Method for manufacturing secondary battery

Abstract

Provided is a method for manufacturing a secondary battery with which it is possible to obtain a laminate having a smooth welding surface. A method for manufacturing a secondary battery according to the present disclosure uses a manufacturing device provided with a laminate restraining plate for sandwiching a laminate, and a welding jig for welding the laminate, the welding jig being provided with a contact plate for contacting the laminate and a heating plate capable of heating the contact plate. This method for manufacturing a secondary battery is provided with: a step for sandwiching a laminate on a laminate restraining plate; a step for welding the laminate by heating the contact plate by means of the heating plate in a state in which the contact plate is in contact with the laminate sandwiched by the laminate restraining plate; and a step for cooling the laminate while pressing the laminate by separating the heating plate from the contact plate and causing the refrigerant to flow through the refrigerant passage in the contact plate in a state in which the contact plate is brought into contact with the laminate after welding the laminate.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a secondary battery. Background Technology

[0002] In recent years, bipolar secondary batteries have been under development for use in automobiles. A bipolar secondary battery is a laminated structure composed of multiple battery cells stacked in series. The edges of each battery cell constituting a bipolar secondary battery are, for example, made of resin. A known technique ensures sealing by welding the sides, i.e., the resin portions, of the laminated bipolar secondary battery.

[0003] For example, Patent Document 1 discloses a technique for smoothing the welded surface after the sides of the laminate are welded together.

[0004] Prior art literature Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-174079 Summary of the Invention

[0005] The problem that the invention aims to solve The inventors discovered the following issues regarding the manufacturing method of secondary batteries.

[0006] If a smoothing process is performed after the welding process, waste is generated because the surface of the welded part is processed and discarded. In addition, the heat energy required for processing the waste is wasted.

[0007] This disclosure was made in view of such a problem, and its purpose is to provide a method for manufacturing a secondary battery that can obtain a laminate with a smooth welded surface without the need for additional smoothing processing after welding.

[0008] Methods for solving problems One way to achieve the above objective is a method for manufacturing a secondary battery, which uses a manufacturing apparatus having a laminate constraint plate for holding a laminate of a bipolar secondary battery and a welding fixture for welding the laminate held by the laminate constraint plate. The welding fixture includes a contact plate and a heating plate. The contact plate is capable of contacting the laminate and has a refrigerant passage inside. The heating plate is capable of heating the contact plate. The contact plate and the heating plate are capable of moving independently via an actuator. The method for manufacturing the secondary battery comprises: The process of clamping the laminate to the laminate constraint plate; A process of welding the laminate by heating the contact plate with the heating plate while the contact plate is in contact with the laminate held by the laminate constraint plate; and After the laminate is welded, while the contact plate is in contact with the laminate, the heating plate is removed from the contact plate and the refrigerant flows in the refrigerant passage, thereby cooling the laminate while pressing it.

[0009] The effects of the invention According to this disclosure, a method for manufacturing a secondary battery that can obtain a smooth welded surface without the need for additional smoothing processing after welding can be provided. Attached Figure Description

[0010] Figure 1 This is a schematic diagram illustrating the configuration of the manufacturing apparatus involved in the embodiment.

[0011] Figure 2 This is a diagram showing the configuration of the manufacturing apparatus during cooling.

[0012] Figure 3 It is a graph representing the temperature changes of the laminate during the heating and cooling processes. Detailed Implementation

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding elements are given the same reference numerals, and repeated descriptions are omitted as needed for clarity. Furthermore, for ease of understanding, the scales of various parts in the drawings may differ from the actual scales.

[0014] Figure 1 This is a schematic diagram illustrating an example of the configuration of the manufacturing apparatus 100 according to the embodiment. Figure 1 In addition to the manufacturing apparatus 100, a laminate 10 is also illustrated. The laminate 10 is a bipolar rechargeable battery suitable for automotive secondary batteries. In the laminate 10, multiple laminated components are stacked, and the resin portions around the outer periphery of the laminated components are sealed by welding. The manufacturing apparatus 100 is a device that welds the laminate 10 by heating and cooling it, and smooths the surface of the welded portion. The manufacturing apparatus 100 includes laminate constraint plates 20a and 20b and a welding fixture 70.

[0015] The laminate constraint plates 20a and 20b are a pair of components capable of clamping the laminate 10. From the perspective of ensuring high thermal insulation, the laminate constraint plates 20a and 20b are, for example, made of thermally insulating ceramic. In addition, it is preferable that the laminate constraint plates 20a and 20b have undergone surface treatment to improve the demolding properties of the laminate 10 after welding.

[0016] The welding fixture 70 welds the laminate 10 held by the laminate constraint plates 20a and 20b. The welding fixture 70 includes a contact plate 30 and a heating plate 40. The contact plate 30 is movable by an actuator 50. The contact plate 30 can contact the laminate 10 held by the laminate constraint plates 20a and 20b. From the perspective of improving thermal conductivity, the contact plate 30 is, for example, made of metal. Preferably, the contact plate 30 has undergone a surface treatment to improve demolding performance from the welded laminate 10. A refrigerant passage 31 is provided in the contact plate 30. A refrigerant such as water can flow through the refrigerant passage 31. By allowing the refrigerant to flow through the refrigerant passage 31, the laminate 10 in contact with the contact plate 30 can be cooled. Alternatively, the contact plate 30 can also be cooled by other cooling methods. For example, the contact plate 30 can also be cooled by contacting a metal (not shown) to be cooled.

[0017] The heating plate 40 can be moved by the actuator 60. The heating plate 40 and the contact plate 30 can move independently of each other. Figure 1 As shown, the heating plate 40 and the contact plate 30 are movable in a direction perpendicular to the stacking direction of the laminate 10, and are arranged in the order of heating plate 40, contact plate 30, and laminate 10. For example... Figure 1 As shown, a through hole is provided on the heating plate 40 for the actuator 50 to pass through. By providing such a through hole, the heating plate 40 can move independently of the contact plate 30.

[0018] The heating plate 40 is a heat source that is always at a high temperature. The heating method of the heating plate 40 is not particularly limited; for example, it can be heated by a heater or by induction heating. The heating plate 40 heats the contact plate 30 by contacting it. Furthermore, the heating plate 40 stops heating the contact plate 30 by separating from it.

[0019] Next, refer to Figure 1 and Figure 2 The manufacturing method of the secondary battery disclosed herein will be described. In the manufacturing method of the secondary battery disclosed herein, firstly, a laminate 10 is clamped between laminate constraint plates 20a and 20b. Next, by actuating the actuator 50, a contact plate 30 is brought into contact with the laminate 10 clamped by the laminate constraint plates 20a and 20b. In this state, a heating plate 40 is brought into contact with the contact plate 30, thereby causing the temperature of the contact plate 30 to rise through heat conduction. Furthermore, since the contact plate 30, after its temperature rise, is in contact with the laminate 10, the portion of the laminate 10 in contact with the contact plate 30 experiences a temperature rise due to heat conduction and is fused together.

[0020] Next, by actuating the actuator 60, the heating plate 40 is disengaged from the contact plate 30, causing refrigerant to flow in the refrigerant passage 31, thereby cooling the contact plate 30. Cooling of the contact plate 30 is performed while it is in contact with the laminate 10. Specifically, the contact plate 30 is cooled while applying force in the direction that pushes it against the laminate 10. When the welded portion is cooled during the cooling process, its volume decreases due to thermal contraction. Therefore, by applying force while cooling in the direction that pushes the contact plate 30 against the laminate 10, it is possible to cool while pressing the contact plate 30 against the surface of the welded portion, thus smoothing the surface of the resin portion after welding. In this way, in the secondary battery manufacturing method according to this disclosure, the surface of the welded portion can be smoothed during the cooling process after welding, eliminating the need for a separate process to smooth the surface of the welded portion.

[0021] Here, we consider the case where a smoothing process is performed after the cooling process to smooth the surface of the welded portion. In this smoothing process, for example, smoothing is achieved by removing the surface of the welded portion. Therefore, when smoothing is performed after the cooling process, it is necessary to anticipate the portion to be removed during the smoothing process and thus add more welded portions. On the other hand, in the secondary battery manufacturing method of this disclosure, since the surface of the welded portion is smoothed during the cooling process, it is unnecessary to add more welded portions; that is, it is unnecessary to form a weld depth that takes into account the amount removed during the smoothing process. Therefore, the welding process can be performed without using the energy required to add more welded portions. Furthermore, since no resin is removed during the smoothing process, the amount of waste can be reduced. Thus, in the secondary battery manufacturing method of this disclosure, energy loss related to waste resin can be suppressed. In this way, in the secondary battery manufacturing method of this disclosure, since the smoothing process can be performed during the cooling process, it is unnecessary to prepare a separate apparatus for the smoothing process in addition to the apparatus for the heating / cooling process. Therefore, the cost required for equipment preparation can be reduced.

[0022] Next, refer to Figure 3 This illustrates an example of the temperature change of the laminate 10 when the manufacturing apparatus 100 involved in this disclosure is operated. Figure 3 This is a graph showing the temperature changes of the laminate 10 during the heating and cooling processes. (The last sentence appears to be incomplete and possibly refers to obtaining a graph.) Figure 3 The data shown is obtained by placing a thermocouple between the laminate 10 and the contact plate 30, and measuring the temperature after heating for 60 seconds and then cooling for 60 seconds. Here, the heating method is a heater. The cooling method involves bringing the heated contact plate 30 into contact with the cooled metal plate. Figure 3As shown, near the portion of the laminate 10 that contacts the contact plate 30, the temperature is raised to 230°C through a heating process, and then lowered to 50°C through a cooling process. Visual inspection confirms that the surface of the welded portion of the laminate 10 after the cooling process is smooth. Thus, it is confirmed that the manufacturing apparatus 100 of this disclosure can obtain a laminate 10 with a smooth surface at the welded portion without requiring a smoothing process.

[0023] According to the invention described above, a method for manufacturing a secondary battery that can produce a laminate with a smooth welded surface can be provided.

[0024] Furthermore, this disclosure is not limited to the above-described embodiments, and appropriate modifications may be made without departing from the spirit of the subject.

[0025] Explanation of reference numerals in the attached figures 10-layer stack 20a and 20b laminated constraint plates 30 Contact plate 31 Refrigerant Pathway 40 heating plate 50, 60 actuators 70 Welding clamps 100 Manufacturing equipment.

Claims

1. A method for manufacturing a secondary battery, comprising a manufacturing apparatus having a laminate constraint plate for holding a laminate of a bipolar secondary battery, and a welding fixture for welding the laminate held by the laminate constraint plate. The welding fixture includes a contact plate and a heating plate. The contact plate is capable of contacting the laminate and has a refrigerant passage inside. The heating plate is capable of heating the contact plate. The contact plate and the heating plate are capable of moving independently via an actuator. The method for manufacturing the secondary battery comprises: The process of clamping the laminate to the laminate constraint plate; A process of welding the laminate by heating the contact plate with the heating plate while the contact plate is in contact with the laminate held by the laminate constraint plate; and After the laminate is welded, while the contact plate is in contact with the laminate, the heating plate is removed from the contact plate and the refrigerant flows in the refrigerant passage, thereby cooling the laminate while pressing it.

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