添加剂对离子液体凝胶聚合物电解质电化学性能的影响

Influence of Additive in Ionic Liquid Gel Polymer Electrolyte on Electrochemical Properties

本文采用1-乙基-3-甲基咪唑六氟磷酸盐(EMIPF6)、六氟磷酸锂(LiPF6)和偏氟乙烯-六氟丙烯共聚物(P(VdF-HFP))为原料制得P(VdF-HFP)-EMIPF6-LiPF6体系离子液体凝胶聚合物电解质,选取碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)以及碳酸乙烯酯(EC)和碳酸丙烯酯(PC)混合物(EC-PC)作为离子液体凝胶聚合物电解质的添加剂,分别研究了它们对聚合物电解质膜电化学性能的影响。结果表明:加入EC-PC的P(VdF-HFP)-EMIPF6-LiPF6电解质膜的电化学窗口达到4.6 V,锂离子迁移数为0.44,30℃时离子电导率为1.65 mS.cm-1;而DEC、DMC、EMC对电解质膜的电化学稳定性、锂离子迁移数存在不良的影响,对离子电导率的提高不明显。研究了正极材料LiCoO2在P(VdF-HFP)-EMIPF6-LiPF6+EC-PC电解质中的充放电循环性能,其首次放电比容量达到116.5 mAh.g-1,充放电20次后,电池容量没有明显衰减。

A composite polymer electrolyte of P（VdF-HFP）-EMIPF6-LiPF6 containing 1-ethyl-3-methylimidazolium hexafluorophosphate（EMIPF6） ionic liquid based on poly（vinylidene fluoride-co-hexafluroproptlene） [P（VdF-HFP）] polymer matrix was prepared.EMC,DMC,DEC,and EC-PC used as additive of the ionic liquid gel polymer electrolyte（ILGPE）,the influence of these additive in ILGPE on electrochemical properties was also investigated.The results show that the electrochemical stability window of P（VdF-HFP）-EMIPF6-LiPF6 joined with EC-PC is approximately 4.6 V,Li＋ transference number is 0.44,the ionic conductivity is 1.65 mS·cm-1 at 30 ℃.While DEC,DMC,EMC have an bad influence on the electrochemical stability of ILGPE and Li＋ transference number and also the ionic conductivity.In combination of the prepared P（VdF-HFP）-EMIPF6-LiPF6＋EC-PC ionic liquid gel polymer electrolytes,LiCoO2 cathode exhibits the initial discharge capacity of 116.5 mAh·g-1 and the capacity remain steady after 20 cycles.