disclosure may be mounted on an electric vehicle. An example in which the battery of the present disclosure is applied to an electric vehicle will be explained below with reference to the figures. In the following explanation, a "battery cell 20" corresponds to the battery of the present disclosure.FIG. 2 is a schematic plan view of a main part of a vehicle 100 to which a battery 10 according to an embodiment has been attached. As illustrated in FIG. 2, the vehicle 100 is an electric vehicle (BEV)) in which the battery pack 10 is mounted under a floor. Note that arrows UP, FR, and LH in the respective figures respectively denote an upper side in the up-down direction, a front side in the front-rear direction, and a left side in the vehicle width direction. In the cases where explanations are given with the front-rear, left-right, and up-down directions, unless otherwise specified, these mean front and rear in the vehicle front-rear direction, left and right in the vehicle width direction, and up and down in the vehicle up-down direction.In the vehicle 100 of the present embodiment, for example, a DC / DC converter 102, an electric compressor 104, and a PTC heater 106 are disposed further toward the vehicle front than the battery 10.The direct current output from the battery 10 is adjusted in voltage by the DC / DC converter 102 and then supplied to the electric compressor 104, the PTC heater 106, the inverter 112, and the like. In addition, since the motor 108 is supplied with power via the inverter 112, the rear wheels rotate to drive the vehicle 100.A charging port 116 is provided at a right side portion of a rear portion of the vehicle 100. By connecting a charging plug of an external charging device, which is not illustrated in the figures, to the charging connection 116, electrical energy can be stored in the battery 10 via the charging device 114.The arrangement, structure, and the like of the respective components configuring the vehicle 100 are not limited to the configuration described above. For example, the present disclosure may be applied to vehicles having a motor such as hybrid vehicles (HV) and plug-in hybrid electric vehicles (PHEV). Although the vehicle is configured as a rear-drive vehicle in which the engine 108 is mounted on the rear portion of the vehicle in the present embodiment, there is no limitation thereto; the vehicle may also be configured as a front-drive vehicle in which the engine 108 is mounted on the front portion of the vehicle, and a pair of engines 108 may also be mounted on the front and rear of the vehicle. Moreover, the vehicle may also be equipped with internal-wheel engines on the respective wheels.The battery pack 10 is configured to include a plurality of battery modules 11. In the present embodiment, for example, ten battery modules 11 are provided. Specifically, five battery modules 11 are disposed on the right side of the vehicle 100 in the vehicle front direction, and five battery modules 11 are disposed on the left side of the vehicle 100 in the vehicle front direction. In addition, all the battery modules 11 are electrically connected to each other.FIG. 3 is a schematic perspective view of a battery module 11. In addition, the outer shell of the battery module 11 is made of an aluminum alloy. The outer shell of the battery module 11 is formed by, for example, joining aluminum die casting to both ends of an aluminum alloy extruded material by laser welding or the like.At both vehicle-wide end portions of the battery module 11, a pair of voltage terminals 12 and a connector 14 are provided. A flexible circuit board 21, which will be described later, is connected to the terminal 14. In addition, bus bars, which are not illustrated in the figures, are welded to both vehicle-wide end portions of the battery module 11.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 and rear direction is, for example, 150 mm to 250 mm, and the height MH in the vehicle height direction is, for example, 80 mm to 110 mm.FIG. 4 is a plan view of the battery module 11 in a state in which an upper lid thereof has been removed. As shown in FIG. 4, a plurality of battery cells 20 are accommodated at an inner space of the battery module 11 in an arranged state. In the present embodiment, for example, twenty-four battery cells 20 are arranged in the vehicle front direction and are bonded to each other.A flexible printed circuit board 21 is disposed on the battery cells 20. The flexible circuit board 21 is in the form of a band whose longitudinal direction extends in the vehicle width direction, and thermistors 23 are respectively attached to both end portions of the flexible circuit board 21. The thermistors 23 are not bonded to the battery cells 20 and are configured to be pressed toward the battery cells 20 side by the upper lid of the battery module 11.Moreover, one or more damping materials, which are not illustrated in the figures, are accommodated in the interior of the battery module 11. The cushioning material is, for example, a thin plate-shaped member that is elastically deformable and is disposed between adjacent battery cells 20 with a thickness direction along an arrangement direction of the battery cells 20. In the present embodiment, the cushioning material is disposed, for example, at both end portions in the longitudinal direction of the battery module 11 and at the central portion in the longitudinal direction of the battery module 11, respectively.FIG. 5 is a schematic diagram in which a battery cell 20 accommodated in the battery module 11 is viewed in the thickness direction thereof. As shown in FIG. 5, the battery cell 20 has the shape of a substantially rectangular plate, and an electrode body, which is not illustrated in the figures, is housed inside thereof. The electrode body is configured by laminating a positive electrode, a negative electrode, and a separator body, and is sealed by a laminate film 22.In the present embodiment, for example, the embossed sheet-shaped laminate sheet 22 is folded and adhered to thereby form a case portion of the electrode body. The laminate film 22 may have either a single-sided embossed pattern in which embossing is done at one location or a two-sided embossed pattern in which embossing is done at two locations. In one embodiment, the laminate film 22 has a one-cup embossed structure having a draw depth of about 8 mm to 10 mm.The upper ends of the two longitudinally end portions of the battery cell 20 are folded over, and their corners form an outer shape. In addition, an upper end portion of the battery cell 20 is folded over, and a fixing tape 24 is wound around the upper end portion of the battery cell 20 along the longitudinal direction.Terminals 26 are respectively provided at both ends in the longitudinal direction of the battery cell 20. In the present embodiment, for example, the terminals 26 are provided at positions offset downward from the center of the battery cell 20 in the up-down direction. The terminals 26 are connected to the bus bars not illustrated in the figures by laser welding or the like.The battery cell 20 has, for example, a length CW 1 in the vehicle width direction of 530 mm to 600 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 mm to 900 mm, or greater than or equal to 1000 mm; a length CW 2 of the region in which the electrode body is accommodated of 500 mm to 520 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, or greater than or equal to 1000 mm; a height CH of 80 mm to 110 mm, or 110 mm to 140 mm; a thickness of 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, or 9.0 mm to 11.0 mm; and a height TH of the terminal 26 of 40 mm to 50 mm, 50 mm to 60 mm, or 60 mm to 70 mm.All publications, patent applications, and technical standards mentioned in the present specification are incorporated herein by reference to the same extent as if each individual publication, patent application, or technical standard were expressly and individually indicated to be incorporated by reference.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2000-195 549 A [0004, 0005]

Claims

A method for manufacturing a battery, the method comprising the steps of: a first step of manufacturing an electrode body including an electrode containing an electrode active material and a solute of an electrolyte solution; and a second step of causing a solvent of the electrolyte solution to permeate into the electrode body.The method for manufacturing a battery according to claim 1, wherein the solvent that is caused to penetrate into the electrode body in the second step does not contain the solute of the electrolyte solution.The method for manufacturing a battery according to claim 1 or 2, wherein the second step comprises depressurizing an inside of an outer body accommodating the electrode body.The method for manufacturing a battery according to claim 1 or 2, wherein the second step comprises heating the electrode body and / or the solvent.The method for manufacturing a battery according to claim 1 or 2, wherein the second step comprises applying ultrasonic vibrations to the electrode body.

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