1. Overcharge performance 26650 Li ion battery After standard charging, measure the initial state of the battery. When the battery state is normal, charge it to 10.0v with 3C current, and then turn to constant voltage termination when the current is 0.01c. Observe the appearance change of the battery. Result: No fire, no explosion

2. The over discharge performance of 26650 lithium-ion battery after standard charging, and the initial state of the battery. When the battery is in normal condition, discharge to 0V at 0.5c. Observe the appearance change of the battery.

3. Results: There were no fire and explosion. After the 26650 lithium-ion battery is charged as standard, the external circuit is shorted, the initial state of the battery is measured, the battery is put into the explosion-proof cover, and the positive and negative electrodes are directly shorted (the total resistance of the line is not greater than 50m). When the battery temperature drops to about 10 ℃ lower than the peak temperature, the test is completed. Observe the temperature and appearance changes of the battery. Result: No fire and explosion. The initial state of 26650 Li ion battery was measured by thermogravimetry. After charging the battery, place it in the oven and raise the temperature to 130 at the rate of (5 ± 2 ℃) min μ N； Keep the temperature at 2 ℃ for 30 minutes. Observe the appearance change of the battery. Results: No fire and explosion occurred in 5 cases. Drop test the initial capacity of 26650 lithium ion battery. After standard charging, measure the initial state of the battery, and drop the test battery vertically and horizontally from the position with a height of 1m (the lowest point height) to the cement floor. It needs to be lowered twice. Results: There were 6 fire explosions. The steel bar with a diameter of 158mm is placed under the impact of the weight of the fully charged battery; Then lower the 10kg hammer from 1.0m to the upper part of the battery. Results: There were no 7 fires and explosions. The extrusion test core is placed between two extrusion surfaces of the extrusion equipment. The cylindrical electric mandrel is parallel to the extrusion surface, and gradually increases the pressure to 13kn, and maintains the pressure for 1min. Result: No fire, no explosion