Introduction of Methods for Testing the Safety of Lithium Battery

Lithium-ion batteries, as well as an overall sample consisting of non-user replacement batters/lithium-ion batteries and their electronic products. For non-user replacement batteries, lithium-ion batteries should be installed in electronic products as a whole sample for standard environmental safety tests; For non-user replacement lithium-ion batteries, they can be placed as a whole sample in electronic products, or they can be taken out separately to conduct standard lithium-ion battery environmental safety tests. It is recommended that priority be given to testing as a whole sample. As the test may occur during the process of deflation, smoke, fire or even explosion, necessary protective measures must be taken, such as the sample is placed in a ventilation device with explosion-proof function.

1, low pressure

Purpose: The low-pressure test is used to simulate the effect of low-pressure conditions on the safety of lithium-ion batteries during the airlift. After the test, the sample should not catch fire, explode, and leak liquid. Instrument equipment: such as vacuum box(or low-pressure test box), charge and discharge tester.

2, temperature cycle

Purpose of test: The temperature cycle test of a lithium-ion battery is used to simulate the safety of lithium-ion battery under low temperature and high temperature during transport or storage. The test is carried out using rapid and extreme temperature changes. After the test, the sample shall not catch fire, explode or leak. Instrument equipment: such as temperature test box, charging and discharging tester.

Thermothermal humidifier test equipment

3, vibration

Purpose of the test: The vibration during the simulation transportation and carrying process should not cause safety problems such as leakage, fire and explosion of lithium-ion batteries. Instruments and equipment: such as vibration test bench, charge and discharge tester, etc..

Note: Lithium-ion battery vibration test needs to pay attention to the following points:(1) The fixed method of the sample must ensure that the vibration signal is accurately transmitted to the sample, but it can not cause the sample to deform; (2) Each sample needs to withstand vibration tests in different directions several times in a row; (3) With regard to the direction of the test, since the shape of the lithium-ion battery may be irregular, it is necessary to test all three vertical directions. In addition, it should be noted that after the vibration test of the lithium-ion battery, a discharge charging cycle is required. (It is recommended that special clamps should be used when vibrating to ensure that there is no change in G value due to sample displacement during vibration).

4, acceleration impact

Purpose: The acceleration impact test of lithium-ion battery is to simulate the safety problems of lithium-ion battery which should not cause fire, explosion or leakage after the acceleration impact is encountered during carrying or transportation. Instruments and equipment: such as acceleration impact test bench, charge and discharge test instrument.

Note: The acceleration impact test of lithium-ion battery needs to pay attention to the following points:(1) The acceleration impact test of lithium-ion battery is similar to the vibration test of a lithium-ion battery. It is necessary to pay attention to the fixed method of the sample, multiple tests of each sample, and the direction of test. (2) Attention to the peak acceleration of the lithium-ion battery acceleration impact test and the acceleration impact test of the battery. (3) In addition, it should be noted that a discharge charging cycle is required after the lithium-ion battery acceleration test.

5, drop

The two end surfaces of cylindrical and button lithium ion batteries fell once, and the cylindrical surface fell twice, and a total of four drop tests were carried out. Each side of the other type of lithium-ion battery dropped once and a total of six tests were conducted. For non-user replacement battery/lithium-ion batteries, a drop test with equipment was performed, with each device falling once. Samples shall be free from fire, explosion, and leakage.

Purpose of the test: this test simulates that accidental falls(such as falls from benches, desktops, and hands) during transportation, carrying, and use should not cause safety problems such as leakage, fire, and explosion of lithium-ion batteries. This test is a simulation of reasonable and foreseeable accidental falls, regardless of the safety problems caused by man-made, intentional, unreasonable and unforeseen falls. Instrument equipment: such as multi-degree of the freedom test bench, charging and discharging tester.

Drop tester

Note: Lithium-ion battery drop test needs to pay attention to the following points:(1) Each sample needs to withstand multiple fall tests in different directions; (2) The necessary measures need to be taken to ensure the accuracy of the test direction, and this measure should not affect the free fall movement; (3) The drop test conditions of lithium-ion batteries also take into account accidental falls during actual use, so 1.5 m drop tests are required for some lithium-ion batteries; In addition, it should be noted that the lithium-ion battery drop also requires a discharge charging cycle.

6, stress elimination

The structure of the thermoplastic shell shall ensure that any shrinkage or deformation of the shell material will not expose the internal parts when the shell material releases the internal stress resulting from the molding or injection forming. The sample housing shall not undergo physical deformation resulting in internal composition exposure.

Test purpose: The stress-elimination test is to simulate the ability of lithium-ion batteries to maintain the integrity of the shell after withstanding appropriate high temperature. Equipment: such as high-temperature test box.

Note: Stress removal tests need to pay attention to the following points:(1) This test is only performed on lithium-ion batteries with molded or molded thermoplastic shells; (2) Before the test, the test box is heated up to 70 °C ± 2 °C and then the sample is put into the text box instead of putting the sample into the test box and then warming up. After the test, the sample is taken out and restored to room temperature instead of in the test box. Room temperature will be restored; (3) If the sample catches fire or explodes during the test, causing damage to the shell, it is also judged to be unqualified. (It is recommended to use clamps and other tools when taking samples to avoid scald. At the same time, the tested samples should be placed in a special explosion-proof box and shelved for more than two hours. ))

7, high-temperature use

Samples should be used at high temperatures with sufficient safety. It is tested for conformity by the following high-temperature test: Place the full electric sample in a high temperature test box, The temperature in the text box is set to the maximum temperature of the charging upper limit and the discharge upper limit temperature of the lithium-ion battery specified by the manufacturer, the charging upper limit temperature of the battery and the discharge upper limit temperature and the maximum value in 80 °C. After the surface temperature of the sample is stabilized, it remains 7H.

The sample should meet one of the following requirements:(1) Cut off the circuit and do not catch fire, do not explode, do not leak liquid; (2) Without cutting off the circuit, the discharge and discharge method during the high-temperature test continues to carry out a discharge charging cycle. The sample shall not catch fire, explode, or leak.

Objective: This test simulates the safety of lithium-ion batteries in a high-temperature environment. For example, a mobile phone that is in a standby or vehicle-charged state is left behind in a car that has been exposed to the sun for a long time. Instrument and equipment: such as high-temperature test box, charging and discharging tester.

Note: The following points should be noted in the high-temperature test of lithium-ion batteries:(1) The high-temperature retention time of 7H starts to be time after the surface temperature of the sample is balanced, and if a discharge charging cycle takes place, the time is greater than 7H. The high-temperature test time can be extended until the end of the current charge and discharge cycle; (2) The choice of test temperature is to select the upper limit temperature(eg 40 °C) and discharge upper limit temperature(eg 55 °C) of the lithium-ion battery, the upper limit temperature of the battery(eg 45 °C), and the upper limit temperature of the discharge(eg 60 °C and 80) The maximum value in °C, in general: the charging upper limit temperature of a lithium-ion battery ≤ the charging upper limit temperature of the battery & lt; 80 °C, discharge upper limit temperature of lithium-ion battery ≤ discharge upper limit temperature of battery & lt; 80 °C, so the test temperature is generally selected as 80 °C. (3) Since the air flow in the test box will accelerate the heat transfer, which will cause the loss of heat on the surface of the battery during the charging and discharging process, it may be necessary to minimize the impact on the sample by reducing the wind speed.

8, conclusion

Lithium-ion batteries are increasingly used in various fields such as communications, transportation, and lighting. With their unique applicability, convenience has become more and more popular with the public. However, the safety of lithium-ion batteries has been criticized and has always been alert to safety tests. We, To take a serious look, the above is some of the simple views on safety testing for readers to discuss.

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