Water has a fatal influence on the performance of lithium ion batteries. In this work, Lithium hexafluoro phosphate(LiPF₆)-ethylene carbonate (EC)/diethyl carbonate (DEC) and lithium bis(oxalato)borate (LiBOB)-tetramethylene sulfone (SL)/DEC are taken as examples to investigate the influences of water concentration for electrochemical window, acidity, impedance and cycling performance for lithium ion batteries by adjusting water concentrations in the electrolytes. Results show that LiBOB-based electrolyte has better water tolerance compared with LiPF₆-based system, due to the formation of LiBOB·xH₂O compounds by consuming the additive trace water. Besides, inductively coupled plasma test result shows that Mn ion dissolution in LiPF₆ systems is extremely severe, which is mainly caused by the corrosive reaction between LiMn₂O₄ and by-product HF acid. And we believe that Mn ion dissolution and the following deposition should be responsible for failure work of LiPF₆-based cells. But for LiBOB-based cells, stable SEI layers and good electrochemical performances have been obtained, benefitting from the synergistic effect between LiBOB salt and SL solvent. And the presence of high-resistance B(C₂O₄) (OH) and LiB(C₂O₄) (OH)₂ products on surface of graphite electrode is the main reason for a small number of capacity fading.

水会对锂离子电池的性能产生致命影响。本文以六氟磷酸锂（LiPF ₆）-碳酸亚乙酯（EC）/碳酸二乙酯（DEC）和双（草酸酯）硼酸锂（LiBOB）-四亚甲基砜（SL）/ DEC为例研究通过调节电解质中的水浓度，可实现锂离子电池的电化学窗口水浓度，酸度，阻抗和循环性能。结果表明，LiBOB基电解质与LiPF ₆基体系相比具有更好的耐水性，这是由于消耗了痕量添加剂水形成了LiBOB·xH ₂ O化合物。此外，电感耦合等离子体测试结果表明Mn离子在LiPF _6中的溶解系统非常严重，这主要是由于LiMn ₂ O ₄与副产物HF酸之间的腐蚀反应所致。并且我们认为，Mn离子的溶解和随后的沉积应负责基于LiPF ₆的电池的失效工作。但是对于LiBOB基电池，得益于LiBOB盐和SL溶剂之间的协同作用，获得了稳定的SEI层和良好的电化学性能。石墨电极表面上高电阻的B（C ₂ O ₄）（OH）和LiB（C ₂ O ₄）（OH）₂产品的存在是导致容量减少的主要原因。