Manufacturing method of battery module

Abstract

To provide a manufacturing method of a battery module, capable of easily determining a failure such as a disconnection of a voltage detection terminal and enhancing detection accuracy in manufacturing of the battery module.SOLUTION: There is provided a manufacturing method of a battery module, to which a plurality of single batteries are serially connected, where a voltage measurement device has a voltage detection part connected via an internal resistance to each single battery. The method includes: a first step of measuring each voltage of the plurality of single batteries by the voltage measurement device; and a second step of determining the presence / absence of a disconnection of the voltage detection part on each voltage thus obtained from a degree of a deviation level of the plurality of voltages measured in the first step. In the two voltage detection parts corresponding to the adjacent single batteries, one internal resistance is larger than the other internal resistance in a resistance value by a predetermined value.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present application relates to a method for manufacturing a battery module, which is a stacked type battery. [Background technology]

[0002] Patent Document 1 discloses a voltmeter that measures the voltage of each unit cell in a battery pack (battery module) in which a plurality of battery cells (unit cells) are connected in series. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-080182 Summary of the Invention [Problem to be solved by the invention]

[0004] In such conventional technology, when an attempt is made to simultaneously measure the voltages of a plurality of unit cells using a voltage measuring device, there is a problem in that the accuracy of detecting a disconnection occurring in a voltage detection terminal is poor.

[0005] In view of the above-mentioned circumstances, the present disclosure aims to provide a manufacturing method for a battery module that can easily determine defects such as broken voltage detection terminals and improve detection accuracy in the manufacture of the battery module. [Means for solving the problem]

[0006] A stacked secondary battery (battery module) is a stack of multiple unit cells connected in series, and has voltage detection terminals on its side that are arranged to extend from each unit cell and measure the voltage of each unit cell. Therefore, in the battery module, multiple voltage detection terminals are arranged at predetermined intervals so as to protrude from the side surface.

[0007] Here, the voltage detection terminals are very thin and easily bent, which can lead to breakage, and this needs to be detected appropriately. However, with conventional measuring instruments (voltage measuring instruments), it was sometimes difficult to determine whether the breakage was due to a break or variations in the voltage of the single cells. In response to this, the inventor got the idea that this was due to the fact that the internal resistance of conventional voltage measuring instruments was uniform, and he came up with the idea of ​​solving the problem by intentionally making the resistance value of the internal resistance of the voltage measuring instrument different, and controlling the voltage difference between the single cells due to voltage division to be large when a break occurs, such as when the voltage detection terminal breaks, thereby improving detection accuracy and completing the present invention.

[0008] The present application discloses a method for manufacturing a battery module in which a plurality of single cells are connected in series, the method comprising: a first step in which a voltage measuring device has a voltage detection unit connected to each of the single cells via an internal resistance, and measures the voltage of each of the plurality of single cells using the voltage measuring device; and a second step in which the presence or absence of a break in the voltage detection unit is determined based on the degree of deviation of each of the obtained voltages from the plurality of voltages measured in the first step, wherein the internal resistance of one of the two voltage detection units corresponding to adjacent single cells is greater by a predetermined value than the internal resistance of the other.

[0009] The predetermined value may be 1% or more, the predetermined value may be 10% or more, or may be a value greater than the standard deviation of a plurality of internal resistances. Effect of the Invention

[0010] In a voltage measuring device equipped with multiple voltage detection units, the internal resistance of one of the adjacent voltage detection units is greater than the internal resistance of the other by a predetermined value.When a malfunction such as a broken voltage detection terminal occurs, the voltage of the single cell is measured by voltage division due to the resistance difference, making it easier to identify the malfunction and improving detection accuracy. [Brief description of the drawings]

[0011] [Figure 1]FIG. 1 is a diagram illustrating the configuration of a voltage detection terminal 12 provided on a side surface 11 of a battery module 10. As shown in FIG. [Diagram 2] FIG. 2 is a diagram showing a schematic diagram of the connection between the battery module 10 and the voltage measuring device 20, and the configuration of the voltage measuring device 20. As shown in FIG. [Diagram 3] FIG. 3 is a diagram for explaining a situation where one of the voltage detection terminals 12 is disconnected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1. Battery module First, a battery module 10 having a voltage detection terminal 12 that is the subject of voltage measurement will be described. The battery module 10 can be constructed as known in the art, but for example, in this embodiment, the battery module 10 is a so-called bipolar secondary battery in which a plurality of unit cells, each having a positive electrode on the front surface of a current collector and a negative electrode on the back surface, are stacked with an electrolyte layer (separator and electrolyte solution, or solid electrolyte) interposed between them. The battery module 10 is therefore in the form of a flat plate that is thicker than the unit cells, and has side surfaces 11 that form the front and back surfaces and the outer peripheral end surface as a whole. Figure 1 shows a portion of the side surface 11 where a voltage detection terminal 12 is provided. The voltage detection terminal 12 is a terminal to which a voltage measuring instrument (described later) is connected in order to obtain the voltage value of each cell, and is provided for each cell, with one end (the base side) disposed inside the cell and electrically connected to the current collector of the cell, and the other end (the tip side) protruding outward.

[0013] The present disclosure is particularly useful for bipolar secondary batteries in which a plurality of unit cells are stacked in a state of being connected in series and charged, but is not limited thereto, and can also be used and effective in cases where a battery module including a battery group in which unit cells are connected in series with a bus bar is charged collectively rather than individually.

[0014] 2. Voltage measuring instrument The voltage measuring device 20 is connected to each of the voltage detection terminals 12 of the battery module 10 and measures the voltage of each cell. FIG. 2 shows a schematic diagram of the connection between the battery module 10 and the voltage measuring device 20, and the configuration of the voltage measuring device 20. The voltage measuring device 20 is equipped with a plurality of voltage detection units 21 that are connected to the voltage detection terminals 12 of the battery module 10, and detects the voltage (V 1 , V 2 , V 3 , V 4 , ...) are measured. The voltages may be acquired by individual voltmeters, but can also be acquired by switching them in sequence using a multiplexer.

[0015] In addition, in the voltage measuring device 20, an internal resistor 22 is arranged for each voltage detection unit 21 so as to be connected in parallel to the unit cell. In the present disclosure, the internal resistors 22 (22a, 22b) provided in the two voltage detection units 21 corresponding to adjacent unit cells are configured so as to have different resistance values ​​(resistance value R 1 and resistance value R 2 As a result, any defect such as a disconnection in the voltage detection terminal 12 is clearly indicated as a voltage difference, and any defect such as a disconnection in the voltage detection terminal 12 can be easily determined, thereby improving the detection accuracy. Specifically, as shown in FIG. 3, when one voltage detection terminal 12 (12a) is disconnected from the same viewpoint as in FIG. 2, V 1 and V 2 is the sum of the voltages of the two stacked cells (cell (1) and cell (2)) that sandwich the disconnected voltage detection terminal 12a. 1 and R 2 The measured value is divided by this R 1 and R 2 If the resistance values ​​are the same, or if they are different but within the range of variation, the difference in resistance values ​​is small, V 1 and V 2 There is no significant difference in V 1 and V 2 And, and, V 3 , V 4 In contrast, the difference is not large for R 1 and R2 If a certain difference in resistance between the two cells is given, the R 1 and R 2 V 1 and V 2 In other words, it is possible to recognize a disconnection as a clear voltage difference, and it is possible to easily determine a problem due to a disconnection in the voltage detection terminal, etc., and to improve the detection accuracy.

[0016] R 1 and R 2 The specific resistance difference between R and R should be such that the voltage difference is clearly visible when the wire is broken, as described above. 1 >R 2 Then, R 1 R 2 It is preferable that the resistance value is 1% or more higher than the resistance value of the resistor, and more preferably 10% or more. This makes it possible to more clearly detect the difference in voltage when a malfunction such as a disconnection occurs, and to more reliably (accurately) detect the occurrence of the malfunction.

[0017] In addition, taking into account the variation in internal resistance, it is desirable that the voltage obtained by the divided voltage at the time of disconnection (when a malfunction occurs) is sufficiently large relative to the standard deviation (for example, 4σ) of the voltage variation of each cell. From this perspective, R 1 and R 2 The difference between the two can be obtained as follows. R in Figure 3 1 , R 2 Using (R 1 >R 2 ), V at the time of disconnection 1 The value of V 1j , V 2 The value of V 2j , V ave is the average voltage of all the cells when there is no break, R d The difference in internal resistance (R 1 -R 2 ), R is set so as to satisfy the following equations (1) to (4). d can be decided.

[0018]

number

[0019] This allows R 1 and R 2 The voltage change due to the difference in the resistance values ​​can be set to a value larger than the standard deviation, which is the variation in voltage between the individual cells.

[0020] 3. Battery module manufacturing method The components of the battery module can be assembled in a known manner. Meanwhile, in the step (first step) of measuring the voltage of each cell when charging the assembled battery module, the voltage of each cell is measured by the voltage measuring device 20 as described above. At this time, in the voltage measuring device 20, by providing a difference in the resistance value of the internal resistance in the voltage detection section 21 as described above, disconnection, poor contact, and other defects are detected for each cell (second process). More specifically, as described above, for the internal resistance 22 of the voltage measuring device 20, the resistance value (R 1 , R 2 ) is changed, a clear difference in the voltage value appears when a malfunction occurs. Therefore, in the second process, it is sufficient to determine that an abnormality has occurred when this difference occurs.

[0021] Alternatively, as in the above formulas (1) to (4), the average voltage and standard deviation of the cells at a certain voltage can be calculated, and if the difference between the voltage of each cell and the average voltage exceeds 4σ, it can be determined that an abnormality has occurred.

[0022] 4. Effects etc. As described above, the resistance values ​​of the internal resistance of the voltage measuring device are intentionally made different so that the voltage difference between the cells due to voltage division by adjacent internal resistances becomes large when there is a malfunction such as a disconnection caused by bending the voltage detection terminal 12, and the malfunction is detected by the voltage value. As a result, the voltage when abnormal is significantly different from the voltage when normal, it is easy to determine the malfunction and the detection accuracy can be improved. [Explanation of symbols]

[0023] 10: battery module, 11: side surface, 12: voltage detection terminal, 20: voltage measuring device, 21: voltage detection section, 22: internal resistance

Claims

1. A method for manufacturing a battery module in which a plurality of unit cells are connected in series, comprising the steps of: a voltage measuring device having a voltage detection unit connected to each of the single cells via an internal resistance; a first step of measuring the voltage of each of the plurality of single cells by the voltage measuring device; a second step of determining whether or not a disconnection has occurred in the voltage detection unit based on a degree of deviation between each of the obtained voltages and the plurality of voltages measured in the first step; In the two voltage detection units corresponding to the adjacent cells, the internal resistance of one of the voltage detection units is greater than the internal resistance of the other voltage detection unit by a predetermined value. A method for manufacturing a battery module.

2. The method for manufacturing a battery module according to claim 1 , wherein the predetermined value is 1% or more.

3. The method for manufacturing a battery module according to claim 1 , wherein the predetermined value is 10% or more.

4. The method for manufacturing a battery module according to claim 1 , wherein the predetermined value is greater than a standard deviation of a plurality of the internal resistances.

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