Battery manufacturing method

Abstract

A battery manufacturing method including: a step in which laminates 30, in which a positive electrode layer 40, an electrolyte layer, and a negative electrode layer 50 are laminated along a lamination direction, are sandwiched by an exterior body 70; a step in which pressure is applied to both surfaces of the laminates 30 in a direction along the lamination direction thereof by means of the exterior body 70; and a high humidity holding step in which the laminates 30 and the exterior body 70 are held in an environment of higher humidity than before applying pressure to the laminates 30 in a state in which the laminates 30 have pressure applied thereto.

Description

Battery manufacturing method

[0001] The present invention relates to a battery manufacturing method.

[0002] Conventionally, there has been known a method for manufacturing an all-solid-state lithium secondary battery, which includes an exposure step of exposing a power generation element having an electrolyte-containing layer containing a sulfide-based solid electrolyte material to ambient air containing moisture to cause the sulfide-based solid electrolyte material to absorb water, thereby forming a deliquescent portion containing an oxide at least in a portion where the electrolyte-containing layer containing the sulfide-based solid electrolyte material comes into contact with the ambient air, thereby obtaining a deliquescent portion-containing power generation element; and a drying step of drying the deliquescent portion to remove moisture, thereby forming an oxide layer formed by oxidizing the sulfide-based solid electrolyte material that is substantially free of moisture, thereby obtaining an oxide layer-containing power generation element (see, for example, Patent Document 1).

[0003] JP 2009-193727 A

[0004] The above manufacturing method has the problem that a thick oxide film layer is formed, which reduces the battery performance.

[0005] The problem to be solved by the present invention is to provide a battery manufacturing method that suppresses deterioration of battery performance.

[0006] The present invention solves the above problem by including a step of sandwiching a laminate formed by stacking a positive electrode layer, an electrolyte layer, and a negative electrode layer along the stacking direction between an outer casing, a step of applying pressure to both sides of the laminate via the outer casing in a direction along the stacking direction, and a step of holding the laminate and the outer casing in a pressurized state in an environment with higher humidity than before the laminate was pressed.

[0007] According to the present invention, the deterioration of battery performance can be suppressed.

[0008] FIG. 1 is a cross-sectional view showing an all-solid-state battery and a pressure mechanism according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an all-solid-state battery and a pressure mechanism according to an embodiment of the present invention. FIG. 3 is a flowchart showing steps of a battery manufacturing method according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing an all-solid-state battery in which an oxide has been formed and a pressure mechanism. FIG. 5A is a cross-sectional view showing an all-solid-state battery and a pressure mechanism. FIG. 5B is a plan view (top view) of an all-solid-state battery. FIG. 6A is a cross-sectional view showing an all-solid-state battery and a pressure mechanism. FIG. 6B is a plan view (top view) of an all-solid-state battery. FIG. 7 is a flowchart showing a sub-flow of a high humidity retention step included in a battery manufacturing method according to a second embodiment.

[0009] First Embodiment A battery manufacturing method according to an embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 are cross-sectional views showing an all-solid-state battery and a pressurizing mechanism 80. An all-solid-state battery 1A includes multiple battery cells 1B and an exterior body 70. The battery cells 1B are lithium secondary batteries and include a positive electrode current collector 10, a negative electrode current collector 20, and a laminate 30 interposed therebetween. FIG. 1 shows the state before the positive electrode current collector 10, the negative electrode current collector 20, and the laminate 30 are sealed with the exterior body 70, while FIG. 2 shows the state after the positive electrode current collector 10, the negative electrode current collector 20, and the laminate 30 are sealed with the exterior body 70. Note that while FIGS. 1 and 2 illustrate one positive electrode current collector 10, two negative electrode current collectors 20, and two laminates 30, the number of positive electrode current collectors 10, the negative electrode current collectors 20, and the laminate 30 is not particularly limited. In the following description, the lithium secondary battery manufactured by the battery manufacturing method of the present embodiment will be described as an all-solid-state battery 1A.

[0010] The positive electrode current collector 10 is a conductive plate-like (or foil-like) member and is made of, for example, a metal or a conductive resin, although it is not particularly limited thereto. Examples of metals that can be used include aluminum, nickel, iron, stainless steel, titanium, and copper. Alternatively, a clad material of nickel and aluminum, or a clad material of copper and aluminum may also be used. Examples of conductive resins include resins in which a conductive filler is added to a non-conductive polymer material.

[0011] The negative electrode current collector 20, like the positive electrode current collector 10, is a conductive plate-like (or foil-like) member and is made of, for example, but not limited to, a metal or a conductive resin. The metal and the conductive resin may be the same materials as those used to make the positive electrode current collector 10. The material used to make the positive electrode current collector 10 and the material used to make the negative electrode current collector 20 may be the same or different.

[0012] A laminate 30 is interposed between the positive and negative electrode current collectors 10, 20. The laminate 30 is a power generating element having a positive electrode layer 40, a negative electrode layer 50, and a solid electrolyte layer 60. In the laminate 30, the positive electrode layer 40, the solid electrolyte layer 60, and the negative electrode layer 50 are stacked in this order along the z direction. The z direction in this embodiment corresponds to an example of the "stacking direction" in the present invention, and corresponds to the stacking direction of the positive electrode layer 40, the solid electrolyte layer 60, and the negative electrode layer 50.

[0013] The positive electrode layer 40 is formed on a main surface of the positive electrode current collector 10. The positive electrode layer 40 is not particularly limited, but can be formed by applying a paste containing a positive electrode active material and a binder to the main surface of the positive electrode current collector 10 and drying the paste. Note that when the positive electrode current collector 10 is not in contact with the exterior body 70, the positive electrode layer 40 may be formed on both main surfaces of the positive electrode current collector 10.

[0014] The anode layer 50 is formed on both main surfaces of the anode current collector 20. The anode layer 50 contains lithium metal deposited on the main surface of the anode current collector 20. The volume of the anode layer 50 increases as lithium metal is deposited during charging of the all-solid-state battery 1A, and decreases as the lithium metal disappears (moves toward the positive electrode layer) during discharging. The anode layer 50 may have an intermediate layer to assist the deposition of lithium metal. The intermediate layer contains a material capable of absorbing and releasing lithium ions. Unlike the example of FIG. 1 , when the anode layer 50 is in contact with the exterior body 70, the anode layer 50 may be formed on one main surface of the anode current collector 20.

[0015] The type of anode active material contained in the anode layer 50 is not particularly limited, and examples thereof include carbon materials, metal oxides, and metal active materials. The anode active material may be a silicon-based anode active material or a tin-based anode active material, or may be metallic lithium or a lithium-containing alloy. Examples of lithium-containing alloys include alloys of Li with at least one of In, Al, Si, and Sn. Two or more anode active materials may be used in combination in the anode layer 50. When the anode active material is metallic lithium or a lithium-containing alloy, the all-solid-state battery 1A may be a so-called lithium deposition type in which lithium metal is deposited as the anode active material on the anode current collector 20 during charging. The anode layer 50 may also include a solid electrolyte and a binder.

[0016] The solid electrolyte layer 60 is interposed between the positive electrode layer 40 and the negative electrode layer 50. A sulfide-based solid electrolyte made of a material with low electronic conductivity can be used as this solid electrolyte. The solid electrolyte layer 60 corresponds to the "electrolyte layer" of the present invention.

[0017] In this embodiment, the positive electrode layer 40, the negative electrode layer 50, and the solid electrolyte layer 60 have rectangular cross sections, but are not limited thereto and may have trapezoidal cross sections. In the examples of FIGS. 1 and 2 , the positive electrode current collector 10 and the negative electrode current collector 20 are separate members from the positive electrode layer 40 and the negative electrode layer 50, but they may be members included in the positive electrode layer 40 and the negative electrode layer 50. In other words, the "positive electrode layer" of the present invention may be a member including the positive electrode current collector 10 and the positive electrode layer 40, and the "negative electrode layer" of the present invention may be a member including the negative electrode current collector 20 and the negative electrode layer 50. The battery cell 1B is composed of the positive electrode current collector 10, the negative electrode current collector 20, and the laminate 30.

[0018] The exterior body 70 is a member that sandwiches the laminate 30. The exterior body 70 has an upper exterior member and a lower exterior member, the upper exterior member covering the top surface of the upper negative electrode current collector 20, and the lower exterior member covering the bottom surface of the lower negative electrode current collector 20. The exterior body 70 seals the battery cell 1B with a portion of the tabs (not shown) connected to the positive electrode current collector 10 and the negative electrode current collector 20 respectively protruding outside the battery.

[0019] The pressure mechanism 80 applies pressure to both surfaces of the laminate 30 via the exterior body 70 in the direction along the lamination direction (z direction in FIGS. 1 and 2 ). The pressure mechanism 80 sandwiches the laminate 30 between a pair of pressure plates and applies a load to the lamination surfaces of the laminate 30 by moving the pressure plates so as to shorten the distance between the pair of pressure plates. An elastic body such as a spring or a motor may be used to move the pressure plates. Note that the specific mechanism of the pressure mechanism 80 is not particularly limited, and the pressure mechanism 80 may have, in addition to the pressure plates, end plates that hold the position of the laminate 30 and elastic bodies such as rubber.

[0020] Next, the battery manufacturing method according to this embodiment will be described with reference to a flowchart shown in FIG.

[0021] In step S1, the positive electrode layer 40, the solid electrolyte layer 60, and the negative electrode layer 50 are stacked in the stacking direction to form the laminate 30. In this embodiment, the positive electrode current collector 10 and the negative electrode current collector 20 are stacked together with the laminate 30. In step S2, the laminate 30 is sandwiched between exterior bodies 70. In step S3, the pressure mechanism 80 presses both surfaces of the laminate 30 via the exterior bodies 70 in a direction along the stacking direction of the laminate 30.

[0022] In step S4, with the laminate 30 in a pressurized state, the laminate 30 and the exterior body 70 are maintained in an environment with a higher humidity than before the laminate 30 was pressurized. In the high-humidity maintaining step of step S4, a humidifier and a device for measuring the amount of hydrogen sulfide generated are provided around the all-solid-state battery 1A. The humidifier injects, for example, a high-humidity gas containing moisture toward the laminate 30 to achieve the high-humidity environment. The battery cell 1B having the laminate 30 is exposed to the high-humidity environment in a pressurized state. Furthermore, when performing the high-humidity maintaining step of step S4, the humidity of the environment in which the laminate 30 and the exterior body 70 are maintained is higher than the humidity of the environment in the steps prior to the pressurizing step of step S3. For example, the humidity of the environment when performing the high-humidity maintaining step of step S4 is higher than the humidity of the environment when performing the steps S1 and / or S2. Instead of injecting a high-humidity gas using a humidifier, for example, the gas surrounding the battery cell 1B may be replaced with a high-humidity gas.

[0023] The high humidity holding step is performed to form an oxide layer 90 along the side surface of the laminate 30. FIG. 4 is a cross-sectional view showing an all-solid-state battery on which an oxide layer has been formed. When the laminate 30, which is an electrolyte-containing layer, is exposed to an environment containing high-humidity gas, an oxide layer 90 is formed on the side surface of the laminate 30, which is a contact portion between the laminate 30 and the outside air containing high-humidity gas. The formation of the oxide layer 90 suppresses deterioration of the solid electrolyte layer 60. The high humidity holding step is performed until a predetermined holding time has elapsed or until a predetermined amount of high-humidity gas has been injected.

[0024] After the high humidity holding step, in step S5, the laminate 30 is kept pressed by the pressurizing mechanism 80, and the exterior body 70 is sealed. Through steps S1 to S5, an all-solid-state battery is manufactured. Note that, if an already formed laminate 30 is prepared, the process of step S1 may be omitted.

[0025] In this embodiment, the high humidity holding step is performed in a state where the laminate 30 is pressurized by the pressurizing mechanism 80. Unlike this embodiment, if the high humidity holding step is performed in a state where the laminate 30 is not pressurized by the pressurizing mechanism 80, the following problems may occur.

[0026] When the laminate 30 is not pressurized by the pressure mechanism 80, the density of the solid electrolyte layer 60 is low, and the moisture contained in the high-humidity gas easily penetrates into the interior of the laminate 30, which causes a problem in that the thickness of the oxide layer 90 formed on the side wall of the laminate 30 increases.

[0027] Furthermore, when the laminate 30 is not pressurized by the pressure mechanism 80, a gap is formed between the exterior body 70 and the main surface of the negative electrode current collector 20. For example, in the all-solid-state battery 1A shown in FIG. 1 or 2 , if the solid electrolyte layer 60 is present between the exterior body 70 and the positive electrode current collector 10, that is, if the solid electrolyte layer 60 is the outermost layer of the laminate 30 facing the exterior body 70, high humidity penetrates into the gap between the exterior body 70 and the solid electrolyte layer 60, forming an oxide layer 90. Therefore, an excess of the oxide layer 90 is formed along the stacking surface of the laminate 30, resulting in a problem of an increased thickness (height along the stacking direction) of the laminate 30.

[0028] In this embodiment, the high-humidity maintenance step is performed while the laminate 30 is pressurized by the pressure mechanism 80. This increases the density of the solid electrolyte layer 60, inhibits moisture penetration into the interior of the laminate 30, and prevents the laminate 30 from becoming thicker in the direction along the lamination surface (the x direction in FIG. 3 ). Furthermore, the exterior body 70 and the main surface of the outermost layer of the laminate 30 facing the exterior body 70 are in close contact with each other. This reduces the space between the exterior body 70 and the outermost layer of the laminate 30 facing the exterior body 70, preventing moisture from penetrating into the space. This prevents the formation of an oxide layer 90 between the exterior body 70 and the battery cell 1B. This also prevents a decrease in battery performance.

[0029] As described above, the battery manufacturing method according to this embodiment includes the steps of sandwiching the stack 30, which is formed by stacking the positive electrode layer 40, the solid electrolyte layer 60, and the negative electrode layer 50 in the stacking direction, between the exterior body 70; applying pressure to both sides of the stack 30 via the exterior body 70 in the stacking direction; and a high-humidity holding step of holding the stack 30 and the exterior body 70 in a pressurized state in an environment with a higher humidity than before applying pressure to the stack 30. The high-humidity holding step prevents moisture from penetrating between the exterior body 70 and the battery cell 1B. Furthermore, the oxide layer 90 can be formed while the solid electrolyte layer is in a high-density state. This reduces the thickness of the battery cell 1B and allows a thin oxide layer 90 to be formed on the side surface of the stack 30. In other words, the formation of an excessive oxide layer 90 is suppressed, deterioration of the solid electrolyte layer 60 is suppressed, and conductivity is achieved. As a result, a decrease in battery performance can be suppressed.

[0030] In the first modification of this embodiment, the battery manufacturing method may include a drying step of drying the laminate 30 by maintaining the laminate 30 in a pressurized state after the high humidity holding step. The drying step may be performed between the control flow of step S4 and the control flow of step S5 in the control flow shown in FIG. 3 . By performing the drying step after the high humidity holding step, the penetration of moisture into the laminate 30 is suppressed. This suppresses the generation of the oxide layer 90, and prevents a decrease in battery performance.

[0031] In Modification 2 of this embodiment, the high humidity maintaining step and the drying step may be performed in a state in which at least one surface of the polyhedral laminate 30 is open and the other surfaces are covered with the exterior body 70. FIG. 5A is a cross-sectional view showing the all-solid-state battery 1A and the pressurizing mechanism 80. FIG. 5B is a plan view (top view) of the all-solid-state battery. The laminate 30 is formed in a rectangular parallelepiped shape, and one side surface of the rectangular parallelepiped (the surface along the yz plane) is the open surface 31. In the high humidity maintaining step and the drying step, the open surface 31 is not covered with the exterior body 70. On the other hand, the other five surfaces of the rectangular parallelepiped (the three side surfaces other than the open surface, the top surface, and the bottom surface) are the sealed surfaces 32. In the high humidity maintaining step and the drying step, the sealed surface 32 is covered with the exterior body 70.

[0032] In the high-humidity holding step, high-humidity gas is injected from the open surface 31, and the sealed surface 32 is covered by the exterior body 70. This increases the rate at which moisture is supplied to the laminate 30. The increased moisture supply rate also increases the rate at which the oxide layer 90 is formed, thereby shortening the high-humidity holding step. In the drying step, the surface of the oxide layer 90 formed along the open surface 31 is open. This allows moisture adsorbed on the surface of the oxide layer 90 to evaporate during the drying step. Furthermore, moisture contained in the sealed space between the sealed surface 32 of the laminate 30 and the exterior body 70 can be expelled during the drying step. In this way, the battery manufacturing method according to Variation 2 can shorten the time required for the high-humidity holding step and the drying step.

[0033] In Modification 3 of this embodiment, the high humidity maintaining step and the drying step may be performed in a state in which two opposing faces of the polyhedral laminate 30 are open and the other faces are covered with the exterior body 70. FIG. 6A is a cross-sectional view showing an all-solid-state battery and a pressure mechanism 80. FIG. 6B is a plan view (top view) of the all-solid-state battery. The laminate 30 is formed in a rectangular parallelepiped shape, and two side faces of the rectangular parallelepiped (faces along the yz plane) are open faces 31. The two open faces are opposed to each other. In Modification 3, the number of open faces 31 is increased by one compared to Modification 2. As with Modification 2, the battery manufacturing method according to Modification 3 can shorten the time for the high humidity maintaining step and the drying step.

[0034] In the fourth modification of this embodiment, the high humidity maintaining step may include a step of increasing the temperature (heating step). The heating step may involve increasing the temperature of the high humidity environment, or may involve applying heat to the laminate 30 to increase the temperature of the high humidity environment. A heating device such as a heater is used in the heating step. When the temperature of the high humidity environment increases, the amount of saturated water vapor increases, increasing the amount of moisture contained in the space and enabling the rate at which moisture is supplied to the laminate 30 to increase. Furthermore, when the moisture supply rate increases, the rate at which the oxide layer 90 is generated increases, allowing the high humidity maintaining step to be shortened.

[0035] In Modification 5 of this embodiment, the high-humidity maintaining step may be performed by pressurizing the laminate 30 while the positive electrode current collector 10, the negative electrode current collector 20, and the laminate 30 are sealed by the exterior body 70. That is, as shown in FIG. 2 , the side, top, and bottom surfaces of the laminate 30 are completely sealed by the exterior body 70, in other words, none of the surfaces of the laminate 30 are open. In the process of the battery manufacturing method of Modification 5, step S5 shown in FIG. 3 may be performed between steps S2 and S3. In the high-humidity maintaining step, while the positive electrode current collector 10, the negative electrode current collector 20, and the laminate 30 are sealed by the exterior body 70, a humidifier introduces high-humidity gas into the interior of the exterior body 70 from the outside. The high-humidity gas may be sealed inside the exterior body 70 through the fused portion where the upper and lower exterior members overlap. A high-humidity environment can be created inside the exterior body 30, and the laminate 30 is exposed to the high-humidity environment while being pressurized. This suppresses the formation of an excess oxide layer 90, suppresses deterioration of the solid electrolyte layer 60, and ensures conductivity. As a result, deterioration of battery performance can be suppressed. That is, in this embodiment, the high-humidity holding step may be performed with the positive electrode current collector 10, the negative electrode current collector 20, and the laminate 30 sealed by the exterior body 70, or with at least one of the surfaces of the laminate 30 left open.

[0036] In Modification 5, the high humidity step may be followed by a drying step as in Modification 1. In Modification 5, the laminate 30 is pressurized and the high humidity maintaining step is performed in a state where the laminate 30 is completely sealed, but the time required for the high humidity step and the drying step can be shortened by performing the high humidity step and the drying step in a state where at least one of the faces of the laminate 30 is left open, as in Modification 2, for example.

[0037] Second Embodiment FIG. 7 is a flowchart showing a sub-flow of a high humidity maintaining step included in a battery manufacturing method according to a second embodiment.

[0038] The battery manufacturing method of this embodiment differs from the first embodiment in that a new step is added to the high humidity maintaining step. In the battery manufacturing method, the steps other than the high humidity maintaining step are the same as the steps of the first embodiment. In addition, the structure of the all-solid-state battery manufactured in this embodiment is the same as that of the first embodiment. Only the differences between the battery manufacturing method of the second embodiment and the first embodiment will be described below, and the same components as those in the first embodiment will be assigned the same reference numerals and will not be described again.

[0039] In the second embodiment, the high humidity holding step executes the following control flow. When the high humidity holding step (step S4) starts after the pressurization step of step S3, high humidity gas is injected toward the stack 30 (high humidity gas injection) in step S41. In step S42, the temperature of the stack 30 (hereinafter also referred to as stack temperature) and the temperature of the high humidity gas (hereinafter also referred to as gas temperature) are measured. The stack temperature and gas temperature are measured by a temperature sensor or the like. In step S43, it is determined whether the stack temperature is higher than the gas temperature.

[0040] If the stack temperature is equal to or lower than the gas temperature, it is determined that the stack temperature is lower than the gas temperature, and in step S44, the stack 30 is heated. After the stack 30 is heated, the control flow returns to step S42. That is, by repeating the control flow loop of steps S42 to S44, the stack 30 is heated so that the stack temperature becomes higher than the gas temperature.

[0041] If the stack temperature is higher than the gas temperature, it is determined whether a predetermined holding time has elapsed. If the holding time has not elapsed, the control flow returns to step S42. On the other hand, if the holding time has elapsed, the high humidity holding step ends and the sealing step of step S5 is executed. That is, by repeating the control flow loop of steps S42, S43, and S45, the stack temperature is maintained higher than the gas temperature during the holding time.

[0042] As described above, in the battery manufacturing method according to this embodiment, the temperature of the laminate during the high humidity maintaining step is higher than the gas temperature in the high humidity space. By making the temperature of the laminate higher than the gas temperature, it is possible to prevent the moisture contained in the high-quality sound gas from condensing and dissolving the solid electrolyte. As a result, it is possible to suppress the deterioration of battery performance.

[0043] In the present embodiment, the high humidity holding step involves introducing high humidity gas toward the laminate 30. This increases the rate at which moisture is supplied to the laminate 30 and increases the rate at which the oxide layer 90 is generated, thereby enabling the high humidity holding step to be shortened.

[0044] In the fifth modification of this embodiment, the high-humidity maintaining step may include a step of introducing high-humidity gas toward the gas injection surface of the polyhedral laminate 30 that is not covered by the outer casing 70. That is, in the high-temperature gas injection step of step S41, high-temperature gas may be introduced toward the gas injection surface. The gas injection surface corresponds to the open surface 31 shown in FIGS. 5B and 6B. While the open surface 31 in FIGS. 5B and 6B is one or two surfaces, it may be three surfaces or all of the side surfaces surrounding the laminate 30 (excluding the top and bottom surfaces of the laminate 30). This increases the rate at which moisture is supplied to the laminate 30 and increases the rate at which the oxide layer 90 is formed. Furthermore, the moisture contact distribution on the side surfaces of the laminate 30 is suppressed, thereby suppressing the formation distribution of the oxide layer 90. As a result, the high-humidity maintaining step can be shortened.

[0045] In addition, in Modification 6 of this embodiment, the high-humidity maintaining step may include a step of measuring the hydrogen sulfide concentration on the side of the polyhedral stack 30 opposite the gas injection surface. The high-humidity maintaining step may be terminated when the measured hydrogen sulfide concentration falls below a predetermined concentration threshold. The concentration threshold is a preset threshold value that is determined experimentally. For example, in the example shown in FIGS. 5A and 5B , the hydrogen sulfide concentration is measured on the sealed surface 32, which is located on the opposite side of the stack 30 from the open surface 31. The hydrogen sulfide concentration is measured in the space enclosed by the sealed surface 32 and the exterior body 70. In other words, on the paper surface of FIG. 5A , high-humidity gas is injected toward the stack 30 from the left (negative direction of the x-axis), and hydrogen sulfide escapes from inside the stack 30 toward the space enclosed by the exterior body 70 located to the right of the stack 30 (positive direction of the x-axis).

[0046] The hydrogen concentration in the space enclosed by the sealing surface 32 and the exterior body 70 reaches its highest point immediately after the high-humidity gas is injected and decreases over time. In other words, there is a correlation between the hydrogen sulfide concentration and the time it takes for the oxide layer 90 to form. Therefore, by identifying the point at which the hydrogen sulfide concentration falls below the concentration threshold, the point at which hydrogen sulfide generation stops can be determined. This allows the high-humidity maintenance process to be shortened.

[0047] In this embodiment, in the control flow of step S44, the stack 30 is heated. However, instead of heating the stack 30, the gas temperature may be lowered by cooling the high humidity gas.

[0048] 1A All-solid-state battery 1B Battery cell 2 Positive electrode current collector 10 Positive electrode current collector 20 Negative electrode current collector 30 Laminate 31 Open surface 32 Sealed surface 40 Positive electrode layer 50 Negative electrode layer 60 Solid electrolyte layer 70 Exterior body 80 Pressurizing mechanism 90 Oxide layer

Claims

A method for manufacturing a lithium secondary battery, comprising: a step of sandwiching a stack formed by stacking a positive electrode layer, an electrolyte layer containing a sulfide-based solid electrolyte, and a negative electrode layer in a stacking direction between exterior bodies; a step of applying pressure to both surfaces of the laminate via the exterior body in a direction along the stacking direction; and a high humidity holding step of holding the laminate and the outer casing in a pressurized state in an environment with a higher humidity than before the pressurization of the laminate. 　 The battery manufacturing method according to claim 1, a drying step of drying the laminate while maintaining the laminate in a pressurized state after the high humidity maintaining step; and after the drying step, sealing the exterior body while maintaining the laminate in a pressurized state. 　 The battery manufacturing method according to claim 2, The battery manufacturing method, wherein the high humidity maintaining step and the drying step are carried out in a state where at least one surface of the polyhedral laminate is open and the other surfaces are covered with the exterior body. 　 The battery manufacturing method according to claim 2, The battery manufacturing method, wherein the high humidity maintaining step and the drying step are carried out in a state where two opposing faces of the polyhedral laminate are open and the other faces are covered with the exterior body. 　 The battery manufacturing method according to any one of claims 1 to 4, The battery manufacturing method, wherein the high humidity maintaining step includes a step of increasing the temperature. 　 The battery manufacturing method according to any one of claims 1 to 5, The battery manufacturing method, wherein the temperature of the laminate during the high humidity holding step is higher than the gas temperature in the high humidity space. 　 The battery manufacturing method according to any one of claims 1 to 6, The high humidity maintaining step includes a step of introducing a high humidity gas toward the stack. 　 The battery manufacturing method according to claim 7, The high humidity maintaining step includes a step of introducing the high humidity gas into a gas injection surface of the polyhedral laminate that is not covered by the exterior body.

9. The battery manufacturing method according to claim 8, The high humidity maintaining step includes: measuring the hydrogen sulfide concentration on a side surface of the polyhedral stack opposite to the gas injection surface; The battery manufacturing method includes terminating the high humidity maintaining step when the measured hydrogen sulfide concentration becomes equal to or lower than a predetermined concentration threshold.

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