How is the lithium ion safety feature achieved?

1. How is the lithium ion safety feature achieved?

Diaphragm 135 ℃ automatic shutdown protection, using internationally advanced Celgas2300PE-PP-PE three-layer composite membrane. 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 hole is closed, the battery is internally open, and the temperature of the battery is no longer increased, ensuring the safety and reliability of the battery.

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 temperature of the battery will no longer rise.

The battery cover of the composite structure of the battery cover adopts the nicked explosion-proof ball structure. When the battery heats up, part of the gas generated during the activation process inside the battery expands, the internal pressure of the battery increases, and the pressure reaches a certain degree of nicked fracture and deflation.

Various environmental abuse tests are conducted to conduct various abuse tests, such as external short circuit, overcharge, acupuncture, impact, incineration, etc., to inspect the safety performance of the battery. At the same time, the temperature shock test and the mechanical performance test 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 at the end of the constant current process, the electrochemical polarization inside the battery will remain at the same level in the whole constant current. During the constant voltage process and under the action of the constant electric field, the concentration polarization of Li+inside the battery will gradually disappear, and the number and speed of ion migration will gradually decrease as the current.

3. What is the capacity of the battery?


The capacity of battery can be divided into rated capacity and actual capacity. The rated capacity of the battery refers to the minimum amount of electricity that the battery should discharge under certain discharge conditions specified or guaranteed during the design and manufacture of the battery. Li-ion stipulates that the battery shall be charged for 3h under normal temperature, constant current (1C) and constant voltage (4.2V) controlled charging conditions. The actual capacity of the battery refers to the actual energy 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 indicate the charging and discharging conditions). The common units of capacity are: mAh, Ah=1000mAh).

4. What is battery internal resistance?

It refers to the resistance of current flowing through the battery when the battery is working. It consists of ohmic internal resistance and polarization internal resistance. The large internal resistance of the battery will lead to the reduction of the battery discharge working voltage and the reduction of 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: The internal resistance in charge state is generally taken as the standard. The internal resistance of the battery shall be measured with a special internal resistance meter, but not with the ohm gear of a multimeter.

5. What is open-circuit voltage?


The open-circuit voltage after full charge is about 4.1-4.2V, and the open-circuit voltage after discharge is about 3.0V. The state of charge of the battery can be determined by the open-circuit voltage of the battery. What is the working voltage? The discharge working voltage is about 3.6V.