CN116296133A - A test method for battery weld reliability - Google Patents

Abstract

The invention discloses a method for testing the reliability of a battery welding seam, which comprises the following steps of S1: introducing pressure gas into the test cell, wherein the total pressure value of the pressure gas is P1; s3, pumping at least part of the pressure gas from the test cell, wherein the pumped pressure gas has a pressure value P3; monitoring and analyzing the pressure change curve in the test cell; the test cell is filled with pressure gas and is pumped out of the pressure gas, the process of charge expansion and discharge contraction of the cell is simulated in sequence, and the reliability of the weld joint of the test cell under each state change is judged by monitoring and analyzing the pressure change curve of the test cell caused by the pressure gas change.

Description

A test method for battery weld reliability

technical field

The invention relates to the field of batteries, in particular to a method for testing the reliability of battery welds.

Background technique

Batteries are widely used as electric energy storage products. The shell of the existing battery cell includes a shell and a cover plate. The shell and the cover plate are usually spliced by welding; in order to ensure the safety of the battery, it will Carry out tightness testing; the existing testing method is to measure the design parameters such as the penetration depth and width of the weld to determine the reliability of the welding.

However, in the actual use process, as the charge and discharge cycle proceeds, the battery cell gradually expands, the thickness of the battery cell increases, and the large surface of the battery cell presents a bulging state, which has certain limitations on the weld between the cover plate and the shell. Therefore, the strength of the weld will be weakened, and whether the weakened weld strength meets the safety of the battery cannot be verified.

Contents of the invention

In order to overcome at least one of the defects described in the above-mentioned prior art, the present invention provides a test method for the reliability of the battery weld seam. The pressure gas is introduced into the test cell and the pressure gas is drawn out, corresponding to the charge expansion and discharge contraction of the simulated cell in sequence. The process, and by monitoring and analyzing the pressure change curve in the test cell caused by the change of pressure gas, judge the reliability of the test cell weld under each state change.

A test method for battery weld reliability, comprising:

S1: Pass the pressure gas into the test cell, the total pressure value of the pressure gas is P1;

S3: extract at least part of the pressure gas from the test cell, and the pressure value P3 of the extracted pressure gas;

Monitoring and analyzing the pressure change curve in the test cell.

Further, after the S3, it also includes:

S5: passing the pressure gas with a pressure value of P5 into the test cell;

S7: extract at least part of the pressure gas from the test cell, and a pressure value P7 of the extracted pressure gas.

Further, S6 is also included between said S5 and said S7;

S6: the pressure gas is kept in the test cell for a duration T3;

And/or S8 is also included after S7;

S8: The pressurized gas is kept in the test cell for a period of time T4.

Further, among the S5, the S6, the S7 and the S8, at least the S5 and the S7 are included as one operation cycle, and the number of the operation cycles is multiple.

Further, S2 is also included between said S1 and said S3;

S2: the pressure gas is kept in the test cell for a duration T1;

And/or S4 is also included between said S3 and said S5;

S4: The pressurized gas is kept in the test cell for a time period T2.

Further, the P3, the P5 and the P7 are equal, and/or the T1 is equal to the T3, and/or the T2 is equal to the T4.

Further, the P1 is 0.45MPa;

And/or the P3, the P5 and the P7 are all 0.3 MPa, the T1 and the T3 are all 1 min, and the T2 and the T4 are all 0.5 min.

Further, the rate at which the pressure gas is introduced into the S1 and the S5 is both 0.01MPa/s;

And/or the rate at which the S3 and the S7 pump out the pressure gas is 0.01 MPa/s.

Further, before the S1, the pressure relief valve of the test cell is blocked.

Further, before the S1, a preload is applied to the test cell.

In summary, a method for testing the reliability of battery welds provided by the present invention has the following technical effects:

1) The pressure gas into and out of the test cell corresponds to the process of charging expansion and discharge contraction of the simulated cell in turn, and by monitoring and analyzing the pressure change curve in the test cell caused by the change of pressure gas, it can be judged under each state change. Test the reliability of the electric core welding seam; if the pressure change curve of the same trend is stable, it indicates that the electric core welding seam is reliable, and vice versa, it indicates that the electric core welding seam is unreliable. From this, it can be known that this method simulates different working states of the electric core The dynamic process of the test cell, and the reliability of the weld seam of the test cell is monitored in real time during the simulation process, so the reliability of all the dynamic processes of the test cell is tested to form a comprehensive dynamic detection advantage;

2) After the start of S1, the test cell will expand (i.e. charge expansion (S1)), and then the continuous introduction of pressure gas and withdrawal of pressure gas S3 (i.e. discharge contraction) are all for the expanded test cell The reliable test of the welding seam is used to complete the first cycle of the cell; and the number of operation cycles is multiple, and S5 and S7 are used as one operation cycle. It can be known that S1 and S3 have completed the test The simulation of the initial charge expansion and discharge contraction of the battery cell, followed by the simulation of charge expansion (S5) and discharge contraction (S7) through S5 and S7 as the operation cycle. The fixed setting of the operation cycle makes the operation of the cycle test more convenient. Standardize, prevent errors in test operations, and ensure the accuracy and reliability of test results.

3) S2 (expansion and rest), S4 (shrinkage and rest), S6 (expansion and rest), and S8 (shrinkage and rest) are all static preservation, and the static preservation can be used to test a certain battery cell. Continuous reliability under state, improve the diversity of test methods to enhance the credibility of test methods.

4) The ventilation rate of S1 and S5 and the extraction rate of S3 and S7 are both 0.01MPa/s, using a specific rate to simulate normal charging and discharging is beneficial to ensure the authenticity of the test;

5) When the pre-tightening force is applied, the pre-tightening force received by the actual product of the test cell is simulated to achieve the effect of simulation.

Description of drawings

Fig. 1 is the pressure change curve diagram of embodiment one and embodiment two of the present invention;

2 is a perspective view of Embodiment 3 of the present invention;

Fig. 3 is a side view of Embodiment 3 of the present invention.

Among them, the reference signs have the following meanings:

1. Test cell; 2. Air duct; 3. End plate; 4. Buffer strip; 5. Splint; 6. Fixing bolt.

Detailed ways

For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device Or elements must have a certain orientation, be constructed and operate in a certain orientation, and thus should not be construed as limiting the invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

Embodiment one

Referring to Figure 1, the present invention discloses a test method for the reliability of battery welds, including:

Test battery 1, specifically, the test battery 1 is a dummy battery with a core package but no liquid injection, its shell includes a shell and a cover plate, the shell and the cover plate are directly connected by welding, and the cover A pressure relief valve is arranged on the board.

In this embodiment, the test cell 1 has a rectangular parallelepiped shape, so the long side of the housing is the large surface of the test cell 1 .

In this test method, the relief valve is plugged before the test begins.

The pre-tightening force is applied to the two large surfaces of the test cell respectively. The size of the pre-tightening force is applied according to the standards corresponding to the test cells of different sizes, and no examples are given here.

The test method for testing cell 1 is:

S1: Introduce pressure gas into the test cell 1, so that the total value of the gas pressure in the test cell 1 reaches P1.

S3: pump out at least part of the gas in the test cell 1, and the pressure of the pumped gas is P3.

By monitoring the change of the pressure value of the pressure gas inside the test cell 1 in S1 and S3 above, it is analyzed whether there is cracking in the weld seam of the test cell under different states.

Specifically, the analysis process is:

First, the step S1 of passing gas into the test cell 1, when the gas is passed into the test cell 1, the test cell 1 expands (simulating the process of charging expansion), at this time, the pressure change curve in the test cell 1 is as follows: Steady rate rise. If the pressure change curve suddenly drops, the rate of rise decreases or stops rising before the pressure value of the pressure gas reaches P1 during the process of testing telecommunications 1. It means that the test cell 1 is The weld seam cracks; the reason is that the weld seam cracking is the leakage of pressure gas, and the pressure value of the test cell 1 decreases, so the originally rising pressure change curve suddenly drops, the rising rate decreases or stops rising; if the pressure changes The pressure value of the curve has been rising steadily and finally reaches P1, which means that although the test cell 1 continues to expand during the process of feeding the pressure gas, the weld seam does not crack, and the weld seam is reliable.

Second, the step S3 of testing the gas out of the battery cell 1, during the process of pumping out the pressure gas with a predetermined pressure value of P3 (the process of simulating the discharge contraction, the discharge contraction is the contraction after the relative charge expansion), the test cell 1 The pressure value of the pressure gas will gradually decrease, and the pressure change curve will drop from P1 at a steady rate. Leakage; when the total pressure value of the pumped pressure gas has reached P3, but the drop rate of the pressure gas in the whole process does not change suddenly, it means that there is no cracking in the weld seam during this process, and the weld seam is reliable.

It can be known from the above that when judging whether the weld is cracked or leaking, it is judged by analyzing the stability of the rising rate and falling rate of the pressure change curve. The influence of the steady line of the pressure curve and the drop rate, that is, the sudden increase or decrease of the pressure gas inlet and outlet rate will affect the pressure change curve rise and fall rate, which may cause misjudgment of the reliability of the weld , so in the process of introducing and extracting the pressure gas into and out of the test cell 1, the rate of the introduction and extraction of the pressure gas should be constant.

Specifically, in this embodiment, the rate at which the pressure gas is introduced into S1 is 0.01 MPa/s; the rate at which the pressure gas is withdrawn from S3 is 0.01 MPa/s.

In S1, the total value P1 of the pressure gas injected into the test cell 1 is 0.45MPa, and in order to ensure the authenticity of the simulation, the pressure value of the extracted pressure gas is 00.45MPa<P3<P1. In this embodiment, P3 is 0.3MPa.

Further, in order to increase the continuous reliability test of the weld under a specific value, this embodiment performs static simulation on the test cell 1 at the maximum pressure value and the minimum pressure value, with:

S2: After step S1 is completed, the pressure value in the test cell 1 reaches the maximum value P1, and the pressure gas with the gas pressure value P1 is maintained in the test cell 1 for a certain period of time. This time is T1. Preferably, T1 is 1min. .

The process S2 of the test cell 1 holding gas, after the pressure gas is injected into S1, the pressure value of the pressure gas in the test cell 1 is P1, and the test cell 1 is kept at this pressure value for a period of time T1 (simulated expansion At this time, the test cell 1 is in a state of maintaining expansion; within T1 time, if the pressure value in the test cell 1 remains unchanged at P1 (that is, the pressure change curve remains horizontal), it means If there is no cracking in the weld seam, the weld seam is reliable; if the pressure value of the test cell 1 suddenly decreases (that is, the pressure change curve drops) within the time T1, that is, the pressure value is less than P1, it means that the weld seam is cracked resulting in leakage of pressurized gas.

Similarly, refer to S2 (expansion and rest), after S3 is completed, the test cell 1 also performs contraction and rest simulation, that is, after the total value of P1 is 0.45MPa, after the pressure gas of P3 is pumped out, there is still 0.15MPa The pressure gas, the test cell is kept under the pressure gas of 0.15 for T2, preferably, T2 is the time of 0.5min.

In summary, S1, S2, S3 and S4 can be used as the first cycle step, and the first cycle step can complete the simulation of the four states of the test cell 1.

In particular, the amount and rate of pressure gas introduced during the test can be changed according to the size of the test sample, for example, the greater the thickness of the shell, the greater the rate of introduction and extraction of pressure gas, and the pressure of the introduction The total value of gas P1 is greater.

Embodiment two

Referring to FIG. 1 , on the basis of the first embodiment, after the first cycle step, it is necessary to perform multiple cycle tests on the test cell, which is called an operation cycle.

Specifically, the operation cycle includes S5 and S7.

S5: Introducing the pressure gas with a pressure value of P5 into the test cell 1 .

S7: At least part of the pressure gas is extracted from the test cell 1, and the pressure value of the extracted pressure gas is P7.

The above S5 corresponds to S1, and S7 corresponds to S3. Between the two groups of corresponding steps, when S5 and S7 are performed, the changes of the test cell 1 are the same as those of S1 and S3, that is, S5 simulates expansion and stands still, and S7 The simulated contraction is left at rest, and will not be repeated here.

Referring to Embodiment 1, it can be known that the first cycle step also includes expansion static simulation S2 and contraction static simulation S4.

Then the operation cycle in this embodiment also includes S6 and S8; specifically, between S5 and S7, there will be an expansion static simulation step S6, in which the pressurized gas is kept in the test cell 1 for a period of time T3; after S7, it will There is a step S8 of contraction and standing simulation (that is, the operation cycle also includes S6 and S8), and the pressure gas in S8 is kept in the test cell 1 for a period of time T4.

In particular, P5=P7=0.3MPa, the rate of S5 feeding pressure gas is 0.01MPa/s; the rate of S7 extracting pressure gas is 0.01MPa/s; it can be known that P5, P5 and P7 are equal, and S1 The rate that feeds described pressure gas with S5 is 0.01MPa/s; The rate that S3 and S7 draws out pressure gas is 0.01MPa/s; T1=T3=1min; T2=T4=0.5min; The uniformity of the data among them is beneficial to simplify the operation difficulty of the steps and reduce the probability of operation errors.

It can be known that the operation cycle can be determined according to various parameters of the tested test cell, that is, the number of operation cycles can be several times, and the number of operation cycles in this embodiment is preferably three.

In this embodiment, before step S5, the pressure value of the pressure gas of the test cell 1 is 0.15MPa. After step S5 is completed, the pressure value of the pressure gas of the test cell 1 reaches the maximum value P1 again. After step S7, the support returns to 0.15MPa, so cycle.

Embodiment three

Referring to FIG. 2 and FIG. 3 , for the testing method of Embodiment 1 and Embodiment 2, the specific testing equipment includes: a testing cell 1 , an air duct 2 , an end plate 3 and a buffer strip 4 .

There are respectively end plates 3 on the two large faces of the test cell 1. Preferably, the end plates 3 are consistent with the shape and area of the large faces (the end plates 3 actually used in battery products are used). A plurality of buffer strips 4 are set between the surface and an end plate 3. In this embodiment, the number of buffer strips 4 is two, and the two buffer strips 4 are respectively arranged at both ends of the large surface and along the edges of the two ends of the large surface. Direction setting, preferably, the buffer strip 4 has viscosity, so the two surfaces of the buffer strip 4 are respectively bonded to the large surface and the end plate 3; it is particularly noted that the buffer strip 4 will not cover the entire large surface, so There is a gap between the large surface and the end plate 3, and this gap is used to test the expansion gap of the cell 1 for expansion.

Before the test cell 1 is tested, a corresponding pretightening force is applied to the end plate according to the specifications of the different test cells 1 .

It can be known from the above that, in order to protect the end plate 3, the test equipment also includes a splint 5 and at least four fixing bolts 6. In this embodiment, four fixing bolts 6 are used as an example; Clamping plate 5, the shape of clamping plate 5 is consistent with the shape of end plate 3 but the area is larger than end plate 3, specifically, the length and width of clamping plate 5 are greater than the length and width of end plate 3 respectively; A fixing bolt 6 passes through two clamping plates 5 in The two corresponding corners in the thickness direction of the battery cell 1 are tested, and the four fixing bolts 6 are used to connect the corresponding corners of the two splints 5 , and the pre-tightening force applied to the splint 5 is adjusted by tightening the nuts.

In addition, two through holes are provided on the cover plate of the test cell 1, and each through hole is respectively provided with a vent valve, and an air guide tube 2 is respectively arranged on the vent valve, and the air guide tube 2 extends to the outside of the test cell 1, and an air guide tube 2 is used as the intake of pressure gas, the other is used as the outlet of pressure gas, and the ventilation valve controls the opening and closing of the corresponding air guide tube 2.

In addition, in the pressure detection and data acquisition of the pressure gas, this implementation installs an air pressure sensor in the test cell, the air pressure sensor is connected to an external pressure display, and the pressure display is used to display the pressure change curve to reflect the internal pressure of the test cell 1 real-time pressure value.

The technical means disclosed in the solutions of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications are also considered as the protection scope of the present invention.

Claims (10)

1. A test method for battery weld reliability, characterized in that, comprising: S1: Pass the pressure gas into the test cell (1), the total pressure value of the pressure gas is P1; S3: extracting at least part of the pressure gas from the test cell (1), the pressure value P3 of the extracted pressure gas; Monitoring and analyzing the pressure change curve in the test cell (1). 2. A method for testing the reliability of battery weld seams according to claim 1, characterized in that, after said S3, it also includes: S5: passing the pressure gas with a pressure value of P5 into the test cell (1); S7: extracting at least part of the pressure gas from the test cell (1), the pressure value P7 of the extracted pressure gas. 3. A test method for battery weld reliability according to claim 2, characterized in that S6 is also included between said S5 and said S7; S6: the pressure gas is kept in the test cell (1) for a duration T3; And/or S8 is also included after S7; S8: The pressurized gas is kept in the test cell (1) for a time period T4. 4. A test method for battery weld reliability according to claim 3, characterized in that, among the S5, the S6, the S7 and the S8, at least the S5 and the S7 are included As one operation cycle, the number of operation cycles is multiple. 5. A test method for battery weld reliability according to claim 3, characterized in that S2 is also included between said S1 and said S3; S2: the pressure gas is kept in the test cell (1) for a duration T1; And/or S4 is also included between said S3 and said S5; S4: The pressurized gas is kept in the test cell (1) for a time period T2. 6. A test method for battery weld reliability according to claim 5, characterized in that said P3, said P5 and said P7 are equal, and/or said T1 is equal to said T3, and/or Or said T2 is equal to said T4. 7. A method for testing the reliability of battery weld seams according to claim 6, wherein the P1 is 0.45MPa; And/or the P3, the P5 and the P7 are all 0.3 MPa, the T1 and the T3 are all 1 min, and the T2 and the T4 are all 0.5 min. 8. A method for testing the reliability of battery weld seams according to claim 2, characterized in that the rates at which the pressure gas is introduced into the S1 and the S5 are both 0.01MPa/s; And/or the rate at which the S3 and the S7 pump out the pressure gas is 0.01 MPa/s. 9. The method for testing the reliability of battery welds according to claim 1, characterized in that, before the S1, the pressure relief valve of the test cell (1) is blocked. 10. The method for testing the reliability of battery weld seams according to claim 1, characterized in that, before the S1, a pre-tightening force is applied to the test cell (1).

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