Manufacturing method for bipolar batteries
The method for manufacturing bipolar batteries addresses structural weakness and internal pressure issues by using temporary sealing and vacuuming to ensure safe activation and performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-12-14
- Publication Date
- 2026-07-07
AI Technical Summary
Bipolar batteries face structural weakness due to laminated electrodes and risk of internal pressure rise during activation, leading to potential damage and electrolyte evaporation, especially in high-capacity designs.
A manufacturing method involving temporary sealing with a smaller opening, followed by activation and high-temperature aging, and final sealing, with intermediate cooling and vacuuming to manage internal pressure and electrolyte evaporation.
Ensures battery performance by preventing damage to the outer casing and minimizing electrolyte loss, allowing safe activation and high-capacity bipolar battery production.
Smart Images
Figure 0007885782000001 
Figure 0007885782000002
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a bipolar battery.
Background Art
[0002] In the manufacture of batteries, it is known that gas is generated during the initial charging in the activation process and high-temperature aging (see Patent Document 1). Also, in high-temperature aging, the gas in the surplus space inside the cell expands.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Therefore, the battery requires an exterior body that can withstand the rising internal pressure. When the exterior body is aluminum, it can withstand the internal pressure rise even in a closed system during the activation process. Also, when the exterior body is a laminate film, the destruction of the exterior body can be prevented by assembling the laminate film in excess. On the other hand, in the case of a bipolar battery, since the electrodes (current collectors) with the positive and negative electrodes coated on one side each are laminated, the structure is structurally weak. Therefore, there is a risk that it cannot withstand the internal pressure rise. In particular, when making a high-capacity battery, a large amount of gas is generated, and since the dead space inside the cell becomes small when as much active material as possible is put into the cell to increase the energy density, this becomes a problem.
[0005] Also, if the activation process is carried out while the system is open to suppress the internal pressure rise, the electrolyte necessary for ensuring the battery performance will volatilize.
[0006] An object of the present invention is to provide a method for manufacturing a bipolar battery that can ensure the battery performance. [Means for solving the problem]
[0007] A method for manufacturing a bipolar battery according to claim 1 includes: an impregnation step of injecting an electrolyte solution through an injection port and impregnating the battery; a temporary sealing step of sealing the battery with a temporary sealing film after the impregnation step; a temporary sealing release step of making a hole in the temporary sealing film with an opening area smaller than the injection port after the temporary sealing step; an activation step of performing an activation treatment including initial charging and high-temperature aging after the temporary sealing release step; and a final sealing step of sealing the battery with a final sealing film after the activation step.
[0008] In the method for manufacturing a bipolar battery according to claim 1, an activation treatment is performed after the temporary seal release step. In the temporary seal release step, a hole with an opening area smaller than the liquid injection port is made in the temporary seal film. Therefore, compared to the case where the activation treatment is performed without a hole in the temporary seal film, the internal pressure does not rise as easily during the activation treatment. As a result, the activation treatment can be performed on a bipolar battery without damaging the outer casing.
[0009] Furthermore, the hole opened during the temporary seal release process has a smaller opening area than the electrolyte injection port. Therefore, compared to simply performing the activation process with the electrolyte injection port open, the evaporation of the electrolyte can be suppressed. As a result, the performance of the battery can be guaranteed.
[0010] The method for manufacturing a bipolar battery according to claim 2 further includes a cooling step of cooling to room temperature after the high-temperature aging in claim 1, and vacuuming before sealing by the temporary sealing step and the main sealing step.
[0011] The method for manufacturing a bipolar battery according to claim 2 further includes a cooling step of cooling to room temperature after high-temperature aging, and vacuuming is performed before sealing by the temporary sealing step and the final sealing step. Gas is particularly likely to be generated in these steps. The generated gas can be removed more efficiently. [Effects of the Invention]
[0012] As described above, the present invention provides a method for manufacturing a bipolar battery that can guarantee the performance of the battery. [Brief explanation of the drawing]
[0013] [Figure 1] This is a flow chart showing the manufacturing method of a bipolar battery according to an embodiment. [Figure 2] This is a schematic diagram showing the structure of a bipolar battery according to an embodiment. [Modes for carrying out the invention]
[0014] The following describes a method for manufacturing a bipolar battery according to an embodiment.
[0015] First, the bipolar battery 10 of the embodiment (hereinafter simply referred to as battery 10) will be described.
[0016] As shown in Figure 2, the battery 10 comprises multiple cells 12 stacked in series. The battery 10 is sometimes called a battery module. Hereafter, the number of cells 12 in the battery 10 will be N.
[0017] Each cell 12 includes a current collector 20 on the positive side, a positive electrode 30, a separator 40, a negative electrode 50, and a current collector 20 on the negative side.
[0018] The battery 10 is a bipolar battery. That is, two adjacent cells 12 out of the N cells 12 share a current collector 20. For example, the current collector 20 on the negative electrode side of cell 12 in the k-th layer and the current collector 20 on the positive electrode side of cell 12 in the (k-1)-th layer are the same current collector 20.
[0019] The current collector 20 has a negative electrode foil 22 and a positive electrode foil 24. The negative electrode foil 22 is, for example, copper foil, and the positive electrode foil 24 is, for example, aluminum foil.
[0020] The positive electrode 30 is, for example, LFP (lithium iron phosphate). The negative electrode 50 is, for example, graphite. The formation region of the negative electrode 50 in the current collector 20 is slightly larger than the formation region of the positive electrode 30.
[0021] The end portion of the separator 40 is held together with the current collector 20 on the negative electrode side of the positive electrode side and the negative electrode side.
[0022] Each cell 12 has a liquid injection port 62 for injecting the electrolytic solution 14 into the cell 12. The liquid injection port 62 is connected to the space on the positive electrode 30 side with respect to the separator 40 in the cell 12. The electrolytic solution 14 is, for example, a non-aqueous electrolytic solution.
[0023] Each cell 12 is held by a holder 60 made of a synthetic resin.
[0024] (Manufacturing method) As shown in FIG. 1, the manufacturing method of the bipolar battery 10 of the present embodiment includes a liquid injection impregnation step, a temporary sealing step, a temporary sealing release step, an activation step including initial charging and high-temperature aging, and a final sealing step.
[0025] In the liquid injection impregnation step, the electrolytic solution 14 is injected from the liquid injection port 62 and impregnated.
[0026] In the temporary sealing step, after the liquid injection impregnation step, it is sealed with a temporary sealing film. Specifically, a vacuum is drawn before sealing. This makes it easier to remove the gas generated inside the battery.
[0027] In the temporary sealing release step, after the temporary sealing step, a hole having an opening area smaller than that of the liquid injection port 62 is formed in the temporary sealing film. Thereby, the gas generated in the subsequent activation step can escape from the hole, and an increase in internal pressure can be suppressed.
[0028] In the activation step, after the temporary sealing release step, an activation treatment including initial charging and high-temperature aging is performed. Specifically, a step of cooling to room temperature is provided after the high-temperature aging. This makes it easier to remove the gas generated inside the battery.
[0029] In this sealing process, the battery is sealed with this sealing film after the activation process. Specifically, a vacuum is applied before sealing. This makes it easier to remove gases generated inside the battery.
[0030] <Effects and Effects> As described above, in this embodiment, an activation treatment is performed after the temporary seal release step. In the temporary seal release step, a hole with an opening area smaller than the liquid injection port 62 is made in the temporary seal film. Therefore, compared to the case where the activation treatment is performed without a hole in the temporary seal film, the internal pressure does not rise as easily during the activation treatment. As a result, even the bipolar battery 10 can be activated without damaging the outer casing.
[0031] Furthermore, the hole opened in the temporary seal release process has a smaller opening area than the electrolyte port 62. Therefore, compared to simply performing the activation process with the electrolyte port 62 open, the evaporation of the electrolyte 14 can be suppressed. As a result, the performance of the battery 10 can be guaranteed.
[0032] [Supplementary explanation of the above embodiment] In the above embodiment, a cooling step is further included in which the temperature is cooled to room temperature after high-temperature aging, but the present invention is not limited thereto.
[0033] Furthermore, in the above embodiment, vacuuming is performed before sealing by the temporary sealing step and the final sealing step, but the present invention is not limited thereto. [Explanation of Symbols]
[0034] 10 Bipolar batteries 62 Injection port
Claims
1. An impregnation process in which the electrolyte is injected through the injection port and impregnated, After the liquid impregnation step, a temporary sealing step is performed in which the film is sealed with a temporary sealing film. After the temporary sealing step, a temporary sealing release step is performed in which a hole with an opening area smaller than the liquid injection port is made in the temporary sealing film, After the temporary sealing release step, an activation step is performed which includes initial charging and high-temperature aging, After the activation step, the sealing step is performed by sealing with the sealing film, A method for manufacturing a bipolar battery, including [a specific component].
2. The process further includes a cooling step of cooling to room temperature after the aforementioned high-temperature aging. Vacuum is applied before sealing by the aforementioned temporary sealing step and the aforementioned main sealing step. A method for manufacturing a bipolar battery according to claim 1.