复合凝胶聚合物电解质的制备及电化学性能

Electrochemical Properties and Preparation of Composite Gel Polymer Electrolyte

以偏氟乙烯和六氟丙烯共聚物为基体,通过与聚甲基丙烯酸甲酯共混,加入导电盐LiPF6、增塑剂聚乙烯吡咯烷酮,制备了高电导率的复合凝胶聚合物电解质(CGPE)。用红外光谱测试了聚合物电解质膜的结构,用交流阻抗法测试了CGPE的导电性能,用线性扫描伏安法研究了它的电化学稳定性。测试了以CGPE为电解质制备的锂离子电池的充放电性能。结果表明,当聚甲基丙烯酸甲酯(PMMA)质量分数为20%时,CGPE电导率大于10-3S/cm,在4.65 V电化学窗口以下稳定。以磷酸亚铁锂为正极时,在0.1 C和0.2 C倍率下放电时,聚合物电解质电池的首次放电容量分别为138 mAh/g和98.3 mAh/g。

The composite gel polymer electrolyte （CGPE） with high ionic conductivity was prepared, in which poly（vinylidene fluoride-hexafluoropropylene （PVDF- HFP） served as the based polymer, polymethyl methacrylate （PMMA） as the blending agent, LiPF6 as the conducting salt, and polyvinylpyrrolidone （PVP） as the plasticizer. The structures were characterized by using IR, the ionic conductivity was determined by AC impedance, and the electrochemical stability was measured by linear sweep voltammetry. The charge-discharge properties of the Li-ion batteries in which the CGPE served as membrane were investigated. The results show that the CGPE conductivity is more than 10^-3 S/cm, and electrochemical window is stable under 4. 65 V when 20% PMMA was mixed. When using LiFePO4 as the cathode material, the initial discharge capacities of Li-ion cell in the CGPE were 138 and 98.3 mAh/g at 0. 1 C and 0.2 C rate respectively.