( 中南大学 冶金科学与工程学院，长沙 410083)
摘 要: 制备了3种1 mol/L LiPF6电解液, 溶剂组成分别为: 1）碳酸乙烯酯，碳酸二甲酯和碳酸甲乙酯；2）碳酸乙烯酯，碳酸二甲酯，碳酸甲乙酯和4%联苯； 3）碳酸乙烯酯，碳酸二甲酯，碳酸甲乙酯和4%环己基苯。采用线性电压扫描法、锂循环效率法、锂离子电池的循环性能法和3 C倍率过充的方法测试了联苯与环己基苯电解液过充添加剂的行为。结果表明：环己基苯是一种较实用的锂离子电池电解液过充添加剂，环己基苯的电化学稳定性比联苯的高，环已基苯的氧化电势为4.72 V(vs Li/Li+)，联苯的为4.54 V(vs Li/Li+)；以1 mA电流循环20次后，联苯的铂电极锂循环效率为15.7%，环己基苯的为59.3%；锂离子电池以1 C循环150次后，环己基苯的容量保持率为88%，联苯的为76.3%。环己基苯与联苯添加剂都改善了锂离子电池的耐过充性能，且两者的效果十分接近。
关键字: 联苯;环己基苯;电解液;锂离子电池;过充
electrolyte used in Li-ion batteries
（ College of Metallurgy Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: Three kinds of 1 mol/L LiPF6 electrolytes were prepared in various mixed solvents. The components of the electrolytes were as follows: 1) ethylene carbonate (EC), dimethylene carbonate (DMC), ethylmethyl carbonate (EMC); 2) EC, DMC, EMC+4% biphenyl (BP); 3) EC, DMC, EMC+4% cyclohexylbenzene (CB). The behaviors of electrolytes were analyzed by linear sweep voltage, lithium cycling efficiency, cycling performance and overcharging with 3C of lithium-ion batteries. The results show that CB is a kind of practical overcharging additive for electrolyte. The CB exhibits better electrochemical stability than BP due to the oxidation potential 4.72 V vs Li/Li+ for CB and 4.54 V vs Li/Li+ for BP. The lithium cycling efficiency of Pt electrode is 15.7% for BP electrolyte and 59.3% for CB electrolyte after 20 cycles with 1 mA. The capacity holding ratio of prismatic lithium-ion batteries is 88% for CB electrolyte and 76.3% for BP electrolyte after 150 cycles at 1 C. The overcharging tolerance of the lithium-ion batteries with CB and BP electrolyte are improved, and both of efficiencies are similar.
Key words: biphenyl; cyclohexylbenzene; electrolyte; lithium-ion battery; overcharging
