Yang Ya-Ping, Huang An-Chi, Tang Yan, Liu Ye-Cheng, Wu Zhi-Hao, Zhou Hai-Lin, Li Zhi-Ping, Shu Chi-Min, Jiang Jun-Cheng, Xing Zhi-Xiang
School of Material Science and Engineering, Changzhou University, Changzhou 213164, China.
School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
Polymers (Basel). 2021 Feb 26;13(5):707. doi: 10.3390/polym13050707.
Lithium-ion batteries with conventional LiPF carbonate electrolytes are prone to failure at high temperature. In this work, the thermal stability of a dual-salt electrolyte of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluoro(oxalato)borate (LiODFB) in carbonate solvents was analyzed by accelerated rate calorimetry (ARC) and differential scanning calorimetry (DSC). LiTFSI-LiODFB dual-salt carbonate electrolyte decomposed when the temperature exceeded 138.5 °C in the DSC test and decomposed at 271.0 °C in the ARC test. The former is the onset decomposition temperature of the solvents in the electrolyte, and the latter is the LiTFSI-LiODFB dual salts. Flynn-Wall-Ozawa, Starink, and autocatalytic models were applied to determine pyrolysis kinetic parameters. The average apparent activation energy of the dual-salt electrolyte was 53.25 kJ/mol. According to the various model fitting, the thermal decomposition process of the dual-salt electrolyte followed the autocatalytic model. The results showed that the LiTFSI-LiODFB dual-salt electrolyte is significantly better than the LiPF electrolyte in terms of thermal stability.
采用传统碳酸锂盐电解质的锂离子电池在高温下容易失效。在本研究中，通过加速量热法（ARC）和差示扫描量热法（DSC）分析了双盐电解质双（三氟甲烷磺酰）亚胺锂（LiTFSI）和二氟草酸硼酸锂（LiODFB）在碳酸酯溶剂中的热稳定性。在DSC测试中，LiTFSI-LiODFB双盐碳酸酯电解质在温度超过138.5°C时分解，在ARC测试中在271.0°C时分解。前者是电解质中溶剂的起始分解温度，后者是LiTFSI-LiODFB双盐。应用Flynn-Wall-Ozawa、Starink和自催化模型来确定热解动力学参数。双盐电解质的平均表观活化能为53.25kJ/mol。根据各种模型拟合，双盐电解质的热分解过程遵循自催化模型。结果表明，LiTFSI-LiODFB双盐电解质在热稳定性方面明显优于LiPF电解质。
