Li_xCoO_2及其与LiPF_6EC+DEC电解液的热稳定性研究

Thermal Stabilities of Li_xCoO_2 and its Coexistingwith LiPF_6/EC+DEC Electrolyte

使用C80微量量热仪对不同充电状态下LixCoO2的热稳定性、LixCoO2与1.0molLLiPF6EC+DEC(质量比=11)电解液的热稳定性进行了研究。结果表明,LixCoO2的放热量和主放热峰温度随x值减小而增加,Li0.05CoO2在271.8℃达到放热峰,总放热量高达1575.5Jg。LixCoO2与电解液反应时,LixCoO2首先分解出的氧气使电解液氧化,同时电解液也发生分解等反应,放热峰温度随x的增大呈增大趋势,放热量随x的增大呈减少的趋势。此外,LixCoO2与电解液反应产生大量的CO2、HF等气体。

In order to study the stability of Li, CoO2 and the reactions thermal characteristics between Li, CoO2 and 1.0mol/L LiPF6 in EC/DEC（ 1：1 mass ratio）for lithium-ion batteries, C80 micro calorimeter was used to study the thermal stabilities of Li,CoO2 alone at different state of charge, and their reaction with electrolyte. The results show that Li0.05 CoO2 reaches to exothermic peak at 271.8℃ with a total heat generation of 1575.5J/g. In general, the heat generation and main exothermic peak temperature of Lix CoO2 are increasing with x decreasing. With the presence of 1.0mol/L LiPF6/EC ＋ DEC electrolyte, LixCoO2 decompose to O2 , and then, electrolyte is oxidated or decomposes. The exothermic peak temperature presents the increase trend with x increasing, while the heat generation presents the decrease trend with x increasing. Furthermore, a large amount of gases, such as CO2, HF and so on, are released from the reactions of Li,CoO2 with electrolyte.