Electrode manufacturing system and electrode manufacturing method

The electrode manufacturing system comprises a cutting device. The cutting device cuts an electrode material along one direction of the electrode material to manufacture electrodes. The electrode material comprises first sections and a second section. The first section includes an active material doped with alkali metal, and extends in the one direction. The second section is located between two adjacent first sections of the first sections. In the second section, the active material doped with alkali metal is absent. The cutting device cuts the second section.

CROSS-REFERENCE TO RELATED APPLICATION

This international application claims the benefit of Japanese Patent Application No. 2019-009584 filed on Jan. 23, 2019 with the Japan Patent Office, and the entire disclosure of Japanese Patent Application No. 2019-009584 is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electrode manufacturing system and an electrode manufacturing method.

BACKGROUND ART

In recent years, reduction in size and weight of electronic devices has been remarkable, and thus, there has been an increased demand for reduction in size and weight of batteries to be used as power supplies for driving such electronic devices.

In order to meet the demand for reduction in size and weight, non-aqueous electrolyte rechargeable batteries, as typified by lithium-ion rechargeable battery, have been developed. Also, lithium ion capacitors are known as power storage devices available for uses requiring high energy density characteristics and high output characteristics. Further known are sodium ion batteries and capacitors using sodium which is lower in cost and more abundant as a natural resource than lithium.

For these batteries and capacitors, a process of previously doping an electrode with alkali metal (generally referred to as pre-doping) is adopted for various purposes. Methods for pre-doping an electrode with alkali metal include, for example, a continuous method. In the continuous method, pre-doping is performed while transferring a strip-shaped electrode plate in an electrolyte solution. The continuous method is disclosed in Patent Documents 1 to 4.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Unexamined Patent Application Publication No. H10-308212Patent Document 2: Japanese Unexamined Patent Application Publication No. 2008-77963Patent Document 3: Japanese Unexamined Patent Application Publication No. 2012-49543Patent Document 4: Japanese Unexamined Patent Application Publication No. 2012-49544

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

There has been a growing demand for manufacturing electrodes more efficiently. In one aspect of the present disclosure, it is desirable to provide an electrode manufacturing system and an electrode manufacturing method capable of manufacturing electrodes efficiently.

Means for Solving the Problems

One aspect of the present disclosure provides an electrode manufacturing system comprising a cutting device configured to cut an electrode material along one direction of the electrode material to manufacture electrodes, wherein the electrode material comprises first sections including an active material doped with alkali metal, the first sections extending in the one direction, and a second section in which the active material doped with alkali metal is absent, the second section arranged between two adjacent first sections of the first sections, and wherein the cutting device is configured to cut the second section.

The electrode manufacturing system as one aspect of the present disclosure is capable of manufacturing two or more electrodes from a single electrode material. Thus, in the electrode manufacturing system as one aspect of the present disclosure, it is possible to efficiently manufacture electrodes.

Another aspect of the present disclosure provides an electrode manufacturing method comprising cutting an electrode material along one direction to manufacture electrodes, wherein the electrode material comprises first sections including an active material doped with alkali metal, the first sections extending in the one direction, and a second section in which the active material doped with alkali metal is absent, the second section arranged between two adjacent first sections of the first sections, and wherein cutting the electrode material along one direction of the electrode material to manufacture electrodes comprises cutting the second section.

In the electrode manufacturing method as another aspect of the present disclosure, two or more electrodes can be manufactured from a single electrode material. Thus, in the electrode manufacturing method as one aspect of the present disclosure, it is possible to efficiently manufacture electrodes.

EXPLANATION OF REFERENCE NUMERALS

MODE FOR CARRYING OUT THE INVENTION

First Embodiment

1. Configuration of Electrode Material1

A configuration of an electrode material1will be described with reference toFIG.1andFIG.2. The electrode material1is used for manufacturing electrodes. The electrode material1has a strip shape. The electrode material1comprises a current collector3and an active material layer5. The current collector3has a strip-shape. The active material layers5are formed on both surfaces of the current collector3. In a width direction W of the electrode material1, the active material layer5has a width smaller than that of the current collector3. The active material layer5extends along a longitudinal direction L of the electrode material1. The active material layer5corresponds to a first section. The longitudinal direction L corresponds to one direction of the electrode material1.

A portion in which the current collector3is exposed (hereinafter, referred to as an exposed portion7) is formed between two active material layers5adjacent to each other in the width direction W. The exposed portion7is also formed at each end of the electrode material1in the width direction W. The exposed portion7extends along the longitudinal direction L of the electrode material1. In the exposed portion7, an active material is absent. The exposed portion7corresponds to a second section.

The current collector3may be preferably a metal foil, such as copper, nickel, and stainless steel. In addition, the current collector3may have a conductive layer, including a carbon material as a main component, formed on the metal foil. The thickness of the current collector3may be, for example, 5 to 50 μm.

The active material layer5may be formed, for example, by applying slurry including an active material before pre-doped with alkali metal (hereinafter, referred to as a non-doped state) and a binder on the current collector3, and drying the slurry.

Examples of the binder may include rubber-based binders, such as styrene-butadiene rubber (SBR) and NBR; fluorine resins, such as polytetrafluoroethylene and polyvinylidene fluoride; polypropylene, polyethylene, and fluorine modified (meth) acrylic binder as disclosed in Japanese Unexamined Patent Application Publication No. 2009-246137.

The slurry may include other components in addition to the active material and the binder. Examples of such other components may include conductive agents, such as carbon black, graphite, vapor-grown carbon fiber, and metal powder; and thickeners, such as carboxyl methyl cellulose, a Na salt or ammonium salt thereof, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, oxidized starch, phophorylated starch, and casein.

A thickness of the active material layer5is not particularly limited. The thickness of the active material layer5may be, for example, 5 to 500 μm, preferably 10 to 200 μm, particularly preferably 10 to 100 μm. The active material included in the active material layer5is not particularly limited, as long as the material is an electrode active material applicable to batteries or capacitors utilizing reactions such as insertion/desorption of alkali metal ions. The active material may be a negative electrode active material or a positive electrode active material.

The negative electrode active material is not particularly limited. Examples of the negative electrode active material may include carbon material, such as graphite, easily-graphitizable carbon, hardly-graphitizable carbon, and a composite carbon material obtained by coating graphite particles with a pitch or a resin carbide; and a material comprising a metal or semi-metal, such as Si and Sn, that can be alloyed with lithium, or an oxide thereof. Examples of the carbon material may include a carbon material described in Japanese Unexamined Patent Application Publication No. 2013-258392. Examples of the material comprising the metal or semi-metal that can be alloyed with lithium or the oxide thereof may include the materials described in Japanese Unexamined Patent Application Publication No. 2005-123175 and Japanese Unexamined Patent Application Publication No. 2006-107795.

Examples of the positive electrode active material may include transition metal oxides, such as cobalt oxide, nickel oxide, manganese oxide, vanadium oxide; and sulfur-based active materials, such as simple sulfur substance and metal sulfide. Any of the positive electrode active material and the negative electrode active material may be made of a single substance or a mixture of two or more types of substances.

The active material included in the active material layer5is pre-doped with alkali metal using an electrode material manufacturing apparatus11described later. The alkali metal to be pre-doped to the active material is preferably lithium or sodium, particularly preferably lithium. In the case of using the electrode material1for manufacturing electrodes of lithium-ion rechargeable batteries, a density of the active material layer5is preferably 1.30 to 2.00 g/cc, and particularly preferably 1.40 to 1.90 g/cc.

2. Configuration of Electrode Material Manufacturing Apparatus11of Electrode Manufacturing System

An electrode manufacturing system of the present disclosure comprises an electrode material manufacturing apparatus11and a cutting device13. A configuration of the electrode material manufacturing apparatus11will be described with reference toFIG.3toFIG.6.

As shown inFIG.3, the electrode material manufacturing apparatus11comprises an immersing tank15, doping tanks17,19,21, a cleaning tank23, conveyor rollers25,27,29,31,33,35,37,39,40,41,43,45,46,47,49,51,52,53,55,57,58,59,61,63,64,65,67,69,70,71,73,75,77,79,81,83,85,87,89,91,93(hereafter also collectively referred to as a conveyor roller group), a supply roll101, a winding roll103, a support105, a circulation filtration unit107, six power supplies109,110,111,112,113,114, a tab cleaner117, a solution collecting unit119, and an end portion sensor121. The conveyor roller group corresponds to a conveyer unit.

The immersing tank15is a rectangular tank with an open top. The immersing tank15has a bottom surface having a generally U-shaped section. The immersing tank15comprises a partition plate123. The partition plate123is supported by a support rod125penetrating an upper end of the partition plate123. The support rod125is fixed to a wall or the like (not shown). The partition plate123extends vertically, and divides the inside of the immersing tank15into two spaces. The partition plate123has the conveyor roller33attached to a lower end thereof. The partition plate123and the conveyor roller33are supported by a support rod127penetrating the partition plate123and the conveyor roller33. The partition plate123is notched in the vicinity of the lower end thereof so as not to come in contact with the conveyor roller33. There is a space between the conveyor roller33and the bottom surface of the immersing tank15.

A configuration of the doping tank17will be described with reference toFIG.4. The doping tank17comprises an upstream tank131and a downstream tank133. The upstream tank131is arranged on a side of the supply roll101(hereinafter, referred to as an upstream side), and the downstream tank133is arranged on a side of the winding roll103(hereinafter, referred to as a downstream side).

First, a configuration of the upstream tank131will be described. The upstream tank131is a rectangular tank with an open top. The upstream tank131has a bottom surface having a generally U-shaped section. The upstream tank131comprises a partition plate135, four counter electrode members137,139,141,143and four masks144.

The partition plate135is supported by a support rod145penetrating an upper end of the partition plate135. The support rod145is fixed to a wall or the like (not shown). The partition plate135extends vertically, and divides the inside of the upstream tank131into two spaces. The partition plate135has the conveyor roller40attached to the lower end thereof. The partition plate135and the conveyor roller40are supported by a support rod147penetrating the partition plate135and the conveyor roller40. The partition plate135is notched in the vicinity of the lower end thereof so as not to come in contact with the conveyor roller40. There is a space between the conveyor roller40and the bottom surface of the upstream tank131.

The counter electrode member137is arranged on the upstream side in the upstream tank131. The counter electrode members139,141are arranged so as to hold the partition plate135from both sides. The counter electrode member143is arranged on the downstream side in the upstream tank131.

There is a space149between the counter electrode member137and the counter electrode member139. There is a space151between the counter electrode member141and the counter electrode member143. The counter electrode members137,139,141,143are connected to one electrode of the power supply109. The counter electrode members137,139,141,143have similar configurations. Here, configurations of the counter electrode members137,139will be described with reference toFIG.5.

The counter electrode members137,139have a configuration in which a conductive base material153, an alkali metal-containing plate155, and a porous insulation member157are stacked. Examples of a material for the conductive base material153may include copper, stainless steel, and nickel. The alkali metal-containing plate155is not limited to a specific form, and may be, for example, an alkali metal plate and an alkali metal alloy plate. The alkali metal-containing plate155may have a thickness of, for example, 0.03 to 5 mm.

The porous insulation member157has a plate shape. The porous insulation member157is stacked on the alkali metal-containing plate155. The plate shape of the porous insulation member157is a shape when the porous insulation member157is stacked on the alkali metal-containing plate155. The porous insulation member157may be a member that maintains a certain shape by itself or may be a member that can be easily deformed, such as a net.

The porous insulation member157is porous. Thus, a dope solution described later can pass through the porous insulation member157. This allows the alkali metal-containing plate155to come in contact with the dope solution.

Examples of the porous insulation member157may include a mesh made of resin. Examples of the resin may include polyethylene, polypropylene, nylon, polyetheretherketone, and polytetrafluoroethylene. A mesh opening of the mesh can be suitably set. The mesh opening of the mesh may be from 0.1 μm to 10 mm, and preferably from 0.1 to 5 mm. The thickness of the mesh can be suitably set. The thickness of the mesh may be, for example, 1 μm to 10 mm, and preferably 30 μm to 1 mm. A mesh opening ratio of the mesh can be suitably set. The mesh opening ratio of the mesh may be, for example, 5 to 98%, and preferably 5 to 95%, and further preferably 50 to 95%.

The porous insulation member157may be entirely made of an insulating material, or may partially comprise an insulating layer.

The counter electrode members137,139,141,143each have a mask144attached thereto. The mask144is attached to a surface of each counter electrode member137,139,141,143on a side of the porous insulation member157.FIG.5shows the masks144attached to the counter electrode members137,139. The mask144covers a part of each counter electrode member137,139,141,143, and exposes the rest portion. The detailed shape of the mask144will be described later. Examples of a material for the mask144may include polyethylene, polypropylene, nylon, polyetheretherketone, polytetrafluoroethylene. The mask144is preferably made of polypropylene. The thickness of the mask144is preferably 10 μm or more and 10 mm or less, and further preferably 50 μm or more and 5 mm or less.

The downstream tank133has a configuration similar to that of the upstream tank131. However, the downstream tank133has the conveyor roller46therein instead of the conveyor roller40. Also, the downstream tank133comprises counter electrode members137,139,141,143connected to one electrode of the power supply110.

The doping tank19comprises a configuration similar to that of the doping tank17. However, the doping tank19has conveyor rollers52,58therein instead of the conveyor rollers40,46. The upstream tank131of the doping tank19comprises the counter electrode members137,139,141,143connected to one electrode of the power supply111. Also, the downstream tank133of the doping tank19comprises the counter electrode members137,139,141,143connected to one electrode of the power supply112.

The doping tank21comprises a configuration similar to that of the doping tank17. However, the doping tank21has conveyor rollers64,70therein instead of the conveyor rollers40,46. The upstream tank131of the doping tank21comprises the counter electrode members137,139,141,143connected to one electrode of the power supply113. Also, the downstream tank133of the doping tank21comprises the counter electrode members137,139,141,143connected to one electrode of the power supply114.

The cleaning tank23has a configuration similar to that of the immersing tank15. However, the cleaning tank23has the conveyor roller75therein instead of the conveyor roller33.

In the conveyor roller group, the conveyor rollers37,39,43,45,49,51,55,57,61,63,67,69are made of an electrically conductive material. In the conveyor roller group, the remaining conveyor rollers are made of elastomer except for bearing portions. The conveyor roller group conveys the electrode material1along a specified path. The path along which the conveyor roller group conveys the electrode material1is a path from the supply roll101to the winding roll103sequentially through the immersing tank15, the doping tank17, the doping tank19, the doping tank21, the cleaning tank23, and the tab cleaner117.

A part of the path passing through the immersing tank15first runs downward by the conveyor rollers29,31, then the path is directed upward by the conveyor roller33.

A part of the above-described path passing through the doping tank17will be described below. First, the path is directed downward by the conveyor roller37, and the path runs downward in the space149of the upstream tank131. Then, the path is directed upward by the conveyor roller40, and the path runs upward in the space151of the upstream tank131. Then, the path is directed downward by the conveyor rollers41,43, and the path runs downward in the space149of the downstream tank133. Then, the path is directed upward by the conveyor roller46, and the path runs upward in the space151of the downstream tank133. Finally, the path is directed in a horizontal direction by the conveyor roller47, and the path runs toward the doping tank19.

A part of the above-described path passing through the doping tank19will be described below. First, the path is directed downward by the conveyor roller49, and the path runs downward in the space149of the upstream tank131. Then, the path is directed upward by the conveyor roller52, and the path runs upward in the space151of the upstream tank131. Then, the path is directed downward by the conveyor rollers53,55, and the path runs downward in the space149of the downstream tank133. Then, the path is directed upward by the conveyor roller58, and the path runs upward in the space151of the downstream tank133. Finally, the path is directed in the horizontal direction by the conveyor roller59, and the path runs toward the doping tank21.

A part of the above-described path passing through the doping tank21will be described below. First, the path of the path is directed downward by the conveyor roller61, and the path runs downward in the space149of the upstream tank131. Then, the path is directed upward by the conveyor roller64, and the path runs upward in the space151of the upstream tank131. Then, the path is directed downward by the conveyor rollers65,67, and the path runs downward in the space149of the downstream tank133. Then, the path is directed upward by the conveyor roller70, and the path runs upward in the space151of the downstream tank133. Finally, the path is directed in the horizontal direction by the conveyor roller71, and the path runs toward the cleaning tank23.

A part of the above-described path passing through the cleaning tank23is a path whose path is first directed downward by the conveyor roller73and the path runs downward, then, the path is directed upward by the conveyor roller75.

The supply roll101has the electrode material1wound around the supply roll101. That is, the supply roll101holds the electrode material1in a wound-up state. The electrode material1held by the supply roll101is in a non-doped state.

The conveyor roller group draws out and conveys the electrode material1held by the supply roll101.

The winding roll103winds up and keeps the electrode material1that is conveyed by the conveyor roller group. The electrode material1conveyed by the conveyor roller group is pre-doped with alkali metal in the doping tanks17,19,21.

The supports105support the immersing tank15, the doping tanks17,19,21, and the cleaning tank23from below. The height of the support105can be changed. The circulation filtration unit107is provided to the respective doping tanks17,19,21. The circulation filtration unit107comprises a filter161, a pump163, and a pipe165.

In the circulation filtration unit107provided to the doping tank17, the pipe165is a circulation pipe that extends from the doping tank17, sequentially passes through the pump163and the filter161, and then returns to the doping tank17. The dope solution in the doping tank17is circulated through the pipe165and the filter161by a driving force of the pump163, and returns to the doping tank17. During this period, impurities and the like in the dope solution are filtered by the filter161. Examples of the impurities may include impurities precipitated from the dope solution and impurities produced from the electrode material1. Examples of the material for the filter161may include resin, such as polypropylene, polytetrafluoroethylene. The pore diameter of the filter161may be suitably set. The pore diameter of the filter161may be, for example, 0.2 μm to 50 μm.

The circulation filtration units107provided to the doping tanks19,21also have the similar configuration and functional effects. InFIG.3andFIG.4, illustration of the dope solution is omitted for the purpose of convenience.

One terminal of the power supply109is connected to the conveyor rollers37,39. Also, the other terminal of the power supply109is connected to the counter electrode members137,139,141,143that the upstream tank131of the doping tank17comprises. The electrode material1is in contact with the conveyor rollers37,39. The electrode material1and the counter electrode members137,139,141,143are located in the dope solution that is an electrolyte solution. Thus, in the upstream tank131of the doping tank17, the electrode material1and the counter electrode members137,139,141,143are electrically connected through the electrolyte solution.

One terminal of the power supply110is connected to the conveyor rollers43,45. Also, the other terminal of the power supply110is connected to the counter electrode members137,139,141,143that the downstream tank133of the doping tank17comprises. The electrode material1is in contact with the conveyor rollers43,45. The electrode material1and the counter electrode members137,139,141,143are located in the dope solution that is the electrolyte solution. Thus, in the downstream tank133of the doping tank17, the electrode material1and the counter electrode members137,139,141,143are electrically connected through the electrolyte solution.

One terminal of the power supply111is connected to the conveyor rollers49,51. Also, the other terminal of the power supply111is connected to the counter electrode members137,139,141,143that the upstream tank131of the doping tank19comprises. The electrode material1is in contact with the conveyor rollers49,51. The electrode material1and the counter electrode members137,139,141,143are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131of the doping tank19, the electrode material1and the counter electrode members137,139,141,143are electrically connected through the electrolyte solution.

One terminal of the power supply112is connected to the conveyor rollers55,57. Also, the other terminal of the power supply112is connected to the counter electrode members137,139,141,143that the downstream tank133of the doping tank19comprises. The electrode material1is in contact with the conveyor rollers55,57. The electrode material1and the counter electrode members137,139,141,143are located in the dope solution that is the electrolyte solution. Thus, in the downstream tank133of the doping tank19, the electrode material1and the counter electrode members137,139,141,143are electrically connected through the electrolyte solution.

One terminal of the power supply113is connected to the conveyor rollers61,63. Also, the other terminal of the power supply113is connected to the counter electrode members137,139,141,143that the upstream tank131of the doping tank21comprises. The electrode material1is in contact with the conveyor rollers61,63. The electrode material1and the counter electrode members137,139,141,143are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131of the doping tank21, the electrode material1and the counter electrode members137,139,141,143are electrically connected through the electrolyte solution.

One terminal of the power supply114is connected to the conveyor rollers67,69. Also, the other terminal of the power supply114is connected to the counter electrode members137,139,141,143that the downstream tank133of the doping tank21comprises. The electrode material1is in contact with the conveyor rollers67,69. The electrode material1and the counter electrode members137,139,141,143are located in the dope solution that is the electrolyte solution. Thus, in the downstream tank133of the doping tank21, the electrode material1and the counter electrode members137,139,141,143arc electrically connected through the electrolyte solution.

The tab cleaner117cleans an end portion of the electrode material1in the width direction W. The solution collecting unit119is provided to each of the immersing tank15, the doping tanks17,19,21, and the cleaning tank23. The solution collecting unit119collects solution taken from the tank by the electrode material1, and returns the collected solution to the tank.

The end portion sensor121detects a position of the end portion of the electrode material1in the width direction W. Based on a detection result of the end portion sensor121, an end position adjusting unit, which is not shown, adjusts positions of the supply roll101and the winding roll103in the width direction W. The end position adjusting unit adjusts the positions of the supply roll101and the winding roll103in the width direction W so that the end portion of the electrode material1in the width direction W is located at a position where the end portion is cleaned by the tab cleaner117.

3. Configuration of Mask144

With reference toFIG.6, a configuration of the mask144will be described.FIG.6shows the masks144attached to the counter electrode members137,139. The masks144attached to the counter electrode members141,143also have a similar configuration.

The mask144covers the exposed portion7in the electrode material1. The meaning of covering the exposed portion7is that the mask144is overlapped with the exposed portion7when seen from a thickness direction T of the electrode material1. The mask144does not cover the active material layer5.

The mask144may entirely or partially cover the exposed portion7. Also, the mask144may cover a part of the active material layer5in addition to the exposed portion7.

4. Composition of Dope Solution

When the electrode material manufacturing apparatus11is used, a dope solution is stored in the doping tanks17,19,21. The dope solution comprises alkali metal ions and a solvent. Examples of the solvent may include an organic solvent. The organic solvent is preferably an aprotic organic solvent. Examples of the aprotic organic solvent may include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1-fluoroethylene carbonate, γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran, dioxolane, methylene chloride, sulfolane, diethylene glycol dimethyl ether (diglyme), diethylene glycol methyl ethyl ether, triethylene glycol dimethyl ether (triglyme), triethylene glycol butyl methyl ether, and tetraethylene glycol dimethyl ether (tetraglyme).

Also, as the organic solvent, ionic liquid, such as quaternary imidazolium salt, quaternary pyridinium salt, quaternary pyrrolidinium salt, quaternary piperidinium salt and the like may be used. The organic solvent may be made of a single component, or may be a mixed solvent of two or more types of components.

The alkali metal ions included in the dope solution are ions forming an alkali metal salt. The alkali metal salt is preferably a lithium salt or a sodium salt. Examples of an anionic moiety forming the alkali metal salt may include phosphorus anion having a fluoro group, such as PF6−, PF3(C2F5)3−, PF3(CF3)3−; boron anion having a fluoro group or a cyano group, such as BF4−, BF2(CF)2−, BF3(CF3)−, and B(CN)4−; sulfonyl imide anion having a fluoro group, such as N(FSO2)2−, N(CF3SO2)2−, and N(C2F5SO2)2−; and organic sulfonic acid anion having a fluoro group, such as CF3SO3−.

A concentration of the alkali metal salt in the dope solution is preferably 0.1 mol/L or more, and more preferably within a range of 0.5 to 1.5 mol/L. When the concentration of the alkali metal salt is within this range, pre-doping of the alkali metal proceeds efficiently.

The dope solution may further comprise a flame retardant, such as a phosphazene compound. From the viewpoint of effective control of a thermal runaway reaction while doping the alkali metal, an added amount of the flame retardant is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more, with respect to 100 parts by mass of the dope solution. From the viewpoint of obtaining a high-quality doped electrode, the added amount of the flame retardant is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 10 parts by mass or less, with respect to 100 parts by mass of the dope solution.

5. Configuration of Cutting Device13of Electrode Manufacturing System

A configuration of the cutting device13will be described with reference toFIG.7. The cutting device13comprises a supply roll162, a conveyor rollers164,166,167, a slitter169, and a winding rolls171,173,175,177.

The supply roll162has the electrode material1wound around the supply roll162. The electrode material1wound around the supply roll162is pre-doped using the electrode material manufacturing apparatus11. The electrode material1is drawn from the supply roll162and is conveyed toward the winding rolls171,173,175,177while guided by the conveyor rollers164,166,167.

The slitter169comprises a body shaft179, two or more circular blades181. The two or more circular blades181are attached to the body shaft179at specified intervals. The slitter169is arranged so as to be opposed to the conveyor roller166. The two or more circular blades181cut the electrode material1along the longitudinal direction L when the electrode material1passes between the slitter169and the conveyor roller166. The electrode material1is cut along three cut ends183shown inFIG.1. As a result, from the electrode material1, two electrodes185,186, a first remaining part187, and a second remaining part189are produced. The first remaining part187and the second remaining part189are remaining portions not to be used for electrodes. The three cut ends183each pass through the exposed portion7.

The winding roll171winds up the first remaining part187. The winding roll173winds up the electrode185. The winding roll175winds up the electrode186. The winding roll177winds up the second remaining part189.

6. Method for Manufacturing Electrode

First, as a preparation for manufacturing the electrode, the following procedures are performed. The electrode material1in the non-doped state is wound around the supply roll101. Then, the electrode material1is drawn from the supply roll101, and is fed to the winding roll103along the aforementioned path. Then, the immersing tank15, the doping tanks17,19,21, and the cleaning tank23are raised and set at a specified position shown inFIG.3.

The dope solution is stored in the immersing tank15, and the doping tanks17,19,21. The dope solution is the solution described in a section of “4. Composition of Dope Solution”. A cleaning solution is stored in the cleaning tank23. The cleaning solution is an organic solvent. Then, the electrode material1is conveyed, by the conveyor roller group, from the supply roll101to the winding roll103, along the aforementioned path. When the electrode material1is passed through the doping tanks17,19,21, the active material included in the active material layer5is pre-doped with alkali metal.

The electrode material1is cleaned in the cleaning tank23while being conveyed by the conveyor roller group. Then, the electrode material1is wound around the winding roll103. The electrode material1may be a positive electrode or a negative electrode. In the case of manufacturing a positive electrode, in the electrode material manufacturing apparatus11, a positive electrode active material is doped with alkali metal, and in the case of manufacturing a negative electrode, in the electrode material manufacturing apparatus11, a negative electrode active material is doped with alkali metal.

When lithium is occluded in a negative electrode active material of a lithium ion capacitor, a doping amount of alkali metal is preferably 70 to 95% with respect to a theoretical capacity of the negative electrode active material; and when lithium is occluded in a negative electrode active material of a lithium-ion rechargeable battery, the doping amount is preferably 10 to 30% with respect to the theoretical capacity of the negative electrode active material.

Finally, the electrode material1that is wounded around the winding roll103is cut using the cutting device13. According to the above-described procedures, the electrodes185,186can be obtained.

7. Effects Achieved by Electrode Manufacturing System

(1A) The electrode manufacturing system is capable of manufacturing two or more electrodes185,186from one electrode material1. Thus, the electrode manufacturing system can manufacture the electrodes185,186efficiently.

(1B) The cutting device13cuts the electrode material1along the cut end183passing through the exposed portion7. Thus, the cutting device13inhibits the active material layer5from being positioned in the end portion in the width direction W of the manufactured electrodes185,186.

(1C) The electrode manufacturing system comprises the electrode material manufacturing apparatus11. Thus, in the electrode manufacturing system, a pre-doped electrode material1can be easily manufactured.

(1D) The electrode material manufacturing apparatus11comprises the mask144. The mask144is arranged between the electrode material1in the doping tanks17,19,21and the counter electrode members137,139,141,143, and covers the exposed portion7. Thus, the electrode material manufacturing apparatus11can inhibit a precipitation of alkali metal on the exposed portion7.

Second Embodiment

1. Difference from First Embodiment

Since a second embodiment has a basic configuration similar to that of the first embodiment, differences therebetween will be described below. It is to be noted that the same reference numerals as those in the first embodiment indicate similar configurations, and reference is made to the preceding description.

In the first embodiment described above, the counter electrode members137,139,141,143each comprise the mask144attached thereto. In contrast, the second embodiment is different from the first embodiment in that the counter electrode members137,139,141,143are divided without comprising the mask144.

FIG.8shows a configuration of the counter electrode members137,139. The divided counter electrode members137,139are arranged in the portions opposed to the active material layers5when seen from the thickness direction T. The counter electrode members137,139are not arranged in the portions opposed to the exposed portions7when seen from the thickness direction T. The counter electrode members141,143also have a configuration similar to that of the counter electrode members137,139.

2. Effects Achieved by Electrode Manufacturing System

According to the second embodiment detailed above, the following effects are achieved in addition to the aforementioned effects (1A) to (1C) of the first embodiment.

(2A) The counter electrode members137,139,141,143are divided and arranged only in the portions opposed to the active material layers5. The counter electrode members137,139,141,143are not arranged in the portions opposed to the exposed portions7. Thus, the electrode material manufacturing apparatus11inhibits the precipitation of alkali metal on the exposed portion7.

Other Embodiments

Although some embodiments of the present disclosure have been described as above, the present disclosure is not limited to the above-described embodiments, but may be practiced in various modified forms.

(1) The electrode material1may have another configuration. For example, the electrode material1may have a configuration shown inFIG.9. The electrode material1comprises four active material layers5. The exposed portions7are formed between two active material layers5adjacent to each other in the width direction W, and also formed at both ends in the width direction W.

The electrode material manufacturing apparatus11inhibits the precipitation of alkali metal on the exposed portion7by the mask144of the first embodiment, or by the divided the counter electrode members137,139,141,143of the second embodiment.

The cutting device13cuts the electrode material1along five cut ends183shown inFIG.9. As a result, four electrodes185,186,191,193are manufactured.

(2) The electrode material1may have another configuration. For example, the electrode material1may have a configuration shown inFIG.10. The electrode material1comprises the active material layer5in a central portion in the width direction W. The active material layer5is divided to a doped portion5A and a non-doped portion5B.

The doped portion5A is pre-doped with alkali metal through a treatment using the electrode material manufacturing apparatus11. The doped portion5A corresponds to the first section. The non-doped portion5B is not pre-doped with alkali metal even after the treatment using the electrode material manufacturing apparatus11. That is, a pre-doped active material is absent in the non-doped portion5B even after the treatment using the electrode material manufacturing apparatus11. The non-doped portion5B corresponds to the second section.

In the electrode material manufacturing apparatus11, the doped portion5A is pre-doped, and the non-doped portion5B is not pre-doped by the mask144of the first embodiment, or by the divided counter electrode members137,139,141,143of the second embodiment. The electrode material manufacturing apparatus11inhibits the precipitation of alkali metal on the exposed portion7by the mask144of the first embodiment, or by the divided counter electrode members137,139,141,143of the second embodiment.

The cutting device13cuts the electrode material1along three cut ends183shown inFIG.10. As a result, two electrodes185,186are manufactured. The cut ends183pass through the non-doped portion5B or the exposed portion7.

(3) The electrode material1may have another configuration. For example, the electrode material1may have a configuration shown inFIG.11. The electrode material1comprises two active material layers5. The exposed portions7are formed between the two active material layers5, and also formed at both ends in the width direction W. Each active material layer5is divided to the doped portion5A and the non-doped portion5B.

The doped portion5A is pre-doped with alkali metal by the treatment using the electrode material manufacturing apparatus11. The doped portion5A corresponds to the first section. The non-doped portion5B is not pre-doped with alkali metal even after the treatment using the electrode material manufacturing apparatus11. That is, the pre-doped active material is absent in the non-doped portion5B even after the treatment using the electrode material manufacturing apparatus11. The non-doped portion5B corresponds to the second section.

In the electrode material manufacturing apparatus11, the doped portion5A is pre-doped, and the non-doped portion5B is not pre-doped by the mask144of the first embodiment, or by the divided the counter electrode members137,139,141,143of the second embodiment. The electrode material manufacturing apparatus11inhibits the precipitation of alkali metal on the exposed portion7by the mask144of the first embodiment, or by the divided counter electrode members137,139,141,143of the second embodiment.

The cutting device13cuts the electrode material1along five cut ends183shown inFIG.11. As a result, four electrodes185,186,191,193are manufactured. The cut ends183pass through the non-doped portion5B or the exposed portion7.

(4) In each embodiment described above, a connection mode of the power supply, the conveyor rollers, and each counter electrode member is the one in which the conveyor rollers and each counter electrode member are connected to a different power supply for each doping tank; however, another connection mode may be adopted. For example, a connection mode may be adopted in which the counter electrode member opposed to one surface of the electrode material1and the counter electrode member opposed to the other surface of the electrode material1may be connected to different power supplies (hereinafter, referred to as a mode A). In the mode A, an amount of alkali metal doped on each surface of the electrode material1is equalized.

In the mode A, the counter electrode members137,143that the upstream tank131of the doping tank17comprises are connected to one electrode of the power supply109. The counter electrode members139,141are connected to one electrode of the power supply110. The counter electrode members137,143that the downstream tank133of the doping tank17comprises are connected to the other electrode of the power supply109. The counter electrode members139,141are connected to the other electrode of the power supply110.

Also, the counter electrode members137,143that the upstream tank131of the doping tank19comprises are connected to one electrode of the power supply111. The counter electrode members139,141are connected to one electrode of the power supply112. The counter electrode members137,143that the downstream tank133of the doping tank19comprises are connected to the other electrode of the power supply111. The counter electrode members139,141are connected to the other electrode of the power supply112.

Also, the counter electrode members137,143that the upstream tank131of the doping tank21comprises are connected to one electrode of the power supply113. The counter electrode members139,141are connected to one electrode of the power supply114. The counter electrode members137,143that the downstream tank133of the doping tank21comprises are connected to the other electrode of the power supply113. The counter electrode members139,141are connected to the other electrode of the power supply114.

In the conveyor roller group, the conveyor rollers37,41,43,47,49,53,55,59,61,65,67,71are each made of an electrically conductive material. The remaining conveyor rollers in the conveyor roller group are each made of elastomer except for a bearing portion.

One terminal of the power supply109is connected to the conveyor rollers37,41,43,47. Also, the other terminal of the power supply109is connected to the counter electrode members137,143that the upstream tank131and the downstream tank133of the doping tank17comprise. The electrode material1is in contact with the conveyor rollers37,41,43,47. The electrode material1and the counter electrode members137,143are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131and the downstream tank133of the doping tank17, the electrode material1and the counter electrode members137,143are electrically connected through the electrolyte solution.

One terminal of the power supply110is connected to the conveyor rollers37,41,43,47. Also, the other terminal of the power supply110is connected to the counter electrode members139,141that the upstream tank131and the downstream tank133of the doping tank17comprise. The electrode material1is in contact with the conveyor rollers41,47. The electrode material1and the counter electrode members139,141are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131and the downstream tank133of the doping tank17, the electrode material1and the counter electrode members139,141are electrically connected through the electrolyte solution.

In the mode A, as described, the counter electrode members137,143that are opposed to one surface of the electrode material1are connected to one terminal of the power supply109, and the counter electrode members139,141that are opposed to the other surface of the electrode material1are connected to one terminal of the power supply110, thereby controlling an amount of alkali metal doped to a front surface of the electrode material1and an amount of alkali metal doped to a back surface of the electrode material1so as to be equal.

One terminal of the power supply111is connected to the conveyor rollers49,53,55,59. Also, the other terminal of the power supply111is connected to the counter electrode members137,143that the upstream tank131and the downstream tank133of the doping tank19comprise. The electrode material1is in contact with the conveyor rollers49,53,55,59. The electrode material1and the counter electrode members137,143are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131and the downstream tank133of the doping tank19, the electrode material1and the counter electrode members137,143are electrically connected through the electrolyte solution.

One terminal of the power supply112is connected to the conveyor rollers49,53,55,59. Also, the other terminal of the power supply112is connected to the counter electrode members139,141that the upstream tank131and the downstream tank133of the doping tank19comprise. The electrode material1is in contact with the conveyor rollers49,53,55,59. The electrode material1and the counter electrode members132,141are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131and the downstream tank133of the doping tank19, the electrode material1and the counter electrode members139,141are electrically connected through the electrolyte solution.

In the mode A, as described above, the counter electrode members137,143that are opposed to one surface of the electrode material1are connected to one terminal of the power supply111, and the counter electrode members139,141that are opposed to the other surface of the electrode material1are connected to one terminal of the power supply112, thereby controlling an amount of alkali metal doped to the front surface of the electrode material1and an amount of alkali metal doped to the back surface of the electrode material1so as to be equal.

One terminal of the power supply113is connected to the conveyor rollers61,65,67,71. Also, the other terminal of the power supply113is connected to the counter electrode members137,143that the upstream tank131and the downstream tank133of the doping tank21comprise. The electrode material1is in contact with the conveyor rollers61,65,67,71. The electrode material1and the counter electrode members137,143are located in the dope solution that is the electrolyte solution. Thus, in the upstream tank131and the downstream tank133of the doping tank21, the electrode material1and the counter electrode members137,143are electrically connected through the electrolyte solution.

One terminal of the power supply114is connected to the conveyor rollers61,65,67,71. Also, the other terminal of the power supply114is connected to the counter electrode members139,141that the doping tank21comprises. The electrode material1is in contact with the conveyor rollers61,65,67,71. The electrode material1and the counter electrode members139,141are located in the dope solution that is the electrolyte solution. Thus, in the doping tank21, the electrode material1and the counter electrode members139,141are electrically connected through the electrolyte solution.

In the mode A, as described above, the counter electrode members137,143that are opposed to one surface of the electrode material1are connected to one terminal of the power supply113, the counter electrode members139,141opposed to the other surface of the electrode material1are connected to one terminal of the power supply114, thereby controlling an amount of alkali metal doped to the front surface of the electrode material1and an amount of alkali metal doped to the back surface of the electrode material1so as to be equal.

(5) The electrode material1may have a shape other than the strip-shape. The electrode material1may have, for example, a rectangular shape or a circular shape.

(6) A function served by a single element in any of the above-described embodiments may be achieved by a plurality of elements, or a function served by a plurality of elements may be achieved by a single element. Also, a part of a configuration in any of the above-described embodiments may be omitted. Further, at least a part of a configuration in any of the above-described embodiments may be added to, or replace, another configuration of the embodiments.

(7) In addition to the electrode manufacturing system described above, the present disclosure may be implemented in various forms, such as an apparatus for manufacturing an electrode material and a method for manufacturing an electrode material.