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采用循环伏安、交流阻抗和充放电测试等研究了使用LiBC_2O_4F_2基电解液的LiFePO_4/Li电池(LiBC_2O_4 F_2电池)和使用LiPF_6基电解液的LiFePO_4/Li电池(LiPF_6电池)的电化学性能.结果表明,常温下LiBC_2O_4 F_2电池和LiPF_6电池的循环伏安曲线都只有1对对应于Fe~(2+)/Fe~(3+)的氧化还原峰,但是高温下LiPF_6电池的氧化还原峰分裂为多个氧化还原峰,而LiBC_2O_4F_2电池的氧化还原峰却与常温下类似,说明LiBC_2O_4F_2电池在高温下工作能保持较好的稳定性.常温下LiBC_2O_4F_2电池的初始放电容量比LiPF_6电池低,但其具有较高的容量保持率,而且在高温下具有比LiPF_6电池更高的放电容量和更优良的循环性能,如经过50次循环后,LiBC_2O_4F_2电池的容量保持率为92.5%,而LiPF_6电池的容量保持率为78.4%.交流阻抗图谱也表明,使用LiBC_2O_4F_2电池在高温下电池的界面电荷传输反应阻抗比室温下有所下降,说明其具有良好的高倍率性能和高温循环性能.

Electrochemical properties of LiFePO_4/Li batteries using LiBC_2O_4F_2-based(LiBC_2O_4F_2 battery)and LiPF_6-based electrolytes(LiPF_6 battery)are studied by cyclic voltammetry,charge-discharge test and AC impedance.The results show that there is only a pair of Fe~(2+)/Fe~(3+)redox peak in cyclic voltammograms of LiBC_2O_4F_2 battery and LiPF_6 battery at room temperature.However,at high temperature,the redox peak of LiPF_6 battery is divided into a number of redox peak,but the redox peak of LiBC_2O_4F_2 battery is very similar to that of LiBC_2O_4F_2 battery at room temperature,which enables LiBC_2O_4F_2 battery tO be operated stably at high temperature.The initial discharge capacity of LiBC_2O_4F_2 battery is lower than that of the LiPF_6 battery,but the retention of its capacity is higher,and LiBC_2O_4F_2 battery processes higher discharge capacity and better cycling pedormance than LiPF_6 battery at high temperatures.For example,after 50 cycles,LiBC_2O_4F_2 battery still retains about 92.5%of the initial capacity at60℃,but LiPF_6 battery only retains about 78.4%of the initial capacity.AC impedance of LiBC_2O_4F_2 battery also shows a low charge-transfer resistance at high temperature,which indieates that LiBC_2O_4F_2 battery processes excellent high-rate performance and cycling performance at high temperature.