All-solid-state battery, method for producing same, and conductive coated current collector

Abstract

The invention relates to an all-solid-state battery, a method for manufacturing the same, and a conductive coated current collector. A method for manufacturing an all-solid-state battery includes the following steps. And a step for forming a conductive first coating layer in the first region. And forming a second coating layer adjacent to the first coating layer in the second region. The second coating layer is easier to peel compared to the first coating layer. And a step for continuously forming a first electrode layer across the surfaces of the first and second coating layers. And a step for forming a solid electrolyte layer on the surface of the first electrode layer. And a step for forming a second electrode layer on the surface of the solid electrolyte layer. And a step for hot-pressing the obtained current collector-electrode composite. And a step for removing the second coating layer from the first current collector together with the layers thereon. And a step for laminating a second current collector on the surface of the second electrode layer.

Description

Technical Field

[0001] The present application relates to an all-solid-state battery, a method for manufacturing the same, and a conductive coating current collector. Background Art

[0002] An all-solid-state battery and a method for manufacturing the same are described in Japanese Unexamined Patent Application Publication No. 2019-200947. Summary of the Invention

[0003] Japanese Unexamined Patent Application Publication No. 2019-200947 describes 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 hot-pressing the laminate to fabricate an all-solid-state battery. However, since the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer are fabricated by coating a slurry, the slurry flows after coating, resulting in deformation (sagging), and deviation from the ideal shape. Sagging (flowing, slumping, ダレ) of each layer causes a reduction in energy density.

[0004] The present invention provides a method for manufacturing an all-solid-state battery capable of reducing performance degradation caused by coating sagging (coating defects). In addition, a conductive coating current collector is provided. In addition, an all-solid-state battery is provided.

[0005] The present invention includes the following embodiments [1] to [3].

[0006] [1] A method for manufacturing an all-solid-state battery, comprising the following steps:

[0007] A step of forming a conductive first coating in a first region that occupies a part of a first surface of a first current collector;

[0008] A step of forming a second coating adjacent to the first coating in a second region of the first surface of the first current collector that occupies the outer peripheral side of the first coating, the second coating being a coating that is more easily peeled off from the first surface of the first current collector than the first coating;

[0009] 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 and the second coating of the conductive coating current collector obtained through the step of forming the first coating and the step of forming the second coating, the first electrode layer being continuously formed over the surfaces of the first coating and the second coating;

[0010] A step of forming a solid electrolyte layer containing a solid electrolyte on the surface of the first electrode layer;

[0011] 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, the second polarity being opposite to the first polarity;

[0012] A step of hot-pressing the current collector-electrode composite obtained through the steps from forming the first coating to forming the second electrode layer;

[0013] A step of removing the second coating from the first current collector together with the portion of the first electrode layer laminated on the second coating, the portion of the solid electrolyte layer laminated on the second coating, and the portion of the second electrode layer laminated on the second coating; and

[0014] A step of laminating a second current collector on the surface of the second electrode layer of the current collector-electrode composite that has undergone the hot-pressing step and the step of removing the second coating.

[0015] [2] A conductive coated current collector having a conductive coating, comprising: a plate-shaped, sheet-shaped or foil-shaped conductive substrate; a conductive first coating provided in a first region occupying a part of the first surface of the conductive substrate; a second coating provided adjacent to the first coating in a second region of the first surface of the conductive substrate that occupies the outer peripheral side of the first coating, the second coating being a coating that is more easily peeled off from the first surface of the conductive substrate than the first coating.

[0016] [3] A all-solid-state battery, comprising: a first current collector; a conductive coating provided in a first region occupying a part of the first surface of the first current collector; a first electrode layer containing a first active material and having a first polarity, which is provided in contact with the coating without directly contacting the first current collector; 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; and a second current collector electrically connected to the second electrode layer, having a laminated structure in which the first current collector, the conductive coating, the first electrode layer, the solid electrolyte layer, the second electrode layer, and the second current collector are laminated in a first direction in sequence, and there is a second region on the outer peripheral side of the first region of the first surface of the first current collector that is not covered by the coating, and the end faces of the coating, the first electrode layer, the solid electrolyte layer, and the second electrode layer are neat.

[0017] In the method for manufacturing an all-solid-state battery of the present invention, a first coating is provided in a first region on the surface of a first current collector (step of forming the first coating), and a second coating is provided in a region outside the first coating adjacent to the first coating (step of forming the second coating). A first electrode layer, a solid electrolyte layer, and a second electrode layer are formed on the first coating and the second coating (steps from forming the first electrode layer to forming the second electrode layer), and the second coating is removed from the first current collector. Thus, the peripheral portions of the layers that are prone to coating sag can be removed together with the second coating. Therefore, according to the method for manufacturing an all-solid-state battery of the present invention, the portions deformed due to coating sag can be removed, and the performance degradation caused by coating sag can be alleviated.

[0018] The conductive coated current collector of the present invention is in a state where the step of forming the first coating and the step of forming the second coating in the above method for manufacturing an all-solid-state battery are completed. Therefore, the conductive coated current collector of the present invention can be preferably used for manufacturing an all-solid-state battery that alleviates the performance degradation caused by coating sag.

[0019] In the all-solid-state battery of the present invention, the end faces of the first electrode layer, the solid electrolyte layer, and the second electrode layer are neat. Therefore, the performance degradation caused by the deformation due to coating sag can be alleviated. Furthermore, the coating 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 coating without directly contacting the first current collector. Therefore, a part that can be used as a terminal is exposed at the outer peripheral portion of the first current collector. Thus, the workability of electrically connecting the all-solid-state battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Hereinafter, the features, advantages, and technical and industrial significance of the exemplary embodiments of the present invention will be described with reference to the drawings, in which like reference numerals denote like elements, and in which:

[0021] Figure 1 is a flowchart for explaining a method S10 for manufacturing an all-solid-state battery according to an embodiment;

[0022] Figure 2A is a cross-sectional view schematically illustrating a first coating step S1;

[0023] Figure 2B is Figure 2A a plan view seen in the direction of I-I of

[0024] Figure 2C is a cross-sectional view schematically illustrating a first coating step S1;

[0025] Figure 2D is Figure 2C a plan view seen in the direction of II-II of

[0026] Figure 2EA cross-sectional view schematically illustrating the second coating step S2;

[0027] Figure 2F For Figure 2E III-III direction view plan of

[0028] Figure 2G A cross-sectional view schematically illustrating the first electrode layer formation step S3;

[0029] Figure 2H For Figure 2G IV-IV direction view plan of

[0030] Figure 2I A cross-sectional view schematically illustrating the solid electrolyte layer formation step S4;

[0031] Figure 2J For Figure 2I V-V direction view plan of

[0032] Figure 2K A cross-sectional view schematically illustrating the second electrode layer formation step S5;

[0033] Figure 2L For Figure 2K VI-VI direction view plan of

[0034] Figure 2M A cross-sectional view schematically illustrating the hot pressing step S6 and the removing step S7;

[0035] Figure 2N For Figure 2M VII-VII direction view plan of

[0036] Figure 2O A cross-sectional view schematically illustrating the second current collector layer stacking step S8; and

[0037] Figure 2P For Figure 2O VIII-VIII direction view plan of Detailed implementation mode

[0038] The following describes the implementation modes of the present invention with reference to the drawings. However, the present invention is not limited to these forms. Furthermore, the drawings do not necessarily reflect the correct dimensions. In addition, in the drawings, some reference numerals may be omitted. In this specification, unless otherwise specified, for numerical values A and B, the expression "A to B" means "A or more and B or less". In this expression, when the unit is only marked at the numerical value B, the unit also applies to the numerical value A. In addition, the terms "or" and "or" mean "logical sum" unless otherwise specified. In addition, for elements E1 and E2, the expression "E1 and / or E2" means "E1 or E2, or a combination thereof". For elements E1, …, EN (N is an integer of 3 or more), "E1, …, E N-1 , and / or E N " such an expression means "E1, …, E N-1 , or E N , or a combination thereof".

[0039] Figure 1 is a flowchart for explaining a manufacturing method S10 of an all-solid-state battery according to an embodiment (hereinafter referred to as "manufacturing method S10"). The manufacturing method S10 successively 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 pressing step S6, a removing step S7, a second current collector laminating step S8, and a housing step S9. Each step will be described in turn below.

[0040] Figures 2A through 2P is a diagram schematically illustrating the manufacturing method S10. Figure 2A and Figure 2C are cross-sectional views schematically illustrating the first coating step S1 (hereinafter referred to as "step S1").

[0041] Figure 2B is Figure 2A a plan view seen in the direction of I-I of Figure 2D is Figure 2C a plan view seen in the direction of II-II of . Step S1 is a step of forming a conductive first coating 2 in a first region R1 that occupies a part of the first surface 1a of the first current collector 1.

[0042] As the first current collector 1 (hereinafter referred to as "current collector 1"), depending on whether the first electrode layer is a positive electrode layer or a negative electrode layer described later, a current collector formed of an appropriate conductive material can be used. 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 made 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, etc.) and the above metal material vapor-deposited or plated on the surface of the substrate can be used as the current collector 1.

[0043] As a composition for coating the first coating 2 (hereinafter referred to as "coating 2"), a composition containing an adhesive (binder) and a conductive filler can be preferably used. In step S1, for example, a conductive first coating 2 can be formed by coating a slurry containing an adhesive and a conductive filler. The slurry may further contain a suitable solvent. One or more adhesives can be used alone or in combination. From the viewpoint of suppressing the peeling of the first coating 2 in the subsequent hot pressing step S6, as the adhesive, a thermoplastic resin with a melting point of 165°C or higher can be preferably used. There is no particular limitation on the upper limit of the melting point of the adhesive resin, and in one embodiment, it can be 200°C or lower. As examples of the thermoplastic resin that can be contained in the first coating 2, halogen-containing polymers such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and poly(chlorotrifluoroethylene) (PCTFE) can be cited. One or more conductive fillers can be used alone or in combination. As the conductive filler, furnace black, carbon black (CB), Ketjen black (KB), acetylene black (AB), activated carbon, carbon, graphite, vapor-grown carbon fiber (VGCF), carbon nanotube (CNT), carbon nanofiber (CNF), etc. can be preferably used as carbon material fillers. The average primary particle size of the carbon material filler can be, for example, 10 nm to 20 μm. Among them, the average primary particle size is obtained, for example, as the arithmetic average of the results of measuring more than 30 primary particle sizes (average of the short diameter and the long diameter) by image analysis using an electron microscope such as SEM (scanning electron microscope).

[0044] As examples of conductive fillers other than carbon material fillers, metal particles such as Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Pb, Co, Cr, Zn, Ge, In, Sn, Zr, etc. can be cited. The average particle size (D 50 ) of the inorganic filler can be, for example, 50 nm to 5 μm. Further, in this specification, the so-called average particle size (D 50 ) means the median diameter corresponding to the median value in the volume distribution measured by the laser diffraction / scattering particle size distribution measurement method based on the spherical approximation.

[0045] From the viewpoint of improving the conductivity of the first coating 2, the content of the conductive filler in the first coating 2 is preferably 15% by volume or more at 25°C based on the total amount of the first coating 2 (100% by volume). From the viewpoint of improving the adhesion of the first coating 2 to the current collector 1, it is preferably 60% by volume or less. From the viewpoint of improving the conductivity of the first coating 2, the content of the adhesive in the first coating 2 is preferably 85% by volume or less at 25°C based on the total amount of the first coating 2 (100% by volume). From the viewpoint of improving the adhesion of the first coating 2 to the current collector 1, it is preferably 40% by volume or more.

[0046] In one embodiment, from the viewpoint of improving the anchoring effect and preventing peeling, the thickness of the first coating 2 is preferably 0.5 μm or more, and from the viewpoint of suppressing peeling caused by elongation in the in-plane direction, it is preferably 4 μm or less.

[0047] Figure 2E A cross-sectional view schematically illustrating the second coating step S2 (hereinafter referred to as "step S2"). Figure 2F is Figure 2E a plan view taken along the line III-III. Step S2 is a step of forming a second coating 3 adjacent to the first coating 2 in a second region R2 of the first surface 1a of the first current collector 1 that occupies the outer peripheral side of the first coating 2 in the current collector 10 precursor including the first coating 2 after step S1. In step S2, the second coating 3 is a coating that is more easily peeled from the first surface 1a of the first current collector 1 than the first coating 2.

[0048] The second coating 3 (hereinafter referred to as "coating 3") preferably contains a binder and a filler. In step S2, for example, the second coating 3 can be formed by coating 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 3, it is possible to preferably use (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 of 2.34 GPa or more at 25°C and a relative dielectric constant of 3.45 or less at 25°C (hereinafter referred to as "binder (b)"). 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 that is 55°C or more lower than the hot pressing temperature in the subsequent hot pressing step S6. In one embodiment, the Young's modulus of binder (b) at 25°C, as the tensile elastic modulus measured at 25°C in accordance with JIS K7161, can be 2.34 GPa or more, for example, 2.34 GPa to 4.50 GPa. In one embodiment, the relative dielectric constant of the binder resin at 25°C, as the relative dielectric constant measured at 25°C and 1 MHz in accordance with JIS C2138, can be 3.45 or less, for example, 3.10 to 3.45. Examples of binder (a) include acrylic adhesives, silicone adhesives, rubber adhesives, polypropylene (PP), polyethylene (PE), etc. Examples of binder (b) include polysulfone (PSU), polyphenylsulfone (PPSU), etc.

[0049] In the second coating 3, one or more fillers can be used alone or in combination. In one embodiment, it is preferred that the second coating 3 contains a carbon material filler. As this carbon material filler, the carbon material filler described above in relation to the first coating 2 can be used. In another embodiment, the second coating 3 can contain inorganic fillers other than carbon materials. As this inorganic filler, the inorganic filler described above in relation to the first coating 2 can be used. The carbon material filler and the inorganic filler can be used in combination.

[0050] The content of the filler in the second coating 3 is, as the volume % at 25°C based on the total amount of the second coating 3 (100% by volume), preferably 20% by volume or more from the viewpoint of facilitating the peeling of the second coating 3 from the current collector 1, and can be preferably 90% by volume or less from the viewpoint of the processability during coating peeling. In one embodiment, from the viewpoint of easily suppressing the adhesion of the second coating 3 to the roller in the subsequent hot pressing step S6, the content of the filler in the second coating 3 is, as the volume % at 25°C based on the total amount of the second coating 3 (100% by volume), 40% by volume or more, and the second coating 3 can be formed in such a manner that the end portion of the second coating 3 is aligned with the end portion of the current collector.

[0051] In one embodiment, from the viewpoint of facilitating the lamination of each layer constituting the battery on the first coating 2 and the second coating 3, the thickness of the second coating 3 can be made equal to the thickness of the first coating 2. From the viewpoint of ensuring the strength of the second coating 3 and facilitating the removal of the second coating 3 together with the layer thereon in the subsequent removal step S7, the thickness of the second coating 3 can be, for example, from 0.5 μm to 5.0 μm.

[0052] The second coating 3 is removed from the surface of the current collector 1 in the subsequent removal step S7. The phenomenon of losing the bonding state between the second coating 3 and the current collector 1 can occur in the hot pressing step S6, or can occur in the second electrode forming step S5 or the solid electrolyte layer forming step S4, or can occur in the first electrode forming step S3.

[0053] Through processes S1 and S2, a conductive coated current collector 10 according to an embodiment is obtained. The conductive coated current collector 10 includes a conductive substrate 1, a conductive first coating 2, and a second coating 3. The conductive substrate 1 is in a plate shape, a sheet shape, or a foil shape. The first coating 2 is provided in a first region R1 that occupies a part of the first surface 1a of the conductive substrate 1. The second coating 3 is provided adjacent to the first coating 2 in a second region R2 of the first surface 1a of the conductive substrate 1 that occupies the outer peripheral side of the first coating 2. In the conductive coated current collector 10, the second coating 3 is a coating that is more easily peeled off than the first coating 2. In one embodiment, the second coating 3 may be a coating that is more easily peeled off from the current collector 1 than the first coating 2 when shear stress is applied together with heat or stress in a direction crossing the first surface 1a of the current collector 1. In another embodiment, the second coating 3 may be a coating that is more easily peeled off from the current collector 1 than the first coating 2 when shear stress or stress in a direction crossing the first surface 1a of the current collector 1 is applied.

[0054] Figure 2G A cross-sectional view schematically illustrating the first electrode layer forming process S3 (hereinafter referred to as "process S3"). Figure 2H is Figure 2G a plan view as viewed in the direction of IV-IV of. Process S3 is a process of forming a first electrode layer 4 containing a first active material and having a first polarity on the surfaces of the first coating 2 and the second coating 3 of the conductive coated current collector 10 including the first coating 2 and the second coating 3. In process S3, the first electrode layer 4 is continuously formed over the surfaces of the first coating 2 and the second coating 3. In the present embodiment, the first electrode layer 4 is a negative electrode layer (hereinafter referred to as "negative electrode layer 4") containing a negative electrode active material.

[0055] 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, in the case of manufacturing a lithium ion secondary battery 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 the elements, boron-added carbon, etc. Examples of the elements that can be alloyed with lithium include silicon (Si) and tin.

[0056] The binder connects the active material or the conductive additive 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 fluororesins 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), resins containing alkoxysilyl groups, acrylic resins containing monomer units such as acrylic acid or methacrylic acid, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester cross-linked bodies, and starch-acrylic acid graft polymers.

[0057] Examples of the conductive additive include acetylene black, carbon black, and graphite. A viscosity-adjusting solvent such as N-methyl-2-pyrrolidone (NMP) can be used in the negative electrode layer 4.

[0058] The negative electrode layer 4 can be formed, for example, through the following steps. The negative electrode active material, the conductive additive, the binder, and optionally the solid electrolyte are put into a solvent and kneaded to obtain a slurry-like negative electrode mixture. Then, the negative electrode mixture is coated on the surfaces of the first coating 2 and the second coating 3 of the conductive coated current collector 10 and dried.

[0059] Figure 2I A sectional view schematically showing the solid electrolyte layer forming step S4 (hereinafter referred to as "step S4"). Figure 2J For Figure 2I a plan view seen in the V-V direction. Step S4 is a step of 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 can be used alone or in combination. The solid electrolyte layer 5 contains a solid electrolyte having conductivity for ions occluded 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 the solid electrolyte 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.

[0060] The solid electrolyte layer 5 can be fabricated by adding a solid electrolyte and an optional binder to a solvent and kneading them to obtain a paste-like electrolyte mixture, and then through steps such as coating and drying the electrolyte composition. As the binder in the solid electrolyte 5, the binder described above in relation to the first electrode layer (negative electrode layer) 4 can be used. The solid electrolyte layer 5 can be formed, for example, by directly coating the electrolyte mixture on the surface of the first electrode layer (negative electrode layer) 4. Additionally, the solid electrolyte layer 5 can be formed, for example, by the following steps. Coating the electrolyte mixture on the surface of a substrate such as a metal foil (e.g., Al foil, etc.), and forming the solid electrolyte layer 5 on the surface of the substrate. Overlay the solid electrolyte layer 5 formed on the surface of the substrate on the surface of the first electrode layer 4 of the composite body 20 on which the first electrode layer 4 is formed on the conductive coating current collector 10. Through pressing processes such as roll pressing, transfer the solid electrolyte layer 5 from the substrate surface to the surface of the first electrode layer 4.

[0061] Figure 2K A cross-sectional view schematically illustrating the second electrode layer forming step S5 (hereinafter referred to as "step S5"). Figure 2L For Figure 2K a plan view taken along the line VI-VI. 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 (hereinafter referred to as "positive electrode layer 6") containing a positive electrode active material. The positive electrode layer 6 contains a positive electrode active material, a conductive additive, 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, and sulfur, etc. The composition of the composite oxide contains, 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, etc. As the conductive additive and binder in the positive electrode layer 6, the same conductive additive and binder as those used in the negative electrode layer 4 can be used. A solid electrolyte can be further included in the positive electrode layer 6. 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.

[0062] The positive electrode layer 6 can be fabricated by putting a positive electrode active material, a conductive additive, a binder, and optionally a solid electrolyte into a solvent and kneading them to obtain a paste-like positive electrode mixture, and then through steps such as coating and drying the positive electrode mixture. For example, the positive electrode layer 6 can be formed by directly coating the positive electrode mixture on the surface of the solid electrolyte layer 5. Additionally, the positive electrode layer 6 can be formed, for example, by the following steps. Coat the positive electrode mixture on the surface of a substrate such as a metal foil (e.g., Al foil, etc.), and form the positive electrode layer 6 on the surface of this substrate. Overlap the positive electrode layer 6 formed on the surface of this substrate 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 coating current collector 10. Through pressing processes such as roll pressing, transfer the positive electrode layer 6 from the substrate surface to the surface of the solid electrolyte layer 5. Examples of the solvent used for forming each layer include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, water, etc. In one embodiment, the second electrode layer 6 can be formed so as to straddle the boundary between the first coating 2 and the second coating 3 in a top view. In one embodiment, the boundary between the first coating 2 and the second coating 3 can be formed on the current collector 1 at a position (e.g., in a straight line) where the first electrode layer 4, the solid electrolyte layer 5, and the second electrode layer 6 are not all cut off at the same time.

[0063] Figure 2M A cross-sectional view schematically illustrating the hot pressing process S6 (hereinafter referred to as "process S6") and the removing process S7 (hereinafter referred to as "process S7"). Figure 2N For Figure 2M a plan view taken along the VII-VII direction of. Process S6 is a process of hot pressing the current collector-electrode composite body 40 obtained through processes S1 to S5. Through process S6, the current collector-electrode composite body is densified. Hot pressing can be carried out, for example, by roll pressing. The temperature of hot pressing can be set, for example, to a temperature not less than 10 °C above the melting point of the binder contained in the first coating 2, or to a temperature not greater than the melting point of the binder contained in the first coating 2. In one embodiment, the temperature of hot pressing can be set from 130 °C to 200 °C. In the case where hot pressing is carried out by roll pressing, for example, the pressure of hot pressing can be set to a line pressure of 3 t / cm to 10 t / cm.

[0064] Step S7 is a step of removing the second coating layer 3 from the current collector 1 together with the portion of the first electrode layer (negative electrode layer) 4 laminated on the second coating layer 3, the portion of the solid electrolyte layer 5 laminated on the second coating layer 3, and the portion of the second electrode layer (positive electrode layer) 6 laminated on the second coating layer 3. In one embodiment, the second coating layer 3 loses its bonding state with the first current collector 1 due to the heat and stress applied during hot pressing in step S6. In another embodiment, the second coating layer 3 loses its bonding state with the first current collector 1 due to the stress applied during 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 due to the stress applied during 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 all embodiments, the bonding state between the second coating layer 3 and the first current collector 1 is lost at 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. After step S7, the peripheral portions of the first electrode layer (negative electrode layer) 4, the solid electrolyte layer 5, and the second electrode layer (positive electrode layer) 6 that have coating sag (coating defects) can be removed together with the second coating layer 3. In the current collector-electrode composite body 50 that has undergone steps S6 and S7, 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 can be obtained in the portion where the second coating layer 3 has been removed without cutting the current collector-electrode composite body.

[0065] Figure 2O A cross-sectional view schematically illustrating the second current collector lamination step S8 (hereinafter sometimes referred to as "step S8"). Figure 2P is Figure 2O a plan view seen in the direction of VIII-VIII. 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 body 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, foil, or porous body formed of the conductive material described above in relation to the first current collector can be used.

[0066] The housing process S9 (hereinafter sometimes referred to as "process S9") is a process of housing the all-solid-state battery 100 obtained through processes S1 to S8 in an outer packaging material (not shown) and sealing it. As the outer packaging material, an outer packaging material usable for an all-solid-state battery can be used. As materials that can constitute such an outer packaging material, for example, metal materials such as aluminum and stainless steel, and resin materials such as polyphenylene sulfide resin and polyimide resin can be cited. In addition, the shape of the outer packaging material is not particularly limited, and for example, it can be circular (cylindrical, coin-shaped, button-shaped), hexahedral (cuboid-shaped, cubic-shaped), or bag-shaped, or a shape obtained by processing and deforming them. After process S8, before housing the all-solid-state battery 100 in the outer packaging material, the all-solid-state battery 100 can be partially cut as needed.

[0067] The all-solid-state battery 100 has a laminated structure in which a first current collector 1, a coating 2, a first electrode layer (negative electrode layer) 4, a solid electrolyte layer 5 containing a solid electrolyte, a second electrode layer (positive electrode layer) 6, and a second current collector 7 electrically connected to the second electrode layer 6 are laminated in sequence. The coating 2 is a conductive coating provided in a first region R1 that occupies a part of the first surface 1a of the first current collector 1. The first electrode layer (negative electrode layer) 4 is provided in contact with the coating 2 without directly contacting the first current collector 1. The first electrode layer (negative electrode layer) 4 contains a first active material (negative electrode active material) and has a first polarity (-). The second electrode layer (positive electrode layer) 6 contains a second active material (positive electrode active material) and has a polarity (+) opposite to the first polarity (-). In the all-solid-state battery 100, the end faces of the coating 2, the first electrode layer 4, the solid electrolyte layer 5, and the second electrode layer 6 are aligned. If there is remaining coating sag, such a structure cannot be obtained. 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 2. The exposed part of the first current collector can be preferably utilized effectively as a terminal.

[0068] In the above description related to the present invention, the manufacturing method S10, the conductive coating current collector 10, and the all-solid-state battery 100 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 are mainly cited, but the present invention is not limited to these forms. For example, it can also be set as a manufacturing method, a conductive coating current collector, and an all-solid-state battery 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.

[0069] In the above description related to the present invention, the manufacturing method S10 in the form of a all-solid-state battery as a lithium-ion secondary battery and the all-solid-state battery 100 in the form of a lithium-ion secondary battery are mainly listed, but the present invention is not limited to these forms. For example, as the positive electrode active material and the negative electrode active material, active materials that occlude and release ions other than lithium ions (such as Na + 、K + 、Mg 2+ 、Ca 2+ 、Al 3+ 、Zn 2+ etc.) can be used. At the same time, as the solid electrolyte, a solid electrolyte having conductivity for the ions occluded and released by the active material can be used. Thus, it is also possible to provide an all-solid-state battery other than a lithium-ion secondary battery, and it is also possible to provide a manufacturing method of an all-solid-state battery in the form of manufacturing such an all-solid-state battery.

[0070] Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to these examples.

[0071] Example 1

[0072] An all-solid-state battery was manufactured using the following steps.

[0073] 1. Fabrication of a negative electrode current collector foil with a carbon coating

[0074] A negative electrode current collector foil with carbon coatings on both sides (both-sided CC foil) was fabricated using the following steps.

[0075] Acetylene black as a conductive material and polyvinylidene fluoride (PVDF) were weighed so that the mixing weight ratio became 20:80. They were mixed together with N-methylpyrrolidone (NMP) to prepare a composition (first CC composition) for the central carbon coating (central CC layer; first CC layer). In addition, acetylene black as a conductive material and an acrylic binder with a melting point of 110 °C were weighed so that the mixing weight ratio became 20:80. They were mixed together with N-methylpyrrolidone (NMP) to prepare a composition (second CC composition) for the end CC layer (second CC layer). On both sides of an Al foil with a width of 120 mm, the first CC composition was centrally coated with a width of 62 mm to form a central CC layer (first CC layer). Next, on both sides of each central CC layer, the second CC composition was coated with a width of 5 mm to form end CC layers (second CC layers).

[0076] 2. Formation of the negative electrode layer

[0077] In a polypropylene container, PVDF, negative electrode active material (lithium titanium oxide (LTO)) particles, and a sulfide solid electrolyte (Li2S-P2S5-based glass-ceramics) are added. They are stirred for 30 minutes using an ultrasonic dispersion device to prepare a negative electrode mixture. The negative electrode composite material is coated on the CC layer surfaces (both sides) of the double-sided CC foil made in Step 1 with a width of 70 mm to form a negative electrode layer, and a double-sided CC foil-negative electrode layer laminate is made.

[0078] 3. Formation of the solid electrolyte layer

[0079] In a polypropylene container, heptane, butadiene rubber (BR), and the same sulfide solid electrolyte as in Step 2 are added, and they are stirred for 15 minutes using an ultrasonic dispersion device to prepare a solid electrolyte mixture. The solid electrolyte mixture is coated on the surface of the Al foil with a width of 70 mm to form a solid electrolyte (SE) layer on the surface of the Al foil, and an Al foil-SE layer laminate is made. A plurality of such Al foil-SE layer laminates are made.

[0080] 4. Formation of the positive electrode layer

[0081] Using a flip-flow coater (manufactured by Pauleck Co., Ltd.), lithium niobate is 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 atmospheric atmosphere. Next, firing is performed in an atmospheric atmosphere to obtain positive electrode active material particles with a coating layer of lithium niobate. In a polypropylene container, 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 K.K.) are added, and they are stirred for 20 minutes using an ultrasonic dispersion device to prepare a positive electrode mixture. The positive electrode mixture is coated on the surface of the Al foil with a width of 65 mm to form a positive electrode layer, and an Al foil-positive electrode layer laminate is made. A plurality of such Al foil-positive electrode layer laminates are made.

[0082] 5. Fabrication of the negative electrode current collector - electrode composite: Transfer pressing process

[0083] Cut the double-sided CC foil - negative electrode layer stack produced in Step 2, the Al foil - SE layer stack produced in Step 3, and the Al foil - positive electrode layer stack produced in Step 4 into lengths of 80 mm respectively. With the central positions of the coating parts aligned, arrange and overlap the Al foil - SE layer stacks on both sides of the double-sided CC foil - negative electrode layer stack. Roll press this stack at a line pressure of 0.4 t / cm to transfer the solid electrolyte layer, obtaining an SE layer - negative electrode layer - double-sided CC foil - negative electrode layer - SE layer stack. Furthermore, arrange and overlap the Al foil - positive electrode layer stacks on both sides thereof and roll press at a line pressure of 0.4 t / cm to transfer the positive electrode layer. Thus, a negative electrode current collector - electrode composite body having a structure in which a positive electrode layer - SE layer - negative electrode layer - double-sided CC foil - negative electrode layer - SE layer - positive electrode layer are stacked in sequence is obtained.

[0084] 6. Hot pressing process

[0085] Roll press the negative electrode current collector - electrode composite body obtained in Step 5 at a temperature of 165 °C and a line pressure of 5 t / cm for 10 minutes to densify it. At this time, peeling of the end CC layer (the second CC layer) was confirmed. Then, cut the negative electrode current collector - electrode composite body so that the size of the positive electrode layer becomes 60 mm in width × 60 mm in length.

[0086] 7. Fabrication and pasting of the positive electrode current collector foil

[0087] Weigh acetylene black and PVDF of the conductive material so that the mixing weight ratio becomes 20:80. Furthermore, add NMP to prepare a carbon coating (CC) composition (the third CC composition). Coat this third CC composition on one side of the Al foil with a thickness of 2 μm and dry it at 100 °C for 1 hour to obtain an Al foil (positive electrode current collector foil) having a CC layer (the third CC layer) on one side. Cut this positive electrode current collector foil so that the size of its CC layer becomes 57 mm in length × 57 mm in width, and paste it on both sides of the current collector - electrode composite body obtained in Step 6 using a styrene - butadiene rubber (SBR) adhesive. Thus, 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 is fabricated. Terminals are respectively joined to the positive electrode current collector foil and the negative electrode current collector foil, and then the battery is vacuum sealed in a laminated film (outer packaging material).

[0088] Examples 2 and 3

[0089] In Step 1, the compositions of the first and second CC compositions for manufacturing the double-sided CC foil were changed as described in Table 1. Otherwise, the batteries were manufactured using the same steps as in Example 1. In Examples 2 and 3, peeling of the end CC layer (second CC layer) could be confirmed in the transfer pressing process (Step 5).

[0090] Comparative Examples 1 to 5

[0091] In Step 1, the compositions of the first and second CC compositions for manufacturing the double-sided CC foil were changed as described in Table 1. Otherwise, the batteries were manufactured using the same steps as in Example 1. However, in Comparative Examples 1, 2, 4, and 5, peeling of the end CC layer (second CC layer) was not confirmed. Therefore, when joining the terminal to the negative electrode current collector foil in Step 7, the terminal was welded outside the end CC layer (second CC layer). In Comparative Example 3, peeling of the end CC layer could be confirmed in the hot pressing process (Step 6).

[0092] Charge-discharge test

[0093] For each of the batteries manufactured in Examples 1 to 3 and Comparative Examples 1 to 5, the following steps were used to conduct a charge-discharge test and measure the internal resistance. The battery to be evaluated was subjected to constant current and constant voltage charging at a charging voltage of 2.95 V and a charging rate (C rate) of 0.3C, and then discharged to a cut-off voltage of 1.5 V. Next, after charging to 2.17 V, a constant current discharge was performed at a discharge rate of 5C, and the internal resistance was calculated from the voltage change ΔV.

[0094] Evaluation results

[0095] In Example 1, the end CC layer (the second CC layer) could be peeled off during the hot pressing process (Step 6), while in Example 2, the peeling of the end CC layer could be confirmed during the transfer pressing process (Step 5). In Comparative Examples 1, 2, 4, and 5, the end CC layer could not be peeled off in all processes. It is considered that the battery in Comparative Example 3 showed a high internal resistance because the electron conductivity of the CC layer in the central part was low. In Example 1, it is considered that due to the dissolution of the adhesive in the end CC layer and the presence of carbon in the end CC layer during the hot pressing process (Step 6), the end CC layer became prone to sliding and peeling. In Examples 2 and 3, since the adhesive in the end CC layer was hard, during the transfer pressing process (Step 7), due to the pressing stress, a difference in elongation rate occurred, and the end CC layer peeled off. Even when an adhesive with a relatively low melting point was used for the end CC layer, in the case where the conductive material (carbon) did not enter (Comparative Examples 1 and 2), the end CC layer did not peel off. The reason is considered to be that there was no sliding between the adhesive and the aluminum foil. Even when a thermosetting resin with a relatively low dielectric constant was used as the adhesive for the end CC layer, in the case of the adhesive alone (Comparative Examples 1 and 2), the end CC layer could not be peeled off. The reason is considered to be that the adhesive force was high. When polyamideimide (PAI) or PVDF was used as the adhesive for the end CC layer (Comparative Examples 4 and 5), the end CC layer could not be peeled off. The reason is considered to be that these adhesives had a high dielectric constant and a high adhesive force.

[0096]

Claims

1. A method for manufacturing an all-solid-state battery, comprising the following steps: forming a conductive first coating layer on a first region occupying a portion of a first surface of a first current collector; The 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 occupying the outer peripheral side of the first coating layer, wherein the second coating layer is more easily peeled off from the first surface of the first current collector than the first coating layer; 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 through the step of forming the first coating layer and the step of forming the second coating layer, wherein the first electrode layer is continuously formed over the surfaces of the first coating layer and the second coating layer; forming a solid electrolyte layer including a solid electrolyte on a surface of the first electrode layer; forming a second electrode layer including a second active material and having a second polarity on a surface of the solid electrolyte layer, wherein the second polarity is opposite to the first polarity; a step of hot-pressing the current collector-electrode complex obtained through the step of forming the first coating layer to the step of forming the second electrode layer; A step of removing the second coating layer from the first current collector together with the portion of the first electrode layer stacked on the second coating layer, the portion of the solid electrolyte layer stacked on the second coating layer, and the portion of the second electrode layer stacked on the second coating layer; and A step of laminating a second current collector on the surface of the second electrode layer of the current collector-electrode complex after the step of hot pressing and the step of removing the second coating layer.

2. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The first coating comprises: As a binder of a thermoplastic resin having a melting point of 165°C or above; and The carbon material filler is 15% by volume or more at 25° C. based on the total amount of the first coating layer. The second coating comprises: An adhesive having a melting point of 110° C. or lower, and / or an adhesive 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 The carbon material filler is 20% by volume or more at 25° C. based on the total amount of the second coating layer.

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

4. A conductive coated current collector having a conductive coating, comprising: A conductive substrate in the form of a plate, sheet or foil; a conductive first coating disposed on a first region occupying a portion of a first side of the conductive substrate; A second coating layer is provided adjacent to the first coating layer in a second region of the first surface of the conductive substrate occupying an outer peripheral side of the first coating layer, The second coating layer is a coating layer that is easier to peel off from the first surface of the conductive substrate than the first coating layer.

5. The current collector according to claim 3, wherein The first coating comprises: As a binder of a thermoplastic resin having a melting point of 165°C or above; and The carbon material filler is 15% by volume or more at 25° C. based on the total amount of the first coating layer. The second coating comprises: An adhesive having a melting point of 110° C. or lower, and / or an adhesive 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 The carbon material filler is 20% by volume or more at 25° C. based on the total amount of the second coating layer.

6. An all-solid-state battery comprising: a first current collector; a conductive coating disposed on a first region occupying a portion of a first face of the first current collector; a first electrode layer which is not in direct contact with the first current collector but is disposed in contact with the coating layer, contains a first active material and has a first polarity; a solid electrolyte layer comprising a solid electrolyte; a second electrode layer comprising a second active material and having a second polarity opposite to the first polarity; and a second current collector electrically connected to the second electrode layer, A stacked structure comprising the first current collector, the conductive coating, the first electrode layer, the solid electrolyte layer, the second electrode layer and the second current collector stacked in sequence in a first direction, A second region not covered by the coating layer exists on the outer peripheral side of the first region of the first surface of the first current collector. The end surface of the coating layer, the end surface of the first electrode layer, the end surface of the solid electrolyte layer, and the end surface of the second electrode layer are neat.

7. The all-solid-state battery according to claim 5, wherein: The coating comprises: As a binder of a thermoplastic resin having a melting point of 165°C or above; and The carbon material filler is 15% by volume or more at 25° C. based on the total amount of the first coating layer.

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