Method for determining pre-tightening force for battery module and method for manufacturing battery module

Abstract

A method for determining a pre-tightening force for a battery module and a method for manufacturing a battery module. The method for determining a pre-tightening force for a battery module includes the following steps: S1, mounting binding straps (2) on a battery module (1); S2, measuring the length of the battery module (1) as a first length after the binding straps (2) are mounted; and S3, removing the binding straps (2), squeezing the battery module (1) until the length of the battery module (1) is equal to the first length, and using the current squeezing force as a pre-tightening force.

Description

Method for determining pre-tightening force of battery module and method for manufacturing battery module

[0001] The present application claims priority to the Chinese patent application No. 202410740030.X, filed on June 7, 2024, to the Chinese Patent Office, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery module, in particular to a method for determining pre-tightening force of battery module and a method for manufacturing battery module. BACKGROUND

[0003] In order to achieve the target energy and voltage requirements, the battery module is generally stacked by multiple battery cells, and a buffer pad is arranged between adjacent two battery cells, and an end plate is arranged outside the outermost battery cell. In order to ensure the integrity and stiffness of the battery module, a binding belt is arranged around the battery module. The installation method is that, after the battery cells, the buffer pad and the end plate in the battery module are stacked, an extrusion tool is used to extrude the battery module along the arrangement direction of the battery cells, so that the length of the battery module is shortened, and then the binding belt is sleeved. Subsequently, the extrusion tool is loosened, the battery module rebounds along the length direction of the battery module, and the binding belt is stretched, so that the pre-tightening force of the binding belt along the length direction of the battery module is generated.

[0004] The size of the pre-tightening force generated by the binding belt directly affects the integrity and stiffness of the battery module, so the judgment of the size of the pre-tightening force of the binding belt is one of the key points of the design of the battery module. The related technology often directly takes the maximum extrusion force of the extrusion tool extruding the battery module as the pre-tightening force of the binding belt. However, according to the generation principle of the pre-tightening force of the binding belt, the pre-tightening force and the extrusion force cannot be directly equivalent, and directly equating the extrusion force and the pre-tightening force will lead to inaccurate judgment of the pre-tightening force, and further lead to inaccurate judgment of the tightness of the battery module, and the integrity and stiffness of the battery module cannot be guaranteed. TECHNICAL PROBLEM

[0005] Directly taking the extrusion force of the battery module as the pre-tightening force leads to inaccurate pre-tightening force value and cannot guarantee the integrity and stiffness of the battery module. SOLUTION

[0006] The present application provides a method for determining pre-tightening force of battery module and a method for manufacturing battery module.

[0007] In a first aspect, the present application provides a method for determining pre-tightening force of battery module, comprising the following steps:

[0008] S1, installing the binding belt on the battery module;

[0009] S2, measuring the length of the battery module after installing the binding belt as a first length;

[0010] S3, remove the bundling tape, extrude the battery module until the length of the battery module is equal to the first length, and the extrusion force at this time is the pre-tightening force.

[0011] In a second aspect, the application provides a battery module manufacturing method, comprising the following steps:

[0012] Step A, measuring the pre-tightening force generated by the bundling tape according to the battery module pre-tightening force determination method in the application;

[0013] Step B, determining whether the pre-tightening force is in the design interval, if yes, using the bundling tape to bundle the battery module, and completing the manufacturing of the battery module; if not, adjusting the size of the buffer pad or adjusting the size of the bundling tape, and repeating steps A to B. Advantageous effects

[0014] The battery module pre-tightening force determination method provided by the application can more accurately estimate the pre-tightening force provided by the bundling tape by increasing the first length determined by the size of the pre-tightening force as a judgment basis, and selecting the extrusion force when the length of the battery module is equal to the first length as the pre-tightening force, so as to more accurately judge the tightness of the battery module and ensure the integrity and rigidity of the battery module;

[0015] The battery module manufacturing method provided by the application first obtains an accurate pre-tightening force value through the battery module pre-tightening force determination method in the application, and then further judges the value of the pre-tightening force, so as to ensure that the pre-tightening force of the bundling tape is in the design interval, thereby avoiding the situation that the rigidity of the battery module is insufficient due to the too small pre-tightening force of the bundling tape, or the situation that the battery module is damaged due to the too large pre-tightening force of the bundling tape. BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a flowchart of a battery module pre-tightening force determination method provided in some embodiments of the application;

[0017] FIG. 2 is a schematic diagram of an extrusion method of a battery module in a battery module pre-tightening force determination method provided in some embodiments of the application;

[0018] FIG. 3 is a schematic diagram of the use of a limiting piece in a battery module pre-tightening force determination method provided in some embodiments of the application;

[0019] FIG. 4 is a flowchart of a battery module manufacturing method provided in some embodiments of the application;

[0020] FIG. 4 is a flowchart of a battery module manufacturing method provided in some embodiments of the application; EMBODIMENTS

[0021] As shown in FIG. 1, a method for determining the pre-tightening force of a battery module includes the following steps:

[0022] S1, installing a bundling tape 2 on a battery module 1;

[0023] S2, measuring the length of the battery module 1 after the installation of the bundling tape 2 as a first length;

[0024] S3, removing the bundling tape 2 and pressing the battery module 1 until the length of the battery module 1 is equal to the first length, and the pressing force at this time is the pre-tightening force.

[0025] The length of the battery module 1 refers to the dimension of the battery module 1 along the direction of the arrangement of the battery cells.

[0026] In step S3, the specific way of pressing the battery module 1 includes but is not limited to: starting from a small initial pressing force and gradually increasing the pressing force until the length of the battery module 1 is equal to the first length; starting from a large initial pressing force and gradually decreasing the pressing force until the length of the battery module 1 is equal to the first length.

[0027] In this embodiment, the battery module 1 is first pressed and the bundling tape 2 is installed, then the battery module 1 is loosened, the length of the battery module 1 in the state of installing the bundling tape 2 is measured, at this time the length of the battery module 1 is negatively correlated with the size of the pre-tightening force; then the bundling tape 2 is removed and the battery module 1 is pressed again, at this time the length of the battery module 1 is also negatively correlated with the size of the pressing force, therefore, if the battery module 1 is pressed until its length is equal to the first length, it can be considered that the pressing force at this time is equal to the pre-tightening force that the bundling tape 2 can provide.

[0028] Compared with the related art in which the maximum pressing force during the process of directly pressing the battery module with a pressing tool is taken as the pre-tightening force of the bundling tape, this embodiment adds the first length determined by the size of the pre-tightening force as a judgment basis, and selects the pressing force when the length of the battery module 1 is equal to the first length as the pre-tightening force, which can more accurately estimate the size of the pre-tightening force that the bundling tape 2 can provide, so as to more accurately judge the tightness of the battery module 1 and protect the integrity and rigidity of the battery module 1.

[0029] In an embodiment, the specific method of step S1 is to press the battery module 1 to a length smaller than the dimension of the bundling tape 2 along the length direction of the battery module 1, and then put the bundling tape 2 into the battery module 1, so as to avoid the bundling tape 2 and the battery module 1 scratching each other during the installation process, or the bundling tape 2 being too difficult to install.

[0030] It should be noted that if the battery module 1 is pressed in step S1 for the convenience of installing the bundling tape 2, the battery module 1 needs to be loosened in step S2 to avoid the situation that the pressing force and the pre-tightening force of the bundling tape 2 act simultaneously, resulting in that the first length cannot accurately match the size of the pre-tightening force.

[0031] In one embodiment, in steps S1 and S3, the battery module 1 is pressed by applying a pressing force to the end plates of the battery module 1, as shown in FIGS. 2 and 3. F in the figures represents the pressing force. Specifically, in steps S1, S3, and subsequently described steps S31, S32, and S322, the battery module 1 is pressed from both sides of the end plates of the battery module 1. A pressing tool can be used during pressing. In this embodiment, the battery module 1 is pressed by the end plates, which can avoid damage to the battery module 1 during pressing.

[0032] In one embodiment, the binding belt 2 comprises a steel belt. In this embodiment, the binding belt 2 comprises a steel belt, which is beneficial for providing the battery module 1 with a required pre-tightening force by using the strength of steel.

[0033] In one embodiment, step S3 comprises:

[0034] S31, pressing the battery module 1 until the length of the battery module 1 is less than the first length, and then removing the binding belt 2;

[0035] S32, reducing the pressing force until the length of the battery module 1 returns to the first length, and the pressing force at this time is the pre-tightening force.

[0036] In step S32, the specific way of reducing the pressing force includes but is not limited to continuous reduction and stepwise reduction.

[0037] In this embodiment, in step S3, the battery module 1 is pressed again to reduce its length, and then the pressing force is reduced to return the battery module 1 to the first length, which can facilitate the removal of the binding belt 2 and prevent the binding belt 2 and the battery module 1 from being too tightly matched, which can cause the binding belt 2 to be unable to be removed or the binding belt 2 and the battery module 1 to be scratched.

[0038] In one embodiment, in step S32, the pressing force decreases linearly with time. For example, the pressing force decreases by 10 N per second, or the pressing force decreases by 20 N per second. Specifically, according to the actual engineering experience of the applicant, the specific value range of the reduction rate of the pressing force is obtained, that is, the rate of the linear decrease of the pressing force with time in this embodiment is less than or equal to 40 N / S.

[0039] The embodiment gradually releases the battery module 1 in a manner that the extrusion force linearly decreases over time until the battery module 1 returns to the first length. On the one hand, this can avoid sudden changes in the extrusion force, causing stress mutations in the battery module 1, and thus inaccurate pre-tightening force readings of the battery module 1, or even damage to the battery module 1. On the other hand, the continuous linear change of the extrusion force in the embodiment can also facilitate the control of the length of the battery module 1, so that the length of the battery module 1 returns to the first length as accurately as possible, and thus more accurate pre-tightening force values are obtained.

[0040] In an embodiment, step S32 comprises:

[0041] S321, a limiting piece 3 is arranged on the battery module 1. The limiting piece 3 is arranged along the length direction of the battery module 1. The limiting piece 3 is provided with a first limiting part 31 and a second limiting part 32 at two ends thereof. The distance between the first limiting part 31 and the second limiting part 32 is equal to the first length.

[0042] S322, the extrusion force is reduced until the two ends of the battery module 1 along the length direction thereof abut against the first limiting part 31 and the second limiting part 32, respectively. The extrusion force at this time is the pre-tightening force.

[0043] The specific arrangement mode of the limiting piece 3 includes but is not limited to being directly connected to the battery module 1, being placed on the battery module 1, or being held by an operator. The specific structure of the first limiting part 31 and the second limiting part 32 includes but is not limited to a limiting block, a limiting column, and a limiting plate.

[0044] The embodiment arranges the limiting piece 3 on the battery module 1. When the two ends of the battery module 1 do not abut against the first limiting part 31 and the second limiting part 32, or only one side can abut against the first limiting part 31 or the second limiting part 32, it indicates that the current length of the battery module 1 is less than the first length. When the two ends of the battery module 1 abut against the first limiting part 31 and the second limiting part 32, respectively, it indicates that the length of the battery module 1 returns to the first length. It can be seen that the embodiment can directly show whether the battery module 1 returns to the first length, without the need for the operator to repeatedly measure the length of the battery module 1, thereby improving the measurement efficiency of the pre-tightening force.

[0045] The use mode of the limiting piece 3 is shown in FIG. 3. X in the figure represents the first length. More specifically, the embodiment selects a caliper as the limiting piece 3. The distance between the first limiting part 31 and the second limiting part 32 can be quantitatively adjusted by the scale and the adjustment function of the caliper itself, so as to adapt to different sizes of the first length. Moreover, the caliper can be directly purchased as related technology. When not in use, it can also be used for other tests. Embodiment

[0046] As shown in FIG. 4, a battery module manufacturing method comprises the following steps:

[0047] Step A, measure the pre-tightening force generated by the bundling belt 2 according to the method for determining the pre-tightening force of the battery module in Example 1;

[0048] Step B, determine whether the pre-tightening force is within the design interval, if yes, use the bundling belt 2 to bundle the battery module, and complete the production of the battery module; if not, adjust the size of the buffer pad or adjust the size of the bundling belt 2, and repeat steps A to B.

[0049] The specific value range of the design interval can be obtained by actual engineering experience, theoretical analysis, simulation calculation, etc., so as to avoid both insufficient rigidity of the battery module 1 caused by too small pre-tightening force and damage of the battery module 1 caused by too large pre-tightening force.

[0050] After obtaining the accurate pre-tightening force value through the method for determining the pre-tightening force of the battery module, the embodiment further determines the size of the pre-tightening force; if the pre-tightening force is within the design interval, the pre-tightening force of the bundling belt 2 of this type meets the design requirements, and the bundling belt 2 of this type can be used for bundling the battery module 1, and subsequent work of the battery module 1 is carried out until the battery module 1 is completed; if not, the pre-tightening force can be adjusted by adjusting the size of the buffer pad or the bundling belt; among them, the method of adjusting the buffer pad is suitable for temporary adjustment on site or occasions where the pre-tightening force deviates from the design interval not much; the method of adjusting the bundling belt is suitable for long-term adjustment of the design party or occasions where the pre-tightening force deviates from the design interval too much.

[0051] In one embodiment, in step S1, the extrusion force for extruding the battery module 1 is greater than the upper limit of the design interval and less than the cell stacking expansion force.

[0052] According to the actual test data of the applicant, the pre-tightening force that can be provided by the bundling belt 2 is actually less than the extrusion force for extruding the battery module 1 in step S1; therefore, the embodiment gives the value range of the extrusion force in step S1, which can not only ensure that the battery module 1 can generate a pre-tightening force meeting the design interval requirement after the bundling belt 2 is installed, but also avoid damage of the battery module 1 during the extrusion process.

[0053] In one embodiment, the embodiment gives the specific adjustment method of the bundling belt 2 when the pre-tightening force does not meet the design interval requirement. If the pre-tightening force is greater than the upper limit of the design interval, increase the size of the bundling belt 2 along the length direction of the battery module 1; if the pre-tightening force is less than the lower limit of the design interval, reduce the size of the bundling belt 2 along the length direction of the battery module 1.

Claims

1. A method for determining the pre-tightening force of a battery module, comprising the following steps: S1, installing a binding belt (2) on a battery module (1); S2, measuring the length of the battery module (1) after the installation of the binding belt (2) as a first length; S3, removing the binding belt (2) and pressing the battery module (1) until the length of the battery module (1) is equal to the first length, and the pressing force at this time is the pre-tightening force.

2. The method of claim 1, wherein, Step S3 comprises: S31, pressing the battery module (1) until the length of the battery module (1) is less than the first length, and removing the binding belt (2); S32, reducing the pressing force until the length of the battery module (1) returns to the first length, and the pressing force at this time is the pre-tightening force.

3. The method of claim 2, wherein, In step S32, the pressing force decreases linearly over time.

4. The method of claim 3, wherein, The rate of linear decrease of the pressing force over time is less than or equal to 40 N / S.

5. The method of claim 2, wherein, Step S32 comprises: S321, providing a limiting piece (3) on the battery module (1), the limiting piece (3) is provided along the length direction of the battery module (1), the limiting piece (3) is provided with a first limiting part (31) and a second limiting part (32) at both ends respectively, and the distance between the first limiting part (31) and the second limiting part (32) is equal to the first length; S322, reducing the pressing force until the both ends of the battery module (1) along the length direction abut against the first limiting part (31) and the second limiting part (32) respectively, and the pressing force at this time is the pre-tightening force.

6. The method of claim 1 to 5, wherein In steps S1 and S3, the battery module (1) is pressed by applying a pressing force to the end plate of the battery module (1).

7. The method of claim 1 to 5, wherein The binding belt (2) comprises a steel belt. 8.A method for manufacturing a battery module, comprising the following steps: Step A, measuring the pre-tightening force generated by the binding belt (2) according to the method for determining the pre-tightening force of a battery module according to any one of claims 1 to 7; Step B, determining whether the pre-tightening force is within a design interval, if yes, using the binding belt (2) to bind the battery module, and completing the manufacturing of the battery module; if no, adjusting the size of the buffer pad or adjusting the size of the binding belt (2), and repeating steps A to B.

9. The method of claim 8, wherein, In step S1, the pressing force for pressing the battery module (1) is greater than the upper limit of the design interval and less than the cell stacking expansion force.

10. The method of claim 8, wherein, In step B, if the pre-tightening force is greater than the upper limit of the design interval, the size of the binding belt (2) along the length direction of the battery module (1) is increased; if the pre-tightening force is less than the lower limit of the design interval, the size of the binding belt (2) along the length direction of the battery module (1) is reduced.

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