一种新型聚合物电解质的研制

合成了聚 (甲基丙烯酸甲酯 丙烯腈 甲基丙烯酸锂 ) (简记为PMAML)新型聚合物电解质基质材料 ,把它与聚偏氟乙烯 (PVDF)共混制备了凝胶化的聚合物电解质 .通过核磁共振波谱确定了PMAML的组份含量 ,并用扫描电镜观察了该聚合物基质膜的表面形貌 .利用交流阻抗技术测试了其电导率 ,室温下电导率可达2 5× 10 - 3S·cm- 1 .采用线性伏安扫描方法研究了该聚合物电解质的电化学稳定性 ,其电化学稳定窗口为4 5V .通过受限扩散实验测得电解质中离子的扩散系数为 8 12× 10 - 7cm2 ·s- 1 .组装的聚合物电解质锂离子电池首次充放电效率为 89% ,前 5次循环容量基本稳定 .

STUDIES ON A NOVEL POLYMER ELECTROLYTE

A copolymer P(MMA-AN-MALi) (PMAML) was synthesized by solution polymerization. It was then blended with PVDF for preparing porous membranes by solution casting,and the non-solvent or extraction step was unnecessary in this process.A novel gelled polymer electrolyte based on the blend of PMAML and PVDF was obtained by soaking the polymer membrane in organic liquid electrolytes.The composition of the copolymer was determined from its 1H-NMR spectrum,and the result showed that the molar ratio of MMA∶AN∶MALi was about 68.6∶21.5∶9.9.The surface structure of the polymer film was characterized by SEM.The pores were well distributed in the surface of the membrane and the porous size was about 5?μm.The ionic conductivity of the polymer electrolyte was measured by the AC impedance method,and it was about 2.5×10 -3S·cm -1 at room temperature.The electrochemical stability window was carried out on the stainless steel electrode with lithium metal electrodes as the reference and counter electrodes by the linear sweep voltammetry method.The polymer electrolyte was electrochemically stable under 4 5?V.The diffusion coefficient of salt in the polymer electrolyte was measured using Li/GPE/Li non-blocking cell by the restricted diffusion experiment,and the value was about 8 12×10 -7cm2·s -1.The coulombic efficiency of the lithium ion battery with the polymer electrolyte in the initial charge-discharge cycle was calculated to be about 89%,and the discharge capacity of the first five cycles changed only in a small range.The test results display that the polymer electrolyte based on blends of PMAML and PVDF was electrochemical stable and can be used in lithium ion batteries.