Manufacturing method for energy storage devices

Abstract

To measure the electrical resistance of wiring connected to energy storage cells in an energy storage device with high precision. [Solution] A method for manufacturing an energy storage device including multiple energy storage cells includes a wiring formation process in which the wiring of the energy storage device is formed so that adjacent energy storage cells in the energy storage device are connected to a common wiring, and a resistance measurement process (S31, S32) for measuring the electrical resistance of at least a portion of the formed wiring. In the resistance measurement process, for the common wiring portion of adjacent first and second energy storage cells in the energy storage device, the voltage of the open circuit including the second energy storage cell and the common wiring portion is measured while current is flowing through the closed circuit including the first energy storage cell and the common wiring portion, and the electrical resistance of the common wiring portion is obtained using the measured voltage.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a power storage device.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2014-180109 (Patent Document 1) discloses a technique for calculating the resistance value of a charging path based on the voltage of a secondary battery (the voltage value across both ends of the secondary battery), the charging current, and the power supply voltage (the output voltage of the power supply) during charging of the secondary battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a power storage device including a plurality of power storage cells, for example, each of the plurality of power storage cells functions as a secondary battery. In such a power storage device, the voltage of the power storage cell tends to increase as the power storage amount of the power storage cell increases. Therefore, the voltage of the power storage cell can fluctuate during charging of the power storage cell. When the output voltage of the power supply connected to the power storage cell is constant, the charging current changes as the voltage of the power storage cell changes. Thus, during charging of the power storage cell, the voltage and charging current of the power storage cell tend to become unstable. For this reason, with the technique described in Patent Document 1, it is difficult to accurately measure the electrical resistance of the wiring (for example, the charging path) connected to the power storage cell.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to measure the electrical resistance of the wiring connected to the power storage cell in a power storage device with high accuracy.

Means for Solving the Problems

[0006] According to one embodiment of the present disclosure, a method for manufacturing an energy storage device including a plurality of energy storage cells is provided. The method includes a wiring formation process for forming wiring in an energy storage device such that adjacent energy storage cells in the energy storage device are connected to common wiring, and a resistance measurement process for measuring the electrical resistance of at least a portion of the formed wiring. In the resistance measurement process, for a common wiring portion of adjacent first and second energy storage cells in the energy storage device, the voltage of an open circuit including the second energy storage cell and the common wiring portion is measured while current is flowing through a closed circuit including the first energy storage cell and the common wiring portion, and the electrical resistance of the common wiring portion is obtained using the measured voltage. [Effects of the Invention]

[0007] According to this disclosure, it becomes possible to measure the electrical resistance of wiring connected to energy storage cells in an energy storage device with high accuracy. [Brief explanation of the drawing]

[0008] [Figure 1] This is a flowchart showing the method for manufacturing the energy storage device according to this embodiment. [Figure 2] This is a cross-sectional view showing the composition of the laminate included in the object being inspected. [Figure 3] This is a diagram illustrating the inspection according to this embodiment. [Figure 4] This is a diagram illustrating the resistance measurement process according to this embodiment. [Figure 5] This figure shows a modified example of the resistance measurement process. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated. In the drawings used below, the X-axis, Y-axis, and Z-axis refer to three mutually orthogonal axes. Hereafter, the direction indicated by the arrows on the X-axis, Y-axis, and Z-axis will be indicated by a "+" sign, and the opposite direction will be indicated by a "-" sign.

[0010] Figure 1 is a flowchart showing the inspection process according to this embodiment. In the manufacturing method of the energy storage device according to this embodiment, first, the object to be inspected is prepared. Then, the inspection is performed on the object to be inspected according to the process flow shown in Figure 1.

[0011] The object to be inspected according to this embodiment includes the laminate 10 shown in Figure 2. Figure 2 is a cross-sectional view showing the configuration of the laminate included in the object to be inspected. Referring to Figure 2, the laminate 10 comprises an energy storage section 10a and a sealing section 3 that seals the energy storage section 10a. The Z direction corresponds to the stacking direction. The energy storage section 10a includes a plurality of cells C (unit batteries) arranged in the Z direction. Each of the plurality of cells C comprises a negative electrode active material layer 12A, a positive electrode active material layer 12B, and a separator 13.

[0012] Each of the multiple cells C is configured to store energy. Each of the multiple cells C functions as a secondary battery. Each of the multiple cells C corresponds to an example of a "storage cell" according to this disclosure. In this embodiment, the energy storage unit 10a includes N cells C. In this embodiment, N is 10 or more and less than 50. However, the total number of cells C (N) may be 3 or more and less than 10, or 50 or more. The sealing unit 3 is formed to surround the energy storage unit 10a. The space surrounded by the sealing unit 3 is filled with electrolyte. The electrolyte is impregnated into the separator 13.

[0013] The laminate 10 includes a plurality of electrodes (one negative terminal electrode 2A, a plurality of bipolar electrodes 1, and one positive terminal electrode 2B) stacked along the Z direction. Separators 13 are placed between the electrodes. The bipolar electrode 1 includes a current collector 11, a negative electrode active material layer 12A provided on the +Z side of the current collector 11, and a positive electrode active material layer 12B provided on the -Z side of the current collector 11. The negative terminal electrode 2A has a configuration in which the positive electrode active material layer 12B is removed from the bipolar electrode 1. An insulating layer 19A covering the periphery of the current collector 11 is formed on the -Z side of the current collector 11 that constitutes the negative terminal electrode 2A. The positive terminal electrode 2B has a configuration in which the negative electrode active material layer 12A is removed from the bipolar electrode 1. An insulating layer 19B is formed on the +Z side surface of the current collector 11 that constitutes the positive terminal electrode 2B, covering the peripheral edge of the current collector 11.

[0014] In this embodiment, a metal foil (e.g., aluminum foil) is used as the current collector 11 for each electrode. Surface treatment (e.g., plating) may be applied to one or both sides of the metal foil. A voltage detection terminal 20 is connected to the current collector 11 of each electrode. In this embodiment, the voltage detection terminal 20 includes stainless steel. Stainless steel has excellent corrosion resistance, heat resistance, and workability. However, the material of the voltage detection terminal 20 can be changed as appropriate.

[0015] The negative electrode active material layer 12A contains a negative electrode active material. The positive electrode active material layer 12B contains a positive electrode active material. In one example, the positive electrode active material is olivine-type lithium iron phosphate (LiFePO4), the negative electrode active material is a carbon-based material, and the electrolyte is a non-aqueous electrolyte. However, other examples of negative electrode active materials include silicon and tin. The electrolyte may also be an aqueous electrolyte. Alternatively, a gel-like or solid electrolyte may be used instead of an electrolyte.

[0016] In the laminate 10, cells C are formed between the multiple stacked current collectors 11. Specifically, a cell C is formed between a current collector 11 (first current collector) and a current collector 11 (second current collector) adjacent to the first current collector. Furthermore, a cell C is also formed between the second current collector and a current collector 11 (third current collector) adjacent to the second current collector. In this way, the current collectors 11 and cells C are arranged alternately in the stacking direction of the laminate 10. The sealing portion 3 includes seal layers 14 and 15 arranged around each of the multiple cells C contained in the laminate 10, and the aforementioned insulating layers 19A and 19B. Any sealing material can be used as the material for the sealing portion 3.

[0017] The laminate 10 functions as a bipolar secondary battery. In the laminate 10, multiple cells C are electrically connected in series. Each of the multiple cells C included in the laminate 10 functions as, for example, an LFP battery (a lithium-ion secondary battery containing lithium iron phosphate as the positive electrode active material). Hereinafter, the 1st, 2nd, ..., N-1th, and Nth cells C from the negative electrode side (-Z side) of the laminate 10 may be denoted as cell C-1, cell C-2, ..., cell CN-1, cell CN, etc. (see Figure 3 below). In the laminate 10, multiple cells are stacked in the Z direction. Adjacent cells have common electrodes. Specifically, the current collector 11 and voltage detection terminal 20 located between adjacent cells function as common electrodes. These common electrodes function as common wiring, as described later (see Figure 3).

[0018] For example, the manufacturing system forms a laminate 10 (Figure 2) to which the aforementioned voltage detection terminals 20 are connected, through various processes such as coating, pressing, seal welding, separator welding, cutting, terminal (voltage detection terminal) welding, end face welding, injection molding, liquid injection, and temporary sealing. Although not shown in Figure 2, a connector 30 (see Figure 3), which will be described later, is further provided for the voltage detection terminals 20. Furthermore, the laminate 10 may be restrained by a restraining jig. The laminate 10 may be sandwiched and pressed between a pair of end plates (restraining plates).

[0019] The manufacturing system according to this embodiment includes a system for preparing the laminate 10 (a system including equipment corresponding to each process for forming the laminate 10) and an inspection system for charging, aging, and inspecting (including circuit resistance measurement and self-discharge inspection) the laminate 10. However, it is not essential that the manufacturing (including inspection) of the energy storage device be performed automatically (i.e., that the equipment performs all processes related to manufacturing), and a person (worker) may perform some of the processes. The structure of the laminate 10 is not limited to the structure shown in Figure 2 and can be changed as appropriate.

[0020] Referring again to Figure 1, when the laminate 10 acquired as described above (for example, the laminate 10 in a constrained state) is passed to the inspection system, the inspection system executes the processing flow shown in Figure 1 for the laminate 10. In the flowchart, "S" represents a step.

[0021] In S10, the inspection system performs the initial charge of the laminate 10. The initial charge is the first charge of the formed laminate 10. For example, the inspection system applies a voltage between the positive and negative terminals of the laminate 10 (for example, the current collectors 11 located at both ends in the Z direction as shown in Figure 2). This charges all cells C connected in series. The inspection system may terminate the initial charge when the State of Charge (SOC) of at least one cell in the laminate 10 becomes equal to or greater than the target SOC value. SOC represents the amount of stored energy, and is expressed as a percentage from 0 to 100% of the current amount of stored energy relative to the amount of stored energy when fully charged. The target SOC value can be set arbitrarily. The target SOC value may be between 50% and 100%, or for example, around 90%. Note that the termination condition for the initial charge may be set by the charging time instead of SOC.

[0022] Next, in S20, the inspection system forms an inspection circuit by connecting the laminate 10 to the power supply unit of the inspection system. The process from S20 onward will be explained below with further use of Figure 3. Figure 3 is a diagram illustrating the inspection of the laminate 10. As shown in Figure 3, a connector 30 is provided for a plurality of voltage detection terminals 20 connected to the laminate 10. The voltage detection terminals 20 are welded, for example, to the +X side end of the current collector 11. Examples of welding methods include ultrasonic welding or laser welding. The connector 30 includes a resin part 31 and a housing 32. For example, with the housing 32 for aligning the voltage detection terminals 20 attached to the tip of the voltage detection terminals 20, the resin part 31 connecting the +X side end face of the laminate 10 and the housing 32 is formed by injection molding. This forms a connector 30 that is joined to the laminate 10. The plurality of voltage detection terminals 20 are configured to be connectable to an external power supply (e.g., a DC power supply 41). Each of the plurality of voltage detection terminals 20 functions as a pin of the connector 30. Connector 30 is a male connector and is configured to be able to accommodate a female connector.

[0023] The inspection system according to this embodiment includes an inspection device 100. The inspection device 100 includes a power supply unit 110, a connection unit 120, and a control device 150. The control device 150 includes a processor and a storage device. In this embodiment, the inspection is performed by the processor executing a program stored in the storage device. However, each process related to the inspection may be performed by hardware (electronic circuits) alone without using software.

[0024] The power supply unit 110 is equipped with multiple test channels (hereinafter referred to as "Ch"). Each Ch is equipped with a DC power supply 41, a switch 42, a voltmeter 43, an ammeter 44, and terminals T1 and T2. The output voltage of the DC power supply 41 is variable. The ammeter 44 is connected in series with the DC power supply 41, and the voltmeter 43 is connected in parallel. The switch 42 switches the circuit between connected and disconnected by its opening and closing operation. The DC power supply 41 and the switch 42 are each controlled by the control device 150. The voltmeter 43 detects the voltage between terminals T1 and T2. The ammeter 44 detects the current flowing through the circuit connected to this Ch.

[0025] The connecting portion 120 functions as a female connector (e.g., Combitac) that can be attached to the connector 30. In S20 of Figure 1, the inspection device 100 connects the connecting portion 120 to the connector 30. The inspection device 100 may include a robot for connecting the connector.

[0026] Each cell in the laminate 10 is connected to the power supply unit 110 of the inspection device 100 by connecting the corresponding terminals (e.g., female terminals) of the connection part 120 to each terminal (e.g., male terminal) of the connector 30. This forms an inspection circuit for each cell. The inspection circuits of adjacent cells C (energy storage cells) have a common wiring section. Each inspection circuit is a circuit that includes cell C, channel (Ch), and common wiring. In any inspection circuit, when switch 42 is closed, the inspection circuit becomes a closed circuit, and when switch 42 is opened, the inspection circuit becomes an open circuit. Hereinafter, the inspection circuits provided for cells C-1, C-2, ..., cell CN-1, and cell CN may be denoted as inspection circuit Dc1, inspection circuit Dc2, ..., inspection circuit DcN-1, and inspection circuit DcN, respectively.

[0027] A total positive terminal T+ is provided at the positive terminal end of the entire laminate 10. A total negative terminal T- is provided at the negative terminal end of the entire laminate 10. Furthermore, wiring (more specifically, wiring connectable to Ch) for termination circuits Dc+ and Dc- is formed inside or outside the laminate 10. When the connection part 120 is connected to the connector 30, the Ch of the power supply unit 110 is connected to the total positive terminal T+, and another Ch of the power supply unit 110 is connected to the total negative terminal T-. This forms a termination circuit Dc+ that does not include a storage cell and a termination circuit Dc- that does not include a storage cell. Termination circuit Dc+ is located next to cell CN on the opposite side of cell CN-1 of cell CN. Termination circuit Dc- is located next to cell C-1 on the opposite side of cell C-2 of cell C-1. Hereafter, the channels (Ch) provided for the total negative terminal T-, cell C-1, cell C-2, ..., cell CN-1, cell CN, and total positive terminal T+ may be denoted as Ch-, Ch1, Ch2, ..., ChN-1, ChN, and Ch+, respectively. Below, the voltage values ​​detected at Ch-, Ch1, Ch2, ..., ChN-1, ChN, and Ch+ (values ​​detected by voltmeter 43) will be denoted as Vx, V1, V2, ..., V N-1 , V N It is sometimes written as Vy.

[0028] In the following S31, the inspection device 100 opens (disconnects) the switches 42 of each channel included in the power supply unit 110, and measures the OCV (Open Circuit Voltage) of each cell included in the laminate 10 in the unpowered state. Below, the OCVs of cells C-1, C-2, ..., CN-1, and CN are referred to as OCV1, OCV2, ..., OCV N-1 OCV N It may be written as shown above. In this embodiment, the process in S31 corresponds to an example of "cell voltage measurement" according to this disclosure.

[0029] After the OCV measurement, the process proceeds to S32. Hereinafter, the process of S32 will be described further with reference to FIG. 4. FIG. 4 is a diagram for explaining the resistance measurement process of each inspection circuit. In FIG. 4, the wiring W1 corresponds to the independent wiring portion of the terminal circuit Dc−, that is, the portion of the terminal circuit Dc− excluding the wiring W2. The wiring W2 corresponds to the common portion (first common wiring portion) between the terminal circuit Dc− and the inspection circuit Dc1 (the wiring of cell C−1). The wiring W3 corresponds to the common wiring portion (second common wiring portion) of cells C−1 and C−2. The wiring W4 corresponds to the common wiring portion (third common wiring portion) of cells C−2 and C−3. The wiring W5 corresponds to the common wiring portion (fourth common wiring portion) of cells C−3 and C−4. The wiring W6 corresponds to the common wiring portion (fifth common wiring portion) of cells C−4 and C−5. The wiring W7 corresponds to the common wiring portion (sixth common wiring portion) of cells C−5 and C−6. The wiring W8 corresponds to the common wiring portion (seventh common wiring portion) of cells C−6 and C−7.

[0030] Although not shown in FIG. 4, the terminal circuit Dc+ also has an independent wiring portion (hereinafter referred to as "wiring WN+3") in a manner similar to the terminal circuit Dc−. The terminal circuit Dc+ and the inspection circuit DcN (the wiring of cell CN) have a common wiring portion (hereinafter referred to as "wiring WN+2"). And cells CN and CN−1 also have a common wiring portion (hereinafter referred to as "wiring WN+1"). In the laminate 10, each pair formed by adjacent cells has a common wiring portion. Hereinafter, the resistance values (electrical resistances) of the wirings W1, W2, ···, WN+1, WN+2, WN+3 are represented as R1, R2, ···, R N+1 , R N+2 , R N+3 respectively. Each of R1 and R N+3 is smaller than the other resistance values (the wiring resistances of the cells). Each of R1 and R N+3 may be 1 / 10 or less of each of R2 to R N+2 , or may be about 0.01 Ω.

[0031] The resistance measurement process according to this embodiment includes the first resistance measurement, the second resistance measurement, and the third resistance measurement described below. The inspection device 100 performs the first to third resistance measurements in S32 of Figure 1. The inspection device 100 may obtain the wiring resistance based on the formula "Wiring resistance = Voltage change of adjacent cells while energized / Current".

[0032] In the first resistance measurement, the inspection device 100 sets the laminate 10 to state A as shown in Figure 4. Specifically, the control device 150 controls the switches 42 of each Ch so that the termination circuit Dc- and the "3 × M"th inspection circuit from the negative terminal end of the laminate 10 become closed circuits, and the other inspection circuits become open circuits. M is an integer between 1 and "N / 3 (N / 3)". Then, for the laminate 10 in state A, the inspection device 100 measures the resistance values ​​(R2, R4, R5, R7, R8, ...) of the wirings W1 to WN+3, excluding the "3 × M"th wiring from the negative terminal end of the laminate 10 and wirings W1, WN+3, as shown below.

[0033] With a predetermined current (hereinafter referred to as "I1") flowing through the termination circuit Dc- including wiring W2, the voltage of the test circuit Dc1 (open circuit including cell C-1 and wiring W2) is measured, and the electrical resistance (R2) of wiring W2 is calculated using the measured voltage (V1) and the open-circuit voltage of cell C-1 (OCV1 measured in S31). The control device 150 may also calculate R2 based on the formula "R2 × I1 = OCV1 - V1".

[0034] With a predetermined current (hereinafter referred to as "I4") flowing through the test circuit Dc3 including wiring W4, the voltage of the test circuit Dc2 (open circuit including cell C-2 and wiring W4) is measured, and the electrical resistance (R4) of wiring W4 is calculated using the measured voltage (V2) and the open-circuit voltage of cell C-2 (OCV2 measured in S31). The control device 150 may also calculate R4 based on the formula "R4 × I4 = OCV2 - V2".

[0035] With the above-mentioned current (I4) flowing through the test circuit Dc3 including wiring W5, the voltage of the test circuit Dc4 (open circuit including cell C-4 and wiring W5) is measured, and the electrical resistance (R5) of wiring W5 is calculated using the measured voltage (V4) and the open-circuit voltage of cell C-4 (OCV4 measured in S31). The control device 150 may also calculate R5 based on the formula "R5 × I4 = OCV4 - V4".

[0036] With a predetermined current (hereinafter referred to as "I7") flowing through the test circuit Dc6 including wiring W7, the voltage of the test circuit Dc5 (open circuit including cell C-5 and wiring W7) is measured, and the electrical resistance (R7) of wiring W7 is calculated using the measured voltage (V5) and the open-circuit voltage of cell C-5 (OCV5 measured in S31). The control device 150 may also calculate R7 based on the formula "R7 × I7 = OCV5 - V5".

[0037] The resistance values ​​of other wiring to be measured (R8 and beyond) can also be obtained in a manner similar to that described above.

[0038] Once the first resistance measurement is complete, the inspection device 100 measures the OCV of each cell again in the same manner as in S31, thereby determining OCV1 to OCV N After updating, the second resistance measurement is performed. In the second resistance measurement, the inspection device 100 sets the laminate 10 to state B as shown in Figure 4. Specifically, the control device 150 controls the switches 42 of each channel so that the termination circuit Dc+ and the "3 × M - 2" test circuit from the negative terminal end of the laminate 10 become closed circuits, and the other test circuits become open circuits. Then, for the laminate 10 in state B, the inspection device 100 measures the resistance values ​​(R3, R6, R9, ...) of the "3 × M" wire from the negative terminal end of the laminate 10 among the wirings W2 to WN+2, as shown below.

[0039] With a predetermined current (hereinafter referred to as "I2") flowing through the test circuit Dc1 including wiring W3, the voltage of the test circuit Dc2 (open circuit including cell C-2 and wiring W3) is measured, and the electrical resistance (R3) of wiring W3 is calculated using the measured voltage (V2) and the open-circuit voltage of cell C-2 (OCV2). The control device 150 may also calculate R3 based on the formula "R3 × I2 = OCV2 - V2".

[0040] With a predetermined current (hereinafter referred to as "I5") flowing through the test circuit Dc4 including wiring W6, the voltage of the test circuit Dc5 (open circuit including cell C-5 and wiring W6) is measured, and the electrical resistance (R6) of wiring W6 is calculated using the measured voltage (V5) and the open-circuit voltage of cell C-5 (OCV5). The control device 150 may also calculate R6 based on the formula "R6 × I5 = OCV5 - V5".

[0041] The resistance values ​​of other wiring to be measured (R9 and beyond) can also be obtained in a manner similar to that described above.

[0042] Furthermore, in state B, the inspection device 100 performs a second measurement of the resistance value (R2, R5, R8, ...) of the 3 × M-1 wire from the negative terminal end of the laminate 10 among the wirings W2 to WN+2, as shown below.

[0043] With the above-mentioned current (I2) flowing through the test circuit Dc1 including wiring W2, the voltage of the termination circuit Dc- including wiring W2 is measured, and R2 is calculated using the measured voltage (Vx) and the potential of the total negative terminal T- (hereinafter referred to as "Vg"). The control device 150 may also calculate R2 based on the formula "R2 × I2 = Vg - Vx". Vg is, for example, 0V. Vx is a negative value.

[0044] With the above-mentioned current (I5) flowing through the test circuit Dc4 including wiring W5, the voltage of the test circuit Dc3 (open circuit including cell C-3 and wiring W5) is measured, and R5 is calculated using the measured voltage (V3) and the open-circuit voltage of cell C-3 (OCV3). The control device 150 may also calculate R5 based on the formula "R5 × I5 = OCV3 - V3".

[0045] The resistance values ​​of other wiring to be measured (R8 and beyond) can also be obtained in a manner similar to that described above.

[0046] Once the second resistance measurement is complete, the inspection device 100 measures the OCV of each cell again in the same manner as in S31, thereby determining OCV1 to OCV N After updating, the third resistance measurement is performed. In the third resistance measurement, the inspection device 100 sets the laminate 10 to state C as shown in Figure 4. Specifically, the control device 150 controls the switches 42 of each Ch so that the 3 × M-1 test circuit from the negative terminal end of the laminate 10 becomes a closed circuit, and the other test circuits and each termination circuit become open circuits. Then, in state C, the inspection device 100 measures the resistance values ​​of the 3 × M wire from the negative terminal end of the laminate 10 (R3, R6, R9, ...) and the resistance values ​​of the 3 × M-2 wire from the negative terminal end of the laminate 10 (R4, R7, R) as shown below. 10 Perform a second measurement on , ...).

[0047] With a predetermined current (hereinafter referred to as "I3") flowing through the test circuit Dc2 including wiring W3, the voltage of the test circuit Dc1 (open circuit including cell C-1 and wiring W3) is measured, and R3 is calculated using the measured voltage (V1) and the open-circuit voltage of cell C-1 (OCV1). The control device 150 may also calculate R3 based on the formula "R3 × I3 = OCV1 - V1".

[0048] With the above-mentioned current (I3) flowing through the test circuit Dc2 including wiring W4, the voltage of the test circuit Dc3 (open circuit including cell C-3 and wiring W4) is measured, and R4 is calculated using the measured voltage (V3) and the open-circuit voltage of cell C-3 (OCV3). The control device 150 may also calculate R4 based on the formula "R4 × I3 = OCV3 - V3".

[0049] With a predetermined current (hereinafter referred to as "I6") flowing through the test circuit Dc5 including wiring W6, the voltage of the test circuit Dc4 (open circuit including cell C-4 and wiring W6) is measured, and R6 is calculated using the measured voltage (V4) and the open-circuit voltage of cell C-4 (OCV4). The control device 150 may also calculate R6 based on the formula "R6 × I6 = OCV4 - V4".

[0050] With the above-mentioned current (I6) flowing through the test circuit Dc5 including wiring W7, the voltage of the test circuit Dc6 (open circuit including cell C-6 and wiring W7) is measured, and R7 is calculated using the measured voltage (V6) and the open-circuit voltage of cell C-6 (OCV6). The control device 150 may also calculate R7 based on the formula "R7 × I6 = OCV6 - V6".

[0051] The resistance values ​​of other wiring to be measured (R9 and beyond) can also be obtained in a manner similar to that described above.

[0052] As a result of the process in S32 above, R2~R N+2 Two measurements are obtained for each of the following. Each of I1 to I7 may be 1A. In the following S41, all resistance values ​​(R2 to R N+2 The control device 150 determines whether the function is normal or not.

[0053] Specifically, the control device 150 controls each resistance value (R2~R) measured in S32. N+2 The system determines whether the difference (measurement error) between the first and second measurement values ​​falls within a predetermined range (hereinafter referred to as the "first range"). The first range is set in advance as the acceptable range for measurement error. If the measurement error exceeds the first range, the system determines NO in S41 and proceeds to S42.

[0054] On the other hand, if the measurement error is within the first range, the control device 150 determines either the first measurement, the second measurement, or the average of these measurements as the final measurement value for each resistance value. Subsequently, the control device 150 calculates all resistance values ​​(R2~R N+2The system determines whether the value is within a predetermined range (hereinafter referred to as the "second range"). The second range is pre-set as the normal range for resistance values.

[0055] If all resistance values ​​are within the second range, the result is determined to be YES in S41, and the process proceeds to S51. On the other hand, if any of the resistance values ​​are outside the second range, the result is determined to be NO in S41, and the process proceeds to S42.

[0056] In S42, the control device 150 determines whether the abnormal resistance value is an abnormality (product defect) caused by the laminate 10 itself. If the measurement error exceeds the first range, it is determined that it is not a product defect (NO in S42), and in the subsequent S43, the control device 150 determines that the abnormal resistance value is an abnormality caused by a measurement error (such as poor contact). R2~R N+2 If any of the final measured values ​​exceed the second range, the determination in S42 is YES, and the control device 150 determines in the subsequent S44 that the laminate 10 is defective. The control device 150 may report and / or record the determination result. This completes the inspection of the laminate 10.

[0057] In S51, the inspection system uses the resistance values ​​(R2~R) measured in S32. N+2 The system performs individual charging of each cell in the laminate 10 using at least one of the following: The inspection system may perform individual charging using an inspection circuit (including Ch) formed for each cell. The inspection system sets the voltage for individual charging using the measured resistance value. The inspection system performs individual charging of each cell, for example, by adding the resistance overvoltage of the common wiring.

[0058] In the following step S52, the inspection system performs high-temperature aging of the laminate 10. The inspection system maintains the temperature of the laminate 10 at a predetermined aging temperature until a predetermined aging time has elapsed. High-temperature aging is aging at a temperature higher than room temperature. The aging temperature may be between 50°C and 85°C. The aging time can be set arbitrarily. The aging time may be between 5 hours and 20 hours. After the aging time has elapsed, the inspection system may cool the laminate 10 to room temperature and perform a self-discharge test of the laminate 10.

[0059] As described above, the method for manufacturing the energy storage device according to this embodiment includes the processes shown in Figure 1. This method includes a wiring formation process (see Figures 2 and 3) in which adjacent energy storage cells in the energy storage device are connected to a common wiring (for example, a current collector 11 and a voltage detection terminal 20), and a resistance measurement process (S31, S32) in which the electrical resistance of at least a portion of the formed wiring is measured. In S32, for the common wiring portion of adjacent first and second energy storage cells in the energy storage device, the voltage of the open circuit including the second energy storage cell and the common wiring portion is measured while current is flowing through the closed circuit including the first energy storage cell and the common wiring portion, and the electrical resistance of the common wiring portion is obtained using the measured voltage.

[0060] In the open circuit described above, charging and discharging of the second energy storage cell does not occur, so the amount of energy stored in the second energy storage cell (and consequently, the cell voltage) remains stable. According to the above method, by using the voltage of such an open circuit to determine the electrical resistance, the electrical resistance of the common wiring portion of adjacent first and second energy storage cells can be obtained with high accuracy. In this embodiment, cells C-1, C-2, C-3, C-4, C-5, and C-6 correspond to the first, second, third, fourth, fifth, and sixth energy storage cells, respectively.

[0061] A laminate 10 that is judged to be a good product by the above inspection can function as an energy storage device (bipolar secondary battery) on its own. However, a multi-module energy storage device may be manufactured by combining multiple modules, with the laminate 10 being treated as a single module. The manufactured energy storage device may be mounted on a mobile device. Examples of mobile devices include automobiles (electric vehicles, hybrid vehicles, etc.), vehicles other than automobiles, and mobile machinery (agricultural machinery, construction machinery, etc.). However, the application of the energy storage device is arbitrary, and a stationary battery may also be manufactured by the above method.

[0062] The processing flow shown in Figure 1 can be modified as needed. For example, the order of processing may be changed, or the content of any of the processing steps may be changed, depending on the purpose.

[0063] In the above embodiment, at S32 in Figure 1, the first resistance measurement, second resistance measurement, and third resistance measurement are performed in states A, B, and C, respectively, as shown in Figure 4. However, the process is not limited to this, and the first resistance measurement, second resistance measurement, and third resistance measurement may also be performed in states D, E, and F, respectively, as shown in Figure 5. Figure 5 shows a modified example of the resistance measurement process.

[0064] In the first resistance measurement according to the modified example, the inspection device 100 sets the laminate 10 to state D as shown in Figure 5. Specifically, the control device 150 controls the switches 42 of each Ch so that the termination circuit Dc+ and the "3 × M"th inspection circuit from the positive terminal end of the laminate 10 become closed circuits, and the other inspection circuits become open circuits. M is an integer between 1 and "N / 3 (N / 3)". Then, in state D, the inspection device 100 sets, for example, the equation "R N+2 ×I N+2 =OCV N -V N Based on R N+2 Obtain the expression "R N ×I N-1 =OCV N-1 -V N-1 Based on R N Obtain the expression "R N-1 ×I N-1 =OCV N-3 -V N-3 Based on RN-1 Obtain the expression "R N-3 ×I N-4 =OCV N-4 -V N-4 Based on R N-3 Obtain I N+2 , I N-1 , I N-4 These represent the currents flowing through the termination circuit Dc+, the test circuit DcN-2, and the test circuit DcN-5, respectively.

[0065] After the first resistance measurement is completed, the inspection device 100 will measure OCV1 to OCV N After updating, the second resistance measurement is performed in state E. Specifically, the control device 150 controls the switches 42 of each Ch so that the termination circuit Dc- and the "3 × M-2"th test circuit from the positive terminal end of the laminate 10 become closed circuits, and the other test circuits become open circuits. Then, in state E, the test device 100 performs, for example, the equation "R N+1 ×I N+1 =OCV N-1 -V N-1 Based on R N+1 Obtain the expression "R N-2 ×I N-2 =OCV N-4 -V N-4 Based on R N-2 To obtain. Furthermore, the inspection device 100 uses the formula "R N+2 ×I N+1 Based on "=Vp-Vy", R N+2 Obtain the expression "R N-1 ×I N-2 =OCV N-2 -V N-2 Based on R N-1 Obtain the following. Note that Vp is the potential of the total positive terminal T+. Vy is a positive value. Also, I N+1 , I N-2 These values ​​represent the currents flowing through test circuit DcN and test circuit DcN-3, respectively.

[0066] Once the second resistance measurement is complete, the inspection device 100 will check OCV1~OCV NAfter updating, the third resistance measurement is performed in state F. Specifically, the control device 150 controls the switches 42 of each Ch so that the "3 × M-1"th test circuit from the positive terminal end of the laminate 10 becomes a closed circuit, and the other test circuits and each termination circuit become open circuits. Then, in state F, the test device 100 performs the equation "R N+1 ×I N =OCV N -V N Based on R N+1 Obtain the expression "R N ×I N =OCV N-2 -V N-2 Based on R N Obtain the expression "R N-2 ×I N-3 =OCV N-3 -V N-3 Based on R N-2 Obtain the expression "R N-3 ×I N-3 =OCV N-5 -V N-5 Based on R N-3 Obtain I N , I N-3 These indicate the currents flowing through test circuit DcN-1 and test circuit DcN-4, respectively.

[0067] The modified method described above also makes it possible to measure the electrical resistance of the wiring connected to the energy storage cells in an energy storage device with high accuracy. Furthermore, obtaining two measurements for the same resistance value can improve the reliability of the measurement. However, it is not essential to perform multiple resistance measurements on the same wiring. For example, the third resistance measurement can be omitted. Even with only the first and second resistance measurements, the resistance values ​​of each common wiring section (R2~R) can be determined. N+2 ) can be obtained.

[0068] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0069] 1 Bipolar electrode, 10 Laminate, 11 Current collector, 20 Voltage detection terminal, 41 DC power supply, 42 Switch, 43 Voltmeter, 44 Ammeter, 100 Inspection device, 150 Control device, C Cell, W1~WN+3 Wiring.

Claims

1. A method for manufacturing an energy storage device including multiple energy storage cells, The aforementioned method, A wiring formation process for forming the wiring of the energy storage device such that adjacent energy storage cells are connected to a common wiring, A resistance measurement process for measuring the electrical resistance of at least a portion of the formed wiring, Includes, A method for manufacturing an energy storage device, wherein, in the resistance measurement process, for the common wiring portion of adjacent first and second energy storage cells in the energy storage device, the voltage of the open circuit including the second energy storage cell and the common wiring portion is measured while current is flowing through the closed circuit including the first energy storage cell and the common wiring portion, and the electrical resistance of the common wiring portion is obtained using the measured voltage.

2. The energy storage device further includes, in addition to the first energy storage cell and the second energy storage cell, a third energy storage cell located next to the second energy storage cell and a fourth energy storage cell located next to the third energy storage cell. The method for manufacturing an energy storage device according to claim 1, wherein in the resistance measurement process, with respect to the common wiring portion of the third energy storage cell and the fourth energy storage cell, the voltage of the open circuit including the third energy storage cell and the common wiring portion is measured while current is flowing through the closed circuit including the fourth energy storage cell and the common wiring portion, and the electrical resistance of the common wiring portion is obtained using the measured voltage.

3. In the wiring formation process, wiring for a termination circuit that does not include a storage cell is formed next to the first storage cell on the side opposite to the second storage cell. The termination circuit is located at either the positive terminal end of the entire energy storage device or the negative terminal end of the entire energy storage device. The method for manufacturing an energy storage device according to claim 2, wherein, in the resistance measurement process, the voltage of the open circuit including the first energy storage cell and the common portion between the termination circuit and the wiring of the first energy storage cell is measured while current is flowing through the closed termination circuit, and the electrical resistance of the common portion is obtained using the measured voltage.

4. The energy storage device further includes a fifth energy storage cell located next to the fourth energy storage cell, and a sixth energy storage cell located next to the fifth energy storage cell. The aforementioned resistance measurement process includes cell voltage measurement, first resistance measurement, and second resistance measurement. In the cell voltage measurement, the open-circuit voltage of each of the first, second, third, fourth, fifth, and sixth energy storage cells is measured in the energy storage device while it is not energized. In the first resistance measurement, With a predetermined current flowing through the first common wiring portion, which is the common part between the termination circuit and the wiring of the first energy storage cell, the voltage of the open circuit including the first energy storage cell and the first common wiring portion is measured, and the electrical resistance of the first common wiring portion is calculated using the measured voltage and the open-circuit voltage of the first energy storage cell, and, With a predetermined current flowing through the third common wiring portion, which is the common wiring portion of the second and third energy storage cells, the voltage of the open circuit including the second and third energy storage cells is measured, and the electrical resistance of the third common wiring portion is calculated using the measured voltage and the open-circuit voltage of the second energy storage cell, and, With a predetermined current flowing through the fourth common wiring portion, which is the common wiring portion of the third and fourth energy storage cells, the voltage of the open circuit including the fourth energy storage cell and the fourth common wiring portion is measured, and the electrical resistance of the fourth common wiring portion is calculated using the measured voltage and the open-circuit voltage of the fourth energy storage cell, and, With a predetermined current flowing through the sixth common wiring portion, which is the common wiring portion of the fifth and sixth energy storage cells, the voltage of the open circuit including the fifth and sixth energy storage cells is measured, and the electrical resistance of the sixth common wiring portion is calculated using the measured voltage and the open-circuit voltage of the fifth energy storage cell. In the second resistance measurement described above, With a predetermined current flowing through the second common wiring portion, which is the common wiring portion of the first and second energy storage cells, the voltage of the open circuit including the second energy storage cell and the second common wiring portion is measured, and the electrical resistance of the second common wiring portion is calculated using the measured voltage and the open-circuit voltage of the second energy storage cell, and, A method for manufacturing an energy storage device according to claim 3, comprising: applying a predetermined current to the fifth common wiring portion, which is a common wiring portion of the fourth energy storage cell and the fifth energy storage cell; measuring the voltage of an open circuit including the fifth energy storage cell and the fifth common wiring portion; and calculating the electrical resistance of the fifth common wiring portion using the measured voltage and the open-circuit voltage of the fifth energy storage cell.

5. The aforementioned energy storage device is a bipolar secondary battery, A method for manufacturing an energy storage device according to any one of claims 1 to 4, wherein the plurality of energy storage cells in the bipolar secondary battery are electrically connected in series.

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