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Thermal Stability And Overcharge, High Temperature And Short Circuit Safety

2022-03-10

The electrolyte commonly uses alkyl carbonate organic solution, which has flammable properties. The cathode material is usually a transition metal oxide, which has strong oxidizing property in the charging state and is easy to decompose and release oxygen at high temperature, and the released oxygen reacts with the electrolyte in oxidation, and then releases a large amount of heat.

Therefore, from the point of view of materials, lithium-ion batteries have a strong danger, especially in the case of abuse, safety issues are more prominent.

Analysis of the thermal stability of lithium-ion battery materials

The fire hazard of lithium-ion batteries is mainly determined by the amount of heat generated by the chemical reaction occurring in the internal parts of the battery. The fire hazard of lithium-ion batteries ultimately depends on the thermal stability of the battery material, and the thermal stability of the battery material depends on the chemical reactions occurring between its internal parts. At present, the thermal stability of battery-related materials is mainly studied by differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), adiabatic accelerated calorimeter (ARC), etc.

Factors affecting the thermal stability of negative electrode materials.

The thermal stability of four different structural carbon materials, carbon fiber, hard carbon, soft carbon and MCMB, was investigated by DSC. It was found that the first exothermic peak of all the four carbons appeared at 100℃, and this exothermic peak was thought to be generated by the decomposition of the SEI film; as the temperature increased to 230℃, the influence of carbon structure and specific surface area on the thermal stability of the materials gradually appeared, and the graphite structure of carbon electrode materials (carbon fiber, MCMB) generated more heat than the amorphous structure of carbon electrode materials (soft carbon, hard carbon). The total loss of embedded lithium is linearly related to the carbon specific surface area at about 230°C.

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