Electricity storage device manufacturing method and electricity storage device manufacturing apparatus

Abstract

To provide a manufacturing method and a manufacturing apparatus for a power storage device, in which a member formed on an outer peripheral side of a battery structure including a columnar electrode, a separation film, and a counter electrode can be removed accurately.SOLUTION: A manufacturing method for a power storage device 40 is a manufacturing method for a power storage device 40 including a battery structure including a columnar electrode 15 containing an electrode active material, a separation film 16 with an insulating property and an ion conductive property formed on an outer peripheral surface of the columnar electrode 15, and a counter electrode containing a counter electrode active material and formed on an outer periphery of the separation film 16 and includes an irradiation step of performing a counter electrode removing process of removing a counter electrode by delivering laser in an energy density range for removing the counter electrode while leaving the separation film 16 with laser light having a wavelength of 480 nm or more and 580 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This specification discloses a method for manufacturing an electricity storage device and an apparatus for manufacturing an electricity storage device. [Background technology]

[0002] Conventionally, a proposed power storage device includes an electrode assembly including a columnar first electrode (columnar electrode) having an electrode active material, an insulating and ion-conductive separation membrane formed around the first electrode, and a second electrode (counter electrode) formed around the first electrode and containing a counter electrode active material (see, for example, Patent Document 1). In this electrode assembly, a portion of the columnar electrode is exposed, allowing the columnar electrode to be connected to a current collector for the columnar electrode.

[0003] Although not a technology related to electricity storage devices, it has been proposed to use a laser to peel off the insulating coating of coils or electric wires (see, for example, Patent Document 2 and Patent Document 3). It has also been proposed to use a plurality of laser light sources with different wavelengths to cut laminated films and to irradiate lasers with wavelengths suitable for cutting each layer (see, for example, Patent Document 4), and to use a single laser light source to remove layers of a laminate and to irradiate lasers with wavelengths suitable for removing each layer by branching and wavelength conversion (see, for example, Patent Document 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-152230 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-23428 [Patent Document 3] Japanese Patent Application Publication No. 2-155142 [Patent Document 4] JP 2019-98400 A [Patent Document 5] Japanese Patent Application Laid-Open No. 2017-69243 Summary of the Invention [Problem to be solved by the invention]

[0005] In the electrode assembly of Patent Document 1, from the viewpoint of ensuring insulation between the columnar electrode and the counter electrode, it is preferable to have an exposed portion of the separation film covering the columnar electrode between the portion of the columnar electrode covered by the counter electrode and the portion of the exposed columnar electrode; however, it is difficult to accurately expose only the separation film. Patent Documents 2 and 3 only consider removing the insulating film, and are unable to leave the separation film. Patent Document 4 does not consider exposing a specific layer. Patent Document 5 makes it possible to expose a specific layer by using different wavelengths, but this is still not sufficient.

[0006] The present disclosure has been made in consideration of such problems, and its main purpose is to provide a method and apparatus for manufacturing an electricity storage device that can accurately remove components formed on the outer periphery of a battery structure that includes a columnar electrode, a separation membrane, and a counter electrode. [Means for solving the problem]

[0007] As a result of intensive research to achieve the above-mentioned object, the inventors discovered that in an energy storage device having a cylindrical battery structure in which a separation film and a counter electrode are formed on the outer periphery of a columnar electrode, it is possible to remove only the counter electrode by using a green laser, and it is also possible to remove only the separation film, and this led to the completion of the invention disclosed in this specification.

[0008] That is, the method for producing an electricity storage device disclosed in the present specification includes the following steps: A method for manufacturing an electricity storage device using a battery structure including a columnar electrode containing an electrode active material, a separator membrane formed on an outer peripheral surface of the columnar electrode and having insulating properties and ion conductivity, and a counter electrode formed on the outer periphery of the separator membrane and containing a counter electrode active material, an irradiation step of performing a counter electrode removal process of removing the counter electrode by irradiating the counter electrode with a laser having a wavelength of 480 nm or more and 580 nm or less within an energy density range in which the separation membrane remains and the counter electrode is removed; It includes:

[0009] The manufacturing apparatus for an electricity storage device disclosed in the present specification includes: An apparatus for manufacturing an electricity storage device using a battery structure including a columnar electrode containing an electrode active material, a separator membrane formed on an outer peripheral surface of the columnar electrode and having insulating properties and ion conductivity, and a counter electrode formed on the outer periphery of the separator membrane and containing a counter electrode active material, an irradiation unit that irradiates a laser having a wavelength of 480 nm or more and 580 nm or less; a control unit that executes a counter electrode removal process in which the irradiation unit irradiates the laser with a laser within an energy density range that leaves the separation film and removes the counter electrode; and It is equipped with the following. [Effects of the Invention]

[0010] The present disclosure provides a method and apparatus for manufacturing an electricity storage device that can accurately remove members formed on the outer periphery of an electricity storage device that includes a columnar electrode, a separation membrane, and a counter electrode. The reason for this effect is presumed to be as follows. For example, a green laser has an energy density range that is suitable for removing the counter electrode but does not remove the separation membrane. Therefore, by irradiating the laser within this energy density range, it is possible to accurately remove the counter electrode and expose the separation membrane. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is an explanatory diagram showing an example of an electricity storage device 40 and a single cell 11. [Figure 2] FIG. 10 is an explanatory diagram showing an example of an irradiation step. [Figure 3] A diagram showing the relationship between green laser energy density and processing rate. [Figure 4] FIG. 2 is an explanatory diagram showing an example of a manufacturing apparatus 20 for removing a coating. [Figure 5] Measurement results of energy density and processing rate at each wavelength. [Figure 6] Photograph of cathode composite removed with IR or green laser. [Figure 7]Photographs of the battery structure after each treatment in the irradiation process. [Figure 8] Photograph of the laser cut surface of a single cell. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Method of manufacturing an electricity storage device) The manufacturing method and manufacturing apparatus for an electricity storage device disclosed in this specification will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of an electricity storage device 40 and a single cell 11. FIG. 2 is an explanatory diagram showing an example of an irradiation step, with FIG. 2A being a diagram of a counter electrode removal process, FIG. 2B being a diagram of a separation film removal process, FIG. 2C being a diagram of a cutting process, and FIG. 2D being an explanatory diagram of the single cell 11 after cutting. FIG. 3 is a relationship diagram between the energy density and processing rate of a green laser. FIG. 4 is an explanatory diagram showing an example of a manufacturing apparatus 20 for removing a coating. First, the single cell 11, which is the product, and the electricity storage device 40 using the same will be described.

[0013] (Electricity storage device) FIG. 1 is an explanatory diagram showing an example of an electricity storage device 40 and a single cell 11. Examples of the electricity storage device 40 include a hybrid capacitor, a pseudo-electric double layer capacitor, a lithium or sodium alkali metal secondary battery, an alkali metal ion battery, and an air battery. Of these, a lithium secondary battery, particularly a lithium ion secondary battery, is preferred as the electricity storage device 40. Here, the electricity storage device 40 will be mainly described as a lithium ion secondary battery. As shown in FIG. 1, the electricity storage device 40 includes, for example, a columnar electrode 15, a separation membrane 16, a counter electrode 18, and current collectors 41 and 42. The columnar electrode 15, the separation membrane 16, and the counter electrode 18 constitute a single cell 11. The columnar electrode 15 is a columnar body containing an electrode active material. Here, the term "columnar" includes not only a columnar electrode having a thickness that does not bend, but also a columnar electrode having a thickness that allows bending. The columnar electrode 15 may be a negative electrode or a positive electrode, but is preferably a negative electrode. The counter electrode 18 may be a positive electrode or a negative electrode, but is preferably a positive electrode. The current collector 41 is a conductive member that collects current from the columnar electrode 15 and is electrically connected to the end surface of the columnar electrode 15. The current collector 42 is a conductive member that collects current from the counter electrode 18 and is electrically connected to the end surface of the counter electrode 18.

[0014] The columnar electrode 15 may be formed by bundling together fibrous bodies 13 containing an electrode active material. The columnar electrode 15 may be columnar, and its cross section may be circular, elliptical, or polygonal. In the electricity storage device 40, a plurality of columnar electrodes 15 are arranged in a predetermined direction. The columnar electrodes 15 preferably have an average diameter of 10 μm or more and 500 μm or less in a cross section perpendicular to the longitudinal direction. The fibrous bodies 13 preferably have an average diameter of 5 μm or more and 50 μm or less. The longitudinal length of the columnar bodies can be determined appropriately depending on the application of the electricity storage device, and may be, for example, 20 mm or more and 200 mm or less. The fibrous bodies 13 may be, for example, metal fibrous bodies or fibers of a carbon material that absorbs and releases lithium ions. Carbon materials have high conductivity and are preferred as the columnar electrodes 15. Examples of carbon materials include one or more of graphites, cokes, glassy carbons, non-graphitizable carbons, and pyrolytic carbons. Of these, graphites such as artificial graphite and natural graphite are preferred. The fibrous body 13 may be carbon fiber having a graphite structure. The columnar electrode 15 may be an integrally molded product. In this case, the electrode active material may be the above-mentioned carbon material, a silicon material, a composite oxide with a transition metal, or a metal-organic framework (iMOF) capable of inserting and desorbing carrier ions. Examples of composite oxides include lithium-titanium composite oxide.

[0015] The separation membrane 16 has ion conductivity for carrier ions (e.g., lithium ions), insulates the columnar electrode 15 from the counter electrode 18, prevents short circuits, and functions as a separator. Examples of the separation membrane 16 include resins such as polyvinylidene fluoride (PVdF), a copolymer of PVdF and hexafluoropropylene (PVdF-HFP), polymethyl methacrylate (PMMA), and a copolymer of PMMA and an acrylic polymer. The thickness of the separation membrane 16 is preferably, for example, 2 μm or more and 40 μm or less to ensure insulation. The thickness of the separation membrane 16 is preferably, for example, 2 μm or more, more preferably 5 μm or more, and may be 8 μm or more. A thickness of 2 μm or more is preferable to ensure insulation. In particular, a thickness of 2 μm or more of the separation membrane 15 is easy to fabricate. The thickness of the separation membrane 16 is preferably 40 μm or less, more preferably 20 μm or less, and may be 12 μm or less. A thickness of 20 μm or less is preferable in that a decrease in ion conductivity can be suppressed and the volume occupied by the cell can be further reduced. Furthermore, when the thickness of separation membrane 16 is in the range of 2 to 40 μm, the ion conductivity and insulating properties are favorable.

[0016] The separator 16 may also be a porous body formed by solidifying an electronically insulating powder with a binder. Such a separator 16 exhibits ionic conductivity by retaining an electrolyte in the pores of the porous body. Examples of the electronically insulating powder include alumina, silica, titania, and boehmite. Examples of the binder include PVdF, polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), and polyimide. The separator 16 may be formed by, for example, preparing a porous, self-supporting film from a raw powder or raw slurry containing the electronically insulating powder and the binder powder, and then coating the surface of the columnar electrode 15 with the self-supporting film. Alternatively, the separator 16 may be formed by immersing the columnar electrode 15 in a raw slurry containing the electronically insulating powder and the binder powder and coating the surface of the columnar electrode 15 with the self-supporting film.

[0017] The separation membrane 16 may contain an electrolyte that conducts ions, which are carriers. Examples of the electrolyte include non-aqueous solvents. Examples of the solvent for the electrolyte include solvents for non-aqueous electrolytes. Examples of the solvent include carbonates, esters, ethers, nitriles, furans, sulfolanes, and dioxolanes, which can be used alone or in combination. Specific examples of the carbonate include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate; chain carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate, ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, and t-butyl-i-propyl carbonate; and γ-butyl carbonate. Examples of suitable electrolytes include cyclic esters such as hydroxyl lactone and γ-valerolactone, chain esters such as methyl formate, methyl acetate, ethyl acetate, and methyl butyrate, ethers such as dimethoxyethane, ethoxymethoxyethane, and diethoxyethane, nitriles such as acetonitrile and benzonitrile, furans such as tetrahydrofuran and methyltetrahydrofuran, sulfolanes such as sulfolane and tetramethylsulfolane, and dioxolanes such as 1,3-dioxolane and methyldioxolane. The electrolyte may also contain a supporting salt dissolved therein that contains ions that serve as carriers for the power storage device 10. Examples of suitable supporting salts include LiPF, LiBF, LiAsF, LiCFSO, LiN(CFSO), LiC(CFSO), LiSbF, LiSiF, LiAlF, LiSCN, LiClO, LiCl, LiF, LiBr, LiI, and LiAlCl. Among these, it is preferable to use a combination of one or more salts selected from the group consisting of inorganic salts such as LiPF6, LiBF4, and LiClO4, and organic salts such as LiCF3SO3, LiN(CF3SO2)2, and LiC(CF3SO2)3, from the viewpoint of electrical properties. The concentration of this supporting salt in the electrolyte is preferably 0.1 mol / L or more and 5 mol / L or less, and more preferably 0.5 mol / L or more and 2 mol / L or less.

[0018] The counter electrode 18 is an electrode having a counter electrode active material and facing the columnar electrode 15 through the separator 16. The counter electrode 18 may be formed on the outer peripheral surface of the separator 16 and have a structure for binding the single cell 11, or may be provided so as to fill the space between adjacent separators 16. Examples of the counter electrode active material include materials capable of occluding and releasing lithium as a carrier. Examples of the counter electrode active material include compounds having lithium and transition metals, such as oxides containing lithium and transition metal elements, and phosphate compounds containing lithium and transition metal elements. Specifically, the basic composition formula is Li (1-x) MnO2 (0 ≤ x ≤ 1, etc., the same applies hereinafter), Li (1-x) Mn2O4, etc., lithium manganese composite oxides, the basic composition formula is Li (1-x) CoO2, etc., lithium cobalt composite oxides, the basic composition formula is Li (1-x) [ NiO2, etc., lithium nickel composite oxides, the basic composition formula is Li (1-x) [ Co a [ Ni b [ Mn c [ O2 (a > 0, b > 0, c > 0, a + b + c = 1), Li (1-x) [ Co a [ Ni b [ Mn c [ O4 (0 < a < 1, 0 < b < 1, 1 ≤ c < 2, a + b + c = [ 1 / 3 [ Ni 1 / 3 [ Mn 1 / 3 [ O2, LiNi 0.4 [ Co 0.3 [ Mn 0.3 [ O2, etc. are preferable. The "basic composition formula" means that it may contain components of other elements, such as Al and Mg.

[0019] The counter electrode 18 preferably contains a larger amount of counter electrode active material, preferably 70% by mass or more, and more preferably 80% by mass or more, based on the total mass of the counter electrode 18. The conductive material content is preferably in the range of 0% by mass to 20% by mass, and more preferably 0% by mass to 10% by mass, based on the total mass of the counter electrode 18. Within such a range, a decrease in battery capacity can be suppressed and sufficient conductivity can be imparted. The binder content is preferably in the range of 0.1% by mass to 5% by mass, and more preferably 0.2% by mass to 3% by mass, based on the total mass of the counter electrode 18. The thickness of the counter electrode 18 is appropriately determined depending on the diameter D of the columnar electrode 15 and the active material capacity ratio, and may be, for example, in the range of 5 μm to 50 μm. In the case of the single cell 11, the thickness of the counter electrode 18 refers to the maximum thickness of the portion formed on the columnar electrode 15. In the electricity storage device 40, the distance between adjacent columnar electrodes 15 is divided by two to obtain an average value.

[0020] The current collector 41 is a conductive member that collects current from the columnar electrodes 15 and is electrically connected to the end faces of the columnar electrodes 15. The current collector 41 may be a member in which 500 or more columnar electrodes 15 are connected in parallel, or a member in which 1,000 or more or 10,000 or more columnar electrodes 15 are connected in parallel. The current collector 41 is a conductive member, and may be made of, for example, carbon paper, aluminum, copper, titanium, stainless steel, nickel, iron, platinum, baked carbon, conductive polymer, conductive glass, or aluminum or copper whose surface is treated with carbon, nickel, titanium, silver, platinum, gold, or the like for the purpose of improving adhesion, conductivity, and oxidation (reduction) resistance. The shape of the current collector 41 is not particularly limited as long as it can be connected to the columnar electrodes 15. Examples of the shape include a plate, foil, film, sheet, net, punched or expanded material, lath, porous material, foam, and fiber formation. The current collector 42 is electrically connected to the counter electrode 18. The current collector 42 is disposed on the bottom or side surface of the electricity storage device 40. The material and shape of the current collector 42 may be, for example, any of the materials and shapes listed for the current collector 41 described above.

[0021] The single cell 11 has a columnar electrode exposed portion A1, a separator membrane exposed portion A2, and a counter electrode cover portion A3. The columnar electrode exposed portion A1 is a portion where the columnar electrode 15 is exposed, and its axial length may be, for example, in the range of 100 μm to 10 mm. A longer length of the columnar electrode exposed portion A1 facilitates electrical connection with the current collector 41, but reduces the capacity of the single cell 11. Therefore, an appropriate length should be selected depending on the intended use of the power storage device 40. The separator membrane exposed portion A2 is a portion where the separation membrane 16 is exposed and serves to prevent short circuits between the positive and negative electrodes. The axial length of the separation membrane exposed portion A2 may be, for example, in the range of 10 μm to 10 mm. A longer length of the separation membrane exposed portion A2 improves short-circuit prevention but reduces the capacity of the single cell 11. Therefore, an appropriate length should be selected depending on the intended use of the power storage device 40. The counter electrode cover A3 is a portion covered by the counter electrode 18, and is the site where the unit cell 11 is charged and discharged. The axial length of the counter electrode cover A3 is, for example, the remaining portion of the columnar electrode exposed portion A1 and the separation membrane exposed portion A2. The counter electrode cover A3 is set to an appropriate length depending on the application of the electricity storage device 40, etc. In the unit cell 11, a step S1 is formed at the boundary between the separation membrane exposed portion A2 and the counter electrode cover A3, and a step S2 is formed at the boundary between the columnar electrode exposed portion A1 and the separation membrane exposed portion A2. The heights of the steps S1 and S2 may be equal to the thickness of the counter electrode 18 and the thickness of the separation membrane 16, respectively.

[0022] In this electricity storage device 40, the volumetric energy density is preferably higher, for example, preferably 400 Wh / L or more, more preferably 500 Wh / L or more, and even more preferably 600 Wh / L or more. In this electricity storage device 40, the positive / negative electrode capacity ratio (negative electrode capacity / positive electrode capacity), which is the ratio of the capacity of the electrode active material (negative electrode active material) to the capacity of the counter electrode active material (positive electrode active material), is preferably in the range of 1.0 to 1.5, and more preferably 1.2 or less.

[0023] (Method of manufacturing an electricity storage device) The method for manufacturing an electricity storage device according to the present disclosure is a method for manufacturing an electricity storage device 40 using a battery structure 10 having a columnar electrode 15 containing an electrode active material, a separator 16 formed on the outer peripheral surface of the columnar electrode 15 and having insulating and ion-conductive properties, and a counter electrode 18 formed on the outer periphery of the separator 16 and containing a counter electrode active material. In this battery structure 10, the columnar electrode 15 is entirely covered with the separator 16 and the counter electrode 18. This manufacturing method involves a process for partially removing the covered counter electrode 18 and separator 16 at least at the end of the columnar electrode 15 to which a current collector 41 is connected. Furthermore, the single cell 11 has a separator membrane exposed portion A2 between the columnar electrode exposed portion A1 and the counter electrode covered portion A3, thereby preventing a short circuit between the columnar electrode 15 and the counter electrode 18. In this manufacturing method, a counter electrode removal process is performed to remove the counter electrode 16 so as to create a step S1 at the boundary between the separation membrane 16 and the counter electrode 18, and a separation membrane removal process is performed to remove the separation membrane 16 so as to create a step S2 at the boundary between the columnar electrode 15 and the separation membrane 16.

[0024] The manufacturing method of the electricity storage device 40 includes an irradiation step, and may also include a bundling step and a connection step. In the irradiation step, as shown in FIG. 2, a counter electrode removal process is performed to remove the counter electrode 18 (FIG. 2A). Preferably, the same laser is then used to perform a separation membrane removal process to remove the separation membrane 16 (FIG. 2B) and a cutting process to cut the battery structure 10 (FIG. 2C). In this irradiation step, a laser having a wavelength of 480 nm or more and 580 nm or less is used, and the laser is irradiated within an energy density range that removes the counter electrode 18 while leaving the separation membrane 16, thereby performing the counter electrode removal process to remove the counter electrode. This laser preferably has a wavelength range of 515 nm or more and 532 nm or less. With a laser in this wavelength range, as shown in FIG. 3, a separation membrane non-processing region is formed, which is an energy density that can remove the counter electrode 18 but not the separation membrane 16, based on the relationship between the processing rate for removing the separation membrane 16, the processing rate for removing the electrode composite of the counter electrode 18, and the laser energy density. In this energy density range, the counter electrode 18 can be removed more reliably while leaving the separation membrane 16. The processing rate in FIG. 3 indicates the thickness (μm) removed per laser shot. In the counter electrode removal process, an energy density that can remove the counter electrode 18 and that corresponds to the thickness to be removed and the processing rate can be appropriately adopted. In the counter electrode removal process, 0.4 J / cm 2 More than 6.0J / cm 2 It is preferable to irradiate the battery structure 10 with a laser having an energy density of 4.0 J / cm or less. 2 Less than 3.0 J / cm is more preferable. 2 More preferably, the energy density is 3.0 J / cm or less. 2 Below this, the separation membrane 16 can be more reliably left. 2 It is preferable to irradiate the battery structure 10 with a laser having an energy density of 1.0 J / cm or more. 2 More preferably, 1.5 J / cm or more 2 More preferably, the energy density is 0.4 J / cm or more. 2 In this way, the counter electrode 18 can be removed more reliably.

[0025] The laser to be irradiated is preferably a pulsed laser. The pulsed laser conditions include, for example, a pulse duration of preferably 0.1 ns to 10 ns, more preferably 0.5 ns to 5 ns. The average power is preferably 100 mW to 100 W, more preferably 1 W to 50 W. The repetition frequency is preferably 10 Hz to 10 MHz, more preferably 0.5 MHz to 5 MHz. The focused beam diameter can be, for example, 5 μm to 50 μm. In the counter electrode removal process, the battery structure 10 is irradiated with the laser multiple times at a predetermined offset. The same region may be scanned multiple times during laser irradiation.

[0026] In this irradiation step, after the counter electrode removal process, it is preferable to perform a separation membrane removal process in which a laser is used to irradiate the separation membrane 16 in an energy density range that removes the separation membrane 16 while leaving the columnar electrode 15. In this separation membrane removal process, the laser is irradiated at a higher energy density than in the counter electrode removal process. In the separation membrane removal process, an energy density that can remove the separation membrane 16 and that corresponds to the thickness and processing rate of the separation membrane 16 to be removed can be appropriately adopted. In the separation membrane removal process, for example, 3.0 J / cm 2 It is preferable to remove the separation film 16 by irradiating a laser having an energy density of 5.0 J / cm or more. 2 More preferably, 6.0 J / cm or more 2 The energy density may be 3.0 J / cm or more. 2 In this way, the separation membrane 16 can be removed more reliably. In addition, in the separation membrane removal process, it is preferable to adopt an energy density that suppresses removal of the columnar electrodes 15 as much as possible, for example, 20 J / cm 2 Less than 10 J / cm is preferable. 2 Less than 8 J / cm is more preferable. 2 The following may also be used.

[0027] Furthermore, in this irradiation step, a laser may be irradiated onto the area where the counter electrode 18 and the separation film 16 have been removed, to perform a cutting process to cut the columnar electrode 15. In this step, the counter electrode removal process, the separation film removal process, and the cutting process described above can be performed using a laser (green laser) irradiated from the same irradiation unit. Therefore, the single cell 11 having the step structure shown in FIG. 1 can be produced using the same configuration. In the cutting process, for example, the laser may be irradiated with a higher energy density than in the counter electrode removal process and the separation film removal process. In the cutting process, the energy density for cutting the columnar electrode 15 can be appropriately selected depending on the diameter and processing rate of the columnar electrode 15. In the cutting process, for example, 6.0 J / cm 2 It is preferable to cut the columnar electrode 15 by irradiating a laser having an energy density of 10 J / cm or more. 2 More preferably, 20 J / cm or more 2 In the cutting process, for example, 200 J / cm 2 Less than 100 J / cm is preferable. 2 Less than 50 J / cm is more preferable. 2 The following may also be used.

[0028] In the bundling step, a process is performed to bundle the plurality of battery structures (single cells 11) cut in the above-mentioned irradiation step. In the bundling process, a stack obtained by arranging the plurality of single cells 11 may be press-molded. In addition, in the connecting step, a process is performed to connect current collectors 41 to the columnar electrodes 15 exposed from the bundled battery structures. The current collectors 41 may be connected, for example, by binding with a conductive binder, or by crimping current collectors 41 such as metal foil. Through these steps, an electricity storage device 40 in which a plurality of single cells 11 are bundled can be produced.

[0029] (Electricity storage device manufacturing equipment) Next, a manufacturing apparatus 20 for carrying out the above-described manufacturing method for an electricity storage device will be described. This manufacturing apparatus 20 uses a battery structure 10 having a columnar electrode 15 containing an electrode active material, a separation membrane 16 formed on the outer peripheral surface of the columnar electrode 15 and having insulating properties and ion conductivity, and a counter electrode 18 formed on the outer periphery of the separation membrane 16 and containing a counter electrode active material. As shown in FIG. 4, this manufacturing apparatus 20 for an electricity storage device includes an irradiation unit 21, a control unit 25, an observation unit 28, and a transport unit 29. Note that the manufacturing apparatus 20 appropriately adopts the conditions described in the above-described manufacturing method, and therefore some of the description thereof will be omitted.

[0030] The irradiation unit 21 includes a light source 22 that generates laser light and a scanning unit 24 that scans the laser light in a predetermined direction when irradiating the battery structure 10, which is the processing target, with the laser light. The irradiation unit 21 irradiates a laser having a wavelength of 480 nm or more and 580 nm or less. The laser irradiated by the irradiation unit 21 is preferably a green laser, and the wavelength range is preferably 515 nm or more and 532 nm or less. The range of energy density that the irradiation unit 21 can output is, for example, 0.4 J / cm. 2 More than 200J / cm 2 The light source 22 may be a variable wavelength light source, but preferably a single wavelength light source. The light source 22 preferably emits a pulsed laser, more preferably a light source with a variable pulse width. The laser light source 52 may be a picosecond laser and / or a nanosecond laser. The scanning unit 24 is a mechanism for moving and adjusting the laser irradiation position, and is configured to be able to move the irradiation position, for example, in a direction perpendicular to the longitudinal axis direction of the battery structure 10 and in a direction along the longitudinal axis direction. The scanning unit 24 is preferably able to move the laser light irradiation position with higher accuracy. For example, the scanning unit 24 is preferably able to control the laser scanning position with an accuracy of 1 μm to 50 μm, and more preferably, with an accuracy of 5 μm to 20 μm. Note that the conveying unit 29 moves the battery structure 10 in a direction perpendicular to the longitudinal axis direction. Therefore, the movement of the battery structure 10 in this perpendicular direction is performed by the conveying unit 29, and may be omitted from the scanning unit 24. The scanning unit 24 can change the laser light irradiation position on the battery structure 10.

[0031] The control unit 25 is configured as a microprocessor centered on a CPU 26 and controls the entire device. The control unit 25 also includes a storage unit 27 configured as a large-capacity storage device such as a hard disk drive (HDD) or flash memory. The control unit 25 acquires information by outputting control signals to the irradiation unit 21 and the transport unit 29 and inputting signals from the observation unit 28. The control unit 25 performs a counter electrode removal process by causing the irradiation unit 21 to irradiate the laser within an energy density range that leaves the separation film 16 of the battery structure 10 and removes the counter electrode 18. After the counter electrode removal process, the control unit 25 performs a separation film removal process by causing the irradiation unit 21 to irradiate the laser within an energy density range that removes the separation film 16 while leaving the columnar electrode 15. Furthermore, the control unit 25 performs a cutting process by causing the irradiation unit 21 to irradiate the portion from which the counter electrode 18 and separation film 16 have been removed with a laser, thereby cutting the columnar electrode 15. The conditions for performing each process may be the same as those described in the manufacturing method above. The control unit 25 controls the scanning unit 24 to reciprocate at a plurality of positions in a direction perpendicular to the axial direction of the battery structure 10, which is the irradiation target. At this time, the control unit 25 may irradiate the laser light only during the forward movement (see FIG. 2A), or may irradiate the laser light during the reciprocating movement. The control unit 25 may also cause the irradiation unit 21 to perform the reciprocating movement of the laser using a shift width set in consideration of the amount of heat input.

[0032] The observation unit 28 grasps the position of the battery structure 10 present on the transport unit 29, and may be, for example, a camera. The observation unit 28 captures an image of the battery structure 10 on the transport unit 29 and transmits a signal of the captured image to the control unit 25.

[0033] The conveying unit 29 is a device that places the battery structure 10 thereon and continuously or intermittently conveys the battery structure 10 through the laser irradiation area of ​​the irradiation unit 21. The conveying unit 29 may be a conveyor that conveys the battery structure 10 placed on a conveyor belt. Alternatively, the conveying unit 29 may be configured to support only both ends of the battery structure 10 while leaving the central area where the laser is irradiated empty. This conveying unit 29 is preferable because it can further suppress deterioration of the conveying member (conveyor belt) of the conveying unit 29 when the irradiation unit 21 irradiates the battery structure 10 with the laser. The conveying unit 29 preferably further includes a rotating unit that holds the ends of the battery structure 10 and rotates the battery structure 10 around its axis. Using this rotating unit, the battery structure 10 can be rotated around its axis and the front and back sides can be irradiated with laser light, thereby more efficiently executing the above-described irradiation process.

[0034] The manufacturing method and manufacturing apparatus 20 for an electricity storage device according to the present embodiment described above can accurately remove components formed on the outer periphery of a battery structure 10 including a columnar electrode 15, a separator 16, and a counter electrode 18. The reason for this effect is believed to be as follows. For example, a battery structure 10 having columnar electrodes 15 used in an electricity storage device 40 has a multilayer structure (positive electrode material layer / separator / negative electrode material layer). When fabricating the current collecting end portions that electrically connect to the current collector 41, mechanical processing can cause deformation of the positive electrode material or negative electrode material, leading to product defects such as short circuits. The manufacturing method according to the present embodiment uses a laser to achieve clean processing that is impossible with mechanical cutting, thereby preventing short circuits at the current collecting end portions. Furthermore, a stepped structure can be achieved at the end portions, which helps prevent short circuits during fabrication of the current collecting portion. In particular, the green laser has an energy density range that is suitable for removing the counter electrode 18 but does not remove the separation film 16, and by irradiating the laser within that energy density range, it is possible to remove the counter electrode 18 with precision and expose the separation film 16 while reducing damage to the separation film 16. Furthermore, by changing the energy density of the green laser, it is possible to further remove the separation film 16 and cut the columnar electrode 15, and the removal and cutting of each layer can be performed with a single irradiation unit 21, thereby improving work efficiency and simplifying the device configuration. Furthermore, in the manufacturing method of this embodiment, the formation of the step structure of the single cell 11 and cutting can be combined into a single process.

[0035] Furthermore, by using laser processing, high-speed processing can be achieved and the processing accuracy of the stepped structure can be at the beam diameter level (tens of microns). Furthermore, by using an apparatus configuration that can control the beam in units of tens of microns, the amount of beam overlap can be controlled, the heat input during processing can be uniformed, and high-precision processing can be achieved. Furthermore, other methods for removing the counter electrode 18 and the separation membrane 16 include a cleaning method using a solution, but cutting is a separate process, which increases the number of steps. On the other hand, in the manufacturing method disclosed herein, each layer can be removed and cut in a single process using laser processing, thereby reducing the number of steps and further reducing the environmental impact of solution processing, etc.

[0036] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure.

[0037] For example, in the above-described embodiment, the electricity storage device 40 has been described as a bundle of a plurality of unit cells 11 each having a columnar electrode exposed portion A1, a separation membrane exposed portion A2, and a counter electrode cover portion A3, but is not particularly limited to this, and the unit cells 11 themselves may be used as the electricity storage device. Each unit cell 11 can be charged and discharged on its own.

[0038] In the above-described embodiment, the irradiation step is performed using one irradiation unit 21. However, a plurality of irradiation units 21 may be provided, and one or more of the counter electrode removal process, separation film removal process, and cutting process may be performed using different irradiation units 21. This increases the device configuration, but allows each process to be performed simultaneously. Note that when a plurality of irradiation units 21 are used, the separation film removal process and cutting process may be performed using irradiation units 21 with wavelengths other than green laser.

[0039] In the above-described embodiment, the present disclosure has been described as a manufacturing method and manufacturing apparatus 20 for the electricity storage device 40, but the present disclosure may be either one of them. [Example]

[0040] Hereinafter, an example in which the manufacturing method and manufacturing apparatus for the electricity storage device of the present disclosure have been specifically examined will be described as an experimental example.

[0041] (manufacturing equipment) The manufacturing apparatus 20 shown in Fig. 4 was fabricated. In addition, in the manufacturing apparatus 20, an irradiation unit capable of irradiating a blue laser, an infrared (IR) laser, etc. in addition to a green laser was prepared.

[0042] (Battery structure 10) A columnar electrode (fiber electrode) as shown in Figure 1 was fabricated. 400 carbon fibers (manufactured by Nippon Graphite Fiber Co., Ltd.) with a diameter d of 7 μm were bundled together by twisting at 0.5 turns per cm of fiber length while applying 0.025 mL of a solution of 5 mass% polyvinylidene fluoride (PVdF) dissolved in N-methylpyrrolidone (NMP) per 1 m of fiber length. The carbon fiber bundle had a diameter D of 156.5 μm. This carbon fiber bundle was used as a columnar electrode (columnar negative electrode). Next, a solution of vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP) dissolved in NMP with alumina particles added was applied to the outer surface of the columnar electrode and dried to form a separator membrane with a thickness of 20 μm. A positive electrode active material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2), acetylene black (HS-100 manufactured by Denka Co., Ltd.) as a conductive material, vapor-grown carbon fiber (VGCF manufactured by Showa Denko K.K.) as a conductive material, and polyvinylidene fluoride (PVdF7305 manufactured by Kureha Co., Ltd.) as a binder were blended in a mass ratio of 90:4:2:4, and NMP was added to the mixture to prepare a counter electrode composite paste. The separator-coated columnar electrode was dip-coated with the counter electrode composite paste to form a counter electrode composite layer with a thickness of 30 μm. A single cell consisting of the columnar electrode / separator / counter electrode composite layer was produced and used in the irradiation process described below.

[0043] (Production of electricity storage device: irradiation process) Using the above-prepared manufacturing apparatus 20, various laser beams were used to measure the energy density (J / cm 2 The processing rate (μm / shot) of the counter electrode and separation membrane was measured by changing the laser beam angle. The processing rate was evaluated as the thickness (μm) of the material removed per shot of laser light.

[0044] (Results and Discussion) Figure 5 shows the energy density (J / cm) at each wavelength. 2 ) and processing rate (J / cm 2) are the measurement results, where Figure 5A shows the results using a blue laser with λ = 355 nm, Figure 5B shows the results using a green laser with λ = 516 nm, and Figure 5C shows the results using an IR laser with λ = 1064 nm. The laser wavelength (nm), the object to be processed, and the energy density (J / cm 2 The processing rates (μm / shot) are summarized in Table 1. As shown in Figure 5A, with the blue laser light source, the difference in processing rates between the counter electrode composite and the separator was small. Furthermore, because there were regions where the processing rate of the separator exceeded that of the counter electrode composite, significant damage to the separator was expected when removing the counter electrode composite. As shown in Figure 5B, with the green laser light source, the difference in processing rates between the counter electrode composite and the separator was significant. Furthermore, there were regions where the processing rate of the separator was zero, while the processing rate of the counter electrode composite was 1 μm / shot, suggesting that the counter electrode composite could be processed with minimal damage to the separator. With the IR (infrared) laser light source (Figure 5C), there was no region where the processing rate of the separator was zero, suggesting significant damage to the insulating layer when removing the counter electrode composite. By utilizing the characteristics of the green laser light source (Figure 5B) and incorporating it into a laser processing device, this technology enabled the formation of a stepped structure in a fiber battery.

[0045] Fig. 6 shows photographs of the positive electrode composite removed with IR or green laser, where Fig. 6A is a photograph after the counter electrode removal treatment with IR laser light, Fig. 6B is a photograph after the counter electrode removal treatment after one scan with green laser light, and Fig. 6C is a photograph after the counter electrode removal treatment after two scans with green laser light. In Fig. 6A, the energy density of the IR laser light was 134 J / cm 2 As shown in Figure 6A, with the IR laser light, the counter electrode composite was completely peeled off, and there were areas where the separation film was exposed and areas where the counter electrode composite remained. In addition, areas where part of the separation film had peeled off were observed, and stable peeling of each layer was not possible. In Figures 6B and 6C, the energy density of the green laser light was set to 2.6 J / cm 2The laser beam was scanned 20 times in Figures 6B and 6C because the energy density of the laser beam was low. As shown in Figure 6B, it was found that the counter electrode composite was peeled off when green laser light was used, revealing the surface of the separation membrane. Furthermore, by irradiating the laser again under the same conditions, it was possible to further remove the remaining counter electrode composite layer. It was found that by processing at an energy density suitable for removing the counter electrode composite shown in Figure 5B, the counter electrode composite could be peeled off without damaging the separation membrane.

[0046] Having found that each layer can be separated and peeled using a green laser, the irradiation process of the present disclosure was specifically investigated. Figure 7 shows photographs of a battery structure subjected to each treatment in the irradiation process: Figure 7A shows a photo of the battery structure before treatment, Figure 7B shows a photo of the battery structure after counter electrode removal treatment, Figure 7C shows a photo of the battery structure after separation film removal treatment, and Figure 7D shows a photo of the battery structure after cutting treatment. In the irradiation process, as shown in Figure 2, the battery structure was irradiated with a laser multiple times to obtain the desired processing area. The laser offset was controlled to maintain a constant heat input. As shown in Figure 7, the counter electrode composite was peeled off (Figure 7B), followed by peeling off the separation film (Figure 7C), and the exposed center of the columnar electrode was cut using a laser (Figure 7D). This processing procedure prevents simultaneous processing of other layers and suppresses short circuits between the counter electrode composite and the columnar electrode. Furthermore, a step structure was formed at both ends after laser cutting, resulting in an efficient processing procedure. Figure 8 shows a photograph of the laser-cut surface of a single cell. Figure 8 shows the laser cut surface observed from a different angle than the laser cut area in Figure 7D. As shown in Figure 8, the counter electrode composite and separation film were peeled off all around the columnar electrode, forming the step structure necessary for current collection by the fiber electrode.

[0047] [Table 1]

[0048] It goes without saying that the method for manufacturing an electricity storage device and the apparatus for manufacturing an electricity storage device disclosed in this specification are not limited to the above-described examples, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure. [Industrial Applicability]

[0049] The present disclosure is applicable to the technical field of manufacturing electricity storage devices. [Explanation of symbols]

[0050] 10 battery structure, 11 single cell, 13 fibrous body, 15 columnar electrode, 16 separation membrane, 18 counter electrode, 20 manufacturing apparatus, 21 irradiation unit, 22 light source, 24 scanning unit, 25 control unit, 26 CPU, 27 memory unit, 28 observation unit, 29 transport unit, 40 electricity storage device, 41 current collector, 42 current collector, A1 columnar electrode exposed portion, A2 separation membrane exposed portion, A3 counter electrode coated portion, S1, S2 steps.

Claims

1. A method for manufacturing an electricity storage device using a battery structure including a columnar electrode containing an electrode active material, a separator membrane formed on an outer peripheral surface of the columnar electrode and having insulating properties and ion conductivity, and a counter electrode formed on the outer periphery of the separator membrane and containing a counter electrode active material, an irradiation step of performing a counter electrode removal process of removing the counter electrode by irradiating the counter electrode with a pulse laser having a wavelength of 480 nm or more and 580 nm or less within an energy density range in which the separation film remains and the counter electrode is removed; A method for manufacturing an electricity storage device comprising:

2. In the irradiation step, 0.4 J / cm 2 6.0J / cm or more 2 The method for manufacturing an electricity storage device according to claim 1 , wherein the counter electrode is removed by irradiating the pulsed laser with an energy density of:

3. 3. The method for manufacturing an electricity storage device according to claim 1 or 2, wherein the irradiation step performs a separation film removal process in which the separation film is removed while leaving the columnar electrode by using the pulsed laser after the counter electrode removal process, and the separation film is removed by irradiating the pulsed laser in an energy density range higher than that of the counter electrode removal process.

4. In the irradiation step, 3.0 J / cm 2 The method for manufacturing an electricity storage device according to claim 3 , wherein the separation film is removed by irradiating the pulsed laser having an energy density of at least 1000 nm.

5. 5. The method for manufacturing an electricity storage device according to claim 3, wherein in the irradiation step, the counter electrode is removed so that a boundary between the separation film and the counter electrode becomes a step, and the separation film is removed so that a boundary between the columnar electrode and the separation film becomes a step.

6. The method for manufacturing an electricity storage device according to any one of claims 3 to 5, wherein the irradiating step comprises performing a cutting process in which a laser is irradiated onto a portion from which the counter electrode and the separation film have been removed, thereby cutting the columnar electrode.

7. The method for manufacturing an electricity storage device according to any one of claims 1 to 6, wherein the irradiation step involves irradiating with a pulsed laser having a wavelength of 515 nm or more and 532 nm or less.

8. A method for manufacturing the electricity storage device according to claim 6, a bundling step of bundling the cut battery structures; a connecting step of connecting current collecting portions to the columnar electrodes exposed from the bundled battery structure; A method for manufacturing an electricity storage device comprising:

9. An apparatus for manufacturing an electricity storage device using a battery structure including a columnar electrode containing an electrode active material, a separator membrane formed on an outer peripheral surface of the columnar electrode and having insulating properties and ion conductivity, and a counter electrode formed on the outer periphery of the separator membrane and containing a counter electrode active material, an irradiation unit that irradiates a pulsed laser having a wavelength of 480 nm or more and 580 nm or less; a control unit that executes a counter electrode removal process by irradiating the irradiation unit with a pulsed laser within an energy density range that leaves the separation film and removes the counter electrode; and An apparatus for manufacturing an electricity storage device comprising:

10. 10. The apparatus for manufacturing an electricity storage device according to claim 9, wherein, after the counter electrode removal process, the control unit performs a separation film removal process in which the irradiation unit is irradiated with the pulsed laser in an energy density range higher than that of the counter electrode removal process, thereby removing the separation film while leaving the columnar electrode.

11. The apparatus for manufacturing an electricity storage device according to claim 10 , wherein the control unit executes a cutting process in which the irradiation unit irradiates a laser onto a portion from which the counter electrode and the separation film have been removed, thereby cutting the columnar electrode.

12. The manufacturing apparatus for an electricity storage device according to any one of claims 9 to 11, a conveying section for placing the battery structure thereon and conveying the battery structure continuously or intermittently through an area where the battery structure is irradiated with the pulsed laser from the irradiating section;

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