Influencing factors on thermal stability of lithium battery cathode materials.CR3032 battery

　　The initial exothermic temperature of cathode material increases with the increase of particle size.

　　The thermal stability of lithium embedded natural graphite with different particle sizes was studied by DSC. It was found that all samples had three exothermic peaks. The first exothermic peak of the sample is located near 150 ℃, and the positions of the last two exothermic peaks are obviously different. The starting temperature of the last two exothermic peaks increases with the increase of particle size. This study shows that the first exothermic peak is the decomposition of SEI film, and the last two exothermic peaks are the reaction of lithium intercalated graphite with PVDF and electrolyte.

　　The relationship between the specific surface area of graphite materials and thermal stability was studied by ARC. It was found that when the specific surface area of graphite materials increased from 0.4 m2/g to 9.2 m2/g, the reaction rate increased by two orders of magnitude. Therefore, the reaction rate of carbon anode materials increases with the increase of specific surface area.

　　Different carbon materials with different structures have different reaction heat yield, and graphite structure produces more heat than amorphous carbon structure.

　　The thermal stability of carbon fiber, hard carbon, soft carbon and MCMB was studied by DSC. It was found that the first exothermic peak of the four kinds of carbon appeared at 100 ℃, which was believed to be produced by the decomposition of SEI film; As the temperature rises to 230 ℃, the influence of carbon structure and specific surface area on the thermal stability of materials gradually appears. Carbon electrode materials with graphite structure (carbon fiber, MCMB) generate more heat than carbon electrode materials with amorphous structure (soft carbon, hard carbon). XRD showed that the total amount of lithium insertion loss was linear with the specific surface area of carbon at about 230 ℃.

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