The mature lipo battery technology and guaranteed quality and safety have promoted the rapid development of the lipo battery industry. In order to use and handle lithium batteries safely, the requirements of the national standard for general safety requirements of civilian lithium batteries are required, and lithium batteries are tested to ensure safe use. How to control and ensure the safe operation of lithium batteries and improve their working life through strict and reliable testing is not only a challenge for engineers engaged in the development and production of lithium batteries, but also a challenge for product design engineers when selecting batteries and designing products. The electrical characteristics need to be fully considered. This paper analyzes the performance testing methods of lithium-ion batteries, and discusses the measures to improve the safety performance of lithium-ion batteries.
1. Overcharge test of lithium batteries
Fully charge the li fe po battery with 1C, and then conduct an overcharge test according to 3C overcharge. When the battery is overcharged, the voltage rises to a certain voltage and stabilizes for a period of time. When approaching a certain time, the battery voltage rises rapidly. When it rises to a certain limit, the battery The high cap is pulled off, the voltage drops to 0V, and the battery does not catch fire or explode.
2. Short circuit test of lithium batteries
After the battery is fully charged, short-circuit the positive and negative electrodes of the battery with wires with a resistance of not more than 50mΩ, and test the surface temperature of the battery.
3. Self-discharge test of lithium batteries
The self-discharge test of lithium battery is: generally use 24-hour self-discharge to quickly test its charge retention capability, discharge the battery to 3.0V at 0.2C, charge it to 4.2V at constant current and constant voltage 1C, cut-off current: 10mA, leave it on hold for 15 After a few minutes, discharge the battery at 1C to 3.0V to measure its discharge capacity C1, then charge the battery to 4.2V with constant current and constant voltage at 1C, with a cut-off current of 100mA, and measure the 1C capacity C2 after leaving it for 24 hours. C2/C1100% should be greater than 99%.
4. Acupuncture test of lithium batteries
Place the fully charged battery on a flat surface and pierce the battery radially with a 3mm diameter steel needle. The test battery does not catch fire or explode.
5. IEC standard cycle life test of lithium batteries
IEC stipulates that the standard cycle life test of lithium batteries is: after the battery is charged at 0.2C3.0V/piece, 1C constant current and constant voltage are charged to 4.2V, the cut-off current is 20MA, and after 1 hour of storage, it is discharged to 3.0V at 0.2C (one cycle ) After 500 cycles, the capacity should be above 60% of the initial capacity.
6. Extrusion test of lithium batteries
Place the fully charged battery on a flat surface, apply a 13+1KN extrusion force by the hydraulic cylinder, and squeeze the battery flat with a steel rod with a diameter of 32mm. Once the extrusion pressure reaches the maximum, stop the extrusion, and the battery will not fire. , without exploding.
7. Vibration test of lithium batteries
The lithium battery vibration test method is as follows: the battery is discharged at 0.2C to 3.0V, then charged at 1C with constant current and constant voltage, charged to 4.2V, and the cut-off current is 10mA. Vibrate between, increasing or decreasing at a vibration rate of 1HZ per minute. After the vibration, the battery voltage change should be between 0.02V and the internal resistance change should be within 5m.
8. High temperature and humidity test of lithium batteries
The lithium battery high temperature and high humidity test is: charge the battery 1C constant current and constant voltage to 4.2V, the cut-off current is 10mA, and then put it in a constant temperature and humidity box at 40℃±2℃ and a relative humidity of 90%-95% for 48 hours. , take out the battery and put it on hold for 2 hours at 20℃±5℃, observe that the appearance of the battery should be normal, then discharge it to 2.75V with a constant current of 1C, and then charge it at 1C under the condition of 20℃±5℃, 1C Discharge cycles until the discharge capacity is not less than 85% of the initial capacity, but the number of cycles is not more than 3 times.
9. Heavy object impact test of lithium batteries
After the battery is fully charged, place it on a flat surface, place a steel column with a diameter of 15.8mm vertically in the center of the battery, and freely drop a weight of 9.1kg onto the steel column above the battery from a height of 610mm, the battery will not catch fire, Just don't explode.
10. Drop test of lithium batteries
After the battery pack is fully charged, drop it on the hard rubber plate from a height of 1m from three different directions, and do it twice in each direction. The battery pack should have normal electrical performance and no damage to the outer packaging.