热致相分离法制备聚偏氟乙烯-六氟丙烯多孔膜及其在聚合物锂离子电池中的应用

Preparation of PVDF-HFP porous membrane via thermally induced phase separation and application in lithium ion battery

采用热致相分离技术成功制备出聚偏氟乙烯-六氟丙烯(PVDF-HFP)多孔膜,相图分析表明,PVDF-HFP/环丁砜体系发生固-液分相.SEM显示膜由球晶和丝状结晶组成.随聚合物浓度增加,多孔膜的结晶度、孔隙率以及平均孔径均降低,由多孔膜制得的凝胶聚合物电解质膜,其吸液率和电导率也降低,但多孔膜的力学性能提高.所有样品在20℃时的电导率超过2×10-3S/cm,电化学窗口大于4.5 V.

Porous PVDF- HFP membranes were successfully prepared via thermally induced phase separation （TIPS）. Phase diagram of PVDF - HFP/sulfolane system showed that solid - liquid phase separation happened during TIPS process. SEM revealed that membranes were composed with spherulites and thread - like crystallization. With the increase in PVDF- HFP content, the crystallinity, porosity, average pore size decreased, which in turn decreased the electrolyte uptake and ionic conductivity of gel polymer electrolyte membranes prepared with porous membranes, but mechanical properties became good improved. Ionic conductivity of all gel polymer electrolyte membranes exceeded 2 × 10^3 S/cm at 20℃. Electrochemical stability window of two sam- ples are stable up to 4.5 V.