Method for producing all-solid-state battery

Abstract

The present invention provides a method for producing an all-solid-state battery which makes it possible to form a favorable interface while avoiding a short circuit between a positive electrode and a negative electrode. This method for producing an all-solid-state battery comprises: a step for forming an all-solid-state battery laminate in which a plurality of battery cells are layered in one direction by pressing, at a first press pressure in at least one direction, a stack in which a negative electrode that contains Li metal or a Li alloy, a solid electrolyte layer, and a positive electrode are repeatedly disposed in one direction; a step for performing discharge processing of the battery cells after pressing at the first press pressure; and a step for pressing, at a second press pressure in at least one direction, the all-solid-state battery laminate after the discharge processing. The first press pressure is smaller than the second press pressure.

Description

Manufacturing method for all-solid-state batteries

[0001] The present invention relates to a method for manufacturing an all-solid-state battery.

[0002] Patent Document 1 discloses "a method for manufacturing an all-solid-state battery, comprising: forming a positive electrode active material layer on each of both sides of a positive electrode current collector layer, and pressing the layer at a first pressing pressure to obtain a positive electrode laminate; forming a negative electrode active material layer on one side of a negative electrode current collector layer, and pressing the layer at a second pressing pressure or without pressing to obtain a negative electrode laminate; laminating a negative electrode laminate on each of both sides of the positive electrode laminate to obtain an all-solid-state battery laminate; and pressing the all-solid-state battery laminate at a third pressing pressure, wherein the second pressing pressure is smaller than the first pressing pressure and the second pressing pressure is smaller than the third pressing pressure."

[0003] Japanese Patent Application Laid-Open No. 2018-147621

[0004] Although molding the all-solid-state battery laminate with a weaker pressing pressure than the positive electrode contributes to preventing short circuits between the positive electrode and the negative electrode, insufficient pressing may reduce the contact strength at the interface between the negative electrode and the solid electrolyte layer. A method for manufacturing an all-solid-state battery that can form a good interface while avoiding short circuits between the positive electrode and the negative electrode is desired.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing an all-solid-state battery that can form a good interface while avoiding short-circuiting between the positive electrode and the negative electrode.

[0006] A method for manufacturing an all-solid-state battery according to one aspect of the present invention includes the steps of: pressing a laminate, in which a negative electrode containing Li metal or a Li alloy, a solid electrolyte layer, and a positive electrode are repeatedly arranged in one direction, with a first pressing pressure in at least the one direction to form an all-solid-state battery laminate in which a plurality of battery cells are stacked in the one direction; discharging the battery cells after pressing with the first pressing pressure; and pressing the all-solid-state battery laminate in at least the one direction with a second pressing pressure after discharging the battery cells, wherein the first pressing pressure is smaller than the second pressing pressure.

[0007] According to one aspect of the present invention, it is possible to provide a method for manufacturing an all-solid-state battery that can form a good interface while avoiding short-circuiting between a positive electrode and a negative electrode.

[0008] Fig. 1 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by a manufacturing method according to an embodiment of the present invention. Fig. 2 is a flowchart showing a method for manufacturing an all-solid-state battery according to an embodiment of the present invention. Fig. 3 is a schematic diagram for explaining in detail step ST1 of the flowchart shown in Fig. 2. Fig. 4 is a graph showing the experimental results of the present invention, illustrating the charging characteristics of each example and comparative example. Fig. 5 is a cross-sectional view schematically showing state changes during charging in Example 1 of the present invention and Comparative Examples 1 and 2.

[0009] An embodiment of the present invention will be described below. In the following description of the drawings, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each device and each component, etc., may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

[0010] The definitions of directions such as up and down in the following explanation are merely for the convenience of explanation and do not limit the technical idea of ​​the present invention. For example, if an object is rotated 90 degrees and observed, up and down are converted to left and right and read as such, and if it is rotated 180 degrees and observed, up and down are obviously read as reversed.

[0011] 1 is a cross-sectional view showing an example of the configuration of an all-solid-state battery 1 manufactured by a manufacturing method according to an embodiment of the present invention. As shown in Fig. 1, the all-solid-state battery 1 manufactured by the manufacturing method according to an embodiment of the present invention includes an anode 4 having an anode layer 2 and an anode current collector 3, a cathode 7 having a cathode layer 5 and a cathode current collector 6, a solid electrolyte layer 8 disposed between the anode 4 and the cathode 7, an anode tab lead 11 joined to the anode current collector 3, and a cathode tab lead 12 joined to the cathode current collector 6.

[0012] The negative electrode layer 2 is provided on both surfaces in the thickness direction of the negative electrode current collector 3 (top and bottom surfaces in FIG. 1 ). For example, the negative electrode 4 can be obtained by pressure-bonding lithium (Li) metal or a Li alloy to both surfaces of the negative electrode current collector 3 as the negative electrode layer 2. For the negative electrode current collector 3 and the negative electrode tab lead 11, for example, a metal foil such as copper (Cu), a Cu alloy, nickel, or a nickel alloy can be used, but is not limited to these. The negative electrode layer 2 is made of Li metal or a Li alloy. More specifically, examples of Li alloys include, but are not limited to, a Li-Mg alloy, a Li-Si alloy, a Li-Al alloy, a Li-Zn alloy, a Li-Sn alloy, and a Li-Bi alloy.

[0013] The positive electrode layer 5 is provided on both surfaces in the thickness direction of the positive electrode current collector 6 (top and bottom surfaces in FIG. 1 ). For example, a positive electrode 7 can be obtained by preparing a slurry by weighing and mixing predetermined amounts of a positive electrode active material, a sulfide solid electrolyte, a conductive additive, a binder, and an organic solvent, applying the slurry to both surfaces of the positive electrode current collector 6, and then drying the slurry. The positive electrode current collector 6 and the positive electrode tab lead 12 can be made of, for example, aluminum (Al) foil, but are not limited to these. The positive electrode layer 5 can be made of, for example, manganese dioxide, sulfide, or fluoride, but are not limited to these.

[0014] The solid electrolyte layer 8 may be made of any material as long as it functions as an electrolyte layer in a secondary battery. For example, the solid electrolyte layer 8 may include a sulfide solid electrolyte. Examples of sulfide solid electrolytes include materials containing Li, phosphorus (P), sulfur (S), and a halide. For example, the solid electrolyte layer 8 can be obtained by weighing and mixing predetermined amounts of the sulfide solid electrolyte, a binder, and an organic solvent to prepare a slurry, which is then applied to a substrate and dried.

[0015] The negative electrodes 4 and positive electrodes 7 are alternately stacked with solid electrolyte layers 8 interposed therebetween to form an all-solid-state battery stack 10. The solid electrolyte layer 8 is interposed between the negative electrode 4 and the positive electrode 7 to form one battery cell 9. The all-solid-state battery stack 10 includes a plurality of battery cells 9. In each battery cell 9, charging and discharging are performed by exchange of alkali metal ions (e.g., Li ions) between the negative electrode 4 and the positive electrode 7 via the solid electrolyte layer 8.

[0016] (Manufacturing Method) Next, a method for manufacturing an all-solid-state battery 1 according to an embodiment of the present invention will be described. FIG. 2 is a flowchart showing a method for manufacturing an all-solid-state battery 1 according to an embodiment of the present invention. Note that other processes may be included between the steps in the flowchart of FIG. 2. FIG. 3 is a schematic diagram for explaining in detail step ST1 of the flowchart shown in FIG. 2. Note that the all-solid-state battery 1 is manufactured using various devices, such as a device for stacking the negative electrode 4, the positive electrode 7, and the solid electrolyte layer 8, a press device for pressing the all-solid-state battery stack 10, a device for performing a discharge process on the all-solid-state battery stack 10, and a welding device for welding a current collector and a tab lead. Hereinafter, these devices will be collectively referred to as manufacturing devices.

[0017] In step ST1 of Fig. 2, the manufacturing apparatus performs a first press. For example, as shown in the left diagram of Fig. 3, the manufacturing apparatus repeatedly arranges a negative electrode 4 containing Li metal or a lithium alloy, a solid electrolyte layer 8, and a positive electrode 7 in one direction (hereinafter also referred to as the stacking direction) to form an unpressed laminate 10'. At this point, a negative electrode layer 2 composed of Li metal or a Li alloy has already been provided on both sides of the negative electrode current collector 3. Similarly, a positive electrode layer 5 has already been provided on both sides of the positive electrode current collector 6.

[0018] In the left-hand drawing, the negative electrode 4 and the solid electrolyte layer 8, and the solid electrolyte layer 8 and the positive electrode 7 are shown separated from each other; however, in the laminate 10′, the negative electrode 4 and the solid electrolyte layer 8, and the solid electrolyte layer 8 and the positive electrode 7 may be in contact with each other in an unpressed state.

[0019] In addition, in the left-hand drawing, the solid electrolyte layer 8 is shown separated from the positive electrode 7, but the solid electrolyte layer 8 may be attached to the positive electrode 7 in advance. That is, the positive electrode 7 may be a positive electrode with a solid electrolyte layer, in which the solid electrolyte layer 8 is pre-laminated on the positive electrode layer 5. For example, the positive electrode 7 and the solid electrolyte layer 8 are overlapped and pressed so that the positive electrode layer 5 and the solid electrolyte layer 8 are in contact with each other, and after pressing, the base material of the solid electrolyte layer 8 is removed, thereby transferring the solid electrolyte layer 8 to the positive electrode 7. A positive electrode with a solid electrolyte layer may be obtained in this manner.

[0020] Next, as shown in the right diagram of FIG. 3 , the manufacturing apparatus applies a first press pressure (i.e., first surface pressure) P1 to the laminate 10′ at least in the stacking direction. The first press pressure P1 is smaller than the second press pressure (i.e., second surface pressure) P2 described below, and is preferably, for example, less than 100 MPa and not more than 20 MPa. The first press pressure P1 is equal to or greater than the yield stress of Li metal, for example, 5 MPa or more. The yield stress of Li metal refers to the stress at which Li metal begins to become plastic. This press (first press) results in low-pressure bonding between the anode layer 2 and the solid electrolyte layer 8, and between the solid electrolyte layer 8 and the cathode layer 5, respectively, and thus pre-molding (molding at low pressure) the all-solid-state battery laminate 10 in which a plurality of battery cells 9 are stacked, as shown in FIG. 1 .

[0021] By this pre-molding, the anode layer 2 made of Li metal or Li alloy is pre-pressed (pressed at low pressure) to the solid electrolyte layer 8. Therefore, each battery cell 9 included in the all-solid-state battery laminate 10 is formed in a charged state. For example, each battery cell 9 included in the all-solid-state battery laminate 10 is formed in a state of SOC (State Of Charge) of 100% or a high SOC (for example, 95%, 90%, or 85%).

[0022] Next, in step ST2 of Fig. 2, the manufacturing device performs a discharge treatment on the battery cells 9 included in the pre-molded all-solid-state battery stack 10. For example, the discharge treatment is performed in an environment above room temperature and in an inert atmosphere (for example, N ２By performing a discharge treatment on all the battery cells 9 included in the all-solid-state battery stack 10 under a constant temperature (atmosphere) or vacuum, all the battery cells 9 can be efficiently discharged. During this discharge treatment, in each battery cell 9, Li ions move from the anode 4 to the cathode 7 via the solid electrolyte layer 8 and are occluded in the cathode layer 5. As described above, each battery cell 9 included in the all-solid-state battery stack 10 is in a charged state when formed. When the discharge treatment is performed on the battery cell 9, the Li metal or Li alloy as the anode layer 2 decreases as the discharge progresses. When the discharge progresses to an SOC of 0%, the Li metal or Li alloy as the anode layer 2 is almost gone. By performing a discharge treatment on all the battery cells 9 included in the all-solid-state battery stack 10, the SOC of all the battery cells 9 can be reduced to 0% or almost 0%.

[0023] 2 , the manufacturing apparatus presses (a second time) the discharged all-solid-state battery stack 10 at least in the stacking direction with a second press pressure P2. The second press pressure P2 is greater than the first press pressure P1 described above, and is, for example, 40 MPa or more. This press (second time) presses the anode layer 2 and the solid electrolyte layer 8, and the solid electrolyte layer 8 and the cathode layer 5, together with high pressure, to form the all-solid-state battery stack 10 (molded at high pressure).

[0024] After the all-solid-state battery laminate 10 is fully formed, the manufacturing equipment bonds the plurality of negative electrode current collectors 3 to the negative electrode tab lead 11. Furthermore, before, after, or in parallel with this, the manufacturing equipment bonds the plurality of positive electrode current collectors 6 to the positive electrode tab lead 12. This bonding is performed by, for example, welding. The welding method is not particularly limited, but examples include welding using an ultrasonic welding machine and laser welding.

[0025] 2 , the manufacturing equipment performs an initial charging process on the molded all-solid-state battery laminate 10. This charging process is performed, for example, via the negative electrode tab lead 11 and the positive electrode tab lead 12. During this charging process, in each battery cell 9, Li ions occluded in the positive electrode layer 5 migrate to the negative electrode current collector 3 via the solid electrolyte layer 8, and Li metal or Li alloy is precipitated as the negative electrode layer 2. Through the above steps, the all-solid-state battery 1 shown in FIG. 1 is completed.

[0026] (Evaluation Experiment) The inventors conducted an experiment to evaluate the electrical characteristics of the all-solid-state battery 1 manufactured using the manufacturing method according to the present embodiment. Experimental samples were prepared under the conditions shown in Table 1, including all-solid-state batteries of Examples 1 to 3 and all-solid-state batteries of Comparative Examples 1 to 3. In Table 1, the first pressing operation is the value of the first pressing pressure P1 in step ST1 of FIG. 2 . The discharge treatment is the value of the treatment conditions (temperature, pressure) in step ST2 of FIG. 2 . The second pressing operation is the value of the second pressing pressure P2 in step ST3 of FIG. 2 . The initial chargeable capacity is the chargeable capacity in step ST4 of FIG. 2 . Note that, in Comparative Examples 1 to 3, step ST3 of FIG. 2 was not performed, and therefore the value of the second pressing pressure P2 is zero (0). Furthermore, in Examples 1 to 3 and Comparative Examples 1 to 3, a lithium-indium alloy was used for the positive electrode layer, and a 30 μm-thick Li foil was used for the negative electrode layer.

[0027]

[0028] Details of the discharge treatment conditions in step ST2 are as follows: Surface pressure: 20 MPa (5 MPa only in Example 3) Temperature during discharge treatment: 60°C Current density during discharge treatment: 0.06 mA / cm ２ Discharge treatment termination condition: Voltage -0.5V Cutoff

[0029] In step ST2, a surface pressure (pressure in the stacking direction) is applied to the all-solid-state battery stack, and a current of 0.06 mA / cm is applied to each battery cell included in the all-solid-state battery stack. ２ The discharge was terminated when the voltages of all the current cells included in the all-solid-state battery stack became −0.5 V or less.

[0030] Details of the charging conditions in step ST4 are as follows: Surface pressure: 20 MPa (5 MPa only in Example 3) Temperature during charging: 25°C Current density during charging: 1.2 mA / cm ２ ・Charging process termination condition: capacity 0.6mAh / cm ２ End

[0031] In step ST4, a surface pressure (pressure in the stacking direction) is applied to the all-solid-state battery stack, and a current of 1.2 mA / cm is applied to the all-solid-state battery stack via the negative electrode tab lead 11 and the positive electrode tab lead 12. ２ The charge capacity was 0.6 mAh / cm ２ At this point, the charging process was terminated.

[0032] 4 is a graph showing the charging characteristics of the examples and comparative examples, which are experimental results of the present invention. The vertical axis of FIG. 4 represents the charging voltage [V], and the horizontal axis represents the charging capacity [mAh / cm ２ As shown in FIG. 4, in Examples 1 to 3, the charge capacity of 0.6 mAh / cm 2, which is the termination condition for the charging process, ２ Up to this point, the charging voltage was stable and the voltage behavior was stable. In contrast, Comparative Examples 1 to 3 exhibited unstable voltage behavior, which is thought to be due to the occurrence of a short circuit in the battery cell within the all-solid-state battery laminate.

[0033] (Mechanism) As described above, Examples 1 to 3 exhibited stable voltage behavior, while Comparative Examples 1 to 3 exhibited unstable voltage behavior. The present inventors believe that the reason for this is due to the mechanism described below.

[0034] 5 is a cross-sectional view schematically illustrating the state change during charging in Example 1 of the present invention and Comparative Examples 1 and 2. In Example 1 and Comparative Examples 1 and 2 shown in FIG. 5, the upper diagram shows the state after the first pressing, and the middle diagram shows the state after the discharge treatment. The latter diagram of Example 1 shows the state after the second pressing and then the charging treatment. The latter diagrams of Comparative Examples 1 and 2 show the state after the charging treatment without the second pressing.

[0035] As shown in the upper diagram of Fig. 5, in Example 1 and Comparative Example 2, the first pressing is a low-pressure press, so a partial gap remains between the anode layer 2 and the solid electrolyte layer 8. Furthermore, in Example 1 and Comparative Example 2, the low-pressure press prevents the Li metal constituting the anode layer 2 from penetrating into the grain boundaries 82 (i.e., the interfaces between particles 81) of the solid electrolyte layer 8. On the other hand, in Comparative Example 1, the first pressing is a high-pressure press, so there is no gap between the anode layer 2 and the solid electrolyte layer 8. Furthermore, in Comparative Example 1, the high-pressure press prevents the Li metal constituting the anode layer 2 from penetrating into the grain boundaries 82 of the solid electrolyte layer 8.

[0036] As shown in the middle diagram of Fig. 5, in all of Example 1, Comparative Example 1, and Comparative Example 2, Li ions migrate from the negative electrode side to the positive electrode side (from top to bottom in Fig. 5) due to the discharge treatment. After the discharge treatment is completed, the negative electrode layer 2 disappears from between the negative electrode current collector 3 and the solid electrolyte layer 8. In Comparative Example 1, at least a portion of the Li metal that has penetrated into the grain boundary 82 remains in the grain boundary 82 even after the discharge treatment because the grain boundary 82 is narrow.

[0037] In Example 1, a second pressure pressing is performed after the discharge treatment, but the second pressure pressing is a high-pressure pressing, so that the negative electrode current collector 3 and the solid electrolyte layer 8 are tightly attached to each other. In contrast, the second pressure pressing is not performed in Comparative Examples 1 and 2. In Comparative Example 2, the high-pressure pressing is not performed after the discharge treatment, so that a gap AG remains between the negative electrode current collector 3 and the solid electrolyte layer 8.

[0038] Thereafter, Li ions migrate from the positive electrode side to the negative electrode side by charging. In Example 1, since no Li metal remains at the grain boundaries 82 of the solid electrolyte layer 8, the Li ions migrate through the solid electrolyte layer 8 and are deposited as the negative electrode layer 2 on the surface of the negative electrode current collector 3.

[0039] On the other hand, in Comparative Example 1, Li metal remains at the grain boundaries 82, and at least some of the Li ions precipitate on the surface of the Li metal remaining at the grain boundaries 82. In Comparative Example 1, a short circuit occurs between the positive electrode and the negative electrode via the Li metal precipitated at the grain boundaries 82.

[0040] In Comparative Example 2, because a gap exists between the negative electrode current collector 3 and the solid electrolyte layer 8, Li ions are preferentially deposited in the region where the negative electrode current collector 3 and the solid electrolyte layer 8 are in contact (i.e., the region where there is no gap). In Comparative Example 2, Li is deposited non-uniformly during charging, and a short circuit occurs between the positive electrode and the negative electrode via this non-uniformly deposited Li metal.

[0041] The present inventors believe that the experimental results shown in FIG. 4 were obtained due to the above mechanism.

[0042] Effect of the embodiment As described above, the method for manufacturing an all-solid-state battery according to the embodiment of the present invention includes the steps of pressing a stack 10′ in which a negative electrode 4 containing Li metal or a Li alloy, a solid electrolyte layer 8, and a positive electrode 7 are repeatedly arranged in one direction with a first pressing pressure P1 in at least one direction to form an all-solid-state battery stack 10 in which a plurality of battery cells 9 are stacked in one direction, a step of performing a discharge treatment on the battery cells 9 after pressing with the first pressing pressure P1, and a step of pressing the all-solid-state battery stack 10 in at least one direction with a second pressing pressure P2 after the discharge treatment. The first pressing pressure P1 is smaller than the second pressing pressure P2.

[0043] According to this method, the all-solid-state battery stack 10 is pre-molded at a first press pressure P1 (low pressure). Because this pre-molding is performed at a low pressure, it is possible to prevent lithium metal from entering the grain boundaries 82 of the solid electrolyte layer 8 from the negative electrode 4, and to prevent the formation of dendrites (dendritic lithium metal). This makes it possible to prevent a short circuit between the positive electrode 7 and the negative electrode 4 via the dendrites.

[0044] After removing Li from the negative electrode 4 by the discharge treatment, the all-solid-state battery stack 10 is finally molded at a second press pressure P2 (high pressure). This improves the contact state at the interface between the negative electrode 4 and the solid electrolyte layer 8, thereby realizing a good interface.

[0045] In the manufacturing method of this embodiment, because Li metal or Li alloy is present in the negative electrode 4 at the beginning of manufacturing, a battery cell in a charged state is formed when the negative electrode 4 and the positive electrode 7 are pressed (pressed) onto the solid electrolyte layer 8. However, by performing a discharge treatment after pre-molding, the main molding and tab lead joining steps can be performed at an SOC of 0%. If the SOC is 0%, current is unlikely to flow through the battery cell 9 even if the positive electrode 7 and the negative electrode 4 are short-circuited. Therefore, in addition to the above effects, the manufacturing method of this embodiment also contributes to reducing the difficulty of manufacturing an all-solid-state battery in which Li metal or Li alloy is present in the negative electrode 4 in the as-manufactured state.

[0046] Other Embodiments As described above, the present invention has been described using embodiments and examples. However, the descriptions and drawings that form part of this disclosure should not be understood as limiting the present invention. Various alternative embodiments and modifications will be apparent to those skilled in the art from this disclosure. For example, in the above embodiment, with reference to the right-hand diagram of FIG. 3, it has been described that the laminate 10′ is pressed (first time) at least in the stacking direction with a first press pressure P1. As indicated by the word "at least," this pressing (first time) may not only be performed with the first press pressure P1 in the stacking direction, but also in a direction intersecting the stacking direction (e.g., a direction diagonally intersecting the stacking direction) with the first press pressure P1. The same applies to the pressing (second time) described in step ST3 of FIG. 2. Not only may the pressing be performed with the second press pressure P2 in the stacking direction, but also in a direction intersecting the stacking direction with the second press pressure P2. As such, the present technology naturally includes various embodiments not described herein. At least one of various omissions, substitutions, and modifications of components may be made without departing from the spirit of the above-described embodiments. Furthermore, the effects described in this specification are merely examples and are not intended to be limiting, and other effects may also be obtained.

[0047] The present invention can also employ the following configurations: (1) A method for manufacturing an all-solid-state battery, comprising: a step of pressing a stack, in which a negative electrode containing Li metal or a Li alloy, a solid electrolyte layer, and a positive electrode are repeatedly arranged in one direction, with a first pressure in at least the one direction to form an all-solid-state battery stack in which a plurality of battery cells are stacked in the one direction; a step of discharging the battery cells after pressing with the first pressure; and a step of pressing the all-solid-state battery stack with a second pressure in at least the one direction after performing the discharge treatment, wherein the first pressure is smaller than the second pressure. (2) The method for manufacturing an all-solid-state battery according to (1), in which the discharge treatment is performed on all of the battery cells included in the all-solid-state battery stack. (3) The method for manufacturing an all-solid-state battery according to (1) or (2), in which a sulfide solid electrolyte is used as the electrolyte material of the all-solid-state electrolyte layer. (4) The method for manufacturing an all-solid-state battery according to (3), in which a material containing Li, P, S, and a halide is used as the electrolyte material of the solid electrolyte layer. (5) The method for producing an all-solid-state battery according to any one of (1) to (4), wherein the first pressing pressure is lower than 100 MPa. (6) The method for producing an all-solid-state battery according to any one of (1) to (5), wherein the first pressing pressure is equal to or higher than the yield stress of Li. (7) The method for producing an all-solid-state battery according to any one of (1) to (6), wherein the first pressing pressure is 5 MPa or higher. (8) The method for producing an all-solid-state battery according to any one of (1) to (7), wherein the second pressing pressure is 40 MPa or higher. (9) The method for producing an all-solid-state battery according to any one of (1) to (8), wherein the discharge treatment is carried out in an environment of room temperature or higher. (10) The method for producing an all-solid-state battery according to (9), wherein the discharge treatment is carried out in an inert atmosphere or in vacuum.

[0048] DESCRIPTION OF SYMBOLS 1... all-solid-state battery, 2... negative electrode layer, 3... negative electrode current collector, 4... negative electrode, 5... positive electrode layer, 6... positive electrode current collector, 7... positive electrode, 8... solid electrolyte layer, 9... battery cell, 10'... laminate, 10... all-solid-state battery laminate, 11... negative electrode tab lead, 12... positive electrode tab lead, 81... particle, 82... grain boundary, AG... gap, P1... first pressing pressure, P2... second pressing pressure

Claims

1. A method for manufacturing an all-solid-state battery, comprising: a step of pressing a laminate in which a negative electrode containing Li metal or a Li alloy, a solid electrolyte layer, and a positive electrode are repeatedly arranged in one direction with a first pressing pressure in at least the one direction to form an all-solid-state battery laminate in which a plurality of battery cells are stacked in the one direction; a step of discharging the battery cells after pressing with the first pressing pressure; and a step of pressing the all-solid-state battery laminate in at least the one direction with a second pressing pressure after discharging, wherein the first pressing pressure is smaller than the second pressing pressure.

2. The method for manufacturing an all-solid-state battery according to claim 1, wherein the discharge treatment is performed on all of the battery cells included in the all-solid-state battery stack.

3. The method for producing an all-solid-state battery according to claim 1 or 2, wherein a sulfide solid electrolyte is used as the electrolyte material of the solid electrolyte layer.

4. The method for producing an all-solid-state battery according to claim 3, wherein a material containing Li, P, S and a halide is used as the electrolyte material of the solid electrolyte layer.

5. The method for producing an all-solid-state battery according to claim 1 or 2, wherein the first pressing pressure is less than 100 MPa.

6. The method for producing an all-solid-state battery according to claim 5, wherein the first pressing pressure is equal to or greater than the yield stress of Li.

7. The method for producing an all-solid-state battery according to claim 6, wherein the first pressing pressure is 5 MPa or more.

8. The method for producing an all-solid-state battery according to claim 1 or 2, wherein the second pressing pressure is 40 MPa or more.

9. The method for producing an all-solid-state battery according to claim 1 or 2, wherein the discharge treatment is carried out in an environment at room temperature or higher.

10. The method for producing an all-solid-state battery according to claim 9, wherein the discharge treatment is carried out in an inert atmosphere or in vacuum.

Images