Energy storage module and method for manufacturing an energy storage module

Abstract

To suppress airtightness defects in a structure in which the liquid injection port of the liquid injection frame is sealed with a sealing film. [Solution] An energy storage module comprising: an electrode stack in which multiple electrodes are stacked; a resin sealing member arranged along the periphery of the electrode stack and having a through hole leading to the interior of the electrode stack; a liquid injection frame arranged on the side of the sealing member and having a liquid injection port communicating with the through hole; and a sealing film welded to the liquid injection frame and sealing the liquid injection port, wherein the sealing film is welded to the open end face of the liquid injection port in the liquid injection frame and is also welded to the inner surface of the liquid injection port.

Description

Technical Field

[0001] The present invention relates to a power storage module and a method for manufacturing the power storage module.

Background Art

[0002] Patent Document 1 discloses a power storage module including an electrode laminate in which a plurality of electrodes are laminated, a liquid injection frame is provided on a side surface of the electrode laminate, and a liquid injection port of the liquid injection frame is sealed with a sealing film.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration described in Patent Document 1, although the liquid injection port is sealed by welding a sealing film to the liquid injection frame, the sealing film is only welded to the opening end surface of the liquid injection port, so that a sufficient welding area cannot be obtained, and there is a risk of poor airtightness.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a power storage module and a method for manufacturing the power storage module that can suppress poor airtightness in a structure in which a liquid injection port of a liquid injection frame is sealed with a sealing film.

Means for Solving the Problems

[0006] The energy storage module according to the present invention comprises: an electrode stack in which a plurality of electrodes are stacked; a resin sealing member arranged along the periphery of the electrode stack and having a through hole that leads to the interior of the electrode stack; a liquid injection frame arranged on the side of the sealing member and having a liquid injection port that communicates with the through hole; and a sealing film welded to the liquid injection frame and sealing the liquid injection port, wherein the sealing film is welded to the open end face of the liquid injection port in the liquid injection frame and is also welded to the inner surface of the liquid injection port.

[0007] A method for manufacturing an energy storage module according to the present invention comprises: an electrode stack in which a plurality of electrodes are stacked; a resin sealing member arranged along the periphery of the electrode stack and having a through hole that leads to the interior of the electrode stack; a liquid injection frame arranged on the side of the sealing member and having a liquid injection port that communicates with the through hole; and a sealing film welded to the liquid injection frame and sealing the liquid injection port, wherein the method for manufacturing an energy storage module includes a sealing step of welding the sealing film and the liquid injection frame with a heat bar to seal the liquid injection port with the sealing film, and the sealing step is characterized in that the sealing step includes welding the sealing film to the open end face of the liquid injection port in the liquid injection frame and welding the sealing film to the inner surface of the liquid injection port. [Effects of the Invention]

[0008] In the present invention, it is possible to suppress airtightness defects in a structure in which the liquid injection port of the liquid injection frame is sealed with a sealing film. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an energy storage module in an embodiment. [Figure 2] This is a cross-sectional view showing a sealing structure in which the liquid injection port is sealed by a sealing film. [Figure 3] This is a cross-sectional view showing the sealed state where the welded part inside the liquid injection port has peeled off due to the rise in internal pressure of the energy storage module. [Figure 4]This is a diagram illustrating the sealing process included in the manufacturing method of an energy storage module. [Figure 5] This diagram illustrates the process of welding the sealing film and the liquid injection frame during the sealing process. [Figure 6] This is a cross-sectional view showing the structure of the heat bar in a modified example. [Figure 7] A cross-sectional view showing the structure of the heat bar in another modified example. [Figure 8] This diagram illustrates a different modification in which a heat bar is used to perform the sealing process. [Modes for carrying out the invention]

[0010] The following describes in detail the energy storage module and the method for manufacturing the energy storage module according to embodiments of the present invention. However, the present invention is not limited to the embodiments described below.

[0011] Figure 1 is a schematic diagram showing an energy storage module in an embodiment. The energy storage module 1 comprises an electrode stack 2 in which a plurality of electrodes are stacked, a resin sealing member 3 that seals the electrode stack 2, a liquid injection frame 4 including a liquid injection port, and a sealing film 5 that seals the liquid injection port.

[0012] The energy storage module 1 is a bipolar battery with stacked bipolar electrodes. The energy storage module 1 is formed in a rectangular parallelepiped shape, with its depth dimension being longer than its width dimension. As shown in Figure 1, the X direction is the same as the depth direction of the energy storage module 1, and the Y direction is the same as the width direction of the energy storage module 1.

[0013] The energy storage module 1 has a structure in which multiple cells are stacked in the direction in which the bipolar electrodes are stacked. The bipolar electrodes are stacked in the Z direction. The Z direction is the same direction as the height direction of the energy storage module 1 and is the same direction as the stacking direction of the electrode stack 2.

[0014] The electrode stack 2 has a structure in which multiple bipolar electrodes, a positive terminal electrode, a negative terminal electrode, and multiple separators are stacked. The bipolar electrode comprises a current collector, a positive electrode active material layer, and a negative electrode active material layer. In the bipolar electrode, the positive electrode active material layer is provided on one side of the current collector, and the negative electrode active material layer is provided on the other side of the current collector. The outer shape of the positive electrode active material layer is smaller than the outer shape of the current collector. One side of the current collector includes an unpainted area. This unpainted area is a region where the positive electrode active material layer is not provided and is located at the periphery of the current collector. The periphery of the current collector is the periphery of the electrode stack 2. The outer shape of the negative electrode active material layer is smaller than the outer shape of the current collector. The other side of the current collector includes an unpainted area. This unpainted area is a region where the negative electrode active material layer is not provided and is located at the periphery of the current collector.

[0015] The positive terminal electrode comprises a terminal positive electrode current collector and a terminal positive electrode active material layer provided on one side of the terminal positive electrode current collector. The negative terminal electrode comprises a terminal negative electrode current collector and a terminal negative electrode active material layer provided on one side of the terminal negative electrode current collector. Bipolar electrodes and separators are alternately stacked between the positive terminal electrode and the negative terminal electrode. Between adjacent bipolar electrodes in the stacking direction, the positive electrode active material layer of one bipolar electrode is stacked with the negative electrode active material layer of the other bipolar electrode, with a separator in between.

[0016] Each cell consists of an electrode stack 2, a sealing member 3, and an electrolyte. Adjacent cells in the stacking direction share one bipolar electrode and are electrically connected in series via that bipolar electrode. The electrolyte is contained in an internal space partitioned by adjacent current collectors in the stacking direction and the sealing member 3 located between these current collectors. The electrolyte is contained in an internal space partitioned by the bipolar electrode, the positive terminal electrode, and the sealing member 3 located between them. The electrolyte is contained in an internal space partitioned by the bipolar electrode, the negative terminal electrode, and the sealing member 3 located between them.

[0017] The sealing member 3 is formed on the frame body that forms the outer frame of the power storage module 1. The sealing member 3 is arranged along the peripheral edge of the electrode laminate 2. The sealing member 3 is provided at the peripheral edge of the current collector and is arranged so as not to touch the positive electrode active material layer and the negative electrode active material layer. The sealing member 3 is composed of a plurality of resins. The sealing member 3 is composed of polypropylene, polyethylene, polyphenylene sulfide, polystyrene, ABS resin, AS resin, etc. The power storage module 1 has a structure in which the peripheral edge of the current collector is laminated with a plurality of resins.

[0018] As shown in FIG. 2, the sealing member 3 has a through hole 31 that leads to the inside of the electrode laminate 2. The through hole 31 is a hole for supplying an electrolytic solution to the inside of the electrode laminate 2 and is provided for each cell. The through hole 31 extends along the X direction and penetrates the sealing member 3, communicating with the internal space of the corresponding cell.

[0019] On the side surface 32 of the sealing member 3, through holes 31 corresponding to each cell are open. The side surface 32 is a surface facing one side in the X direction. The side surfaces of the sealing member 3 include two side surfaces facing the X direction and two side surfaces facing the Y direction. The sealing member 3 has four side surfaces.

[0020] The liquid injection frame 4 is a resin member installed on the side surface 32 of the sealing member 3. The liquid injection frame 4 has a liquid injection port 41 for supplying an electrolytic solution to the inside of the electrode laminate 2. The liquid injection port 41 extends along the X direction and communicates with the through hole 31 of the sealing member 3. The liquid injection port 41 is provided for each through hole 31. The liquid injection port 41 opens facing one side in the X direction. The liquid injection frame 4 has an opening end surface 4a of the liquid injection port 41 and an inner surface 4b of the liquid injection port 41.

[0021] The opening end surface 4a is a surface on one side in the X direction. When the liquid injection frame 4 is viewed from one side in the X direction, the liquid injection port 41 opens in a rectangular shape. The opening end surface 4a is formed in a rectangular frame shape. The inner surface 4b includes two inner surfaces facing the Z direction and two inner surfaces facing the Y direction. The inner surface 4b includes four surfaces.

[0022] The sealing film 5 is a sealing member that seals the liquid injection port 41. The sealing film 5 includes a heat-flexible resin layer and a metal layer that prevents moisture from entering. The sealing film 5 has a structure in which the resin layer and the metal layer are laminated. The portion of the sealing film 5 that contacts the liquid injection frame 4 is made up of the resin layer. The resin layer contains a heat-flexible resin. The resin layer of the sealing film 5 and the liquid injection frame 4 are heat-welded together.

[0023] The energy storage module 1 has a welded portion where the sealing film 5 and the liquid injection frame 4 are welded together. The welded portion includes a first welded portion where the sealing film 5 and the open end face 4a are welded together, and a second welded portion where the sealing film 5 and the inner surface 4b are welded together.

[0024] The sealing film 5 includes a portion welded to the liquid injection frame 4 and a portion (unwelded portion) that covers the liquid injection port 41 without being welded to the liquid injection frame 4. The sealing film 5 is welded to the open end face 4a of the liquid injection port 41 in the liquid injection frame 4, and is also welded to the inner surface 4b along the X direction from the open end of the liquid injection port 41 toward the inside of the liquid injection port 41. In the second welded portion, the sealing film 5 is welded to the inner surface 4b over the entire circumference of the liquid injection port 41. In other words, in the second welded portion, the sealing film 5 is welded to all four surfaces included in the inner surface 4b.

[0025] The welding area between the sealing film 5 and the liquid injection frame 4 is represented by the sum of the welding area by the first welding area and the welding area by the second welding area. Compared to a conventional sealing structure that seals the open end face, the energy storage module 1 has a larger welding area due to the second welding area. The increased welding area between the sealing film 5 and the liquid injection frame 4 improves airtightness. In the energy storage module 1, the increased welding area between the sealing film 5 and the liquid injection frame 4 prevents airtightness defects in the energy storage module 1.

[0026] As shown in Figure 3, in the energy storage module 1, when the internal pressure of the electrode laminate 2 increases, the welding state between the sealing film 5 and the inner surface 4b is released while the welding state between the sealing film 5 and the open end surface 4a is maintained. In this case, although the welding area decreases by the amount of the second welding area, the area of ​​the first welding area remains. Since the first welding area is the part where the open end surface 4a and the sealing film 5 are welded, it is possible to secure a welding area equivalent to that of a conventional sealing structure in which the open end surface and the sealing material are welded. Furthermore, since the non-welded portion of the sealing film 5 becomes larger by the amount of the second welding area that has peeled off, this non-welded portion can expand in response to the increase in internal pressure, thereby securing a wider internal space in the energy storage module 1. In this way, by increasing the internal space of the energy storage module 1 when the internal pressure of the energy storage module 1 increases, it is possible to suppress the increase in the internal pressure of the energy storage module 1 and prevent sealing defects.

[0027] The manufacturing method for the energy storage module 1 in this embodiment includes a liquid injection step, an initial charging step, a high-temperature aging step, and a sealing step.

[0028] The electrolyte injection process involves injecting electrolyte into the electrode stack 2 through the injection port 41. In the electrolyte injection process, electrolyte is supplied from the injection port 41 to the through-hole 31, and injected into the internal space of the cell through the through-hole 31. The initial charging process is the process of performing initial charging after the electrolyte injection process. The high-temperature aging process is a known high-temperature aging process performed after the initial charging process. The sealing process is the process of sealing the injection port 41 with a sealing film 5 after the high-temperature aging process.

[0029] As shown in Figures 4 and 5, the sealing process involves heat-welding the sealing film 5 and the liquid injection frame 4 with a heat bar 6 to seal the liquid injection port 41 with the sealing film 5. A heater 7 is provided inside the heat bar 6. The heat bar 6 can increase its temperature by receiving heat from the heater 7. As shown in Figure 5, the sealing process involves pressing the heat bar 6 against the sealing film 5 and the liquid injection frame 4 to heat-weld the open end surface 4a to the sealing film 5, and also heat-welding the inner surface 4b to the sealing film 5.

[0030] The heat bar 6 has a flat portion 61 and a convex portion 62. The flat portion 61 is the part that presses the sealing film 5 against the open end surface 4a to heat-seal the sealing film 5 and the liquid injection frame 4. The flat portion 61 is formed to be flat. In the sealing process, the flat portion 61 heat-seals the open end surface 4a and the sealing film 5, and the convex portion 62 heat-seals the inner surface 4b and the sealing film 5.

[0031] The protrusion 62 is a portion that protrudes from the flat portion 61. The protrusion 62 is the portion that presses the sealing film 5 against the inner surface 4b, welding the sealing film 5 to the liquid injection frame 4. The protrusion 62 is formed in a shape that matches the opening shape of the liquid injection port 41. For example, the protrusion 62 is formed in a shape that is slightly smaller than the opening shape of the liquid injection port 41. If the liquid injection port 41 has a rectangular opening when viewed from the X direction, the protrusion 62 is formed in a rectangular shape that matches that opening shape. Therefore, by inserting the protrusion 62 into the liquid injection port 41 from one side in the X direction, the sealing film 5 can be sandwiched between the protrusion 62 and the inner surface 4b.

[0032] As described above, according to the embodiment, the welding area between the sealing film 5 and the liquid injection frame 4 can be increased, thereby improving the airtightness of the energy storage module 1. Furthermore, when the internal pressure of the energy storage module 1 increases, the second welding portion peels off while the first welding portion is maintained at the welding portion where the sealing film 5 and the liquid injection frame 4 are welded together. As a result, the internal space of the energy storage module 1 increases when the internal pressure of the energy storage module 1 rises, thereby reducing the internal pressure of the energy storage module 1.

[0033] Furthermore, the second welded portion where the sealing film 5 and the inner surface 4b are welded is not limited to a structure in which it is welded to the inner surface 4b over the entire circumference of the liquid injection port 41, but may be a structure in which it is welded to at least one of the four surfaces included in the inner surface 4b.

[0034] Furthermore, the shape of the heat bar 6 and the arrangement of the heaters 7 are not limited to the structures exemplified in Figures 4 and 5. As shown in Figure 6, the heat bar 6 may have a trapezoidal protrusion 63. Also, as shown in Figures 7 and 8, the heater 7 may have a first heater 71 and a second heater 72 provided inside the protrusion 63. As shown in Figure 8, when melting the sealing film 5 in the sealing process, the temperature of the first heater 71 and the temperature of the second heater 72 can be adjusted independently, so the temperature of the heat bar 6 can be controlled independently at the open end face 4a and the inner surface 4b. [Explanation of Symbols]

[0035] 1. Energy storage module 2-electrode stack 3 Sealing member 4. Injection Frame 5. Sealing film 6 Heat Bars

Claims

1. An electrode stack in which multiple electrodes are stacked, A resin sealing member is arranged along the periphery of the electrode stack and has a through hole that leads to the interior of the electrode stack, A liquid injection frame is provided, which is positioned on the side of the sealing member and has a liquid injection port that communicates with the through hole, A sealing film is welded to the aforementioned liquid injection frame and seals the liquid injection port, A battery storage module equipped with, The sealing film is welded to the open end surface of the liquid injection port in the liquid injection frame, and also welded to the inner surface of the liquid injection port. A battery storage module characterized by the following features.

2. The sealing film is welded to the inner surface of the liquid injection port over its entire circumference. The energy storage module according to claim 1.

3. An electrode stack in which multiple electrodes are stacked, A resin sealing member is arranged along the periphery of the electrode stack and has a through hole that leads to the interior of the electrode stack, A liquid injection frame is provided, which is positioned on the side of the sealing member and has a liquid injection port that communicates with the through hole, A sealing film is welded to the aforementioned liquid injection frame and seals the liquid injection port, A method for manufacturing an energy storage module, comprising: The sealing step includes welding the sealing film and the liquid injection frame with a heat bar to seal the liquid injection port with the sealing film, The sealing step includes welding the sealing film to the open end surface of the liquid injection port in the liquid injection frame, and welding the sealing film to the inner surface of the liquid injection port. A method for manufacturing an energy storage module, characterized by the following:

4. The aforementioned heat bar is A flat portion for pressing the sealing film against the open end face to weld the sealing film and the liquid injection frame, It has a protrusion that extends from the flat portion, In the sealing process, the flat portion is used to weld the open end face and the sealing film, and the convex portion is used to weld the inner surface and the sealing film. A method for manufacturing an energy storage module according to claim 3.

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