All-solid-state battery

Abstract

To provide an all-solid battery which can suppress damage of a positive electrode layer end, while sufficiently securing insulation between a positive electrode and a negative electrode, to application of compression stress by compression input, can suppress stress concentration on an end in a lamination direction of an electrode laminate, against expansion / contraction of a negative electrode by charge / discharge of an all-solid battery, and can suppress abnormal precipitation of lithium metal due to localization of a battery reaction, and lowering of capacity of an all-solid battery.SOLUTION: An all-solid battery includes an electrode laminate in which a plurality of electrodes are laminated, where a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector are laminated in this order, wherein a resin coat following expansion / contraction of the electrode laminate is provided on the end in a lamination direction of the electrode laminate.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

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

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

[0003] Lithium metal batteries are secondary batteries that use lithium metal as the anode and can be high-capacity batteries. Among them, so-called all-solid-state lithium metal batteries, which are all-solid-state by replacing the electrolyte solution with a solid electrolyte layer, have attracted attention for their excellent safety. All-solid-state lithium metal batteries have a cell structure that includes, for example, a lithium metal anode, a positive electrode, and a solid electrolyte layer.

[0004] Fig. 5 is a cross-sectional view showing the configuration of an all-solid-state battery according to one embodiment. The electrode laminate 1 of the all-solid-state battery shown in Fig. 5 includes a negative electrode formed of a negative electrode current collector 2a and a lithium metal layer (negative electrode layer) 3a or a negative electrode current collector 2b and a lithium metal layer (negative electrode layer) 3b, a positive electrode formed of a positive electrode current 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] The electrode laminate 1 of the all-solid-state battery shown in FIG. 5 includes 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 materials 8a are disposed on both ends of the positive electrode active material layer (positive electrode layer) 5a, and insulating materials 8b are disposed on both ends of the positive electrode active material layer (positive electrode layer) 5b. Materials without electronic conductivity are used for the insulating materials 8a and 8b, but ionically conductive materials and solid electrolytes are also applicable. In the figure, Ld indicates the stacking direction of the electrode laminate 1 constituting the all-solid-state battery, and Vd indicates the direction (plane direction) perpendicular to the stacking direction of the electrode laminate 1 constituting the all-solid-state battery.

[0007] The module assembly process for all-solid-state batteries involves a compression input step, during which a compressive stress of about 1 MPa is applied. As shown in Fig. 6, the compression input is 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, as shown in FIG. 5, the electrode laminate 1 has a structure in which the positive electrode active material layer (positive electrode layer) 5a or 5b having insulating materials 8a, 8b at its end extends outward from the end of the electrode laminate 1 in a direction Vd (plane direction) perpendicular to the stacking direction Ld of the electrode laminate 1, and therefore, when compressive stress is applied, damage such as bending may occur.

[0009] Therefore, it has been proposed to provide a resin coating (9 in Figure 6) at the end of the electrode stack in the stacking direction in order to prevent damage to the end of the positive electrode while ensuring sufficient insulation between the positive and negative electrodes against the application of compressive stress due to compressive input. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2023-39756 Summary of the Invention [Problem to be solved by the invention]

[0011] However, if a resin coating is provided at the end of the electrode laminate in the stacking direction, stress concentration occurs particularly in the positive electrode and solid electrolyte layer located at both end of the electrode laminate in the stacking direction due to expansion and contraction of the negative electrode caused by charging and discharging of the all-solid-state battery. Figures 7 and 7B are diagrams for explaining stress concentration caused by charging and discharging for an all-solid-state battery provided with a resin coating 9 at the end of the electrode laminate 1 in the stacking direction Ld. Figure 7A is a diagram showing the state of the all-solid-state battery when fully discharged (SOC: 0%), and Figure 7B is a diagram showing the state of the all-solid-state battery when fully charged (SOC: 100%).

[0012] As shown in FIG. 7A, in the all-solid-state battery at the time of full discharge (SOC: 0%), the lithium metal layers (negative electrode layers) 3a and 3b are not expanded, and the resin coat 9 provided in the stacking direction Ld of the electrode laminate 1 extends to the end of the electrode laminate 1 by a size equivalent to the thickness of the electrode laminate 1.

[0013] In an all-solid-state battery, the expansion of the negative electrode increases as the charging rate increases. As shown in FIG. 7B , in an all-solid-state battery when fully charged (SOC: 100%), the thickness (size in the stacking direction Ld) of the electrode laminate 1 becomes larger than the thickness (length in the stacking direction Ld) of the electrode laminate 1 when fully discharged (SOC: 0%) due to the expansion of the lithium metal layers (negative electrode layers) 3a, 3b, etc. As a result, the thickness (length in the stacking direction Ld) of the electrode laminate 1 becomes larger than the length of the resin coat 9 provided in the stacking direction Ld of the electrode laminate 1, and the resin coat 9 pulls the positive electrode and solid electrolyte layer located at both ends of the electrode laminate 1 in the stacking direction Ld, causing stress concentration in these areas.

[0014] Furthermore, repeated charge-discharge cycles of the all-solid-state battery repeatedly cause stress concentration in the positive electrode and solid electrolyte layer located at both ends of the electrode stack in the stacking direction. As a result, for example, if damage such as cracking occurs in the solid electrolyte layer at the end of the electrode stack in the stacking direction, abnormal deposition of lithium metal occurs due to localized battery reaction. Furthermore, if damage such as cracking occurs in the positive electrode active material layer (positive electrode layer) at the end of the electrode stack in the stacking direction, the capacity of the all-solid-state battery will decrease.

[0015] The present invention has been made in view of the above, and has an object to provide an all-solid-state battery that can suppress damage to the end of the positive electrode while ensuring sufficient insulation between the positive electrode and the negative electrode when compressive stress is applied due to a compressive input, and that can suppress stress concentration at the end of the electrode stack in the stacking direction when the negative electrode expands and contracts due to charging and discharging of the all-solid-state battery, thereby suppressing abnormal precipitation of lithium metal due to localization of the battery reaction and a decrease in the capacity of the all-solid-state battery. [Means for solving the problem]

[0016] The present inventors have conducted extensive research to achieve the above object and have found that the above problem can be solved by providing a resin coating, which can follow the expansion and contraction of the electrode stack, at the end of the electrode stack in the stacking direction, and have thus completed the present invention.

[0017] The all-solid-state battery of the present disclosure includes the following aspects.

[0018] (1) An all-solid-state battery including an electrode assembly including a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector stacked in this order, the electrode assembly being a stack of a plurality of the electrode assemblies, wherein the positive electrode current collector has an insulating material on a surface thereof facing the positive electrode layer and adjacent to an end of the positive electrode layer, the solid electrolyte layer being disposed in contact with the positive electrode layer and the insulating material, the end of the insulating material being located outside the end of the negative electrode layer and the end of the negative electrode current collector in a direction perpendicular to the stacking direction of the electrode stack, and a resin coating is disposed at the end of the electrode stack in the stacking direction of the electrode stack so as to abut against the end of the insulating material, the resin coating being composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the electrode stack, the hard layers being disposed at both end portions of the electrode stack in the stacking direction.

[0019] (2) The all-solid-state battery according to (1), wherein the length of the hard layer of the resin coat is greater than the length of the soft layer at an end portion of the resin coat that does not contact the insulating material in the stacking direction of the electrode stack.

[0020] (3) The all-solid-state battery according to (1) or (2), wherein the soft layer is present in two or more layers.

[0021] (4) The all-solid-state battery according to (1) or (2), wherein an end of the soft layer is located outside an end of the hard layer in a direction perpendicular to the stacking direction of the electrode stack.

[0022] (5) The all-solid-state battery according to (1) or (2), wherein the soft layer has a thickness that decreases in a direction perpendicular to the stacking direction of the electrode stack from an end that abuts the insulating material toward an end that does not abut the insulating material. [Effects of the Invention]

[0023] In the all-solid-state battery of aspect (1), damage to the end of the positive electrode can be suppressed while ensuring sufficient insulation between the positive electrode and the negative electrode against the application of compressive stress due to a compressive input. In addition, stress concentration at the end of the electrode laminate in the stacking direction against expansion and contraction of the negative electrode due to charge and discharge can be suppressed, thereby suppressing abnormal precipitation of lithium metal due to localization of the battery reaction and a decrease in the capacity of the all-solid-state battery.

[0024] In the all-solid-state battery of aspect (2), the relatively long hard layer effectively distributes stress to the end portions of the electrode laminate in the stacking direction, thereby making it possible to suppress stress concentration.

[0025] In the all-solid-state battery of aspect (3), the two or more soft layers deform to accommodate expansion and contraction of the negative electrode due to charge and discharge, and can suppress stress concentration at the end of the electrode stack in the stacking direction.

[0026] In the all-solid-state battery of aspect (4), the end of the soft layer is located outside the end of the hard layer in the direction perpendicular to the stacking direction of the electrode stack. This ensures the ratio of the hard layer in the stacking direction, and increases the range in which the soft layer can deform to accommodate the expansion and contraction of the negative electrode due to charge and discharge.

[0027] In the all-solid-state battery of aspect (5), the thickness of the soft layer decreases in a direction perpendicular to the stacking direction of the electrode laminate from the end that contacts the insulating material to the end that does not contact the insulating material, and the proportion of the hard layer in the stacking direction is relatively high on the end that does not contact the insulating material. This allows the hard layer to distribute compression input in the region of the end that does not contact the insulating material, while the soft layer present over a wide area can deform to follow the expansion and contraction of the negative electrode due to charge and discharge. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1 is a cross-sectional view showing the configuration of an all-solid-state battery according to a first embodiment (when fully discharged). [Figure 1B] FIG. 1 is a cross-sectional view showing the configuration of an all-solid-state battery (fully charged) according to a first embodiment. [Figure 2A] FIG. 4 is a cross-sectional view showing the configuration of an all-solid-state battery according to a second embodiment. [Figure 2B] FIG. 2B is a cross-sectional view showing the configuration of a first modified example of the all-solid-state battery of FIG. 2A. [Figure 2C] FIG. 2B is a cross-sectional view showing the configuration of a second modified example of the all-solid-state battery of FIG. 2A. [Figure 3] FIG. 10 is a cross-sectional view showing the configuration of an all-solid-state battery according to a third embodiment. [Figure 4] FIG. 10 is a cross-sectional view showing the configuration of an all-solid-state battery according to a fourth embodiment. [Figure 5] 1 is a cross-sectional view showing a configuration of an electrode stack according to an embodiment. [Figure 6] FIG. 1 is a cross-sectional view illustrating a configuration of an all-solid-state battery according to an embodiment. [Figure 7A] FIG. 2 is a diagram for explaining stress concentration (at the time of complete discharge) due to charge and discharge of the all-solid-state battery of the embodiment. [Figure 7B] FIG. 2 is a diagram for explaining stress concentration (at full charge) due to charging and discharging of an all-solid-state battery according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] (All-solid-state battery) The all-solid-state battery of the present disclosure includes an electrode assembly including a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector stacked in this order, and includes an electrode stack in which multiple electrode assemblies are stacked. The positive electrode current collector includes an insulating material on the surface facing the positive electrode layer and adjacent to an end of the positive electrode layer, and the solid electrolyte layer is disposed in contact with the positive electrode layer and the insulating material.

[0030] In the all-solid-state battery of the present disclosure, the end of the insulating material is located outside the end of the negative electrode layer and the end of the negative electrode current collector in a direction perpendicular to the stacking direction of the electrode stack, and a resin coating is arranged on the end of the electrode stack so as to abut against the end of the insulating material in the direction perpendicular to the stacking direction of the electrode stack.

[0031] In the all-solid-state battery of the present disclosure, the resin coat 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 layers are disposed at both ends of the electrode stack in the stacking direction.

[0032] The resin coating has two layers with different hardnesses, a hard layer and a soft layer, and the hard layer serves to alleviate compressive stress due to compressive input. As a result, the all-solid-state battery of the present invention can suppress damage to the positive electrode end while ensuring sufficient insulation between the positive and negative electrodes.

[0033] The resin coating may be chamfered or rounded at the corners of the ends that do not come into contact with the insulating material in the stacking direction of the electrode laminate. By chamfering the corners with a chamfer or round, it is possible to prevent uneven contact at the ends and improve robustness against stack misalignment during stacking or compression input.

[0034] In the resin coating, the length of the hard layer is preferably longer than the length of the soft layer at the end of the electrode laminate that does not abut against the insulating material in the stacking direction. By making the length of the hard layer longer than the length of the soft layer, stress at the time of compressive input can be sufficiently alleviated and deformation due to bending when the cell is restrained or during charging can be suppressed.

[0035] Furthermore, in the all-solid-state battery of the present disclosure, a resin coating is arranged at the end of the electrode laminate in a direction perpendicular to the stacking direction of the electrode laminate so as to abut against the end of the insulating material, and the resin coating is made of a hard layer and a soft layer in the stacking direction of the electrode laminate, and the hard layers are arranged at both end portions of the electrode laminate in the stacking direction. As a result, damage to the end of the positive electrode can be suppressed while sufficiently ensuring insulation between the positive electrode and the negative electrode when compressive stress is applied by a compressive input, and stress concentration at the end of the electrode laminate in the stacking direction when the negative electrode expands and contracts due to charging and discharging can be suppressed, and abnormal precipitation of lithium metal due to localized battery reaction and a decrease in capacity of the all-solid-state battery can be suppressed.

[0036] (First embodiment) 1A and 1B are cross-sectional views showing the configuration of the all-solid-state battery according to embodiment 1. Fig. 1A is a diagram showing the state of the all-solid-state battery according to embodiment 1 at the time of complete discharge (SOC: 0%), and Fig. 1B is a diagram showing the state of the all-solid-state battery according to embodiment 1 at the time of full charge (SOC: 100%).

[0037] The electrode laminate 1 of the all-solid-state battery shown in FIGS. 1A and 1B includes a negative electrode formed of a negative electrode current collector 2a and a lithium metal layer (negative electrode layer) 3a or a negative electrode current collector 2b and a lithium metal layer (negative electrode layer) 3b, a positive electrode formed of a positive electrode current 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.

[0038] 1A and 1B, the electrode laminate 1 of the all-solid-state battery includes an intermediate layer 7a between a lithium metal layer (negative electrode layer) 3a and a solid electrolyte layer 6a, and an intermediate layer 7b between a lithium metal layer (negative electrode layer) 3b and a solid electrolyte layer 6b. Furthermore, insulating materials 8a are disposed on both ends of the positive electrode active material layer (positive electrode layer) 5a, and insulating materials 8b are disposed on both ends of the positive electrode active material layer (positive electrode layer) 5b. Note that Vd in the figures indicates the direction (plane direction) perpendicular to the lamination direction of the electrode laminate 1 constituting the all-solid-state battery.

[0039] In the all-solid-state battery according to the first embodiment, in the direction perpendicular to the stacking direction of the electrode stack 1, the ends of the insulating materials 8a and 8b are located outside the ends of the lithium metal layers (negative electrode layers) 3a and 3b and the ends of the negative electrode current collectors 2a and 2b.

[0040] In the all-solid-state battery according to the first embodiment, a resin coat 9a is arranged at the end of the electrode laminate 1 in a direction Vd perpendicular to the lamination direction of the electrode laminate 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0041] In the all-solid-state battery according to the first embodiment, the resin coat 9a is made up of two hard layers 11a and one soft layer 12a in a direction perpendicular to the stacking direction of the electrode laminate 1. In the resin coat 9a of the all-solid-state battery according to the first embodiment, the hard layers 11a are arranged at both ends in the stacking direction of the electrode laminate 1, and the soft layer 12a is arranged approximately in the center of the resin coat 9a.

[0042] As shown in FIG. 1A, in the all-solid-state battery at a fully discharged state (SOC: 0%), the lithium metal layers (negative electrode layers) 3a and 3b are not expanded, and the resin coat 9a provided at the end of the electrode laminate 1 in the stacking direction extends to the end of the electrode laminate 1 by a length equivalent to the thickness of the electrode laminate 1.

[0043] As shown in FIG. 1B, in an all-solid-state battery when fully charged (SOC: 100%), the lithium metal layers (negative electrode layers) 3a and 3b expand, and therefore the thickness (length in the stacking direction) of the electrode stack 1 becomes larger than the thickness (length in the stacking direction) of the electrode stack 1 when fully discharged (SOC: 0%) shown in FIG. 1A.

[0044] At this time, the resin coat 9a of the all-solid-state battery according to the first embodiment follows the expansion of the lithium metal layers (negative electrode layers) 3a, 3b, and extends the length in the stacking direction of the electrode laminate 1. Specifically, the soft layer 12a arranged approximately in the center of the resin coat 9a follows the expansion of the lithium metal layers (negative electrode layers) 3a, 3b, and thereby the resin coat 9a of the all-solid-state battery according to the first embodiment follows the increase in the thickness (length in the stacking direction) of the electrode laminate 1 caused by the expansion of the lithium metal layers (negative electrode layers) 3a, 3b.

[0045] As a result, in the all-solid-state battery according to 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 both ends of the electrode stack in the stacking direction can be prevented from being pulled by the resin coat, and stress concentration in these areas can be avoided.

[0046] In the resin coat 9a of the all-solid-state battery according to 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 end portion that does not abut against the insulating materials 8a, 8b in the stacking direction of the electrode stack 1. Since the total length Ta of the hard layers 11a is greater than the length Tb of the soft layers 12a, it is possible to sufficiently relieve stress during compression input, and also to suppress deformation due to bending when the cell is restrained or when charging.

[0047] (Second embodiment) 2A is a cross-sectional view showing the configuration of the all-solid-state battery according to Embodiment 2. The configuration of the electrode laminate 1 of the all-solid-state battery according to Embodiment 2 is the same as the configuration of the electrode laminate 1 of the all-solid-state battery according to Embodiment 1 described above.

[0048] In the all-solid-state battery according to the second embodiment, similarly to the first embodiment, a resin coat 9b is arranged at the end of the electrode laminate 1 in a direction perpendicular to the stacking direction of the electrode laminate 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0049] In the all-solid-state battery according to the second embodiment, the resin coat 9b is made up of three hard layers 11b and two soft layers 12b in a direction perpendicular to the stacking direction of the electrode laminate 1. In the resin coat 9b of the all-solid-state battery according to the second embodiment, the hard layers 11b are arranged at both ends of the electrode laminate 1 in the stacking direction, and the soft layers 12b are arranged so as to be sandwiched between the hard layers 11b.

[0050] The resin coat of the all-solid-state battery of the present disclosure preferably has two or more soft layers. A resin coat having two or more soft layers can stretch at multiple locations in response to the expansion of the lithium metal layer (negative electrode layer), and can therefore more evenly follow the increase in thickness (length in the stacking direction) of the electrode laminate caused by the expansion of the lithium metal layer (negative electrode layer). As a result, stress concentration at the end of the electrode laminate in the stacking direction due to the expansion and contraction of the negative electrode caused by charge and discharge can be further suppressed.

[0051] In the resin coat 9b of the all-solid-state battery according to the second embodiment, at the end portion that does not abut against the insulating materials 8a, 8b in the stacking direction of the electrode stack 1, the total length Ta of the hard layers 11b is greater than the total length Tb of the soft layers 12b.

[0052] It should be noted that the embodiment of Fig. 2A may be modified as shown in Fig. 2B and Fig. 2C. In Fig. 2B and Fig. 2C, parts corresponding to those in Fig. 2A are denoted by the same reference numerals, and the explanations in Fig. 2A are used for the individual explanations.

[0053] In the modified example shown in Fig. 2B, the cross section of each of the two soft layers 12ba is trapezoidal, and the relative lengths of the top and bottom sides of these trapezoids are reversed in the stacking direction. The length Tb of the soft layer 12ba in Fig. 2B is indicated at a position (averaged in the Vd direction) that is functionally approximately equivalent to the length Tb of the soft layer 12b in Fig. 2A.

[0054] In the modified example of Fig. 2C, the three soft layers 12bb have circular cross sections, and these circles have the same diameter. The dimension notation of the length Tb of the soft layer 12bb in Fig. 2C is attached at a position (averaged in the Vd direction) that is functionally approximately equivalent to the length Tb of the soft layer 12b in Fig. 2A.

[0055] In the modified examples of Figures 2B and 2C, similarly to the embodiment of Figure 2A, the expansion and contraction of the negative electrode due to charge and discharge can be accommodated by deformation of the soft layer 12ba and the soft layer 12bb in the Ld direction, thereby further suppressing stress concentration at the end of the electrode stack in the stacking direction.

[0056] (Third embodiment) 3 is a cross-sectional view showing the configuration of the all-solid-state battery according to the third embodiment. The configuration of the electrode laminate 1 of the all-solid-state battery according to the third embodiment is the same as the configuration of the electrode laminate 1 of the all-solid-state battery according to the first embodiment described above.

[0057] In the all-solid-state battery according to the third embodiment, similarly to the first embodiment, a resin coat 9c is arranged at the end of the electrode laminate 1 in a direction perpendicular to the stacking direction of the electrode laminate 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0058] In the all-solid-state battery according to the third embodiment, the resin coat 9c is made up of three hard layers 11c and two soft layers 12c in a direction perpendicular to the stacking direction of the electrode laminate 1. In the resin coat 9c of the all-solid-state battery according to the third embodiment, the hard layers 11c are arranged at both ends of the electrode laminate 1 in the stacking direction, and the soft layers 12c are arranged so as to be sandwiched between the hard layers 11c.

[0059] In the resin coat 9c of the all-solid-state battery according to the third embodiment, the ends of the two soft layers 12c are located outside 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 wider than in the second embodiment. This ensures the proportion of the hard layers in the stacking direction while increasing the range over which the soft layers can deform to accommodate the expansion and contraction of the negative electrode due to charge and discharge.

[0060] In the resin coating of the all-solid-state battery of the present disclosure, the end of the soft layer may be located outside the end of the hard layer in a direction perpendicular to the stacking direction of the electrode laminate. Such a structure can be easily formed, for example, by first coating the end surface of the electrode laminate with a resin for forming the soft layer to form walls of the soft layer, and then coating the resin for forming the hard layer between the walls of the soft layer.

[0061] In the resin coat 9c of the all-solid-state battery according to the third embodiment, at the end portion that does not abut against the insulating materials 8a, 8b in the stacking direction of the electrode stack 1, the total length Ta of the hard layers 11c is greater than the total length Tb of the soft layers 12c.

[0062] (Fourth embodiment) 4 is a cross-sectional view showing the configuration of the all-solid-state battery according to Embodiment 4. The configuration of the electrode laminate 1 of the all-solid-state battery according to Embodiment 4 is the same as the configuration of the electrode laminate 1 of the all-solid-state battery according to Embodiment 1 described above.

[0063] In the all-solid-state battery according to the fourth embodiment, similarly to the first embodiment, a resin coat 9d is arranged at the end of the electrode laminate 1 in a direction perpendicular to the stacking direction of the electrode laminate 1 so as to abut against the ends of the insulating materials 8a and 8b.

[0064] In the all-solid-state battery according to the fourth embodiment, the resin coat 9d is composed of two hard layers 11d and one soft layer 12d in a direction perpendicular to the stacking direction of the electrode laminate 1. In the resin coat 9d of the all-solid-state battery according to the fourth embodiment, the thickness of the soft layer 12d decreases in a direction perpendicular to the stacking direction of the electrode laminate 1 from the end that abuts the insulating materials 8a, 8b to the end that does not abut the insulating materials 8a, 8b. In other words, the boundary between the hard layer 11d and the soft layer 12d is inclined with respect to the Ld direction as shown in the figure.

[0065] The resin coat of the all-solid-state battery according to the present disclosure may have a thickness that decreases in a direction perpendicular to the stacking direction of the electrode laminate from an end that abuts the insulating material to an end that does not abut the insulating material. In other words, the hard layer and the soft layer do not need to be parallel to the direction perpendicular to the stacking direction of the electrode laminate, as long as they are layers that are perpendicular to the stacking direction of the electrode laminate.

[0066] If the soft layer 12d is present over a wide range, like the resin coat 9d of the all-solid-state battery according to the fourth embodiment, it can follow the expansion and contraction of the negative electrode due to charge and discharge, and therefore, it is possible to further suppress stress concentration at the end of the electrode stack 1 in the stacking direction.

[0067] Furthermore, like the resin coat 9d of the all-solid-state battery according to the fourth embodiment, if the hard layers 11d are arranged at both end portions in the stacking direction of the electrode stack 1, and the total length Ta of the hard layers 11d is greater than the length of the soft layers 12d at the end portions that do not abut against the insulating materials 8a, 8b in the stacking direction of the electrode stack 1, it is possible to sufficiently relieve stress during compression input, and also to suppress deformation due to bending when the cell is restrained or when charging.

[0068] (Structure of all-solid-state batteries) Hereinafter, each component of the all-solid-state battery of the present disclosure will be described.

[0069] (Positive electrode current collector) The positive electrode current collector used in the all-solid-state battery of the present disclosure is disposed 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, and among these, at least one selected from the group consisting of aluminum, aluminum alloys, and stainless steel is preferred.

[0070] The shape of the positive electrode current collector is not particularly limited, and examples thereof include foil and plate shapes. The thickness of the positive electrode current collector is also not particularly limited, and may be the same as that used in the positive electrode of a general all-solid-state battery. The thickness of the positive electrode current collector may be, for example, in the range of 0.5 μm or more and 0.5 mm or less.

[0071] (positive electrode layer) 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 used in the positive electrode layer of a general all-solid-state battery. For example, in the case of a lithium ion battery, examples of the positive electrode active material include a layered active material containing lithium, a spinel-type active material, and an olivine-type active material. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and LiNi p Mn q Co r O2(p+q+r=1), LiNi p Al q Co r Examples of such an element-substituted Li-Mn spinel include lithium manganate (LiMnO), LiMnO (p+q+r=1), lithium manganate (LiMnO), LiMnMyO (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate (oxide containing Li and Ti), and lithium metal phosphate (LiMPO, M=at least one selected from Fe, Mn, Co, and Ni).

[0072] The content of the positive electrode active material in the positive electrode layer may be, for example, in the range of 50% by mass 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.

[0073] The positive electrode layer may optionally contain a solid electrolyte (described later) for the purpose of improving lithium ion conductivity. The positive electrode layer may also optionally contain a binder, a conductive additive, etc. As these materials, materials generally used in all-solid-state batteries can be used.

[0074] The thickness of the positive electrode layer is not particularly limited and can be appropriately set depending on the desired performance of the battery. The thickness of the positive electrode layer may be, for example, in the range of 1 μm to 1 mm.

[0075] When the all-solid-state battery of the present disclosure includes an intermediate layer described below, the positive electrode layer preferably has an area on the stacking surface equivalent to that of the intermediate layer. This can improve the durability of the all-solid-state battery. The area of ​​the positive electrode layer in the all-solid-state battery of the present disclosure may be, for example, up to 100% of the area of ​​the intermediate layer, or may be 90% to 100%, or may be 80% to 90%.

[0076] The method for producing the positive electrode layer is not particularly limited, and the positive electrode layer can be produced by a known method. For example, the positive electrode layer can be produced by mixing the materials constituting the positive electrode layer with a solvent to form a slurry, applying the slurry to the above-mentioned positive electrode current collector, and drying it.

[0077] (Solid electrolyte layer) The solid electrolyte layer is a layer containing a solid electrolyte and is disposed in contact with the positive electrode layer and the insulating material.

[0078] The solid electrolyte material is not particularly limited as long as it has lithium ion conductivity and insulating properties. Materials generally used in all-solid-state lithium ion batteries can be used as the solid electrolyte material, and examples thereof include sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as lithium-containing salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based solid electrolytes containing lithium-containing salts and lithium ion-conductive ionic liquids. Among these, sulfide solid electrolyte materials are preferred from the viewpoints of high lithium ion conductivity, structural formability by pressing, and interfacial bonding.

[0079] The form of the solid electrolyte material is not particularly limited and may be, for example, particulate. Furthermore, in the solid electrolyte layer of the all-solid-state battery of the present disclosure, the content of the solid electrolyte is not particularly limited. The content of the solid electrolyte may be, for example, in the range of 50% by mass to 99% by mass.

[0080] The solid electrolyte layer may optionally contain a binder. It may also optionally contain an adhesive for the purpose of imparting mechanical strength and flexibility. These materials may be those generally used in all-solid-state batteries.

[0081] The solid electrolyte layer may be disposed so that its end is at approximately the same position as the end of the insulating material in a direction perpendicular to the stacking direction of the electrode stack of the all-solid-state battery of the present disclosure.

[0082] In an electrode laminate having such a shape, the solid electrolyte layer does not protrude from the end face of the electrode laminate, and therefore, for example, when pressure is applied by a roll press or the like during the manufacturing process of the electrode laminate, it is possible to suppress the occurrence of cracks in the solid electrolyte layer.

[0083] The method for producing the solid electrolyte layer is not particularly limited, and the solid electrolyte layer can be produced by a known method. For example, the solid electrolyte layer can be produced by mixing materials constituting the solid electrolyte layer with a solvent to form a slurry, applying the slurry to a substrate, and drying the slurry.

[0084] (Negative electrode current collector) The negative electrode current collector used in the all-solid-state battery of the present disclosure is disposed in contact with the negative electrode layer and functions to collect current from the negative electrode layer. The material of the negative electrode current collector is not particularly limited as long as it can collect current from the negative electrode layer, but it is preferably composed of a substance with high conductivity. Examples of substances with high conductivity include metals containing at least one metal element selected from the group consisting of silver, palladium, gold, platinum, aluminum, copper, and nickel, alloys such as stainless steel, and non-metals such as carbon (C).

[0085] Among these highly conductive materials, it is preferable to use at least one selected from the group consisting of copper, SUS, and nickel, taking into consideration not only high conductivity but also manufacturing costs. In particular, stainless steel is less likely to react with the negative electrode active material, the positive electrode active material, and the solid electrolyte, and therefore, when stainless steel is used as the material for the negative electrode current collector, the internal resistance of the all-solid-state battery can be reduced.

[0086] The shape of the negative electrode current collector is not particularly limited, and examples thereof include foil, plate, mesh, nonwoven fabric, foam, etc. Furthermore, the negative electrode current collector may have a carbon layer or the like disposed on its surface, or the surface may be roughened, in order to improve adhesion with the negative electrode layer.

[0087] The thickness of the negative electrode current collector is not particularly limited and may be the same as that used in negative electrodes of general all-solid-state batteries, and may be, for example, in the range of 0.5 μm to 0.5 mm.

[0088] (negative electrode layer) 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 one that is commonly used in negative electrode layers of all-solid-state batteries. However, it is preferable to use a material with high electronic conductivity that can reversibly release and absorb lithium ions and facilitate electron transport. Examples of such negative electrode active materials include silicon-based active materials such as silicon and silicon alloys, carbon-based active materials such as graphite and hard carbon, various oxide-based active materials such as lithium titanate, and lithium-based active materials such as metallic lithium and lithium alloys. The negative electrode active material may be a single material or a combination of two or more materials.

[0089] In the all-solid-state battery of the present disclosure, the negative electrode layer may be made of metallic lithium or a lithium metal alloy, either alone or in combination. A negative electrode layer made of lithium metal or a lithium metal alloy, either alone or in combination, has a large electrical capacity per unit weight, making it possible to realize a high-capacity all-solid-state battery.

[0090] The content of the negative electrode active material in the negative electrode layer may be, for example, in the range of 30% by mass to 100% by mass.

[0091] The negative electrode layer may optionally contain the above-mentioned solid electrolyte for the purpose of improving lithium ion conductivity. The negative electrode layer may also optionally contain a binder, a conductive additive, etc. As these materials, materials generally used in all-solid-state batteries can be used.

[0092] The thickness of the negative electrode layer is not particularly limited and can be appropriately set depending on the desired performance of the battery. The thickness of the negative electrode layer may be, for example, in the range of 0.5 μm to 0.5 mm.

[0093] The method for producing the negative electrode layer is not particularly limited, and the negative electrode layer can be produced by a known method. For example, the negative electrode layer can be produced by mixing the materials constituting the negative electrode layer with a solvent to form a slurry, applying the slurry to the above-mentioned negative electrode current collector, and drying it.

[0094] (middle class) When the all-solid-state battery according to the present disclosure includes an intermediate layer, the intermediate layer is provided between the solid electrolyte and the anode layer. When the anode layer of the all-solid-state battery according to the present disclosure is a layer of metallic lithium or a lithium metal alloy, either alone or in combination, providing the intermediate layer between the solid electrolyte layer and the anode layer can suppress non-uniform deposition of dendrites at the interface between the solid electrolyte layer and the anode layer and can improve interfacial adhesion.

[0095] The intermediate layer is a layer that has both electronic conductivity and ionic conductivity. Since the intermediate layer has ionic conductivity, it can pass, for example, lithium ions. Therefore, as the all-solid-state battery is repeatedly charged and discharged, lithium ions (Li + ) passes through the intermediate layer. The presence of the intermediate layer allows lithium metal to be uniformly deposited between the intermediate layer and the negative electrode layer. Furthermore, if the intermediate layer has flexibility that allows it to follow the volumetric changes of each layer that occur during charge and discharge, it is possible to maintain interfacial adhesion even when the all-solid-state battery is repeatedly charged and discharged, thereby improving the durability of the all-solid-state battery.

[0096] The intermediate layer may be disposed such that an end thereof is substantially flush with an end of the negative electrode layer in a direction perpendicular to the stacking direction of the electrode stack of the all-solid-state battery of the present disclosure, or may be disposed more inward than the end of the negative electrode layer, thereby allowing the above-described effect of disposing the intermediate layer to be fully exerted.

[0097] The material constituting the intermediate layer is not particularly limited, and may contain, for example, amorphous carbon, metal nanoparticles, and a binder as a binding material.

[0098] Unlike graphite, amorphous carbon does not react with lithium metal to form an alloy, which can suppress the formation of dendrites and improve the cycle characteristics of all-solid-state batteries.

[0099] Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and ketjen black, coke, activated carbon, etc. The amorphous carbon may be easily graphitized carbon (soft carbon), hardly graphitized carbon (hard carbon), CNT (carbon nanotube), fullerene, or graphene.

[0100] The inclusion of metal nanoparticles in the intermediate layer can increase the electronic conductivity of the intermediate layer, resulting in more uniform deposition of lithium metal. Metal nanoparticles are not particularly limited, but examples include metal nanoparticles of tin, silicon, zinc, magnesium, gold, platinum, palladium, silver, aluminum, bismuth, antimony, etc.

[0101] The binder contained in the intermediate layer maintains the structure of the intermediate layer and improves 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 any binder generally used in all-solid-state batteries can be used.

[0102] (insulation material) The insulating material is provided on the surface of the positive electrode current collector facing the positive electrode layer, 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 cell structure are assembled to function as a battery, the bending of the tab wires prevents contact between the tab wires and the positive electrode end, thereby suppressing short circuits. This also suppresses short circuits caused by cracks that occur during repeated charge and discharge. Furthermore, this also suppresses cracks at the end of the positive electrode mixture caused by roll riding on the roll when the positive electrode is roll-pressed.

[0103] The shape of the insulating material is not particularly limited as long as it is provided at the end of the positive electrode layer. The size of the insulating material is not particularly limited, and it is sufficient that the insulating material has a thickness equal to or less than the thickness of the positive electrode layer in the stacking direction of the electrode stack, abuts against part or all of the end face of the positive electrode layer, and is disposed at the end of the positive electrode layer in a direction perpendicular to the stacking direction of the electrode stack.

[0104] The insulating material is not particularly limited as long as it exhibits insulating properties, and may be any so-called insulator other than a semiconductor or a conductor. The insulating material can be appropriately selected depending on the properties desired to be added to the insulating properties.

[0105] 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 on which a positive electrode layer has been formed, and then drying the slurry.

[0106] (Resin coated) The resin coating of the all-solid-state battery of the present disclosure is provided so as to abut against the end of the electrode laminate and the end of the insulating material in the stacking direction of the electrode laminate, and is composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the electrode laminate. The resin coating of the all-solid-state battery of the present disclosure only needs to be provided so as to abut against the end of the insulating material, and may or may not penetrate into spaces adjacent to the end of the negative electrode layer and the end of the negative electrode current collector, which are located inside the end of the insulating material in the direction perpendicular to the stacking direction of the electrode laminate.

[0107] There are no particular limitations on the manufacturing method of such a resin coating having two types of layers, but examples include a method in which a resin that forms a soft layer is applied in stripes to create walls, and then a resin that forms a hard layer is applied so that it fills the gaps between the walls. Another example is a method in which a UV-curable resin is used to mask the UV-irradiated area, and the hard and soft layers are provided by varying the UV irradiation intensity and irradiation time to achieve different degrees of curing.

[0108] The resin coating material is not particularly limited as long as it can be used to form a hard layer and a soft layer. A resin with a high Young's modulus may be used as the material for forming the hard layer, and a resin with a low Young's modulus may be used as the material for forming the soft layer. Alternatively, as described above, one type of UV-curable resin may be used to form the hard layer and the soft layer by varying the UV irradiation intensity and irradiation time. The thickness of the resin coating (average thickness taking into account stacking misalignment of each electrode group and coating unevenness) is, for example, 0.05 mm to 20 mm.

[0109] Examples of materials for the hard layer include resins. Resins include rubber and elastomers. Examples of resins include PE, PP, PTFE, PVdF, and SBR. These resins may be used alone or in combination of two or more. Examples of materials for the soft layer include those with a small Young's modulus among the candidate materials for the hard layer described above. Examples of UV-curable resins that can be adjusted by UV irradiation include acrylic resins and epoxy resins.

[0110] (Manufacturing method of all-solid-state batteries) The method for manufacturing the all-solid-state battery of the present disclosure is not particularly limited and can be a known method. For example, an electrode assembly is produced by stacking an anode current collector, an anode layer, an intermediate layer, a solid electrolyte layer, a cathode layer, and a cathode current collector in this order, and forming an insulating material on the cathode current collector at both ends of the cathode layer. Then, a plurality of electrode assemblies are stacked and optionally pressed together to produce an electrode laminate. Furthermore, a resin coating can be formed on the ends of the electrode laminate to produce the all-solid-state battery of the present disclosure.

[0111] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and any modifications or improvements that can achieve the object of the present invention are included in the present invention. [Explanation of symbols]

[0112] 1 Electrode laminate 2a, 2b Negative electrode current collector 3a, 3b Lithium metal layer (negative electrode layer) 4 Positive electrode current collector 5a, 5b Positive electrode active material layer (positive electrode layer) 6a, 6b solid electrolyte layer 7a, 7b middle layer 8a, 8b Insulation material 9 Resin Coat 11a, 11b, 11c hard layer 12a, 12b, 12c soft layer Ld Electrode laminate stacking direction Vd: Direction perpendicular to the stacking direction of the electrode stack (surface direction) Thickness of the hard layer at the edge of the Ta resin coating Tb Thickness of the soft layer at the edge of the resin coating

Claims

1. An all-solid-state battery including an electrode assembly in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector are stacked in this order, and including an electrode stack in which a plurality of the electrode assemblies are stacked, the positive electrode current collector includes an insulating material on a surface facing the positive electrode layer, the insulating material being 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, 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 in a direction perpendicular to the stacking direction of the electrode stack; 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 coat is composed of a hard layer and a soft layer in a direction perpendicular to the stacking direction of the electrode stack, The hard layers are disposed at both ends of the electrode stack in the stacking direction. All-solid-state battery.

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

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

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

5. 3. The all-solid-state battery according to claim 1, wherein the soft layer has a thickness that decreases in a direction perpendicular to a stacking direction of the electrode stack from an end that abuts the insulating material toward an end that does not abut the insulating material.

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