What is the quality inspection method of lithium battery?

If you want to understand the quality inspection of lithium batteries , you must first know what the performance indicators of lithium batteries are. So what are the performance indicators of lithium battery quality? Three main indicators of electrical performance, cycle life and safety. Then the quality inspection of lithium batteries is divided into single battery and module battery inspection. The specific method steps are as follows:

1. Test of charge recovery ability after storage

The charge recovery ability test after storage mainly tests the capacity recovery of lithium-ion batteries after a certain period of storage.

1. Under the ambient temperature of (20±5) ℃, discharge the lithium-ion battery with a constant current of 0.2C to the specified termination voltage (usually 3.0V), and then charge it with a constant current to the termination voltage of 0.2C (usually 0.2C). 3.0V). 4.2V), switch to constant voltage charging (the charging termination current is generally 0.02C);

2. The lithium-ion battery is discharged to the specified discharge termination voltage at a constant current of 0.2C at an ambient temperature of (20±5) °C;

3. The lithium-ion battery should be discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C;

4. Calculate the capacity (Ah) released by the battery in step ⑤.

5. Lithium-ion batteries should be stored in an open circuit for 90 days at an ambient temperature of (40±2) °C;

6. The lithium-ion battery is charged according to the method of step ①, and the ambient temperature is (20±5) ℃;

The charge recovery capability after storage is expressed as a percentage of the calculated capacity to the rated capacity.

Second, lithium battery charging retention ability and charging recovery ability detection:

The test of charge retention capability and charge recovery capability is mainly to test the capacity retention capability of the lithium-ion battery after being stored for a period of time, and to charge the battery after the charge retention capability test to check its capacity recovery.

1. Under the ambient temperature of (20±5) ℃, discharge the lithium-ion battery with a constant current of 0.2C to the specified termination voltage (usually 3.0V), and then charge it with a constant current to the termination voltage of 0.2C (usually 0.2C). 3.0V). 4.2V), switch to constant voltage charging (the charging termination current is generally 0.02C);

2. Lithium-ion batteries should be stored open circuit for 28 days at (20±5)℃ ambient temperature;

3. The lithium-ion battery should be discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C;

4. Calculate the capacity (Ah) released by the lithium-ion battery in step ③;

5. The charge retention capacity should be expressed as the percentage of the capacity calculated in step ④ to the rated capacity;

6. The lithium-ion battery should be charged according to the first step within 24 hours after the third step of discharge;

7. The lithium-ion battery should be discharged to the specified discharge termination voltage at a constant current of 0.2C at an ambient temperature of (20±5) °C;

8. Calculate the capacity (Ah) released by the lithium-ion battery in step ⑦;

9. The charge recovery capacity shall be expressed as a percentage of the capacity calculated in step 8 to the rated capacity.

3. Cycle life test

The cycle life test mainly examines the number of charge and discharge times of the lithium-ion battery when the usable capacity drops to the allowable value.

① The lithium-ion battery is discharged at a constant current of 0.2C to the specified termination voltage (usually 3.0V) at an ambient temperature of (20±5) °C, and then charged to the termination voltage (usually 4.2V) with a constant current of 0.2C. V), transfer to constant voltage charging (the charging termination current is generally 0.02C);

② The lithium-ion battery should be discharged to the specified discharge termination voltage at a constant current of 0.2C at an ambient temperature of (20±5) °C;

③ Lithium-ion batteries should be used in cycles at an ambient temperature of (20±5) °C, and the battery’s shelving time between charging and discharging or charging and discharging should not exceed 1h;

④The lithium battery should be charged and discharged according to steps ① and ② until the discharge capacity is lower than 70% of the rated capacity.