All-solid battery, manufacturing method thereof, and conductive coating current collector

Abstract

To provide a manufacturing method of an all-solid battery capable of reducing performance degradation caused by coating sagging.SOLUTION: A manufacturing method of an all-solid battery includes the steps (a) to (h) of: (a) forming a conductive first coating layer in a first region occupying a part of a first surface of a first collector; (b) forming a second coating layer adjacently to the first coating layer in a second region occupying an outer peripheral side of the first coating layer, the second coating layer being easier to peel than the first coating layer; (c) forming a first electrode layer continuously over surfaces of the first and second coating layers; (d) forming a solid electrolyte layer on a surface of the first electrode layer; (e) forming a second electrode layer on a surface of the solid electrolyte layer; (f) thermally pressing an obtained collector-electrode assembly; (g) removing the second coating layer from a collector 1 together with the layers thereon; and (h) laminating a second collector on a surface of the second electrode layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present application relates to all-solid-state batteries, manufacturing methods thereof, and conductive coated current collectors.

Background Art

[0002] Patent Document 1 describes an all-solid-state battery and a manufacturing method thereof.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 describes that an all-solid-state battery is manufactured by a process of laminating a positive electrode body, a solid electrolyte layer, and a negative electrode body to obtain a laminate, and a process of thermally pressing the laminate. However, since the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer are manufactured by coating a slurry, deformation (sagging) occurs due to the flow of the slurry after coating, resulting in a deviation from the ideal shape. The sagging of each layer causes a decrease in energy density.

[0005] The present invention provides a manufacturing method of an all-solid-state battery capable of reducing performance degradation due to coating sagging. Further, a conductive coated current collector is provided. Further, an all-solid-state battery is provided.

Means for Solving the Problems

[0006] The present invention includes the following embodiments [1] to [3]. [1] A method for manufacturing an all-solid-state battery, comprising: (a) forming a conductive first coat layer in a first region occupying a part of a first surface of a first current collector; (b) A step of forming a second coating layer adjacent to the first coating layer in a second region of the first surface of the first current collector that occupies the outer peripheral side of the first coating layer, wherein the second coating layer is a coating layer that is more easily peeled from the first surface of the first current collector than the first coating layer. (c) A step of forming a first electrode layer containing a first active material and having a first polarity on the surfaces of the first coating layer and the second coating layer of the conductive coated current collector obtained by passing through the steps (a) and (b), wherein the first electrode layer is continuously formed across the surfaces of the first coating layer and the second coating layer. (d) A step of forming a solid electrolyte layer containing a solid electrolyte on the surface of the first electrode layer. (e) A step of forming a second electrode layer containing a second active material and having a second polarity on the surface of the solid electrolyte layer, wherein the second polarity is opposite to the first polarity. (f) A step of thermally pressing the current collector-electrode composite obtained by passing through the steps (a) to (e). (g) A step of removing the second coating layer together with the portion laminated on the second coating layer of the first electrode layer, the portion laminated on the second coating layer of the solid electrolyte layer, and the portion laminated on the second coating layer of the second electrode layer from the current collector 1. (h) A step of laminating a second current collector on the surface of the second electrode layer of the current collector-electrode composite that has passed through the steps (f) and (g). A method for manufacturing an all-solid-state battery, characterized by including the above steps.

[0007] [2] A current collector having a conductive coating layer, A plate-shaped, sheet-shaped, or foil-shaped conductive substrate, A conductive first coating layer provided in a first region occupying a part of the first surface of the conductive substrate, A second coating layer provided adjacent to the first coating layer in a second region of the first surface of the conductive substrate that occupies the outer peripheral side of the first coating layer, Comprising The conductive coated current collector is characterized in that the second coat layer is a coat layer that is more easily peeled off from the first surface of the conductive base material than the first coat layer.

[0008] [3] A first current collector, A conductive coat layer provided in a first region that occupies a part of the first surface of the first current collector, A first electrode layer that is provided in contact with the coat layer without directly contacting the first current collector, contains a first active material, and has a first polarity, A solid electrolyte layer containing a solid electrolyte, A second electrode layer containing a second active material and having a second polarity opposite to the first polarity, A second current collector electrically connected to the second electrode layer, Comprises a laminated structure laminated in the first direction in the above order, On the outer peripheral side of the first region on the first surface of the first current collector, there is a second region not covered by the coat layer, The all-solid-state battery is characterized in that the end faces of the coat layer, the first electrode layer, the solid electrolyte layer, and the second electrode layer are aligned.

Advantages of the Invention

[0009] In the method for manufacturing an all-solid-state battery of the present invention, a first coat layer is provided in a first region on the surface of a first current collector (step (a)), and a second coat layer is provided in a region outside the first coat layer adjacent to the first coat layer (step (b)). A first electrode layer, a solid electrolyte layer, and a second electrode layer are formed on the first coat layer and the second coat layer (steps (c) to (e)), and the second coat layer is removed from the first current collector in step (g). Thereby, the peripheral portions of the layers where coating sag is likely to occur can be removed together with the second coat layer. Therefore, according to the method for manufacturing an all-solid-state battery of the present invention, it is possible to remove the portions deformed due to coating sag and reduce the performance degradation due to coating sag.

[0010] The conductive coat current collector of the present invention is in a state where steps (a) and (b) of the method for manufacturing the all-solid-state battery are completed. Therefore, the conductive coat current collector of the present invention can be preferably used for manufacturing an all-solid-state battery with reduced performance degradation due to coating sagging.

[0011] In the all-solid-state battery of the present invention, since the end faces of the first electrode layer, the solid electrolyte layer, and the second electrode layer are aligned, it is possible to reduce performance degradation resulting from deformation due to coating sagging. Furthermore, the coat layer is provided on a part of the first surface of the first current collector, and the first electrode layer is provided in contact with the coat layer without directly contacting the first current collector. Therefore, a portion that can be used as a terminal is exposed on the outer peripheral portion of the first current collector. This makes it possible to improve the workability of electrically connecting the all-solid-state battery.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. Note that the drawings do not necessarily reflect exact dimensions. Also, in the drawings, some reference numerals may be omitted. In this specification, unless otherwise specified, the notation "A to B" for numerical values A and B means "A or more and B or less". When a unit is attached only to numerical value B in such notation, the unit is also applied to numerical value A. Also, the words "or" and "or alternatively" mean logical disjunction unless otherwise specified. Also, the notation "E1 and / or E2" for elements E1 and E2 means "E1 or E2, or a combination thereof", and for elements E1, …, E N (where N is an integer of 3 or more) "E1, …, E N-1 and / or E N " means "E1, …, E N-1 or E N or a combination thereof".

[0014] FIG. 1 is a flowchart for explaining a method S10 for manufacturing an all-solid-state battery according to one embodiment (hereinafter referred to as "manufacturing method S10"). The manufacturing method S10 includes a first coating step S1, a second coating step S2, a first electrode layer forming step S3, a solid electrolyte layer forming step S4, a second electrode layer forming step S5, a hot press step S6, a removal step S7, a second current collector lamination step S8, and a housing step S9 in this order. Hereinafter, each step will be described in order.

[0015] FIGS. 2(A) to (P) are diagrams for schematically explaining the manufacturing method S10. FIGS. 2(A) and 2(C) are cross-sectional views for schematically explaining the first coating step S1 (hereinafter referred to as "step S1"). FIG. 2(B) is a plan view taken along line B-B of FIG. 2(A), and FIG. 2(D) is a plan view taken along line D-D of FIG. 2(C). Step S1 is a step of forming a conductive first coating layer 2 in a first region R1 that occupies a part of the first surface 1a of the first current collector 1.

[0016] As the first current collector 1 (hereinafter referred to as "current collector 1"), a current collector formed of an appropriate conductive material can be adopted according to whether the first electrode layer described later is a positive electrode layer or a negative electrode layer. The current collector 1 includes, for example, a plate-shaped, sheet-shaped, or foil-shaped conductive substrate. As such a current collector 1, for example, a member composed of a metal material containing one or more elements selected from Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Pb, Co, Cr, Zn, Ge, In, Sn, and Zr can be used. As another example, a member including a conductive or electrically insulating substrate (such as a resin film or the like) and the above metal material vapor-deposited or plated on the surface of the substrate may be used as the current collector 1.

[0017] As a composition for applying the first coating layer 2 (hereinafter referred to as "coating layer 2"), a composition containing a binder (adhesive) and a conductive filler can be preferably used. In step S1, forming the conductive first coating layer 2 can be performed, for example, by applying a slurry containing a binder and a conductive filler. The slurry may further contain a suitable solvent. One or more binders can be used alone or in combination. From the viewpoint of suppressing the peeling of the first coating layer 2 in the heat press step S6 described later, a thermoplastic resin having a melting point of 165°C or higher can be preferably used as the binder. The upper limit of the melting point of the binder resin is not particularly limited, but in one embodiment, it can be 200°C or lower. Examples of the thermoplastic resin that can be contained in the first coating layer 2 include halogen-containing polymers such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polychlorotrifluoroethylene (PCTFE). One or more conductive fillers can be used alone or in combination. As the conductive filler, carbon material fillers such as furnace black, carbon black (CB), ketjen black (KB), acetylene black (AB), activated carbon, carbon, graphite, vapor-grown carbon fiber (VGCF), carbon nanotube (CNT), and carbon nanofiber (CNF) can be preferably used. The average primary particle diameter of the carbon material filler can be, for example, 10 nm to 20 μm. Here, the average primary particle diameter is obtained, for example, as the arithmetic average of the results of measuring the primary particle diameters (average of the minor axis and the major axis) of 30 or more particles based on image analysis using an electron microscope such as SEM (scanning electron microscope).

[0018] Examples of conductive fillers other than carbon material fillers include metal particles such as Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Pb, Co, Cr, Zn, Ge, In, Sn, and Zr. The average particle diameter (D 50 ) of the inorganic filler can be, for example, 50 nm to 5 μm. In this specification, the average particle diameter (D 50) means the median diameter corresponding to the median of the volume distribution measured based on the spherical approximation by the laser diffraction / scattering particle size distribution measurement method.

[0019] From the viewpoint of enhancing the conductivity of the first coating layer 2, the content of the conductive filler in the first coating layer 2 is preferably 15% by volume or more, as the volume% at 25°C with respect to the total amount of the first coating layer 2 (100% by volume). From the viewpoint of enhancing the adhesion of the first coating layer 2 to the current collector 1, it can be preferably 60% by volume or less. The content of the binder in the first coating layer 2 is preferably 85% by volume or less, as the volume% at 25°C with respect to the total amount of the first coating layer 2 (100% by volume) from the viewpoint of enhancing the conductivity of the first coating layer 2. From the viewpoint of enhancing the adhesion of the first coating layer 2 to the current collector 1, it can be preferably 40% by volume or more.

[0020] In one embodiment, the thickness of the first coating layer 2 is preferably 0.5 μm or more from the viewpoint of enhancing the anchor effect and preventing peeling, and can be preferably 4 μm or less from the viewpoint of suppressing peeling caused by the in-plane elongation.

[0021] FIG. 2(E) is a cross-sectional view schematically illustrating the second coating step S2 (hereinafter referred to as "step S2"). FIG. 2(F) is a plan view taken along the F-F arrow of FIG. 2(E). Step S2 is a step of forming a second coating layer 3 adjacent to the first coating layer 2 in the second region R2 of the first surface 1a of the first current collector 1 that occupies the outer peripheral side of the first coating layer 2 in the current collector 10pre provided with the first coating layer 2 after step S1. In step S2, the second coating layer 3 is a coating layer that is more likely to peel from the first surface 1a of the first current collector 1 than the first coating layer 2.

[0022] The second coating layer 3 (hereinafter referred to as "coating layer 3") preferably contains a binder and a filler. In step S2, forming the second coating layer 3 can be performed, for example, by applying a slurry containing a binder and a filler. The slurry may further contain a suitable solvent. One or more binders can be used alone or in combination. As the binder in the second coating layer 3, (a) a binder having a melting point of 110°C or lower (hereinafter referred to as "binder (a)"), and / or (b) a binder having a Young's modulus at 25°C of 2.34 GPa or more and a relative permittivity at 25°C of 3.45 or less (hereinafter referred to as "binder (b)") can be preferably used. In one embodiment, the melting point of binder (a) can be 110°C or lower, for example, 40 to 110°C. In one embodiment, the melting point of binder (a) can be a temperature 55°C or more lower than the hot pressing temperature in the hot pressing step S6 described later. In one embodiment, the Young's modulus of binder (b) at 25°C can be 2.34 GPa or more, for example, 2.34 to 4.50 GPa, as the tensile elastic modulus measured at 25°C in accordance with JIS K7161. In one embodiment, the relative permittivity of the binder resin at 25°C can be 3.45 or less, for example, 3.10 to 3.45, as the relative permittivity measured at 25°C and 1 MHz in accordance with JIS C2138. Examples of binder (a) include acrylic adhesives, silicone adhesives, rubber adhesives, polypropylene (PP), polyethylene (PE), and the like. Examples of binder (b) include polysulfone (PSU), polyphenylsulfone (PPSU), and the like.

[0023] In the second coating layer 3, one or more fillers can be used alone or in combination. In one embodiment, the second coating layer 3 preferably contains a carbon material filler. As the carbon material filler, the carbon material fillers described above in connection with the first coating layer 2 can be used. In other embodiments, the second coating layer 3 may contain inorganic fillers other than carbon materials. As the inorganic filler, the inorganic fillers described above in connection with the first coating layer 2 can be used. The carbon material filler and the inorganic filler may be used in combination.

[0024] From the viewpoint of facilitating peeling of the second coating layer 3 from the current collector 1, the content of the filler in the second coating layer 3 is preferably 20% by volume or more at 25°C based on the total amount of the second coating layer 3 (100% by volume), and may be preferably 90% by volume or less from the viewpoint of handling properties during peeling of the coating layer. In one embodiment, from the viewpoint of facilitating suppression of adhesion of the second coating layer 3 to the roll in the heat pressing step S6 described later, the content of the filler in the second coating layer 3 is 40% by volume or more at 25°C based on the total amount of the second coating layer 3 (100% by volume), and the second coating layer 3 can be formed so that the end of the second coating layer 3 and the end of the current collector are aligned.

[0025] In one embodiment, from the viewpoint of facilitating lamination of each layer constituting the battery on the first coating layer 2 and the second coating layer 3, the thickness of the second coating layer 3 can be made equal to the thickness of the first coating layer 2. From the viewpoint of ensuring the strength of the second coating layer 3 and facilitating removal of the second coating layer 3 together with the layer thereon in the removal step S7 described later, the thickness of the second coating layer 3 can be, for example, 0.5 μm to 5.0 μm.

[0026] The second coating layer 3 is removed from the surface of the current collector 1 in the removal step S7 described later. The phenomenon in which the bonding state between the second coating layer 3 and the current collector 1 is lost may occur in the hot press step S6, may occur in the second electrode formation step S5 or the solid electrolyte layer formation step S4, or may occur in the first electrode formation step S3.

[0027] By going through steps S1 and S2, a conductive coated current collector 10 according to one embodiment is obtained. The conductive coated current collector 10 includes a plate-shaped, sheet-shaped, or foil-shaped conductive base material 1, a first conductive coating layer 2 provided in a first region R1 that occupies a part of the first surface 1a of the conductive base material 1, and a second region R2 of the first surface 1a of the conductive base material 1 that occupies the outer peripheral side of the first coating layer 2, and a second coating layer 3 provided adjacent to the first coating layer 2. In the conductive coated current collector 10, the second coating layer 3 is a coating layer that is more easily peeled off than the first coating layer 2. In one embodiment, the second coating layer 3 may be a coating layer that is more easily peeled off from the current collector 1 than the first coating layer 2 when heat is applied together with a shear stress or a stress in a direction intersecting the first surface 1a of the current collector 1. In another embodiment, the second coating layer 3 may be a coating layer that is more easily peeled off from the current collector 1 than the first coating layer 2 when a shear stress or a stress in a direction intersecting the first surface 1a of the current collector 1 is applied.

[0028] FIG. 2(G) is a cross-sectional view schematically illustrating the first electrode layer formation step S3 (hereinafter referred to as "step S3"), and FIG. 2(H) is a plan view taken along the line H-H of FIG. 2(G). Step S3 is a step of forming a first electrode layer 4 containing a first active material and having a first polarity on the surfaces of the first coating layer 2 and the second coating layer 3 of the conductive coated current collector 10 including the first coating layer 2 and the second coating layer 3. In step S3, the first electrode layer 4 is continuously formed across the surface of the first coating layer 2 and the surface of the second coating layer 3. In the present embodiment, the first electrode layer 4 is a negative electrode layer containing a negative electrode active material (hereinafter referred to as "negative electrode layer 4").

[0029] The negative electrode layer 4 contains a negative electrode active material, a conductive assistant, and a binder, and may optionally further contain a solid electrolyte described later. For example, when a lithium-ion secondary battery is manufactured as an all-solid-state battery, examples of the negative electrode active material include carbon materials such as graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, Li4Ti5O 12、 metal compounds, elements that can be alloyed with lithium or compounds of such elements, boron-added carbon, and the like. Examples of elements that can be alloyed with lithium include silicon and tin.

[0030] The binder binds the active material or the conductive assistant to the surface of the conductive-coated current collector 10 and serves to maintain the conductive network in the electrode. One or more binders can be used alone or in combination. Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and fluororubber, thermoplastic resins such as polypropylene (PP) and polyethylene (PE), imide resins such as polyimide (PI) and polyamideimide (PAI), alkoxysilyl group-containing resins, acrylic resins containing monomer units such as acrylic acid and methacrylic acid, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester crosslinked products, starch-acrylic acid graft polymers, and the like.

[0031] Examples of the conductive assistant include acetylene black, carbon black, graphite, and the like. A viscosity-adjusting solvent such as N-methyl-2-pyrrolidone (NMP) may be used in the negative electrode layer 4.

[0032] The negative electrode layer 4 can be formed by putting a negative electrode active material, a conductive assistant, a binder, and optionally a solid electrolyte into a solvent and kneading to obtain a slurry-like negative electrode mixture, and then subjecting the negative electrode mixture to procedures such as coating and drying on the surfaces of the first coat layer 2 and the second coat layer 3 of the conductive-coated current collector 10.

[0033] FIG. 2(I) is a cross-sectional view for explaining the solid electrolyte layer forming step S4 (hereinafter referred to as "step S4"), and FIG. 2(J) is a plan view taken along the line JJ in FIG. 2(I). Step S4 is a step for forming a solid electrolyte layer 5 containing a solid electrolyte on the surface of the first electrode layer (negative electrode layer) 4. One or more solid electrolytes may be used alone or in combination. The solid electrolyte layer 5 contains a solid electrolyte having conductivity of ions absorbed and released by the negative electrode active material contained in the negative electrode layer 4 and the positive electrode active material contained in the positive electrode layer 6 described later. For example, examples of solid electrolytes having lithium ion conductivity include oxide solid electrolytes such as Li3PO4; and sulfide solid electrolytes such as Li2S-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Si2S-P2S5, LiI-Li2S-P2O5, and LiI-Li3PO4-P2S5.

[0034] The solid electrolyte layer 5 can be prepared by adding a solid electrolyte and, optionally, a binder to a solvent and kneading them to obtain a slurry-like electrolyte mixture, and then applying and drying the electrolyte composition. The binder in the solid electrolyte 5 can be the binder described above in relation to the first electrode layer (negative electrode layer) 4. The solid electrolyte layer 5 may be formed, for example, by directly applying the electrolyte mixture to the surface of the first electrode layer (negative electrode layer) 4. Alternatively, for example, the electrolyte mixture may be applied to the surface of a substrate such as a metal foil (e.g., Al foil, etc.) to form a solid electrolyte layer 5 on the surface of the substrate, and then the solid electrolyte layer 5 formed on the surface of the substrate may be superimposed on the surface of the first electrode layer 4 of the composite 20 in which the first electrode layer 4 is formed on the conductive-coated current collector 10, and the solid electrolyte layer 5 may be transferred from the surface of the substrate to the surface of the first electrode layer 4 by pressing such as a roll press.

[0035] FIG. 2(K) is a cross-sectional view schematically illustrating the second electrode layer formation step S5 (hereinafter referred to as "step S5"), and FIG. 2(L) is a plan view taken along the line L-L of FIG. 2(K). Step S5 is a step of forming a second electrode layer 6 containing a second active material and having a second polarity on the surface of the solid electrolyte layer 5. In step S5, the second polarity (+ / -) is opposite to the first polarity (- / +). In the present embodiment, the second electrode layer 6 is a positive electrode layer containing a positive electrode active material (hereinafter referred to as "positive electrode layer 6"). The positive electrode layer 6 includes a positive electrode active material, a conductive assistant, and a binder. For example, when the all-solid-state battery manufactured in the manufacturing method S10 is a lithium ion secondary battery, examples of the positive electrode active material include composite oxides, metallic lithium, sulfur, and the like. The composition of the composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. Examples of the composite oxide include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, LiNiMnCoO2, and the like. As the conductive assistant and the binder in the positive electrode layer 6, the same ones as those used in the negative electrode layer 4 can be used. The positive electrode layer 6 may further contain a solid electrolyte. As the solid electrolyte in the positive electrode layer 6, the solid electrolyte described above in relation to the solid electrolyte layer 5 can be used.

[0036] The positive electrode layer 6 can be fabricated by kneading a positive electrode active material, a conductive assistant, a binder, and optionally a solid electrolyte in a solvent to obtain a slurry-like positive electrode mixture, and then subjecting the positive electrode mixture to procedures such as coating and drying. The positive electrode layer 6 may be formed, for example, by directly coating the positive electrode mixture on the surface of the solid electrolyte layer 5. Alternatively, for example, after coating the positive electrode mixture on the surface of a substrate such as a metal foil (e.g., Al foil, etc.) to form the positive electrode layer 6 on the surface of the substrate, the positive electrode layer 6 formed on the surface of the substrate may be overlaid on the surface of the solid electrolyte layer 5 of the composite body 30 on which the negative electrode layer 4 and the solid electrolyte layer 5 are formed on the conductive coated current collector 10, and the positive electrode layer 6 may be transferred from the surface of the substrate to the surface of the solid electrolyte layer 5 by pressing such as roll pressing. Examples of the solvent for forming each layer include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, water, and the like. In one embodiment, the second electrode layer 6 can be formed across the boundary between the first coat layer 2 and the second coat layer 3 in plan view. In one embodiment, the boundary between the first coat layer 2 and the second coat layer 3 is on the current collector 1 and can be formed (e.g., linearly) at a position where the first electrode layer 4, the solid electrolyte layer 5, and the second electrode layer 6 are not cut together.

[0037] Figure 2(M) is a cross-sectional view schematically illustrating the hot pressing step S6 (hereinafter referred to as "step S6") and the removing step S7 (hereinafter referred to as "step S7"), and Figure 2(N) is a plan view taken along the line N-N of Figure 2(M). Step S6 is a step of hot pressing the current collector-electrode composite body 40 obtained through steps S1 to S5. By going through step S6, the current collector-electrode composite body is densified. The hot pressing can be performed, for example, by roll pressing or the like. The temperature of the hot pressing can be, for example, a temperature not exceeding 10°C above the melting point of the binder contained in the first coat layer 2, or a temperature not exceeding the melting point of the binder contained in the first coat layer 2, and in one embodiment, it can be 130 to 200°C. The pressure of the hot pressing can be, for example, when the hot pressing is performed by roll pressing, a linear pressure of 3 to 10 t / cm, for example.

[0038] Step S7 is a step of removing the second coating layer 2 together with the portions laminated on the second coating layer 3 of the first electrode layer (negative electrode layer) 4, the portions laminated on the second coating layer 3 of the solid electrolyte layer 5, and the portions laminated on the second coating layer 3 of the second electrode layer (positive electrode layer) 6 from the current collector 1. In one embodiment, the second coating layer 3 loses its bonding state with the first current collector 1 by receiving the heat and stress of hot pressing in step S6. In another embodiment, the second coating layer 3 loses its bonding state with the first current collector 1 by receiving the stress of pressing when bonding the solid electrolyte layer 5 formed by coating on a substrate such as an Al foil to the first electrode layer (negative electrode layer) 4 in step S4. In another embodiment, the second coating layer 3 loses its bonding state with the first current collector 1 by receiving the stress of pressing when bonding the second electrode layer (positive electrode layer) 6 formed by coating on a substrate such as an Al foil to the solid electrolyte layer 5 in step S5. In any of the embodiments, the bonding state between the second coating layer 3 and the first current collector 1 is lost by the end of step S6. Therefore, the operation of removing the second coating layer 3 from the current collector 1 in step S7 can be easily performed. By passing through step S7, the peripheral portions where coating sagging has occurred in the first electrode layer (negative electrode layer) 4, the solid electrolyte layer 5, and the second electrode layer (positive electrode layer) 6 can be removed together with the second coating layer 3. In the current collector-electrode composite 50 that has undergone steps S6 and S7, it is possible to obtain a state where the end faces of the first coating layer 2, the first electrode layer (negative electrode layer) 4, the solid electrolyte layer 5, and the second electrode layer (positive electrode layer) 6 are aligned at the portion where the second coating layer 3 has been removed without performing cutting of the current collector-electrode composite.

[0039] FIG. 2(O) is a cross-sectional view schematically illustrating the second current collector lamination step S8 (hereinafter sometimes referred to as "step S8"). FIG. 2(P) is a plan view taken along the P-P arrow in FIG. 2(O). Step S8 is a step of laminating a second current collector (positive electrode current collector) 7 on the surface of the second electrode layer (positive electrode layer) 6 of the current collector-electrode composite 50 that has undergone steps S6 and S7. As the second current collector 7, for example, a current collector in the form of a plate, sheet, or foil made of the conductive material described above in relation to the first current collector, or a porous current collector can be used.

[0040] The housing step S9 (hereinafter sometimes referred to as "step S9") is a step of housing and encapsulating the all-solid-state battery 100 obtained through steps S1 to S8 in an exterior material (not shown). As the exterior material, an exterior material that can be used for an all-solid-state battery can be used. Examples of materials that can constitute such an exterior material include metal materials such as aluminum and stainless steel, as well as resin materials such as polyphenylene sulfide resin and polyimide resin. Further, the shape of the exterior material is not particularly limited, and can be, for example, circular (cylindrical, coin-shaped, button-shaped), hexahedral (rectangular parallelepiped-shaped, cubic-shaped), or bag-shaped, or a shape obtained by processing and deforming them. After step S8 and before housing the all-solid-state battery 100 in the exterior material, the all-solid-state battery 100 may be partially cut as necessary.

[0041] The all-solid-state battery 100 includes a first current collector 1; a conductive coating layer 2 provided in a first region R1 that occupies a part of the first surface 1a of the first current collector 1; a first electrode layer (negative electrode layer) 4 that is provided in contact with the coating layer 2 without directly contacting the first current collector 1, contains a first active material (negative electrode active material), and has a first polarity (−); a solid electrolyte layer 5 containing a solid electrolyte; a second electrode layer (positive electrode layer) 6 that contains a second active material (positive electrode active material) and has a polarity (+) opposite to the first polarity (−); and a second current collector 7 electrically connected to the second electrode layer 6, and has a laminated structure in which the above components are laminated in the above order. In the all-solid-state battery 100, the end surfaces of the coating layer 2, the first electrode layer 4, the solid electrolyte layer 5, and the second electrode layer 6 are aligned. Such a configuration cannot be obtained if there is a coating drip. Further, on the outer peripheral side of the first region R1 of the first surface 1a of the first current collector, there is a second region R2 where the first current collector is exposed and not covered by the coating layer 2. The exposed portion of the first current collector can be preferably utilized as a terminal.

[0042] In the above description of the present invention, the manufacturing method S10 of the all-solid-state battery, the conductive coating current collector 10, and the all-solid-state battery 100 in the form in which the first electrode layer 4 is a negative electrode layer containing a negative electrode active material and the second electrode layer 6 is a positive electrode layer containing a positive electrode active material have been mainly exemplified, but the present invention is not limited to these forms. For example, it is also possible to use a manufacturing method of an all-solid-state battery, a conductive coating current collector, and an all-solid-state battery in a form in which the first electrode layer 4 is a positive electrode layer containing a positive electrode active material and the second electrode layer 6 is a negative electrode layer containing a negative electrode active material.

[0043] In the above description of the present invention, the manufacturing method S10 of manufacturing an all-solid-state battery that is a lithium-ion secondary battery, and the all-solid-state battery 100 in the form of a lithium-ion secondary battery have been mainly exemplified, but the present invention is not limited to these forms. For example, as the positive electrode active material and the negative electrode active material, ions other than lithium ions (for example, Na + , K + , Mg 2+ , Ca 2+ , Al 3+ , Zn 2+By using an active material that occludes and releases (such as), and using a solid electrolyte having conductivity for the ions occluded and released by the active material as the solid electrolyte, it is also possible to obtain an all-solid-state battery other than a lithium-ion secondary battery, and it is also possible to provide a method for manufacturing an all-solid-state battery in a form for manufacturing such an all-solid-state battery.

Example

[0044] Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples.

[0045] <Example 1> An all-solid-state battery was manufactured according to the following procedure. (1. Preparation of a negative electrode current collector foil having a carbon coating layer) A negative electrode current collector foil having carbon coating layers on both sides (double-sided CC foil) was prepared according to the following procedure. Acetylene black as a conductive material and polyvinylidene fluoride (PVDF) were weighed so that their mixing weight ratio was 20:80, and mixed together with N-methylpyrrolidone (NMP) to prepare a composition (first CC composition) for the central carbon coating layer (central CC layer; first CC layer). Also, acetylene black as a conductive material and an acrylic binder having a melting point of 110°C were weighed so that their mixing weight ratio was 20:80, and mixed together with N-methylpyrrolidone (NMP) to prepare a composition (second CC composition) for the end CC layer (second CC layer). The first CC composition was center-coated with a width of 62 mm on both sides of an Al foil with a width of 120 mm to form a central CC layer (first CC layer). Then, the second CC composition was coated with a width of 5 mm on both sides of each central CC layer to form an end CC layer (second CC layer).

[0046] (2. Formation of the negative electrode layer) PVDF, negative electrode active material (lithium titanium oxide (LTO)) particles, and a sulfide solid electrolyte (Li2S-P2S5-based glass ceramic) were added to a polypropylene container and stirred for 30 minutes with an ultrasonic disperser to prepare a negative electrode mixture. A negative electrode layer was formed by coating the CC layer surfaces (both sides) of the double-sided CC foil created in Step 1 with the negative electrode mixture at a width of 70 mm, and a double-sided CC foil-negative electrode layer laminate was produced.

[0047] (3. Formation of the solid electrolyte layer) Heptane, butadiene rubber (BR), and the same sulfide solid electrolyte as in Step 2 were added to a polypropylene container and stirred for 15 minutes with an ultrasonic disperser to prepare a solid electrolyte mixture. A solid electrolyte (SE) layer was formed on the surface of the Al foil by coating the surface of the Al foil with the solid electrolyte mixture at a width of 70 mm, and an Al foil-SE layer laminate was produced. A plurality of these Al foil-SE layer laminates were produced.

[0048] (4. Formation of the positive electrode layer) Using a rolling fluidized coating device (manufactured by Paulekk), lithium niobate was coated on positive electrode active material particles (particles with Li 1.15 Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2 as the main phase) in an air atmosphere, and then fired in an air atmosphere to obtain positive electrode active material particles with a coating layer of lithium niobate. PVDF, the above positive electrode active material particles, the sulfide solid electrolyte used in Step 2, and vapor-grown carbon fiber (VGCF; manufactured by Showa Denko) were added to a polypropylene container and stirred for 20 minutes with an ultrasonic disperser to prepare a positive electrode mixture. A positive electrode layer was formed by coating the surface of the Al foil with the positive electrode mixture at a width of 65 mm, and an Al foil-positive electrode layer laminate was produced. A plurality of these Al foil-positive electrode layer laminates were produced.

[0049] (5. Fabrication of Negative Current Collector-Electrode Composite: Transfer Press Process) The double-sided CC foil-negative electrode layer laminate fabricated in Procedure 2, the Al foil-SE layer laminate fabricated in Procedure 3, and the Al foil-positive electrode layer laminate fabricated in Procedure 4 were each cut to a length of 80 mm. The Al foil-SE layer laminate was placed and overlapped on both sides of the double-sided CC foil-negative electrode layer laminate so that the center positions of the coating parts were aligned, and the transfer of the solid electrolyte layer was performed by roll pressing at a line pressure of 0.4 t / cm to obtain an SE layer-negative electrode layer-double-sided CC foil-negative electrode layer-SE layer laminate. Further, the Al foil-positive electrode layer laminate was placed and overlapped on both sides thereof, and the transfer of the positive electrode layer was performed by roll pressing at a line pressure of 0.4 t / cm to obtain a negative current collector-electrode composite having a structure in which the positive electrode layer-SE layer-negative electrode layer-double-sided CC foil-negative electrode layer-SE layer-positive electrode layer were laminated in this order.

[0050] (6. Hot Press Process) The negative current collector-electrode composite obtained in Procedure 5 was densified by roll pressing at a temperature of 165 °C and a line pressure of 5 t / cm for 10 minutes. At that time, the peeling of the end CC layer (the second CC layer) was confirmed. Thereafter, the negative current collector-electrode composite was cut so that the dimensions of the positive electrode layer were 60 mm in width × 60 mm in length.

[0051] (7. Fabrication and Attachment of Positive Current Collector Foil) Acetylene black as a conductive material and PVDF were weighed so that the mixing weight ratio was 20:80, and further NMP was added to prepare a composition for carbon coating (the third CC composition). The third CC composition was coated on one side of the Al foil to a thickness of 2 μm and dried at 100 °C for 1 hour to obtain an Al foil (positive current collector foil) provided with a CC layer (the third CC layer) on one side. The positive current collector foil was cut so that the dimensions of its CC layer were 57 mm in length × 57 mm in width, and was attached to both sides of the current collector-electrode composite obtained in Procedure 6 using a styrene-butadiene rubber (SBR) binder to fabricate a battery having a laminated structure of Al foil-third CC layer-positive electrode layer-SE layer-negative electrode layer-double-sided CC foil (first CC layer-Al foil-first CC layer)-negative electrode layer-SE layer-positive electrode layer-third CC layer-Al foil. After joining terminals to the positive current collector foil and the negative current collector foil respectively, the battery was vacuum-sealed in a laminate film (outer packaging material).

[0052] <Example 2 and 3> A battery was fabricated according to the procedure of Example 1, except that in Step 1, the compositions of the first and second CC compositions for fabricating the double-sided CC foil were changed as described in Table 1. In both Example 2 and 3, peeling of the end CC layer (the second CC layer) was confirmed in the transfer press step (Step 5).

[0053] <Comparative Examples 1 to 5> A battery was fabricated according to the procedure of Example 1, except that in Step 1, the compositions of the first and second CC compositions for fabricating the double-sided CC foil were changed as described in Table 1. However, in Comparative Examples 1, 2, 4, and 5, since peeling of the end CC layer (the second CC layer) was not confirmed, when joining the terminal to the negative current collector foil in Step 7, the terminal was welded outside the end CC layer (the second CC layer). In Comparative Example 3, peeling of the end CC layer was confirmed in the hot press step (Step 6).

[0054] <Charge and Discharge Test> For each battery manufactured in Examples 1 to 3 and Comparative Examples 1 to 5, a charge and discharge test was performed according to the following procedure, and the internal resistance was measured. The battery to be evaluated was charged at a constant current and constant voltage at a charging voltage of 2.95 V and a charging rate (C rate) of 0.3 C, and then discharged to a cut-off voltage of 1.5 V. Then, after charging to 2.17 V, it was discharged at a constant current at a discharge rate of 5 C, and the internal resistance was calculated from the voltage change ΔV.

[0055] <Evaluation Results> In Example 1, the end CC layer (the second CC layer) was peelable in the hot press process (Step 6), while in Example 2, peeling of the end CC layer was confirmed in the transfer press process (Step 5). In Comparative Examples 1, 2, 4, and 5, the end CC layer could not be peeled in any of the processes. The fact that the battery of Comparative Example 3 showed a high internal resistance is considered to be due to the low electron conductivity of the CC layer in the central part. In Example 1, it is considered that the binder in the end CC layer melted in the hot press process (Step 6), and due to the presence of carbon in the end CC layer, the end CC layer became slippery and peeled off. In Examples 2 and 3, since the binder in the end CC layer was hard, in the transfer press process (Step 7), a difference in elongation occurred due to the pressing stress, and peeling of the end CC layer occurred. Even when a binder with a low melting point was used for the end CC layer, when there was no conductive material (carbon) (Comparative Examples 1 and 2), the end CC layer did not peel. This is considered to be because slippage did not occur between the binder and the aluminum foil. Even when a thermosetting resin with a low dielectric constant was used as the binder for the end CC layer, in the case of only the binder (Comparative Examples 1 and 2), the end CC layer could not be peeled. This is considered to be because the adhesive force was high. When polyamideimide (PAI) or PVDF was used as the binder for the end CC layer (Comparative Examples 4 and 5), the end CC layer could not be peeled. These binders are considered to be due to their high dielectric constant and high adhesive force.

[0056]

Table 1

Explanation of Symbols

[0057] 1: First current collector, 1a: First surface, R1: First region, R2: Second region, 2: First coat layer, 3: Second coat layer, 4: First electrode layer, 5: Solid electrolyte layer, 6: Second electrode layer, 7: Second current collector, 10: Conductive coat current collector, 20, 30, 40, 50: Current collector - electrode composite, 100: All - solid - state battery

Claims

1. A method for manufacturing an all-solid-state battery, comprising: (a) forming a first conductive coat layer in a first region occupying a part of the first surface of a first current collector; (b) forming a second coat layer adjacent to the first coat layer in a second region of the first surface of the first current collector, which occupies the outer peripheral side of the first coat layer, wherein the second coat layer is a coat layer that is more easily peeled off from the first surface of the first current collector than the first coat layer; (c) forming a first electrode layer containing a first active material and having a first polarity on the surfaces of the first coat layer and the second coat layer of the conductive coat current collector obtained through steps (a) and (b), wherein the first electrode layer is continuously formed across the surfaces of the first coat layer and the second coat layer; (d) forming a solid electrolyte layer containing a solid electrolyte on the surface of the first electrode layer; (e) forming a second electrode layer containing a second active material and having a second polarity on the surface of the solid electrolyte layer, wherein the second polarity is opposite to the first polarity; (f) thermally pressing the current collector-electrode composite obtained through steps (a) to (e); (g) removing the second coat layer together with the portions laminated on the second coat layer of the first electrode layer, the portions laminated on the second coat layer of the solid electrolyte layer, and the portions laminated on the second coat layer of the second electrode layer from the current collector 1; (h) laminating a second current collector on the surface of the second electrode layer of the current collector-electrode composite that has undergone steps (f) and (g). A method for manufacturing an all-solid-state battery, characterized by including the above steps.

2. The first coat layer comprises: a binder that is a thermoplastic resin with a melting point of 165°C or higher; and a carbon material filler in a volume percentage at 25°C of 15% by volume or more based on the total amount of the first coat layer. The second coat layer comprises: a binder with a melting point of 110°C or lower and / or a binder with a Young's modulus at 25°C of 2.34 GPa or higher and a relative permittivity at 25°C of 3.45 or lower; and a carbon material filler in a volume percentage at 25°C of 20% by volume or more based on the total amount of the second coat layer. The method for manufacturing an all-solid-state battery according to Claim 1.

3. ​ The first electrode layer is a negative electrode layer containing a negative electrode active material, The second electrode layer is a positive electrode layer containing a positive electrode active material, The method for manufacturing an all-solid-state battery according to claim 1 or 2.

4. A current collector having a conductive coating layer, A plate-like, sheet-like, or foil-like conductive substrate, and A first conductive coating layer provided in a first region occupying a part of the first surface of the conductive substrate, A second coating layer provided adjacent to the first coating layer in a second region of the first surface of the conductive substrate, which occupies the outer peripheral side of the first coating layer, Comprising, The second coating layer is a coating layer that is more easily peeled off from the first surface of the conductive substrate than the first coating layer. A conductive coating current collector characterized by this.

5. The first coating layer is A binder that is a thermoplastic resin having a melting point of 165°C or higher, and A carbon material filler, as the volume% at 25°C based on the total amount of the first coating layer, is 15 volume% or more, Including, The second coating layer is A binder having a melting point of 110°C or lower and / or a binder having a Young's modulus at 25°C of 2.34 GPa or higher and a relative dielectric constant at 25°C of 3.45 or lower, and A carbon material filler, as the volume% at 25°C based on the total amount of the second coating layer, is 20 volume% or more, The current collector according to claim 3, comprising.

6. A first current collector, A conductive coating layer provided in a first region occupying a part of the first surface of the first current collector, A first electrode layer provided in contact with the coating layer without directly contacting the first current collector, containing a first active material and having a first polarity, A solid electrolyte layer containing a solid electrolyte, A second electrode layer containing a second active material and having a second polarity opposite to the first polarity, A second current collector electrically connected to the second electrode layer, Is provided with a laminated structure laminated in the first direction in the above order, On the outer peripheral side of the first region on the first surface of the first current collector, there is a second region not covered by the coating layer, An all-solid-state battery characterized in that the end faces of the coating layer, the first electrode layer, the solid electrolyte layer, and the second electrode layer are aligned.

7. The coating layer is A binder that is a thermoplastic resin having a melting point of 165°C or higher, and A carbon material filler, as the volume% at 25°C based on the total amount of the first coating layer, is 15 volume% or more, The all-solid-state battery according to claim 5, comprising

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