① Positive material

The safety performance of cathode materials mainly includes overcharge safety and thermal stability. In the oxidation state, the cathode materials undergo exothermic decomposition reaction and release oxygen.

② Negative material

Although the negative material is relatively stable, the carbon negative electrode in lithium state will react with electrolyte at high temperature first.

③ Electrolyte

Electrolyte includes inorganic conductive agent and organic solvent, and the flammability of organic solvent will have a certain influence on the safety of the battery.

④ Production process

The production process of battery is very complex, even if strictly controlled, metal impurities or burr in the production process can not be avoided completely. If impurities, burr or dendrites appear in the battery, the conductivity will increase and the temperature will rise after amplification and deterioration. The heat generated by chemical reaction and discharge heating will accumulate continuously, which may eventually cause the heat loss of the battery.

02

1、 Problem description

The temperature distribution of a single 18650 cylindrical lithium-ion battery was calculated by discharging for 100s at a constant current of 2A at 23 ℃.

2、 Problem analysis

To get the temperature distribution of the battery, we need to establish the geometry model, material model and boundary condition of the battery. The geometry model of 18650 cylindrical lithium-ion battery is easy to establish, and the material model can be obtained by previous literature.