All-solid-state battery production method and laminate for all-solid-state battery production

Abstract

Provided is a method for producing an all-solid-state battery in which Li metal or an Li alloy is provided on the negative electrode side at the time of production and which has an improved negative electrode utilization rate when performing an initial discharge operation. The method for producing an all-solid-state battery comprises: a step for forming a laminate in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer that has an area not greater than the area of the positive electrode layer in a plan view and that contains lithium metal or a lithium alloy, and a negative electrode current collector are stacked; and a step for performing a discharge operation on the laminate.

Description

Manufacturing method for all-solid-state battery and laminate for manufacturing all-solid-state battery

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

[0002] When manufacturing an all-solid-state battery, there are cases where a lithium-containing positive electrode layer is used, and cases where the positive electrode layer does not contain lithium and lithium is provided on the negative electrode side. Patent Document 1 describes a battery in which a solid electrolyte layer is arranged to cover a positive electrode active material layer, and the area of ​​the negative electrode active material layer is larger than the area of ​​the solid electrolyte layer in a plan view. Patent Document 2 describes a battery control system and a battery control method that prevent short circuits at edge portions.

[0003] International Publication No. 2020 / 136971 Japanese Patent Application Laid-Open No. 2022-062468

[0004] When a positive electrode layer containing lithium is used during manufacturing, the battery is manufactured with an SOC of 0%. Then, when the first charging operation is performed, lithium is deposited on the negative electrode side. In contrast, an all-solid-state battery in which lithium (Li) metal or a Li alloy is provided on the negative electrode side during manufacturing is manufactured with an SOC of 100%. Then, when the first discharging operation is performed, Li on the negative electrode side moves to the positive electrode side and is absorbed into the positive electrode layer.

[0005] The present invention aims to provide a method for producing an all-solid-state battery in which lithium (Li) metal or a Li alloy is provided on the negative electrode side during production, and a laminate for use in producing the all-solid-state battery, in which the negative electrode utilization rate is improved during the first discharge operation.

[0006] A method for producing an all-solid-state battery according to one aspect of the present invention includes the steps of forming a laminate in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer having an area equal to or less than that of the positive electrode layer in a plan view and containing lithium metal or a lithium alloy, and a negative electrode current collector are stacked, and discharging the laminate.

[0007] According to one aspect of the present invention, in an all-solid-state battery that contains lithium (Li) metal or a Li alloy on the negative electrode side during manufacturing, the negative electrode utilization rate during the initial discharge operation can be improved.

[0008] 1 is a cross-sectional view showing an example of the configuration of an all-solid-state battery according to Comparative Example 1. FIG. 2 is a cross-sectional view showing an example of the configuration of an all-solid-state battery according to Comparative Example 2. FIG. 3 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by the method for manufacturing an all-solid-state battery according to Embodiment 1. FIG. 4 is a flowchart showing a method for manufacturing a battery according to Embodiment 1. FIG. 5 is a schematic view for explaining steps ST1 to ST2 of the flowchart shown in FIG. 2. FIG. 6 is a cross-sectional view showing an example of the configuration of an all-solid-state battery according to Embodiment 1 and a first discharge operation. FIG. 7 is a graph showing experimental results of the negative electrode utilization rate when the first discharge operation is performed on all-solid-state batteries according to the examples of Embodiment 1 and Comparative Example 3. FIG. 8 is a diagram showing the configuration of an all-solid-state battery manufacturing system according to Embodiment 3. FIG. 9 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by the method for manufacturing an all-solid-state battery according to Embodiment 3. FIG. 10 is a graph showing creep strain. FIG. 11 is a flowchart showing a method for manufacturing a battery according to Embodiment 3. FIG. 12 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by the method for manufacturing an all-solid-state battery according to Modification 1 of Embodiment 3. FIG. 13 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by the method for manufacturing an all-solid-state battery according to Modification 2 of Embodiment 3. FIG. 14 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by the method for manufacturing an all-solid-state battery according to Modification 2 of Embodiment 3. FIG. 15 is a schematic view showing a first area smaller than the area of ​​the positive electrode layer. 10 is a flowchart showing a method for manufacturing a battery according to a fourth embodiment.

[0009] An embodiment of the present invention (the present embodiment) will be described below. In 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 ratios of each device and each component, and the like may differ from those in reality. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. It goes without saying that the dimensional relationships and ratios of parts included in the drawings may differ from one another. The definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical concept of the present invention. For example, if an object is rotated 90 degrees and observed, up and down are read as being converted to left and right, and if it is rotated 180 degrees and observed, up and down are read as being reversed.

[0010] [Embodiment 1] <<Overview>> An all-solid-state battery 9A according to Comparative Example 1 shown in FIG. 1 includes a positive electrode layer 5A containing Li and is manufactured at a state of charge (SOC) of 0%. An all-solid-state battery 9B according to Comparative Example 2 shown in FIG. 2 includes a negative electrode layer 2A of Li disposed between a negative electrode current collector 3 and a solid electrolyte layer 8 and is manufactured at an SOC of 100%. As shown in FIG. 1 , when the all-solid-state battery 9A is subjected to an initial charging operation (hereinafter referred to as the initial charging operation) from a state in which no electrochemical operation such as charging or discharging has been performed, a negative electrode layer 2 of Li is deposited in a region of the negative electrode current collector 3 that overlaps the positive electrode layer 5A in a planar view. An advantage of manufacturing the all-solid-state battery 9B shown in FIG. 2 is that, for example, since it is not necessary to occlude Li in the positive electrode layer 5 in advance, the choice of materials for the positive electrode layer 5 can be broadened. In manufacturing the all-solid-state battery 9B, as shown in FIG. 2 , when a first discharge operation (hereinafter referred to as the first discharge operation) is performed from a state in which no electrochemical operation such as charge or discharge has been performed, the anode layer 2A moves to the cathode layer 5 and is occluded.

[0011] In general, the material of the positive electrode layer 5 is more expensive than the material of the negative electrode layer 2. Therefore, when manufacturing an all-solid-state battery 9B, as shown in FIG. 2 , a negative electrode layer 2A having a larger area in a planar view than the positive electrode layer 5 is provided in order to maximize the capacity of the positive electrode layer 5. However, such a negative electrode layer 2A includes a facing portion 21 facing the positive electrode layer 5 and a non-facing portion 22 not facing the positive electrode layer 5. When an initial discharge operation is performed, the reaction in the facing portion 21 tends to proceed faster than the reaction in the non-facing portion 22. As a result, the non-facing portion 22 may not fully react and remain on the negative electrode side, resulting in a void X in the region where the facing portion 21 was located.

[0012] 3 , the all-solid-state battery 1 manufactured by the manufacturing method according to the first embodiment 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. The all-solid-state battery laminate 10 may be covered and sealed by an exterior body (not shown).

[0013] 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. 3 ). 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.

[0014] 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. 3 ). 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.

[0015] 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.

[0016] 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. The number of battery cells 9 may be one. 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.

[0017] <<Manufacturing Method>> Next, a manufacturing method of the all-solid-state battery 1 according to this embodiment will be described with reference to the flowchart shown in FIG. 4. Note that other processes may be included between the steps in the flowchart of FIG. 4. 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 pressure device for pressurizing the all-solid-state battery stack 10, a device for discharging the all-solid-state battery stack 10, and a welding device for welding the current collector and the tab lead. Hereinafter, these devices will be collectively referred to as manufacturing devices.

[0018] In step ST1, the manufacturing equipment places a cathode 7 with a solid electrolyte layer 8. For example, the cathode 7 with a solid electrolyte layer 8 is placed, in which the solid electrolyte layer 8 is pre-laminated on the cathode layer 5. The manufacturing method involves stacking the cathode 7 and the solid electrolyte layer 8 so that the cathode layer 5 and the solid electrolyte layer 8 are in contact with each other and applying pressure. After pressing, the substrate of the solid electrolyte layer 8 is removed, thereby transferring the solid electrolyte layer 8 to the cathode 7. The cathode 7 with the solid electrolyte layer 8 can be obtained by this manufacturing method. Note that the manufacturing method according to the first embodiment is not limited to this. For example, the solid electrolyte layer 8 may be provided on the anode 4 instead of the cathode 7. In this case, step ST1 simply becomes a step of placing the cathode 7, and step ST2, described later, becomes a step of placing the anode 4 with the solid electrolyte layer 8. Alternatively, the solid electrolyte layer 8 may be prepared separately from the cathode 7 and the anode 4. In this case, for example, a step of placing the solid electrolyte layer 8 may be provided between the step of placing the cathode 7 (step ST1) and the step of placing the anode 4 (step ST2). Next, in step ST2, the manufacturing equipment places the negative electrode 4 at a position facing the positive electrode 7 in the stacking direction with the solid electrolyte layer 8 interposed therebetween.

[0019] Steps ST1 and ST2 constitute the stacking process for one battery cell. Steps ST1 and ST2 are repeated a preset number of times (i.e., a predetermined number of times). The predetermined number of times corresponds, for example, to the number of stacked battery cells 9 (see FIG. 3 ). As a result, as shown in FIG. 5 , an unbonded laminate 10′ is formed in which an anode 4 containing Li metal or Li alloy as an anode layer 2, a solid electrolyte layer 8, and a cathode 7 are repeatedly arranged in the stacking direction. More specifically, an unbonded laminate 10′ is formed in which a cathode current collector 6, a cathode layer 5, a solid electrolyte layer 8, an anode layer 2, and an anode current collector 3 are stacked in this order. When the unbonded laminate 10′ is viewed from above, the entire anode layer 2 is arranged so as to overlap the cathode layer 5. Note that the stacking direction from the cathode current collector 6 to the anode current collector 3 is the vertical direction of the page in FIG. 5 , and this direction is referred to as the stacking direction. In the following description, the manufacturing method of the all-solid-state battery 1 according to the first embodiment will be described in some cases, taking as an example a case where the number of stacked battery cells 9 is one.

[0020] Next, in step ST3 of FIG. 4 , the manufacturing equipment applies pressure to the unbonded laminate 10′. For example, as shown in FIG. 5 , the manufacturing equipment applies pressure P1 to the unbonded laminate 10′ at least in the stacking direction. The pressure P1 shown in FIG. 5 is equal to or greater than the yield stress of Li metal, e.g., 5 MPa or greater. The yield stress of Li metal refers to the stress at which Li metal begins to become plastic. This pressurization causes high 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, thereby forming the all-solid-state battery laminate 10. When viewed from above, the anode layer 2 is disposed so that the entire anode layer 2 overlaps the cathode layer 5. The all-solid-state battery laminate 10 is the laminate after pressurization. When the all-solid-state battery laminate 10 after pressurization and the unbonded laminate 10′ are not distinguished from each other, they are simply referred to as laminates.

[0021] By this molding, the anode layer 2 made of Li metal or Li alloy is pressure-bonded to the solid electrolyte layer 8. Therefore, each battery cell 9 included in the all-solid-state battery stack 10 is formed in a charged state. For example, each battery cell 9 included in the all-solid-state battery stack 10 is formed in a state of 100% SOC or a high SOC.

[0022] The all-solid-state battery laminate 10 shown in Figures 5 and 6 is in a state where electrochemical processes such as charging and discharging have not yet been performed. As shown in Figure 6, in a state where electrochemical processes have not yet been performed, the width W1 of the anode layer 2 of the all-solid-state battery laminate 10 is set to be equal to or smaller than the width W2 of the cathode layer 5 (W1 ≦ W2). In other words, the area of ​​the anode layer 2 is set to be equal to or smaller than the area of ​​the cathode layer 5 in a plan view. The widths W1 and W2 are dimensions in a direction perpendicular to the stacking direction. Furthermore, the all-solid-state battery laminate 10 shown in Figure 6 shows an example where W1 < W2, while the all-solid-state battery laminate 10 shown in Figure 5 shows an example where W1 = W2.

[0023] 5 is also in a state where electrochemical processes such as charging and discharging have not yet been carried out on the unbonded laminate 10′. Similarly, in the unbonded laminate 10′, the width W1 of the anode layer 2 is set to be equal to or smaller than the width W2 of the cathode layer 5 (W1≦W2), and the area of ​​the anode layer 2 is set to be equal to or smaller than the area of ​​the cathode layer 5.

[0024] Next, in step ST4 of Fig. 4, the manufacturing equipment performs tab joining. For example, the manufacturing equipment joins the negative electrode current collector 3 to the negative electrode tab lead 11 (see Fig. 3). The manufacturing equipment also joins the multiple positive electrode current collectors 6 to the positive electrode tab lead 12 (see Fig. 3). These joining steps are performed by welding, for example. The welding method is not particularly limited, but examples include welding using an ultrasonic welder and laser welding.

[0025] Next, in step ST5 of Fig. 4, the manufacturing apparatus performs a discharging process. In the discharging process, the manufacturing apparatus performs an initial discharging operation on the all-solid-state battery stack 10 formed in a charged state. For example, a discharging operation is performed on all battery cells 9 included in the all-solid-state battery stack 10 via the negative electrode tab lead 11 and positive electrode tab lead 12 shown in Fig. 3. In the discharging operation, in each battery cell 9, Li ions move from the negative electrode 4 through the solid electrolyte layer 8 to the positive electrode 7 and are occluded in the positive electrode layer 5. When the discharging operation is performed, the Li metal or Li alloy as the negative electrode layer 2 decreases as the discharge progresses. When the discharge progresses to an SOC of 0%, the Li metal or Li alloy as the negative electrode layer 2 is almost completely depleted.

[0026] 6 , when no electrochemical operation such as charge / discharge is being performed, the width W1 of the anode layer 2 is equal to or smaller than the width W2 of the cathode layer 5. The anode layer 2 does not have any portion that does not face the cathode layer 5. Therefore, the entire lower surface (the surface on the solid electrolyte layer 8 side) of the anode layer 2 faces the cathode layer 5, and non-uniform reaction of Li or a Li alloy in the anode layer 2 is unlikely to occur during discharge. Therefore, Li or a Li alloy is unlikely to remain on the anode 4 side after discharge is completed.

[0027] FIG. 7 is a graph showing experimental results of the negative electrode utilization rate when the all-solid-state batteries according to the Example of Embodiment 1 and Comparative Example 3 were subjected to an initial discharge operation. The vertical axis of the graph represents voltage, and the horizontal axis represents the negative electrode utilization rate. The negative electrode utilization rate is an index showing what percentage of the negative electrode layer 2 provided on the negative electrode 4 side was occluded by the positive electrode layer 5 during the discharge operation, assuming that the amount of the negative electrode layer 2 provided on the negative electrode 4 side is 100%. Samples prepared under the following conditions were used for the all-solid-state batteries according to the Example and Comparative Example 3. In the Example, W1 = 5 mm, W2 = 10 mm, and in Comparative Example 3, W1 = 10 mm, W2 = 5 mm. The solid electrolyte layer 8 was 10 mm in the Example and Comparative Example 3.

[0028] As a result of the experiment, the negative electrode utilization rate of the example was approximately 98.8%, while the negative electrode utilization rate of Comparative Example 3 was approximately 80%. Thus, the negative electrode utilization rate of the example was higher than that of Comparative Example 3. The reason why the negative electrode utilization rate of Comparative Example 3 was low is thought to be that the reaction of Li became non-uniform on the underside of the negative electrode layer 2, and some Li, such as in the unopposed portion, did not react and remained on the negative electrode 4 side.

[0029] The manufacturing apparatus may perform an initial charging operation on the all-solid-state battery stack 10 that has been subjected to the discharging operation. This charging operation is performed via the negative electrode tab lead 11 and the positive electrode tab lead 12. During this charging operation, in each battery cell 9, Li ions that have been occluded in the positive electrode layer 5 move to the negative electrode current collector 3 via the solid electrolyte layer 8, and Li metal or a Li alloy is deposited as the negative electrode layer 2. The negative electrode layer 2 is deposited at a position facing the positive electrode layer 5.

[0030] [Embodiment 2] In the above-described embodiment 1, the width W1 of the anode layer 2 of the laminate is set to be equal to or smaller than the width W2 of the cathode layer 5 (W1≦W2), and the area of ​​the anode layer 2 of the laminate is set to be equal to or smaller than the area of ​​the cathode layer 5 in a planar view. However, the present technology is not limited thereto. In embodiment 2, the width W1 of the anode layer 2 of the laminate (all-solid-state battery laminate 10, unbonded laminate 10′) is set to be smaller than the width W2 of the cathode layer 5 (W1<W2), and the area of ​​the anode layer 2 is set to be smaller than the area of ​​the cathode layer 5 in a planar view. The area of ​​the anode layer 2 is set to, for example, a first area smaller than the area of ​​the cathode layer 5 in a planar view. The first area is not limited to this, but may be, for example, an area of ​​approximately 25% to 50% of the area of ​​the positive electrode layer 5, an area of ​​approximately 50% to 80%, an area of ​​approximately 80% to 90%, or an area of ​​approximately 90% to 99%.

[0031] [Embodiment 3] In the above-described Embodiments 1 and 2, the amount of creep that occurs in the anode layer 2 due to the pressurizing process is not taken into consideration when manufacturing the all-solid-state battery 1, but the amount of creep is taken into consideration in Embodiment 3. Note that, in this embodiment, as in the above-described Embodiment 2, the width W1 of the anode layer 2 of the laminate (all-solid-state battery laminate 10, unpressurized laminate 10') is set smaller than the width W2 of the cathode layer 5 (W1<W2), and the area of ​​the anode layer 2 is set smaller than the area of ​​the cathode layer 5.

[0032] As shown in FIG. 8 , the battery manufacturing system 1000 includes a laminate, a pair of plate-shaped members 101 and 102, a sensor 200, and a controller 300. The battery manufacturing system 1000 is mainly used in the pressurizing step. As shown in FIG. 8 , the pair of plate-shaped members 101 and 102 are used to pressurize the unbonded laminate 10′. The plate-shaped member 101 is disposed on the upper side of the unbonded laminate 10′, and the plate-shaped member 102 is disposed on the lower side of the unbonded laminate 10′. The pair of plate-shaped members 101 and 102 are used to pressurize the unbonded laminate 10′ with a pressure P1 at least in the stacking direction thereof to obtain the all-solid-state battery laminate 10. The pair of plate-shaped members 101 and 102 may be part of a pressurizing device that pressurizes the unbonded laminate 10′ in the pressurizing step.

[0033] The sensor 200 detects a physical quantity of the unbonded laminate 10' during the pressurizing process and outputs the detected physical quantity as a detection result to the controller 300. As shown in Fig. 9, in this embodiment, the sensor 200 is a pressure sensor 201. The detection portion of the pressure sensor 201 is disposed, for example, between the plate-like member 101 (Fig. 8) and the unbonded laminate 10'. The pressure sensor 201 detects the pressure applied to the unbonded laminate 10' during the pressurizing process and outputs the detected pressure as a detection result to the controller 300.

[0034] As shown in FIG. 8 , the controller 300 is a control device and includes an arithmetic unit 310 and a storage device 320. The arithmetic unit 310 is configured, for example, with a CPU, an ASIC, an FPGA, etc. The storage device 320 is, for example, a known memory such as RAM, and stores information necessary for the arithmetic unit 310 to perform calculations. The arithmetic unit 310 includes a pressure control function 311 and a creep amount estimation function 312. The pressure control function 311 controls the pressurizing device in the pressurizing process to pressurize the unbonded laminate 10′. The pressure control function 311 also controls the pressurizing device to stop pressurizing in the pressurizing process. For example, the pressure control function 311 controls the pressurizing device to stop pressurizing based on the creep amount estimated by the creep amount estimation function 312 (hereinafter referred to as the estimated creep amount). The creep amount and the creep amount estimation function 312 will be described below.

[0035] When the negative electrode layer 2 is pressurized during the pressurization process, a so-called creep phenomenon, in which the shape of the Li metal changes, may occur. When the creep phenomenon occurs, the negative electrode layer 2 expands in a direction perpendicular to the stacking direction, as shown by the arrow in FIG. 9 . This increases the area of ​​the negative electrode layer 2 in a planar view. The creep amount estimation function 312 estimates the amount of creep occurring in the negative electrode layer 2 during the pressurization process based on the detection result of the sensor 200. For example, the creep amount estimation function 312 estimates the amount of creep using the detection result and data indicating the relationship between the detection result and the creep amount. Such data may be stored in the storage device 320 in advance. In this embodiment, the sensor 200 is the pressure sensor 201, and therefore the creep amount estimation function 312 estimates the amount of creep occurring in the negative electrode layer 2 during the pressurization process based on the pressure (detection result) detected by the pressure sensor 201.

[0036] For example, the creep amount estimation function 312 estimates the creep amount based on the pressure detected by the pressure sensor 201 and the creep strain data shown in FIG. 10 . The data of the graph shown in FIG. 10 is stored in advance in the storage device 320, with the vertical axis representing creep strain and the horizontal axis representing time, i.e., the elapsed time since pressurization began. The graph shows the change in creep strain over time for each of different pressures Pa, Pb, and Pc (Pa<Pb<Pc). Note that the creep strain data is not limited to pressures Pa, Pb, and Pc, and data for other pressures may also be stored in the storage device 320. The creep amount estimation function 312 may estimate the creep amount by referencing data that is the same as or similar to the detected pressure. It can be seen that the creep amount changes depending on the pressure and the elapsed time. The creep amount estimation function 312 may estimate the creep amount, for example, depending on the pressure detected by the pressure sensor 201 and the time during which the pressure is applied. The creep amount estimation function 312 outputs the estimated creep amount to the pressure control function 311 .

[0037] Based on the estimated creep amount, the pressure control function 311 performs control to stop the application of pressure by the pressure device before the area of ​​the negative electrode layer 2 reaches the area of ​​the positive electrode layer 5. For example, the pressure control function 311 calculates the area of ​​the negative electrode layer 2 including the estimated creep amount, and when the calculated area reaches a first area, performs control to stop the application of pressure by the pressure device.

[0038] <<Manufacturing Method>> Next, a manufacturing method of the all-solid-state battery 1 according to this embodiment will be described with reference to the flowchart shown in Fig. 11. The flowchart in Fig. 11 explains the control of the arithmetic device 310 in the pressurizing step. Note that other steps may be included between the steps in the flowchart in Fig. 11.

[0039] In step ST6, the pressure control function 311 controls the pressure device to start applying pressure to the unbonded laminate 10'. When the pressure starts, the pressure sensor 201 detects the pressure continuously or at regular intervals and outputs the detected pressure as a detection result to the controller 300.

[0040] In step ST7, the creep amount estimation function 312 estimates the creep amount based on the detection result. In step ST8, the pressure control function 311 determines whether the area of ​​the anode layer 2 has reached a first area based on the estimated creep amount. If it is determined that the first area has been reached (ST8: YES), the pressure control function 311 performs control to stop the application of pressure by the pressure device. This completes the application of pressure to the unbonded laminate 10', and the all-solid-state battery laminate 10 is obtained. If it is determined that the first area has not been reached (ST8: NO), the process proceeds to step ST7, and the processes of steps ST7 and ST8 are repeated.

[0041] When estimating the creep amount of the negative electrode layer 2, the creep amount estimation function 312 may estimate the time when the area of ​​the negative electrode layer 2 including the estimated creep amount is expected to reach the area of ​​the positive electrode layer 5, for example, based on the graph shown in Fig. 10. In this case, the pressure control function 311 performs control to stop the application of pressure by the pressure device before the estimated time.

[0042] [Variation 1 of Embodiment 3] In Variation 1 of Embodiment 3, a plurality of sensors 200 are provided. The amount of creep changes depending on temperature as well as pressure. Therefore, in this variation, as shown in FIG. 12 , a temperature sensor 202 is provided as the sensor 200 in addition to a pressure sensor 201. The temperature sensor 202 detects the temperature of the unbonded laminate 10′ during the pressurization step and outputs the detected temperature as a detection result to the controller 300. The detection result received by the controller 300 includes both the pressure detection result from the pressure sensor 201 and the temperature detection result from the temperature sensor 202.

[0043] 10 may be prepared for a plurality of different temperatures, and the data may be stored in the storage device 320. The creep amount estimation function 312 estimates the creep amount based on the detected pressure and temperature. The creep amount estimation function 312 may estimate the creep amount by referring to data that is the same as or close to the detected pressure and temperature.

[0044] [Variation 2 of Embodiment 3] In Variation 2 of Embodiment 3, as shown in FIG. 13 , the sensor 200 is a distance measurement sensor 203. The distance measurement sensor 203 is, for example, a laser distance meter. The distance measurement sensor 203 measures the thickness D of the unbonded laminate 10′ during the pressurizing process and outputs the measured thickness D to the controller 300 as a detection result. The distance measurement sensor 203 may, for example, measure the distance between a pair of plate-like members 101, 102 that pressurize the unbonded laminate 10′ and output the measured distance as the thickness D to the controller 300. Data indicating the relationship between the thickness of the laminate and the creep amount is calculated in advance, and such data is stored in the storage device 320 in advance. The creep amount estimation function 312 estimates the creep amount using the thickness D and the data stored in advance in the storage device 320.

[0045] [Fourth Embodiment] In the fourth embodiment, as shown in FIG. 14 , the sensor 200 is a pressure distribution measurement sensor 204. In the fourth embodiment, the area of ​​the negative electrode layer 2 is measured using the pressure distribution measurement sensor 204 instead of estimating the amount of creep. The pressure distribution measurement sensor 204 is, for example, a film-type pressure sensor, and can measure the pressure distribution within a surface. The detection portion of the pressure distribution measurement sensor 204 is disposed, for example, between the plate-like member 101 ( FIG. 8 ) and the unbonded laminate 10′. In addition, the detection portion of the pressure distribution measurement sensor 204 has an area equal to or larger than that of the positive electrode layer 5 in a plan view.

[0046] A higher pressure is detected in the portion of the pressure distribution measuring sensor 204 that overlaps with the negative electrode layer 2 than in the non-overlapping portion. The pressure distribution measuring sensor 204 outputs the in-plane pressure distribution as a detection result to the controller 300. The controller 300 can identify the area of ​​the negative electrode layer 2 from such a detection result. The pressure distribution measuring sensor 204 may also identify the area of ​​the negative electrode layer 2 from the in-plane pressure distribution and output the identified area of ​​the negative electrode layer 2 as a detection result to the controller 300.

[0047] <Manufacturing Method> Next, a manufacturing method of the all-solid-state battery 1 according to this embodiment will be described with reference to the flowchart shown in FIG. 16 . The flowchart shown in FIG. 16 differs from the flowchart shown in FIG. 11 in that it includes step ST71 instead of step ST7 and step ST10. Steps ST1 to ST6, ST8, and ST9 are similar to those shown in FIG. 11 , and therefore may not be described here. In step ST71, the controller 300 obtains the area of ​​the anode layer 2 based on the detection results from the pressure distribution measurement sensor 204. Then, in step ST8, it determines whether the obtained area of ​​the anode layer 2 reaches a first area. If it is determined that the first area has been reached (ST8: YES), the pressure control function 311 controls the pressure device to stop applying pressure. If it is determined that the first area has not been reached (ST8: NO), the process proceeds to step ST10. Note that FIG. 15 illustrates a first area 2X that is smaller than the area of ​​the cathode layer 5 in a plan view.

[0048] 16 , the controller 300 determines whether the side of the negative electrode layer 2 reaches the side of the positive electrode layer 5 in a plan view. If it is determined that the side of the positive electrode layer 5 has been reached (ST10: YES), the process proceeds to step ST9, and the pressure control function 311 performs control to stop the application of pressure by the pressure device. If it is determined that the side of the positive electrode layer 5 has not been reached (ST10: NO), the process proceeds to step ST71, and the processes of steps ST71 and ST8 are repeated.

[0049] <Other Embodiments> As described above, the present invention has been described using embodiments and modifications. However, the descriptions and drawings that form part of this disclosure should not be understood as limiting the present invention. For example, in Modifications 1 and 2 of Embodiment 3, the pressure control function 311 may control the pressure device to stop applying pressure before the estimated time. Various alternative embodiments and modifications will be apparent to those skilled in the art from this disclosure. It goes without saying that the present technology includes various embodiments not described herein. At least one of various omissions, substitutions, and modifications of components can be made without departing from the spirit of the above-described embodiments. Furthermore, the effects described in this specification are merely exemplary and are not limiting, and other effects may also be present.

[0050] The present invention can also employ the following configurations. Furthermore, the following configurations can be combined with each other. (1) A method for manufacturing an all-solid-state battery, including: forming a laminate including a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer having an area equal to or smaller than that of the positive electrode layer in a plan view and containing lithium metal or a lithium alloy, and a negative electrode current collector; and discharging the laminate. This configuration allows the entire bottom surface (lower surface) of the negative electrode layer 2 to face the positive electrode layer 5, preventing the formation of unopposed portions that are difficult to react with, and preventing the material constituting the negative electrode layer 2 from reacting unevenly within the bottom surface of the negative electrode layer 2. Therefore, the negative electrode layer 2 is less likely to remain on the negative electrode side (negative electrode current collector 3 side) during the initial discharge operation, preventing a decrease in discharge efficiency and a decrease in the negative electrode utilization rate. (2) In the step of forming the laminate, the area of ​​the negative electrode layer may be smaller than the area of ​​the positive electrode layer. In order to maximize the capacity of the positive electrode layer 5 while suppressing the generation of unreacted portions in the negative electrode layer 2, it is desirable to provide the negative electrode layer 2 with the same size as the positive electrode layer 5 and to provide the negative electrode layer 2 so that it exactly overlaps the positive electrode layer 5. However, if the negative electrode layer 2 is designed to be the same size as the positive electrode layer 5, there is a possibility that the negative electrode layer 2 may be unintentionally formed larger than the positive electrode layer 5 due to manufacturing errors or the like. As such, it may be difficult to provide the negative electrode layer 2 with the same size as the positive electrode layer 5. In contrast, according to the manufacturing method of the all-solid-state battery 1 according to this embodiment, the area of ​​the negative electrode layer 2 is set smaller than the area of ​​the positive electrode layer 5, thereby more reliably suppressing the generation of unopposed portions of the negative electrode layer 2 that do not face the positive electrode layer 5. Therefore, the negative electrode layer 2 is less likely to remain on the negative electrode side during the initial discharge operation, more reliably suppressing a decrease in discharge efficiency and more reliably suppressing a decrease in the utilization rate of the negative electrode. (3) The method may include a step of applying pressure to the laminate in the stacking direction, the step of applying pressure including a step of estimating a creep amount of the negative electrode layer due to the pressure based on a detection result of a sensor, and a step of stopping the pressure before the area of ​​the negative electrode layer reaches the area of ​​the positive electrode layer based on the estimated creep amount. Even if creep occurs in the negative electrode layer 2 during the pressurizing step, the amount of creep can be prevented from becoming too large based on the detection result of the sensor 200.This more reliably prevents the negative electrode layer 2 from having a portion that does not face the positive electrode layer 5. This makes it more difficult for the negative electrode layer 2 to remain on the negative electrode side during the initial discharge operation, more reliably preventing a decrease in discharge efficiency and a decrease in the negative electrode utilization rate. (4) The sensor may be a pressure sensor, and the detection result may be a result of the pressure sensor detecting the pressure applied to the stack. The amount of creep can be prevented from becoming too large based on the detection result of the pressure sensor. (5) The sensor may include a pressure sensor and a temperature sensor, and the detection result may include a result of the pressure sensor detecting the pressure applied to the stack and a result of the temperature sensor detecting the temperature of the stack. Since the amount of creep is estimated based on the pressure and temperature, the amount of creep can be estimated more accurately. (6) The sensor may be a distance sensor, and the detection result may be a result of the distance sensor detecting the thickness of the stack. The same effect as in (3) above can be obtained. (7) The method may include applying pressure to the laminate in the stacking direction, the applying pressure including: determining the area of ​​the negative electrode layer based on the detection results of a pressure distribution measurement sensor; and stopping the application of pressure before the area of ​​the negative electrode layer reaches the area of ​​the positive electrode layer based on the area of ​​the negative electrode layer. Because the area of ​​the negative electrode layer 2 is directly measured by the pressure distribution measurement sensor 204, the area of ​​the negative electrode layer 2 can be controlled more accurately. (8) Even if the area of ​​the negative electrode layer does not reach the area of ​​the positive electrode layer, the application of pressure may be stopped when an edge of the negative electrode layer reaches an edge of the positive electrode layer in a plan view. This more reliably prevents the negative electrode layer 2 from having an unopposed portion that does not face the positive electrode layer 5. (9) The application of pressure may be stopped when the area of ​​the negative electrode layer reaches a first area smaller than the area of ​​the positive electrode layer. Similar effects to those of (3) to (7) above can be achieved. (10) The step of estimating the creep amount may include estimating a time when the area of ​​the negative electrode layer will reach the area of ​​the positive electrode layer, and the step of stopping the application of pressure may stop the application of pressure before the estimated time, thereby achieving the same effects as those of (3) to (6) above.(11) A laminate for manufacturing an all-solid-state battery, comprising: a positive electrode current collector; a positive electrode layer; a solid electrolyte layer; a negative electrode layer having an area equal to or less than that of the positive electrode layer in a plan view and containing lithium metal or a lithium alloy; and a negative electrode current collector, which allows for highly efficient initial discharge and prevents a decrease in the utilization rate of the negative electrode.

[0051] 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, 109... battery cell, 10'... laminate, 10... all-solid-state battery laminate, 11... negative electrode tab lead, 12... positive electrode tab lead, 200... sensor, 201... pressure sensor, 202... temperature sensor, 203... distance measurement sensor, 204... pressure distribution measurement sensor

Claims

1. A method for manufacturing an all-solid-state battery, comprising: forming a laminate in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer having an area equal to or less than that of the positive electrode layer in a plan view and containing lithium metal or a lithium alloy, and a negative electrode current collector are stacked; and discharging the laminate.

2. The method for manufacturing an all-solid-state battery according to claim 1, wherein in the step of forming the laminate, the area of ​​the negative electrode layer is set smaller than the area of ​​the positive electrode layer.

3. The method for manufacturing an all-solid-state battery according to claim 2, further comprising the step of applying pressure to the laminate in the stacking direction, the step of applying pressure comprising the steps of: estimating an amount of creep of the negative electrode layer due to pressure based on a detection result of a sensor; and stopping the application of pressure before the area of ​​the negative electrode layer reaches an area of ​​the positive electrode layer based on the estimated amount of creep.

4. The method for manufacturing an all-solid-state battery according to claim 3, wherein the sensor is a pressure sensor, and the detection result is a result of the pressure sensor detecting a pressure applied to the laminate.

5. The method for producing an all-solid-state battery according to claim 3, wherein the sensor includes a pressure sensor and a temperature sensor, and the detection results include a result of the pressure sensor detecting the pressure applied to the laminate and a result of the temperature sensor detecting the temperature of the laminate.

6. The method for manufacturing an all-solid-state battery according to claim 3, wherein the sensor is a distance measuring sensor, and the detection result is a result of the distance measuring sensor detecting the thickness of the laminate.

7. The method for manufacturing an all-solid-state battery according to claim 2, further comprising the step of applying pressure to the laminate in the stacking direction, the step of applying pressure comprising: obtaining an area of ​​the negative electrode layer based on a detection result of a pressure distribution measurement sensor; and stopping the application of pressure before the area of ​​the negative electrode layer reaches the area of ​​the positive electrode layer based on the area of ​​the negative electrode layer.

8. The method for producing an all-solid-state battery according to claim 7, wherein even if the area of ​​the negative electrode layer does not reach the area of ​​the positive electrode layer, the application of pressure is stopped when an edge of the negative electrode layer reaches an edge of the positive electrode layer in a plan view.

9. The method for manufacturing an all-solid-state battery according to any one of claims 3 to 8, wherein the step of stopping the application of pressure stops the application of pressure when the area of ​​the negative electrode layer reaches a first area that is smaller than the area of ​​the positive electrode layer.

10. The method for producing an all-solid-state battery according to any one of claims 3 to 6, wherein the step of estimating the amount of creep includes estimating the time when the area of ​​the negative electrode layer will reach the area of ​​the positive electrode layer, and the step of stopping the application of pressure stops the application of pressure before the estimated time.

11. A laminate for use in producing an all-solid-state battery, comprising: a positive electrode current collector; a positive electrode layer; a solid electrolyte layer; a negative electrode layer having an area equal to or less than that of the positive electrode layer in a plan view and containing lithium metal or a lithium alloy; and a negative electrode current collector, stacked together.

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