LiODFB电解液的高低温性能

High and low temperature performance of LiODFB electrolyte

采用DSC、电化学工作站和电池测试系统研究LiODFB/(EC+DMC+EMC)和LiPF6/(EC+DMC+EMC)电解液的热稳定性、高低温下的电化学窗口及其对铝箔集流体的稳定性、LiFePO4/G(石墨,graphite,简称G)电池在60和-20℃的高循环性能,通过SEM分析循环后的正负极极片形貌,探索高低温下电解液与极片的相互作用机理。研究结果表明:LiODFB电解液在250℃才会分解,而LiPF6电解液的分解温度为120℃;在-20和60℃时,LiODFB电解液的电化学窗口及其对集流体铝箔的稳定性比LiPF6电解液的大;以LiFePO4/G为电极的LiODFB电池在-20和60℃循环100次后的容量保持率均比LiPF6电池的大,LiODFB电解液能够帮助石墨表面SEI膜的形成,而LiPF6电解液在高温下会产生HF破坏SEI膜,致使电池性能降低。

The thermal stability of LiODFB/（EC＋DMC＋EMC） electrolyte and LiPF6/（EC＋DMC＋EMC） electrolyte, electrochemical window and stability with the aluminum foil at high and low temperature, and the cycle performance of LiFePOa/G （graphite） battery at 60 and -20 ℃ were studied by DSC, electrochemical workstations and battery test system. SEM was used to analyse the anode morphology after cycle, and the interaction mechanism between the electrolyte and electrode at high and low temperature was also investigated. The results show that LIODFB electrolyte is decomposed at 250 ℃, while LiPF6 electrolyte has a decomposition temperature of 120 ℃. The electrochemical of LiODFB electrolyte and its stability with aluminum foil are superior to those of LiPF6 electrolyte at -20 and 60 ℃. LiODFB battery with LiFePO4/G for electrode has better capacity retention than the LiPF6 battery at -20 and 60 ℃. LiODFB electrolyte is benefitial to the formation of the SEI film on the G electrode. However, LiPF6 electrolyte would generate HF to destroy the SEI film at high temperature.