Rechargeable battery manufacturing apparatus and manufacturing method

Abstract

The present invention provides a secondary battery manufacturing apparatus and manufacturing method that suppress the pressure of the electrode material during circulation operation from becoming greater than the pressure during coating operation. [Solution] The secondary battery manufacturing apparatus of the present disclosure includes a tank 10 for storing electrode material, a die 20 for discharging electrode material, a first pipe 30 connecting the tank 10 and the die 20, a second pipe 50 connecting a branching section 45 and the tank 10, a pump 40 for supplying electrode material to the branching section 45, and flow path switching valves 61 and 62 located in the branching section 45. The tank 10 is fitted with a depressurization mechanism 11 for reducing the pressure inside the tank 10.

Description

Technical Field

[0001] The present disclosure relates to a manufacturing apparatus and a manufacturing method for secondary batteries.

Background Art

[0002] Patent Document 1 discloses a manufacturing apparatus for an electrode plate for a non-aqueous secondary battery, which includes a tank for storing an electrode material, a pump for supplying the electrode material, a die coater for coating the electrode material on a current collector sheet, a flow path switching valve for switching the flow path of the electrode material, a return line connecting the flow path switching valve and the tank, and a back pressure regulating valve provided on the return line. During non-coating, the electrode material is passed through the back pressure regulating valve to raise the pressure of the electrode material to the pressure during coating.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During the circulation operation of the electrode material performed before the coating operation on the current collector sheet, the electrode material may be subjected to a pressure exceeding the pressure required during the coating operation. This is affected by factors such as the increase in the total length of the piping connecting the flow path switching valve and the tank as the manufacturing apparatus for secondary batteries becomes larger. In this case, immediately after switching from the circulation operation to the coating operation, the film thickness of the electrode layer formed on the current collector sheet may not be constant due to the pressure drop of the electrode material. The present disclosure solves such problems and provides a manufacturing apparatus and a manufacturing method for secondary batteries that suppress the pressure of the electrode material from becoming greater than the pressure during the coating operation during the circulation operation.

Means for Solving the Problems

[0005] The secondary battery manufacturing apparatus of the present disclosure includes a tank for storing electrode material to be coated onto a current collector sheet, a die for discharging the electrode material onto the current collector sheet, a first pipe connecting the tank and the die, a second pipe connecting a branch section provided in the first pipe to the tank, a pump disposed in the first pipe between the tank and the branch section for supplying the electrode material stored in the tank to the branch section, and a flow path switching valve disposed in the branch section for switching the flow of the electrode material supplied from the pump to either the die or the tank, wherein the tank is fitted with a pressure reducing mechanism for reducing the pressure inside the tank. This configuration prevents the pressure of the electrode material from becoming greater than the pressure during the coating operation during the circulating operation.

[0006] The pressure reduction mechanism may be a vacuum pump. This configuration prevents the pressure of the electrode material from becoming greater than the pressure during the coating operation during the circulation operation.

[0007] A method for manufacturing a secondary battery according to the present disclosure includes: a circulation operation step of operating the pump to supply electrode material to the branching section, and operating the depressurization mechanism to depressurize the inside of the tank while switching the flow path switching valve so that the electrode material supplied to the branching section flows to the tank; a coating operation step of switching the flow path switching valve so that the electrode material supplied to the branching section flows to the die and discharging the electrode material from the die; and a coating operation interruption step of switching the flow path switching valve so that the electrode material supplied to the branching section flows to the tank and returning the electrode material to the tank. This configuration prevents the pressure of the electrode material from becoming greater than the pressure during the coating operation during the circulating operation. [Effects of the Invention]

[0008] This disclosure provides a secondary battery manufacturing apparatus and manufacturing method that suppress the pressure of the electrode material during circulating operation from becoming greater than the pressure during coating operation. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a secondary battery manufacturing apparatus according to Embodiment 1, showing the electrode material flowing from the branching section to the die. [Figure 2] This is a schematic diagram of a secondary battery manufacturing apparatus according to Embodiment 1, showing the electrode material flowing from the branching section to the tank. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described below with reference to Figures 1 and 2. Figure 1 is a schematic diagram of a secondary battery manufacturing apparatus of Embodiment 1, showing the electrode material flowing from the branching section to the die. Figure 2 is a schematic diagram of a secondary battery manufacturing apparatus of Embodiment 1, showing the electrode material flowing from the branching section to the tank.

[0011] Embodiment 1 The secondary battery manufacturing apparatus 1 shown in Figure 1 is an apparatus for manufacturing electrode sheets for secondary batteries by intermittently coating an electrode material onto a current collector sheet 21. The secondary battery manufacturing apparatus 1 includes a tank 10, a die 20, a first pipe 30, a pump 40, a second pipe 50, a first flow path switching valve 61, a second flow path switching valve 62, and a suck-back valve 63.

[0012] Tank 10 stores electrode material to be coated onto the current collector sheet 21. Electrode material can include positive electrode material (the material for the positive electrode active layer) and negative electrode material (the material for the negative electrode active layer). When coating the current collector sheet 21 with electrode material, the electrode material stored in tank 10 is supplied to die 20 through first piping 30.

[0013] As shown in Figure 1, the die 20 discharges electrode material toward a current collector sheet 21 supported by a support roll 22 rotating at a predetermined speed. The flow rate of electrode material discharged from the die 20 is controlled by a suck-back valve 63. The electrode material coated onto the current collector sheet 21 is dried by a drying apparatus (not shown). In this way, an electrode sheet with an electrode layer 23 formed is manufactured.

[0014] As shown in Figure 1, the first pipe 30 connects the tank 10 and the die 20. The first pipe 30 is provided with a branch section 45, at which point it branches off to the second pipe 50. The second pipe 50 connects the branch section 45 to the tank 10. Electrode material flows through both the first pipe 30 and the second pipe 50. The first pipe 30 is equipped with, in order from the tank 10 side, a pump 40, a flow meter 41, a first flow path switching valve 61, and a suck-back valve 63. The second pipe 50 is equipped with a second flow path switching valve 62.

[0015] Pump 40 is located in the first piping 30 between the tank 10 and the branching section 45, and supplies the electrode material stored in the tank 10 to the branching section 45. Pump 40 is a rotary positive displacement mono pump with a single-screw eccentric screw. However, pump 40 is not limited to this; any pump 40 that can discharge a fixed amount may be used. Flow meter 41 measures the flow rate of the electrode material flowing through the first piping 30 between pump 40 and the branching section 45.

[0016] As shown in Figure 1, the first flow path switching valve 61 is located in the first piping 30 between the branch section 45 and the die 20. The second flow path switching valve 62 is located in the second piping 50 between the branch section 45 and the tank 10.

[0017] The first flow path switching valve 61 is substantially cylindrical and has a through hole 61a that penetrates radially. The diameter of the through hole 61a is substantially the same as the inner diameter of the first pipe 30. The first flow path switching valve 61 is rotated around its central axis by a motor 61b.

[0018] As shown in Figure 1, when the motor 61b rotates the first flow path switching valve 61 and connects the through hole 61a and the first pipe 30, the first flow path switching valve 61 opens. When the first flow path switching valve 61 opens, the electrode material can pass through the through hole 61a, and the electrode material flows from the branching section 45 toward the die 20.

[0019] On the one hand, as shown in FIG. 2, when the first flow path switching valve 61 is rotated by the motor 61b and the through hole 61a and the first pipe 30 are not in communication, the first flow path switching valve 61 is in a closed valve state. When the first flow path switching valve 61 closes, the electrode material cannot pass through the through hole 61a, so the electrode material does not flow from the branch portion 45 toward the die 20.

[0020] The second flow path switching valve 62 has a substantially cylindrical shape and has a through hole 62a penetrating in the radial direction. The diameter of the through hole 62a is substantially the same as the inner diameter of the second pipe 50. The second flow path switching valve 62 is rotated around the central axis by the motor 62b.

[0021] As shown in FIG. 2, when the second flow path switching valve 62 is rotated by the motor 62b and the through hole 62a and the second pipe 50 are in communication, the second flow path switching valve 62 is in an open valve state. When the second flow path switching valve 62 opens, the electrode material can pass through the through hole 62a, so the electrode material flows from the branch portion 45 toward the tank 10.

[0022] On the one hand, as shown in FIG. 1, when the second flow path switching valve 62 is rotated by the motor 62b and the through hole 62a and the second pipe 50 are not in communication, the second flow path switching valve 62 is in a closed valve state. When the second flow path switching valve 62 closes, the electrode material cannot pass through the through hole 62a, so the electrode material does not flow from the branch portion 45 toward the tank 10.

[0023] The first flow path switching valve 61 and the second flow path switching valve 62 work in conjunction to function as flow path switching valves that switch the flow of electrode material supplied from the pump 40 to either the die 20 or the tank 10. Specifically, as shown in Figure 1, by opening the first flow path switching valve 61 and closing the second flow path switching valve 62, the electrode material supplied from the pump 40 flows from the branching section 45 to the die 20. On the other hand, as shown in Figure 2, by closing the first flow path switching valve 61 and opening the second flow path switching valve 62, the electrode material supplied from the pump 40 flows from the branching section 45 to the tank 10. In this embodiment, the flow of electrode material is switched using the first flow path switching valve 61 and the second flow path switching valve 62, but the flow of electrode material may be switched by other means, such as a three-way valve.

[0024] The suck-back valve 63 is approximately cylindrical in shape and moves back and forth in the central axis direction by a motor 63b. The section of the first piping 30 where the suck-back valve 63 is located has a larger diameter than other sections to allow the suck-back valve 63 to move back and forth. The flow rate of the electrode material discharged from the die 20 is adjusted by the movement of the suck-back valve 63. When the discharge of the electrode material from the die 20 is finished, the suck-back valve 63 performs a pull-in operation, which allows the electrode material remaining near the tip of the die 20 to be pulled towards the suck-back valve 63.

[0025] As shown in Figure 1, a vacuum pump 11 is attached to the tank 10. The vacuum pump 11 functions as a pressure reducing mechanism that reduces the pressure inside the tank 10. Note that other pressure reducing mechanisms, such as a vacuum tank, can also be used as long as the pressure inside the tank 10 can be reduced.

[0026] Next, a method for manufacturing electrode sheets using the secondary battery manufacturing apparatus 1 will be described. The method for manufacturing electrode sheets includes a circulation operation step, a coating operation step, and a coating operation interruption step. In the circulation operation step, the first flow path switching valve 61 is closed, the second flow path switching valve 62 is opened, and the pump 40 is activated. As a result, the electrode material supplied from the pump 40 returns to the tank 10 via the first pipe 30, the branch section 45, and the second pipe 50. In this way, the electrode material is circulated and the first pipe 30 is filled with electrode material.

[0027] After the circulation operation is performed for a predetermined time, the process moves to the coating operation step. In the coating operation step, as shown in Figure 1, the first flow path switching valve 61 is opened and the second flow path switching valve 62 is closed while the pump 40 is still operating. As a result, the electrode material supplied from the pump 40 flows from the branch section 45 through the through hole 61a toward the die 20. In this way, the electrode material is discharged from the die 20 and the coating operation is performed on the current collector sheet 21.

[0028] After performing the coating operation for a predetermined time, the process moves to the coating operation interruption step. In the coating operation interruption step, as shown in Figure 2, the first flow path switching valve 61 is closed and the second flow path switching valve 62 is opened while the pump 40 remains operating. As a result, the electrode material supplied from the pump 40 is returned to the tank 10 through the branch section 45 and through the through hole 62a. In this way, the coating operation on the current collector sheet 21 is interrupted.

[0029] After the coating operation is interrupted for a predetermined time, the process returns to the coating operation step. By repeating the coating operation step and the coating operation interruption step in this manner, intermittent coating of the electrode material onto the current collector sheet 21 is achieved, and the electrode sheet is manufactured.

[0030] Here, during the coating operation, a predetermined pressure is applied to the electrode material flowing through the first pipe 30 between the pump 40 and the die 20 in order to discharge the electrode material from the die 20. On the other hand, during the circulation operation, the electrode material flowing through the first pipe 30 and the second pipe 50 between the pump 40 and the branch section 45 may be subjected to a pressure exceeding the pressure required during the coating operation. This is due to factors such as the increased overall length of the second pipe 50 as the secondary battery manufacturing equipment has become larger. In this case, immediately after switching from the circulation operation to the coating operation, the film thickness of the electrode layer 23 formed on the current collector sheet 21 may not be constant due to a drop in the pressure of the electrode material.

[0031] Therefore, in the secondary battery manufacturing apparatus 1 of this disclosure, a vacuum pump 11 is attached to the tank 10. During circulation, the vacuum pump 11 is operated to reduce the pressure inside the tank 10 to below atmospheric pressure. As a result, the electrode material flowing through the second pipe 50 is drawn into the tank 10, and consequently, the pressure on the electrode material decreases.

[0032] Thus, in this disclosure, the vacuum pump 11 is operated during the circulation operation to reduce the pressure inside the tank 10, thereby suppressing the pressure of the electrode material during the circulation operation from becoming greater than the pressure during the coating operation.

[0033] Here, a pressure gauge for measuring the pressure of the electrode material may be installed in the first pipe 30 between the pump 40 and the branch section 45, and the operation of the vacuum pump may be controlled during circulation so that the pressure of the electrode material approaches the pressure required during coating.

[0034] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. [Explanation of symbols]

[0035] 10... tanks 11. Vacuum pump 20...Dai 21...Current collection sheet 30..First Piping 40... pump 45... Branching point 50...Second pipe 61...First flow path switching valve 62...Second flow path switching valve

Claims

1. A tank for storing electrode material to be coated onto current collector sheets, The current collector sheet is provided with a die for dispensing the electrode material, A first pipe connecting the tank and the die, A branch section provided in the first piping and a second piping connected to the tank, A pump is provided in the first piping between the tank and the branching section, and supplies the electrode material stored in the tank to the branching section. The branch section includes a flow path switching valve that switches the flow of the electrode material supplied from the pump to either the die or the tank, The tank is equipped with a pressure reduction mechanism that reduces the pressure inside the tank. Manufacturing equipment for secondary batteries.

2. The aforementioned pressure reduction mechanism is a vacuum pump. The apparatus for manufacturing a secondary battery according to claim 1.

3. A method for manufacturing a secondary battery using the secondary battery manufacturing apparatus described in either claim 1 or claim 2, A circulation operation step in which the pump is operated to supply electrode material to the branching section, the flow path switching valve is switched so that the electrode material supplied to the branching section flows into the tank, and the pressure reducing mechanism is operated to reduce the pressure inside the tank, A coating operation step in which the flow path switching valve is switched so that the electrode material supplied to the branch section flows to the die, and the electrode material is discharged from the die, A coating operation interruption step in which the flow path switching valve is switched so that the electrode material supplied to the branching section flows to the tank, thereby returning the electrode material to the tank, A method for manufacturing a secondary battery, including [the following].

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