1) The 135 ℃ automatic shutdown protection of diaphragm adopts the internationally advanced Celgars2300PE-PP-PE three-layer composite film. When the temperature of the battery reaches 120 ℃, the membrane holes on both sides of the PE composite membrane are closed, the internal resistance of the battery increases, and the internal temperature of the battery slows down. When the temperature of the battery reaches 135 ℃, the PP membrane holes are closed, the internal circuit of the battery is open, and the battery will not rise again, so as to ensure the safety and reliability of the battery.

2) Add additives to the electrolyte. When the battery is overcharged and the battery voltage is higher than 4.2V, the electrolyte additives will polymerize with other substances in the electrolyte, and the internal resistance of the battery will greatly increase. A large area of open circuit will be formed inside the battery, and the battery will no longer heat up.

3) The battery cover with composite structure adopts a scored explosion-proof ball structure. When the battery heats up, part of the gas generated during the internal activation process of the battery expands, the internal pressure of the battery increases, and the pressure reaches a certain degree of scoring, cracking and venting.

4) Various environmental abuse tests were conducted to conduct various abuse experiments, such as external short circuit, overcharge, acupuncture, impact, incineration, etc., to investigate the safety performance of the battery. At the same time, temperature impact test and mechanical performance tests such as vibration, drop and impact were carried out to investigate the performance of the battery in the actual use environment.

2. Why does the constant voltage charging current decrease gradually?

Because when the constant current process ends, the electrochemical polarization inside the battery will maintain the same level as that in the whole constant current. Under the constant voltage process and the constant electric field, the concentration polarization of internal Li+will gradually eliminate, and the migration number and speed of ions will show that the current will gradually decrease.

3. What is the battery capacity?

The capacity of battery can be divided into rated capacity and actual capacity. The rated capacity of the battery refers to the provision or guarantee that the battery should discharge the minimum amount of electricity under certain discharge conditions when designing and manufacturing the battery. Li ion stipulates that the battery shall be charged for 3h at room temperature and under the charging condition controlled by constant current (1C) and constant voltage (4.2V). The actual capacity of the battery refers to the actual power released by the battery under certain discharge conditions, which is mainly affected by the discharge rate and temperature (so strictly speaking, the battery capacity shall specify the charging and discharging conditions). Common units of capacity are: mAh, Ah=1000 mAh).

4. What is the internal resistance of the battery?

It refers to the resistance of current flowing through the battery during operation. It is composed of ohmic internal resistance and polarized internal resistance. The large internal resistance of the battery will reduce the working voltage of battery discharge and shorten the discharge time. The internal resistance is mainly affected by the battery material, manufacturing process, battery structure and other factors. It is an important parameter to measure battery performance. Note: Generally, the charging internal resistance is taken as the standard. The internal resistance of the battery shall be measured with a special internal resistance meter, rather than the ohm scale of the multimeter.