Secondary battery manufacturing method

Abstract

A method for manufacturing a secondary battery that can obtain a laminate with a smooth welded surface is provided. [Solution] The method for manufacturing a secondary battery according to the present disclosure is a method for manufacturing a secondary battery using a manufacturing apparatus 100 equipped with stack constraint plates 20a, 20b that sandwich the stack 10 and a welding jig 70 that welds the stack 10, wherein the welding jig 70 has a contact plate 30 that contacts the stack 10 and a heating plate 40 that can heat the contact plate 30, and includes the steps of sandwiching the stack 10 between the stack constraint plates 20a, 20b, welding the stack 10 by heating the contact plate 30 with the contact plate 30 in contact with the stack 10 sandwiched between the stack constraint plates 20a, 20b, and, after welding the stack 10, separating the heating plate 40 from the contact plate 30 with the contact plate 30 in contact with the stack 10 and flowing a refrigerant through the refrigerant passage 31 in the contact plate 30 to press and cool the stack 10.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a secondary battery. [Background technology]

[0002] In recent years, bipolar secondary batteries have been developed as secondary batteries for automobiles. Bipolar secondary batteries have a stacked structure in which multiple cells are stacked in series. The edges of each cell that makes up a bipolar secondary battery are made of, for example, resin. A technique for ensuring sealing by welding the side surfaces of the stack, i.e., the resin parts, of a bipolar secondary battery is known. For example, Patent Document 1 discloses a technique in which, after welding the entire side surface of a laminate, processing is carried out to smooth the welded surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-174079 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have found the following problems with respect to the method for manufacturing a secondary battery. If a smoothing step is carried out after the welding step, the surface of the welded portion will be processed and discarded, resulting in waste and wasting the heat energy required to process the waste.

[0005] The present disclosure has been made in consideration of such problems, and aims to provide a method for manufacturing a secondary battery that can obtain a laminate with a smooth welded surface without performing a separate smoothing process after welding. [Means for solving the problem]

[0006] One aspect of the present invention to achieve the above object is to A method for manufacturing a secondary battery using a manufacturing device including stack constraint plates that sandwich a stack of a bipolar secondary battery, and a welding jig that welds the stack sandwiched between the stack constraint plates, the welding jig includes a contact plate that can come into contact with the laminate and has a refrigerant passage provided therein, and a heating plate that can heat the contact plate, the contact plate and the heating plate being independently movable by an actuator; sandwiching the laminate between the laminate restraint plates; a step of welding the laminate by heating the contact plate with the heating plate in a state where the contact plate is in contact with the laminate sandwiched between the laminate restraint plates; a step of, after welding the laminate, moving the heating plate away from the contact plate while keeping the contact plate in contact with the laminate, and flowing a refrigerant through the refrigerant passage, thereby pressing and cooling the laminate; Equipped with. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a method for manufacturing a secondary battery that can obtain a laminate having a smooth welded surface without performing a separate smoothing process after welding. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a configuration of a manufacturing apparatus according to an embodiment. [Figure 2] FIG. 10 is a diagram showing the configuration of the manufacturing apparatus during cooling. [Figure 3] 4 is a graph showing temperature changes of a laminate in a heating step and a cooling step. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary. In addition, for ease of understanding, the scale of each part in the drawings may differ from the actual scale.

[0010] FIG. 1 is a schematic diagram showing an example of the configuration of a manufacturing apparatus 100 according to an embodiment. In addition to the manufacturing apparatus 100, FIG. 1 also shows a laminate 10. The laminate 10 is a bipolar storage battery suitable for use as a secondary battery for automobiles. The laminate 10 is made up of a plurality of laminate members stacked one on top of another, and the resin portions on the outer periphery of the laminate members are sealed by welding. The manufacturing apparatus 100 heats and cools the laminate 10 to weld the laminate 10 and smooth the surface of the welded portion. The manufacturing apparatus 100 includes laminate restraint plates 20a and 20b and a welding jig 70.

[0011] The laminate restraint plates 20a, 20b are a pair of members that can sandwich the laminate 10. The laminate restraint plates 20a, 20b are made of, for example, insulating ceramic to ensure high thermal insulation. Furthermore, the laminate restraint plates 20a, 20b are preferably surface-treated to improve releasability from the welded laminate 10.

[0012] The welding jig 70 welds the laminate 10 sandwiched between the laminate restraint plates 20a and 20b. The welding jig 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 is capable of contacting the laminate 10 sandwiched between the laminate restraint plates 20a and 20b. The contact plate 30 is made of, for example, metal to enhance thermal conductivity. The contact plate 30 is preferably surface-treated to enhance releasability from the welded laminate 10. The contact plate 30 is provided with a refrigerant passage 31. A refrigerant such as water can be passed through the refrigerant passage 31. The laminate 10 in contact with the contact plate 30 can be cooled by passing the refrigerant through the refrigerant passage 31. The contact plate 30 may also be cooled by other cooling methods. For example, the contact plate 30 may be cooled by contact with a cooled metal (not shown).

[0013] The heating plate 40 is movable by an actuator 60. The heating plate 40 and the contact plate 30 are movable independently of each other. As shown in FIG. 1, 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 installed in the order of the heating plate 40, the contact plate 30, and the laminate 10. For example, as shown in FIG. 1, the heating plate 40 is provided with a through-hole through which the actuator 50 passes. By providing such a through-hole, the heating plate 40 is movable independently of the contact plate 30.

[0014] The heating plate 40 is a heat source that is constantly kept at a high temperature. The heating method of the heating plate 40 is not particularly limited, and may be, for example, heater heating or induction heating. The heating plate 40 heats the contact plate 30 by coming into contact with the contact plate 30. Furthermore, the heating plate 40 stops heating the contact plate 30 by moving away from the contact plate 30.

[0015] Next, a method for manufacturing a secondary battery according to the present disclosure will be described with reference to Figures 1 and 2. In the method for manufacturing a secondary battery according to the present disclosure, first, the stack 10 is sandwiched between stack restraint plates 20a and 20b. Next, the actuator 50 is operated to bring the contact plate 30 into contact with the stack 10 sandwiched between the stack restraint plates 20a and 20b. When the heating plate 40 is brought into contact with the contact plate 30 in this state, the temperature of the contact plate 30 rises due to thermal conduction. Then, because the heated contact plate 30 and the stack 10 are in contact, the temperature of the portion of the stack 10 in contact with the contact plate 30 rises due to thermal conduction and the portions are welded together.

[0016] Next, actuator 60 is operated to separate heating plate 40 from contact plate 30, and refrigerant is circulated through refrigerant passage 31 to cool contact plate 30. Cooling of contact plate 30 is performed while contact plate 30 is in contact with stack 10. Specifically, contact plate 30 is cooled while applying force in a direction that pushes contact plate 30 into stack 10. When the welded portion is cooled during the cooling process, its volume decreases due to thermal contraction. Therefore, by applying force in a direction that pushes contact plate 30 into stack 10 while cooling, contact plate 30 can be cooled while being pressed against the surface of the welded portion, thereby smoothing the surface of the welded resin portion. In this way, in the manufacturing method of a secondary battery according to the present disclosure, the surface of the welded portion can be smoothed during the cooling process after welding, eliminating the need for a separate process for smoothing the surface of the welded portion.

[0017] Consider the case where a smoothing process is performed after the cooling process to smooth the surface of the welded portion. In the smoothing process, for example, the surface of the welded portion is scraped off. Therefore, if the smoothing process is performed after the cooling process, it is necessary to provide a larger welded portion in anticipation of the portion that will be scraped off by the smoothing process. On the other hand, in the manufacturing method of a secondary battery according to the present disclosure, since the surface of the welded portion is smoothed in the cooling process, there is no need to provide a larger welded portion. In other words, there is no need to set the welding depth considering the portion to be removed in the smoothing process. Therefore, the welding process can be performed without using the energy required to provide a larger welded portion. Furthermore, since no resin is scraped off during the smoothing process, the amount of waste can be reduced. Therefore, the manufacturing method of a secondary battery according to the present disclosure can suppress energy loss related to discarded resin. As such, in the manufacturing method of a secondary battery according to the present disclosure, since the smoothing process can be performed in the cooling process, there is no need to prepare a separate device for the smoothing process from the device for the heating and cooling processes. This reduces the cost required for preparing equipment.

[0018] Next, referring to FIG. 3 , an example of temperature change of the laminate 10 during operation of the manufacturing apparatus 100 according to the present disclosure will be described. FIG. 3 is a graph showing temperature change of the laminate 10 during the heating and cooling processes. To obtain the data shown in FIG. 3 , a thermocouple was placed between the laminate 10 and the contact plate 30, and the temperature was measured after heating for 60 seconds and then cooling for 60 seconds. Here, the heating method was a heater. The cooling method involved contacting the heated contact plate 30 with a cooled metal plate. As shown in FIG. 3 , the temperature near the portion of the laminate 10 in contact with the contact plate 30 rose to 230°C during the heating process and then dropped to 50°C during the cooling process. Visual inspection of the laminate 10 after the cooling process revealed that the surface of the welded portion was smooth. Thus, it was confirmed that the manufacturing apparatus 100 according to the present disclosure can produce a laminate 10 with a smooth surface at the welded portion without performing a smoothing process.

[0019] According to the invention according to the embodiments described above, it is possible to provide a method for manufacturing a secondary battery that can obtain a laminate having a smooth welded surface.

[0020] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0021] 10 Laminate 20a, 20b Laminated body restraint plates 30 Contact plate 31 Refrigerant passage 40 heating plate 50,60 Actuator 70 Welding jig 100 Manufacturing equipment

Claims

[Claim 1] A method for manufacturing a secondary battery using a manufacturing device including stack constraint plates that sandwich a stack of a bipolar secondary battery, and a welding jig that welds the stack sandwiched between the stack constraint plates, the welding jig includes a contact plate that can come into contact with the laminate and has a refrigerant passage provided therein, and a heating plate that can heat the contact plate, the contact plate and the heating plate being independently movable by an actuator; sandwiching the laminate between the laminate restraint plates; a step of welding the laminate by heating the contact plate with the heating plate in a state where the contact plate is in contact with the laminate sandwiched between the laminate restraint plates; a step of, after welding the laminate, moving the heating plate away from the contact plate while keeping the contact plate in contact with the laminate, and flowing a refrigerant through the refrigerant passage to press and cool the laminate; A method for manufacturing a secondary battery comprising the steps of:

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