All-solid-state battery

Abstract

The problem to be solved by the present invention is to provide an all-solid-state battery capable of suppressing damage to the end of the positive electrode while sufficiently ensuring insulation between the positive electrode and the negative electrode against compressive stress applied by compressive input, and capable of suppressing damage to the end of the positive electrode while suppressing damage to the end of the negative electrode against expansion and contraction of the negative electrode caused by charging and discharging of the all-solid-state battery. Consequently, it is possible to suppress the concentration of stress on the ends of the electrode laminate in the lamination direction, thereby suppressing abnormal precipitation of lithium metal due to localization of the battery reaction, or a decrease in the capacity of the all-solid-state battery. In order to solve the problem, this all-solid-state battery is provided with an electrode laminate in which a positive electrode current collector, a positive electrode layer, a solid-state electrolyte layer, a negative electrode layer, and a negative electrode current collector are laminated in this order, said electrode laminate including a plurality of electrode bodies that are laminated, said electrode bodies being formed by laminating a positive electrode layer, a solid-state electrolyte layer, a negative electrode layer, and a negative electrode layer in this order at the ends of the electrode laminate in the lamination direction. A resin coating layer capable of following expansion and contraction of the electrode laminate is provided.

Description

Technical Field

[0001] The present invention relates to an all-solid-state battery. Background Art

[0002] In recent years, research and development of secondary batteries that contribute to energy efficiency has been underway to ensure more people have access to affordable, reliable, sustainable, and advanced energy. As a secondary battery, lithium metal batteries, with their high energy density, have attracted attention.

[0003] Lithium metal batteries are secondary batteries that use lithium metal as the negative electrode and can be high-capacity. Among them, so-called all-solid-state lithium metal batteries achieve a fully solid-state structure by replacing the electrolyte with a solid electrolyte layer, and have attracted attention for their excellent safety. For example, an all-solid-state lithium metal battery has a single-cell structure comprising a negative electrode composed of lithium metal, a positive electrode, and a solid electrolyte layer.

[0004] Figure 5 It is a cross-sectional view showing the structure of a conventional all-solid-state battery. Figure 5 The electrode stack 1 of the all-solid-state battery shown comprises: a negative electrode, formed by a negative electrode collector 2a and a lithium metal layer (negative electrode layer) 3a, or a negative electrode collector 2b and a lithium metal layer (negative electrode layer) 3b; a positive electrode, formed by a positive electrode collector 4 and a positive electrode active material layer (positive electrode layer) 5a or 5b; and solid electrolyte layers 6a and 6b, adjacent to the positive electrode active material layer (positive electrode layer) 5a or 5b.

[0005] Figure 5 The electrode stack 1 of the illustrated all-solid-state battery has an intermediate layer 7a between the lithium metal layer (negative electrode layer) 3a and the solid electrolyte layer 6a, and an intermediate layer 7b between the lithium metal layer (negative electrode layer) 3b and the solid electrolyte layer 6b.

[0006] Insulating material 8a is placed at both ends of the positive electrode active material layer (positive electrode layer) 5a, and insulating material 8b is placed at both ends of the positive electrode active material layer (positive electrode layer) 5b. While insulating materials 8a and 8b are made of materials that lack electron conductivity, ion-conducting materials or solid electrolytes can also be used. In the figure, Ld represents the stacking direction of the electrode stack 1 constituting the all-solid-state battery, and Vd represents the direction perpendicular to the stacking direction (the plane direction) of the electrode stack 1 constituting the all-solid-state battery.

[0007] The all-solid-state battery has a compression input step in the module assembly process, at which time a compressive stress of about 1 MPa is applied. Figure 6 As shown, the compression input is a pressure applied from the outside of the electrode stack 1 in a direction Vd perpendicular to the stacking direction Ld of the electrode stack 1 .

[0008] At this time, if Figure 5 As shown, the electrode stack 1 has the following structure: the positive electrode active material layer (positive electrode layer) 5a or 5b having insulating materials 8a, 8b at the end extends outward from the end of the electrode stack 1 in a direction (surface direction) Vd perpendicular to the stacking direction Ld of the electrode stack 1. Therefore, due to the application of compressive stress, damage such as breakage may sometimes occur.

[0009] Therefore, in order to fully ensure the insulation between the positive and negative electrodes and suppress damage to the positive terminal portion against the compressive stress applied by the compressive input, it is proposed to provide a resin coating ( Figure 6 9 in the above).

[0010] [Prior Art Literature]

[0011] (Patent Document)

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-39756 Summary of the Invention

[0013] [Problems to be solved by the invention]

[0014] However, if a resin coating is provided at the ends of the electrode stack in the stacking direction, the expansion and contraction of the negative electrode caused by the charge and discharge of the all-solid-state battery will cause stress concentration, especially on the positive electrode and solid electrolyte layer located at the two ends of the electrode stack in the stacking direction. Figure 7B This is a diagram for explaining stress concentration caused by charge and discharge in an all-solid-state battery having a resin coating layer 9 at the end portion of the electrode stack 1 in the stacking direction Ld. Figure 7A This is a diagram showing the state of an all-solid-state battery when fully discharged (SOC: 0%). Figure 7B This diagram shows the state of an all-solid-state battery when fully charged (SOC: 100%).

[0015] like Figure 7A As shown, in the all-solid-state battery at full discharge (SOC: 0%), the lithium metal layers (negative electrode layers) 3a and 3b are in an unexpanded state, and the resin coating 9 provided in the stacking direction Ld of the electrode stack 1 extends at the end of the electrode stack 1 to the same size as the thickness of the electrode stack 1.

[0016] In all-solid-state batteries, the expansion of the negative electrode increases with the increase of charging rate. Figure 7BAs shown, in a fully charged (SOC: 100%) all-solid-state battery, the expansion of the lithium metal layers (negative electrode layers) 3a, 3b, etc., causes the thickness of the electrode stack 1 (the dimension in the stacking direction Ld) to be greater than the thickness (the length in the stacking direction Ld) of the electrode stack 1 when fully discharged (SOC: 0%). As a result, the thickness of the electrode stack 1 (the length in the stacking direction Ld) is greater than the length of the resin coating 9 provided in the stacking direction Ld of the electrode stack 1. The resin coating 9 stretches the positive electrode and solid electrolyte layers located at both ends of the electrode stack 1 in the stacking direction Ld, causing stress to concentrate in these areas.

[0017] Furthermore, repeated charge and discharge cycles of all-solid-state batteries cause stress to repeatedly concentrate on the positive electrode and solid electrolyte layer at the ends of the electrode stack in the stacking direction. As a result, for example, if the solid electrolyte layer at the ends of the electrode stack in the stacking direction suffers damage, such as cracks, abnormal lithium metal precipitation occurs due to localized battery reactions. Furthermore, if the positive electrode active material layer (positive electrode layer) at the ends of the electrode stack in the stacking direction suffers damage, such as cracks, the capacity of the all-solid-state battery decreases.

[0018] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide an all-solid-state battery that can fully ensure the insulation between the positive and negative electrodes for the compressive stress applied due to the compression input, while suppressing the damage to the positive terminal, and can suppress the stress concentration on the end of the electrode stack in the stacking direction due to the expansion and contraction of the negative electrode caused by the charging and discharging of the all-solid-state battery, thereby suppressing the abnormal precipitation of lithium metal caused by the localization of the battery reaction or the decrease in the capacity of the all-solid-state battery.

[0019] [Technical means to solve the problem]

[0020] The inventors of this invention have conducted extensive research to achieve the above-mentioned objectives and have discovered that providing a resin coating that can follow the expansion and contraction of the electrode stack at the ends of the electrode stack in the stacking direction can solve the above-mentioned problems, thereby completing the present invention.

[0021] The all-solid-state battery disclosed herein includes the following aspects.

[0022] (1) An all-solid-state battery comprising an electrode stack, wherein the electrode stack includes an electrode body and is formed by stacking a plurality of the aforementioned electrode bodies, wherein the electrode body is formed by stacking a positive electrode collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode collector in this order, and wherein the aforementioned positive electrode collector has an insulating material adjacent to an end of the aforementioned positive electrode layer on a surface on the side of the aforementioned positive electrode layer, the aforementioned solid electrolyte layer is arranged in contact with the aforementioned positive electrode layer and the aforementioned insulating material, and in a direction perpendicular to the stacking direction of the aforementioned electrode stack, the end of the aforementioned insulating material is further outward than the end of the aforementioned negative electrode layer and the end of the aforementioned negative electrode collector, and in the stacking direction of the aforementioned electrode stack, a resin coating is arranged at the end of the aforementioned electrode stack in a manner in contact with the end of the aforementioned insulating material, the aforementioned resin coating is composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the aforementioned electrode stack, and the aforementioned hard layer is arranged at both ends of the aforementioned electrode stack in the stacking direction.

[0023] (2) The all-solid-state battery according to (1), wherein, in the resin coating layer, at an end portion of the electrode stack in the stacking direction that does not abut against the insulating material, the length of the hard layer is greater than the length of the soft layer.

[0024] (3) The all-solid-state battery according to (1) or (2), wherein the soft layer comprises two or more layers.

[0025] (4) The all-solid-state battery according to (1) or (2), wherein an end portion of the soft layer is located outside an end portion of the hard layer in a direction perpendicular to the stacking direction of the electrode stack.

[0026] (5) An all-solid-state battery according to (1) or (2), wherein the thickness of the soft layer decreases from the end portion abutting against the insulating material toward the end portion not abutting against the insulating material in a direction perpendicular to the stacking direction of the electrode stack.

[0027] (Effects of the Invention)

[0028] In the all-solid-state battery of the embodiment (1), the insulation between the positive electrode and the negative electrode can be fully ensured for the compressive stress applied due to the compression input, while suppressing the damage to the positive terminal. Moreover, for the expansion and contraction of the negative electrode caused by charging and discharging, the stress can be suppressed from concentrating on the end in the stacking direction of the electrode stack, thereby suppressing the abnormal precipitation of lithium metal caused by the localization of the battery reaction or the decrease in the capacity of the all-solid-state battery.

[0029] In the all-solid-state battery of the aspect (2), the relatively long hard layer can effectively disperse stress to the end portions of the electrode stack in the stacking direction, thereby suppressing stress concentration.

[0030] In the all-solid-state battery of the embodiment (3), two or more soft layers can follow the expansion and contraction of the negative electrode caused by charge and discharge by deformation, thereby suppressing the concentration of stress on the ends of the electrode stack in the stacking direction.

[0031] In the all-solid-state battery of embodiment (4), since the end of the soft layer is located further outward than the end of the hard layer in the direction perpendicular to the stacking direction of the electrode stack, the proportion of the hard layer in the stacking direction can be ensured, while increasing the range in which the soft layer can deform to follow the expansion and contraction of the negative electrode caused by charging and discharging.

[0032] In the all-solid-state battery of the embodiment (5), the thickness of the soft layer decreases in a direction perpendicular to the stacking direction of the electrode stack from the end portion contacting the insulating material to the end portion not contacting the insulating material. Relatively speaking, the proportion of the hard layer in the stacking direction is maintained on the side of the end portion not contacting the insulating material. Thus, in the region of the end portion not contacting the insulating material, the hard layer disperses the compression input, and the soft layer, which exists over a wide area, can deform to follow the expansion and contraction of the negative electrode caused by charge and discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1A This is a cross-sectional view showing the structure of the all-solid-state battery according to the first embodiment (at the time of full discharge).

[0034] Figure 1B This is a cross-sectional view showing the structure of the all-solid-state battery according to the first embodiment (when fully charged).

[0035] Figure 2A It is a cross-sectional view showing the structure of an all-solid-state battery according to a second embodiment.

[0036] Figure 2B It is a drawing Figure 2A A cross-sectional view of the structure of a first variation of an all-solid-state battery.

[0037] Figure 2C It is a drawing Figure 2A A cross-sectional view of the structure of a second variation of the all-solid-state battery.

[0038] Figure 3 It is a cross-sectional view showing the structure of an all-solid-state battery according to a third embodiment.

[0039] Figure 4 It is a cross-sectional view showing the structure of an all-solid-state battery according to a fourth embodiment.

[0040] Figure 5 It is a cross-sectional view showing the structure of an electrode stack according to one embodiment.

[0041] Figure 6 It is a cross-sectional view showing the structure of a conventional all-solid-state battery.

[0042] Figure 7A This is a diagram for explaining stress concentration (at the time of complete discharge) caused by charge and discharge of a conventional all-solid-state battery.

[0043] Figure 7B This is a diagram for explaining stress concentration (at full charge) caused by charging and discharging of a conventional all-solid-state battery. DETAILED DESCRIPTION

[0044] (All-solid-state battery)

[0045] The all-solid-state battery disclosed herein comprises an electrode stack comprising a plurality of electrode bodies stacked together. The electrode stack is formed by sequentially stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector. The positive electrode current collector has an insulating material on its surface facing the positive electrode layer, adjacent to an end of the positive electrode layer. The solid electrolyte layer is disposed in contact with the positive electrode layer and the insulating material.

[0046] In the all-solid-state battery disclosed herein, in a direction perpendicular to the stacking direction of the electrode stack, the end of the insulating material is located further outward than the end of the negative electrode layer and the end of the negative electrode collector, and in a direction perpendicular to the stacking direction of the electrode stack, a resin coating is arranged at the end of the electrode stack in a manner that abuts the end of the insulating material.

[0047] Furthermore, in the all-solid-state battery of the present disclosure, the resin coating layer is composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the electrode stack, and the hard layer is arranged at both ends of the electrode stack in the stacking direction.

[0048] By having two layers of differing hardness, a hard layer and a soft layer, the resin coating layer mitigates the compressive stress caused by the compressive input. As a result, the all-solid-state battery of the present invention can fully ensure insulation between the positive and negative electrodes while minimizing damage to the positive terminal.

[0049] In the resin coating, the corners of the electrode stack in the stacking direction that do not contact the insulating material may be C-chamfered or R-chamfered. By having C or R corners, localized contact of the ends can be prevented and robustness against stacking misalignment during stacking or compression input can be improved.

[0050] Preferably, the hard layer of the resin coating is longer than the soft layer at the ends of the electrode stack in the stacking direction that do not contact the insulating material. This longer hard layer can effectively mitigate stress during compression input and also suppress deformation caused by flexure during cell restraint and charging.

[0051] In addition, in the all-solid-state battery disclosed herein, a resin coating is arranged at the end of the electrode stack in a direction perpendicular to the stacking direction of the electrode stack in a manner abutting against the end of the insulating material. In the stacking direction of the electrode stack, the resin coating is composed of a hard layer and a soft layer, and the hard layer is arranged at both ends of the electrode stack in the stacking direction. Thus, the insulation of the positive electrode and the negative electrode can be fully ensured for the compressive stress applied due to the compression input, while suppressing the damage to the positive terminal. Moreover, the expansion and contraction of the negative electrode caused by charging and discharging can be suppressed from concentrating on the end of the electrode stack in the stacking direction, thereby suppressing the abnormal precipitation of lithium metal caused by the localization of the battery reaction or the decrease in the capacity of the all-solid-state battery.

[0052] (First embodiment)

[0053] Figure 1A and Figure 1B It is a cross-sectional view showing the structure of the all-solid-state battery according to the first embodiment. Figure 1A is a diagram showing the state of the all-solid-state battery of the first embodiment when fully discharged (SOC: 0%). Figure 1B This is a diagram showing the state of the all-solid-state battery according to the first embodiment when fully charged (SOC: 100%).

[0054] Figure 1A and Figure 1B The electrode stack 1 of the all-solid-state battery shown comprises: a negative electrode, formed by a negative electrode collector 2a and a lithium metal layer (negative electrode layer) 3a, or a negative electrode collector 2b and a lithium metal layer (negative electrode layer) 3b; a positive electrode, formed by a positive electrode collector 4 and a positive electrode active material layer (positive electrode layer) 5a or 5b; and solid electrolyte layers 6a and 6b, adjacent to the positive electrode active material layer (positive electrode layer) 5a or 5b.

[0055] Figure 1A and Figure 1B The electrode stack 1 of the all-solid-state battery shown has an intermediate layer 7a between the lithium metal layer (negative electrode layer) 3a and the solid electrolyte layer 6a, and an intermediate layer 7b between the lithium metal layer (negative electrode layer) 3b and the solid electrolyte layer 6b. Furthermore, insulating material 8a is disposed at both ends of the positive electrode active material layer (positive electrode layer) 5a, and insulating material 8b is disposed at both ends of the positive electrode active material layer (positive electrode layer) 5b. Vd in the figure represents the direction (plane direction) perpendicular to the stacking direction of the electrode stack 1 constituting the all-solid-state battery.

[0056] In the all-solid-state battery of the first embodiment, in a direction perpendicular to the stacking direction of the electrode stack 1, the ends of the insulating materials 8a and 8b are located further outward than the ends of the lithium metal layers (negative electrode layers) 3a and 3b and the ends of the negative electrode collectors 2a and 2b.

[0057] In the all-solid-state battery of the first embodiment, the resin coating 9a is disposed at the ends of the electrode stack 1 in a direction Vd perpendicular to the stacking direction of the electrode stack 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0058] In the all-solid-state battery of the first embodiment, the resin coating layer 9a is composed of two hard layers 11a and one soft layer 12a in a direction perpendicular to the stacking direction of the electrode stack 1. In the resin coating layer 9a of the all-solid-state battery of the first embodiment, the hard layers 11a are arranged at both ends in the stacking direction of the electrode stack 1, and the soft layer 12a is arranged approximately near the center of the resin coating layer 9a.

[0059] like Figure 1A As shown, in the all-solid-state battery at full discharge (SOC: 0%), the lithium metal layers (negative electrode layers) 3a and 3b are in an unexpanded state, and the resin coating 9a provided at the end of the electrode stack 1 in the stacking direction extends at the end of the electrode stack 1 to the same length as the thickness of the electrode stack 1.

[0060] like Figure 1B As shown, in the fully charged (SOC: 100%) all-solid-state battery, the lithium metal layers (negative electrode layers) 3a and 3b expand, so the thickness of the electrode stack 1 (the length in the stacking direction) is greater than Figure 1A The thickness (length in the stacking direction) of the electrode stack 1 at the time of full discharge (SOC: 0%) is shown.

[0061] At this time, the resin coating layer 9a of the all-solid-state battery of the first embodiment extends its length in the stacking direction of the electrode stack 1 as the lithium metal layers (negative electrode layers) 3a and 3b expand. Specifically, the soft layer 12a disposed approximately near the center of the resin coating layer 9a extends as the lithium metal layers (negative electrode layers) 3a and 3b expand. As a result, the resin coating layer 9a of the all-solid-state battery of the first embodiment follows the increase in thickness (length in the stacking direction) of the electrode stack 1 caused by the expansion of the lithium metal layers (negative electrode layers) 3a and 3b.

[0062] As a result, in the all-solid-state battery of the first embodiment, even if the lithium metal layer (negative electrode layer) expands during charging, the positive electrode active material layer (positive electrode layer) and the solid electrolyte layer located at the two end portions in the stacking direction of the electrode stack can be prevented from being stretched by the resin coating, thereby avoiding stress concentration in these portions.

[0063] In the resin coating layer 9a of the all-solid-state battery of the first embodiment, the total length Ta of the hard layers 11a is greater than the length Tb of the soft layers 12a at the ends of the electrode stack 1 in the stacking direction that do not contact the insulating materials 8a and 8b. This greater total length Ta of the hard layers 11a than the length Tb of the soft layers 12a effectively mitigates stress during compression input and suppresses deformation caused by flexure during cell restraint or charging.

[0064] (Second embodiment)

[0065] Figure 2A 1 is a cross-sectional view showing the structure of an all-solid-state battery according to the second embodiment. The structure of the electrode stack 1 of the all-solid-state battery according to the second embodiment is the same as that of the electrode stack 1 of the all-solid-state battery according to the first embodiment.

[0066] In the all-solid-state battery of the second embodiment, similarly to the first embodiment, the resin coating 9b is arranged at the end of the electrode stack 1 in a direction perpendicular to the stacking direction of the electrode stack 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0067] In the all-solid-state battery of the second embodiment, the resin coating layer 9b is composed of three hard layers 11b and two soft layers 12b arranged perpendicular to the stacking direction of the electrode stack 1. In the resin coating layer 9b of the all-solid-state battery of the second embodiment, the hard layers 11b are arranged at both ends in the stacking direction of the electrode stack 1, and the soft layers 12b are arranged so as to be sandwiched between the hard layers 11b.

[0068] The resin coating of the all-solid-state battery disclosed herein preferably includes two or more soft layers. A resin coating including two or more soft layers allows the layers to expand at multiple locations, thereby more evenly following the increase in thickness (length in the stacking direction) of the electrode stack caused by the expansion of the lithium metal layer (negative electrode layer). As a result, the concentration of stress on the ends of the electrode stack in the stacking direction can be suppressed due to the expansion and contraction of the negative electrode caused by charging and discharging.

[0069] In the resin coating 9b of the all-solid-state battery of the second embodiment, at the ends of the electrode stack 1 in the stacking direction that do not contact the insulating materials 8a and 8b, the total length Ta of the hard layers 11b is greater than the total length Tb of the soft layers 12b.

[0070] in addition, Figure 2A The implementation methods can be considered as follows Figure 2B and Figure 2C Such a modification. Figure 2B and Figure 2CIn, with Figure 2A The corresponding parts are marked with the same symbols, and the various instructions refer to Figure 2A Instructions in .

[0071] exist Figure 2B In the modified example, the cross sections of the two soft layers 12ba are respectively trapezoidal in shape, and the relative length relationship between the upper side and the bottom side of these trapezoids is reversed in sequence according to the position in the stacking direction. Figure 2B The length Tb of the soft layer 12ba is marked in the dimension mark. Figure 2A The length Tb of the soft layer 12b is substantially equivalent (average in the Vd direction).

[0072] exist Figure 2C In the modified example, the cross sections of the three soft layers 12bb are circular, and the diameters of these circles are the same. Figure 2C The length Tb of the soft layer 12bb is marked in the dimension mark. Figure 2A The length Tb of the soft layer 12b is substantially equivalent (average in the Vd direction).

[0073] exist Figure 2B and Figure 2C In the variation of Figure 2A Similarly, for the expansion and contraction of the negative electrode caused by charge and discharge, the deformation of the soft layer 12ba or the soft layer 12bb is used to follow the displacement in the Ld direction, thereby further suppressing the concentration of stress on the end of the electrode stack in the stacking direction.

[0074] (Third embodiment)

[0075] Figure 3 1 is a cross-sectional view showing the structure of an all-solid-state battery according to a third embodiment. The structure of the electrode stack 1 of the all-solid-state battery according to the third embodiment is the same as that of the electrode stack 1 of the all-solid-state battery according to the first embodiment.

[0076] In the all-solid-state battery of the third embodiment, similarly to the first embodiment, the resin coating 9c is arranged at the ends of the electrode stack 1 in a direction perpendicular to the stacking direction of the electrode stack 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0077] In the all-solid-state battery of the third embodiment, the resin coating layer 9c is composed of three hard layers 11c and two soft layers 12c arranged perpendicular to the stacking direction of the electrode stack 1. In the resin coating layer 9c of the all-solid-state battery of the third embodiment, the hard layers 11c are arranged at both ends in the stacking direction of the electrode stack 1, and the soft layers 12c are arranged so as to be sandwiched between the hard layers 11c.

[0078] In the resin coating 9c of the all-solid-state battery of the third embodiment, the ends of the two soft layers 12c are positioned further outward than the ends of the three hard layers 11c in the direction Vd perpendicular to the stacking direction of the electrode stack 1. In other words, the width of the two soft layers 12c in the Vd direction is greater than that of the second embodiment described above. This ensures the proportion of the hard layers in the stacking direction while increasing the range within which the soft layers can deform to follow the expansion and contraction of the negative electrode caused by charging and discharging.

[0079] In the resin coating of the all-solid-state battery disclosed herein, the ends of the soft layer may be positioned further outward than the ends of the hard layer in a direction perpendicular to the stacking direction of the electrode stack. This structure can be easily achieved, for example, by first applying a resin for forming the soft layer to the end surfaces of the electrode stack to form the walls of the soft layer, and then applying a resin for forming the hard layer between the walls of the soft layer.

[0080] In the resin coating 9c of the all-solid-state battery of the third embodiment, at the ends of the electrode stack 1 in the stacking direction that do not contact the insulating materials 8a and 8b, the total length Ta of the hard layers 11c is greater than the total length Tb of the soft layers 12c.

[0081] (Fourth embodiment)

[0082] Figure 4 1 is a cross-sectional view showing the structure of an all-solid-state battery according to a fourth embodiment. The structure of the electrode stack 1 of the all-solid-state battery according to the fourth embodiment is the same as that of the electrode stack 1 of the all-solid-state battery according to the first embodiment.

[0083] In the all-solid-state battery of the fourth embodiment, similarly to the first embodiment, a resin coating 9d is arranged at the end of the electrode stack 1 in a direction perpendicular to the stacking direction of the electrode stack 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0084] In the all-solid-state battery of the fourth embodiment, the resin coating 9d is composed of two hard layers 11d and one soft layer 12d, arranged perpendicularly to the stacking direction of the electrode stack 1. In the resin coating 9d of the all-solid-state battery of the fourth embodiment, the thickness of the soft layer 12d decreases from the end in contact with the insulating materials 8a and 8b toward the end not in contact with the insulating materials 8a and 8b, perpendicularly to the stacking direction of the electrode stack 1. In other words, as shown in the figure, the boundary between the hard layer 11d and the soft layer 12d is inclined relative to the Ld direction.

[0085] In the direction perpendicular to the stacking direction of the electrode stack, the thickness of the resin coating layer of the all-solid-state battery disclosed herein may decrease from the end in contact with the insulating material toward the end not in contact with the insulating material. In other words, the hard layer and the soft layer may be layers that are not parallel to the direction perpendicular to the stacking direction of the electrode stack, as long as they are layers in the direction perpendicular to the stacking direction of the electrode stack.

[0086] If the soft layer 12d exists over a wide area, as in the resin coating 9d of the all-solid-state battery of the fourth embodiment, it can further follow the expansion and contraction of the negative electrode caused by charge and discharge, thereby further suppressing the concentration of stress on the ends of the electrode stack 1 in the stacking direction.

[0087] In addition, like the resin coating 9d of the all-solid-state battery of the fourth embodiment, the hard layer 11d is arranged at both ends of the electrode stack 1 in the stacking direction. At the ends of the electrode stack 1 in the stacking direction that are not in contact with the insulating materials 8a and 8b, as long as the total length Ta of the hard layer 11d is greater than the length of the soft layer 12d, the stress during compression input can be fully alleviated. In addition, deformation caused by bending when constraining a single cell or charging can also be suppressed.

[0088] (Composition of all-solid-state batteries)

[0089] Next, each structure of the all-solid-state battery disclosed in the present invention will be described.

[0090] (Positive electrode collector)

[0091] The positive electrode current collector used in the all-solid-state battery of the present disclosure is arranged in contact with the positive electrode layer and has the function of collecting current from the positive electrode layer. The material of the positive electrode current collector is not particularly limited as long as it can collect current from the positive electrode layer. Examples of materials for the positive electrode current collector include aluminum, aluminum alloys, stainless steel, nickel, iron, and titanium, among which at least one selected from the group consisting of aluminum, aluminum alloys, and stainless steel is preferred.

[0092] The shape of the positive electrode current collector is not particularly limited, and examples thereof include foil and plate shapes. Furthermore, the thickness of the positive electrode current collector is not particularly limited and can be the same as that used in the positive electrode of a typical all-solid-state battery. For example, the thickness of the positive electrode current collector can be in the range of 0.5 μm to 0.5 mm.

[0093] (positive electrode layer)

[0094] The positive electrode layer is a layer containing at least a positive electrode active material. The positive electrode active material contained in the positive electrode layer is not particularly limited as long as it is a material used in the positive electrode layer of a general all-solid-state battery. As the positive electrode active material, for example, if it is a lithium ion battery, a layered active material containing lithium, a spinel type active material, an olivine type active material, etc. can be listed. Specific examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), LiNiO2, etc. p Mn q Co r O2(p+q+r=1), LiNi p Al q Co r O2(p+q+r=1), lithium manganate (LiMn2O4), Li 1+x Mn 2-x-y Li-Mn spinel substituted with a heterogeneous element represented by MyO4 (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni and Zn), lithium titanate (an oxide containing Li and Ti), lithium metal phosphate (LiMPO4, M=at least one selected from Fe, Mn, Co and Ni), etc.

[0095] The content of the positive electrode active material in the positive electrode layer may be, for example, in the range of 50% to 99% by mass. The surface of the positive electrode active material may be covered with an oxide layer such as a lithium niobate layer, a lithium titanate layer, or a lithium phosphate layer.

[0096] In order to improve lithium ion conductivity, the positive electrode layer may optionally contain the following solid electrolyte. In addition, the positive electrode layer may optionally contain a binder or a conductive additive. As these substances, substances commonly used in all-solid-state batteries can be used.

[0097] The thickness of the positive electrode layer is not particularly limited and can be appropriately set according to the desired battery performance. For example, the thickness of the positive electrode layer can be in the range of 1 μm to 1 mm.

[0098] When the all-solid-state battery disclosed herein has the following intermediate layer, the positive electrode layer preferably has the same area as the intermediate layer in the stacked surface. This can improve the durability of the all-solid-state battery. The area of ​​the positive electrode layer in the all-solid-state battery disclosed herein can be, for example, a maximum of 100% of the area of ​​the intermediate layer, or 90% to 100%, or even 80% to 90%.

[0099] The method for producing the positive electrode layer is not particularly limited and can be produced by a known method. The positive electrode layer can be produced, for example, by mixing the materials constituting the positive electrode layer with a solvent to form a slurry, applying the slurry on the positive electrode current collector, and drying the slurry.

[0100] (Solid electrolyte layer)

[0101] The solid electrolyte layer is a layer containing a solid electrolyte and is arranged in contact with the positive electrode layer and the insulating material.

[0102] As the material of the solid electrolyte, as long as it has lithium ion conductivity and insulation, there is no particular limitation. As the material of the solid electrolyte, the material commonly used in all-solid-state lithium ion batteries can be used, for example, sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as lithium salts, polymer solid electrolytes such as polyethylene oxide, gel-type solid electrolytes containing ionic liquids containing lithium salts or lithium ion conductivity, etc. can be listed. Among them, from the perspective of the high conductivity of lithium ions and the structural formability or interface bonding caused by compression, sulfide solid electrolyte materials are preferably used.

[0103] The form of the solid electrolyte material is not particularly limited and may be, for example, granular. Furthermore, the content of the solid electrolyte in the solid electrolyte layer of the all-solid-state battery disclosed herein is not particularly limited. For example, the solid electrolyte content may be in the range of 50% to 99% by mass.

[0104] The solid electrolyte layer may optionally contain a binder. In addition, a binder may be optionally contained to impart mechanical strength or flexibility. As these substances, substances commonly used in all-solid-state batteries can be used.

[0105] In the direction perpendicular to the stacking direction of the electrode stack of the all-solid-state battery of the present disclosure, the end of the solid electrolyte layer may be arranged to be located substantially at the same position as the end of the insulating material.

[0106] Since the electrode stack of this shape does not have the solid electrolyte layer protruding from the end surface of the electrode stack, cracks in the solid electrolyte layer can be suppressed when pressure such as rolling is applied during the production of the electrode stack.

[0107] The method for producing the solid electrolyte layer is not particularly limited and can be produced using a known method. The solid electrolyte layer can be produced, for example, by mixing the material constituting the solid electrolyte layer with a solvent to form a slurry, applying the slurry on a substrate, and drying the slurry.

[0108] (Negative electrode current collector)

[0109] The negative electrode current collector used in the all-solid-state battery of the present disclosure is arranged in contact with the negative electrode layer and has the function of collecting the current of the negative electrode layer. As the material of the negative electrode current collector, there is no particular limitation as long as the current collection of the negative electrode layer can be performed, and it is preferably composed of a substance with a higher electrical conductivity. As a substance with a higher electrical conductivity, for example, a metal containing at least one metal element selected from the group consisting of silver, palladium, gold, platinum, aluminum, copper and nickel, or an alloy such as a stainless steel material, or a non-metal such as carbon (C) can be listed.

[0110] Among these highly conductive materials, considering both conductivity and manufacturing cost, it is preferred to use at least one selected from the group consisting of copper, SUS, and nickel. Stainless steel, in particular, is less likely to react with the negative electrode active material, positive electrode active material, and solid electrolyte. Therefore, using stainless steel as the negative electrode current collector material can reduce the internal resistance of all-solid-state batteries.

[0111] The shape of the negative electrode current collector is not particularly limited, and examples thereof include foil, plate, mesh, nonwoven fabric, foam, etc. In addition, the negative electrode current collector may be provided with a carbon layer or roughened surface to improve adhesion to the negative electrode layer.

[0112] The thickness of the negative electrode current collector is not particularly limited and can be the same as that used in negative electrodes of general all-solid-state batteries. For example, the thickness of the negative electrode current collector can be in the range of 0.5 μm to 0.5 mm.

[0113] (Negative electrode layer)

[0114] The negative electrode layer is a layer containing a negative electrode active material that donates and accepts lithium ions and electrons. The negative electrode active material contained in the negative electrode layer is not particularly limited as long as it is a material used in the negative electrode layer of a general all-solid-state battery. It is preferred to use a material with high electronic conductivity so that it can reversibly release and absorb lithium ions and can easily transport electrons. As such a negative electrode active material, for example, silicon-based active materials such as silicon and silicon alloys, or carbon-based active materials such as graphite and hard carbon, various oxide-based active materials such as lithium titanate, lithium-based active materials such as metallic lithium and lithium alloys, etc. can be listed. The negative electrode active material can use one of the above materials alone, or two or more can be used in combination.

[0115] In the all-solid-state battery disclosed herein, the negative electrode layer can be composed solely of metallic lithium or a lithium metal alloy, or a mixture thereof. A negative electrode layer composed solely of lithium metal or a lithium metal alloy, or a mixture thereof, can achieve a high-capacity all-solid-state battery due to its high capacitance per unit weight.

[0116] The content of the negative electrode active material in the negative electrode layer can be, for example, in the range of 30% by mass to 100% by mass.

[0117] In order to improve lithium ion conductivity, the negative electrode layer may optionally contain the above-mentioned solid electrolyte. In addition, the negative electrode layer may also optionally contain a binder or a conductive additive. As these substances, substances commonly used in all-solid-state batteries can be used.

[0118] The thickness of the negative electrode layer is not particularly limited and can be appropriately set according to the desired battery performance. For example, the thickness of the negative electrode layer can be in the range of 0.5 μm to 0.5 mm.

[0119] The method for producing the negative electrode layer is not particularly limited and can be produced by a known method. The negative electrode layer can be produced, for example, by mixing the materials constituting the negative electrode layer with a solvent to form a slurry, applying the slurry on the negative electrode current collector, and drying the slurry.

[0120] (Middle layer)

[0121] When the all-solid-state battery of the present disclosure includes an intermediate layer, the intermediate layer is disposed between the solid electrolyte and the negative electrode layer. When the negative electrode layer of the all-solid-state battery of the present disclosure is composed solely of metallic lithium or a lithium-metal alloy, or a mixture thereof, the intermediate layer disposed between the solid electrolyte layer and the negative electrode layer can suppress the uneven precipitation of dendrites at the interface between the solid electrolyte layer and the negative electrode layer, and can improve interfacial adhesion.

[0122] The middle layer is a layer with both electron conductivity and ion conductivity. Since the middle layer has ion conductivity, it can allow lithium ions to pass through. Therefore, as the all-solid-state battery is repeatedly charged and discharged, the lithium ions (Li + ) through the intermediate layer. The presence of the intermediate layer allows for uniform precipitation of lithium metal between the intermediate layer and the negative electrode layer. Furthermore, if the intermediate layer is flexible enough to follow the volume changes of the layers associated with charge and discharge, the interfacial adhesion can be maintained even during repeated charge and discharge of the all-solid-state battery, thereby improving the durability of the all-solid-state battery.

[0123] In the intermediate layer, the end portion, in a direction perpendicular to the stacking direction of the electrode stack of the solid-state battery disclosed herein, can be positioned approximately at the same position as the end portion of the negative electrode layer, or can be positioned further inward than the end portion of the negative electrode layer. This allows the effect of the intermediate layer to be fully realized.

[0124] The material constituting the intermediate layer is not particularly limited, and the intermediate layer may contain, for example, amorphous carbon, metal nanoparticles, and a binder as a binding material.

[0125] Unlike graphite, amorphous carbon does not react with lithium metal to form an alloy, thus suppressing the formation of dendrites and improving the cycle characteristics of all-solid-state batteries.

[0126] Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and Ketjen black, coke, and activated carbon. Amorphous carbon may be easily graphitized carbon (soft carbon), hardly graphitized carbon (hard carbon), carbon nanotubes (CNTs), fullerenes, or graphene.

[0127] By including metal nanoparticles in the intermediate layer, the electronic conductivity of the intermediate layer can be improved, resulting in more uniform precipitation of lithium metal. The metal nanoparticles are not particularly limited, and examples thereof include nanoparticles of metals such as tin, silicon, zinc, magnesium, gold, platinum, palladium, silver, aluminum, bismuth, and antimony.

[0128] The binder contained in the intermediate layer maintains the structure of the intermediate layer and improves the adhesion between the particles constituting the intermediate layer and between the intermediate layer and the solid electrolyte layer. The binder is not particularly limited and substances commonly used in all-solid-state batteries can be used.

[0129] (Insulation material)

[0130] The insulating material is disposed on the positive electrode layer side of the positive electrode current collector, adjacent to the end of the positive electrode layer. By arranging the insulating material at the end of the positive electrode layer, when the tab wires extending from the negative electrode current collectors of each monomer structure are assembled to form a battery, the bending of the tab wires can be utilized to avoid contact between the tab wires and the positive terminal, thereby suppressing short circuits. Furthermore, short circuits caused by cracks generated during repeated charging and discharging can be suppressed. Furthermore, cracks at the ends of the positive electrode mixture caused by excessive rolling during rolling of the positive electrode can be suppressed.

[0131] The insulating material can be provided at the end of the positive electrode layer, and its shape is not limited. The size of the insulating material is not particularly limited, as long as it has a thickness less than that of the positive electrode layer in the stacking direction of the electrode stack, abuts a portion or all of the end surface of the positive electrode layer, and is arranged at the end of the positive electrode layer in a direction perpendicular to the stacking direction of the electrode stack.

[0132] The material of the insulating material is not particularly limited as long as it exhibits insulating properties, and may be a so-called insulator other than a semiconductor or a conductor. The material of the insulating material can be appropriately selected depending on the properties desired to be added in addition to the insulating properties.

[0133] The method for producing the insulating material is not particularly limited, and the insulating material can be produced, for example, by applying a slurry containing an insulating material onto a positive electrode current collector having a positive electrode layer formed thereon, and then drying the slurry.

[0134] (resin coating)

[0135] The resin coating of the all-solid-state battery disclosed herein is disposed in contact with the ends of the electrode stack and the ends of the insulating material in the stacking direction of the electrode stack, and is composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the electrode stack. The resin coating of the all-solid-state battery disclosed herein only needs to be disposed in contact with the ends of the insulating material, and may or may not enter the space adjacent to the ends of the negative electrode layer and the negative electrode current collector, which are located inward of the ends of the insulating material, in the direction perpendicular to the stacking direction of the electrode stack.

[0136] The method for producing this dual-layer resin coating is not particularly limited. For example, a method may include applying a resin for forming the soft layer in stripes to create walls, and then applying a resin for forming the hard layer in an embedded manner between the walls. Another method may include using a UV-curable resin to shield the UV irradiation area, and then providing the hard and soft layers by varying the degree of curing by varying the UV irradiation intensity and irradiation time.

[0137] The material for the resin coating is not particularly limited as long as it can produce a hard layer and a soft layer. A resin with a relatively high Young's modulus can be used as the material for forming the hard layer, and a resin with a relatively low Young's modulus can be used as the material for forming the soft layer. Alternatively, as described above, a single UV-curable resin can be used, and the hard and soft layers can be formed by varying the UV irradiation intensity and duration. The thickness of the resin coating (average thickness taking into account stacking misalignment or uneven coating of the respective electrode assemblies) is, for example, 0.05 mm to 20 mm.

[0138] As the material of the hard layer, for example, resin can be cited. The resin includes rubber and elastomer. As examples of resins, polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVdF), and styrene-butadiene rubber (SBR) can be cited. These resins can be used alone or in combination of two or more. As the material of the soft layer, for example, materials with a smaller Young's modulus among the candidate materials for the above-mentioned hard layer can be cited. As UV-curable resins that can be adjusted according to UV irradiation, for example, acrylic resins or epoxy resins can be cited.

[0139] (Manufacturing method of all-solid-state batteries)

[0140] The manufacturing method of the all-solid-state battery disclosed in the present invention is not particularly limited, and a known method can be used. For example, the negative electrode collector, the negative electrode layer, the intermediate layer, the solid electrolyte layer, the positive electrode layer, and the positive electrode collector are stacked in sequence, and an insulating material is formed on the positive electrode collector at both ends of the positive electrode layer, thereby making an electrode body. Afterwards, a plurality of electrode bodies are stacked, optionally pressed and integrated, thereby making an electrode stack. Further, a resin coating is formed at the end of the electrode stack, thereby making the all-solid-state battery disclosed in the present invention.

[0141] While preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and modifications and improvements within the scope that can achieve the object of the present invention are encompassed by the present invention.

[0142] Reference numerals

[0143] 1 electrode stack

[0144] 2a, 2b negative electrode collector

[0145] 3a, 3b lithium metal layer (negative electrode layer)

[0146] 4Positive electrode collector

[0147] 5a, 5b Positive electrode active material layer (positive electrode layer)

[0148] 6a, 6b solid electrolyte layer

[0149] 7a, 7b middle layer

[0150] 8a, 8b insulation materials

[0151] 9. Resin coating

[0152] 11a, 11b, 11c hard layer

[0153] 12a, 12b, 12c soft layer

[0154] Lamination direction of Ld electrode stack

[0155] Vd is the direction perpendicular to the stacking direction of the electrode stack (plane direction)

[0156] Thickness of the hard layer at the end of the Ta resin coating

[0157] Thickness of the soft layer at the end of the Tb resin coating

Claims

1. An all-solid-state battery comprising an electrode stack, wherein the electrode stack comprises an electrode body and is formed by stacking a plurality of the electrode bodies, wherein the electrode body is formed by stacking a positive electrode collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode collector in this order, and The positive electrode current collector includes an insulating material on the positive electrode layer side surface adjacent to the end of the positive electrode layer. The solid electrolyte layer is arranged in contact with the positive electrode layer and the insulating material. In a direction perpendicular to the stacking direction of the electrode stack, an end of the insulating material is located outside an end of the negative electrode layer and an end of the negative electrode current collector. A resin coating is disposed at an end of the electrode stack in a stacking direction of the electrode stack so as to abut against an end of the insulating material. The resin coating layer is composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the electrode stack. The hard layer is disposed at both ends of the electrode stack in a stacking direction.

2. The all-solid-state battery according to claim 1, wherein: In the resin coating layer, at an end portion of the electrode stack in the stacking direction that does not contact the insulating material, the length of the hard layer is greater than the length of the soft layer.

3. The all-solid-state battery according to claim 1 or 2, wherein: The soft layer may include two or more layers.

4. The all-solid-state battery according to claim 1 or 2, wherein: In a direction perpendicular to the stacking direction of the electrode stack, an end portion of the soft layer is located outside an end portion of the hard layer.

5. The all-solid-state battery according to claim 1 or 2, wherein: The thickness of the soft layer decreases from an end portion in contact with the insulating material toward an end portion not in contact with the insulating material in a direction perpendicular to a stacking direction of the electrode stack.

Images