高性能锂离子电池隔膜的结构设计及其制备与表征  

Design and Characterization of High Performance Electrospun Separator for Lithium Ion Battery

作　　者：姜红娟[1,2] 张燕青[1,2] 吴大勇[1] 于晓慧[1] 操建华[1] 

机构地区：[1]中国科学院理化技术研究所,北京100190 [2]中国科学院大学,北京100049

出　　处：《高分子学报》2015年第11期1271-1279,共9页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21272243;20904064);中国科学院战略性先导科技专项(基金号XDA09010105)资助

摘　　要：设计并采用高压静电纺丝法制备了单层结构的聚偏氟乙烯(PVDF)/偏氟乙烯与六氟丙烯的共聚物(PVDF-HFP)纳米纤维膜及三层结构、二层结构的PVDF/PVDF-HFP/Al2O3复合纳米纤维膜.复合膜的表面形貌、热物理性质和电化学性能通过扫描电子显微镜(SEM)、示差扫描量热法(DSC)、高温尺寸收缩率、交流阻抗法进行了表征.单层结构的PVDF/PVDF-HFP纳米纤维膜的纤维表面光滑,平均纤维直径2μm,纤维分布较均匀,而PVDF与Al2O3复合后的纤维表面粗糙,平均纤维直径变小,结晶度降低,吸液率增大.二层结构的PVDF/PVDF-HFP/Al2O3复合隔膜在170℃下受热1 h收缩率为3%.将3种结构的复合膜在1 mol/L Li PF6/(EC+DMC+DEC,1∶1∶1,W/W/W)电解质溶液中活化得到聚合物电解质.25℃时,二层结构的PVDF/PVDF-HFP/Al2O3复合隔膜吸液率高达497 wt%,离子电导率可达5.04×10-3S/cm,电化学稳定窗口达到4.62 V(Li/Li+).组装成Li Fe PO4/Li电池测试其电池性能,结果表明,二层结构的PVDF/PVDF-HFP/Al2O3复合膜朝向锂负极时,电池的循环性能更好,且与锂金属负极具有更好的相容性和界面稳定性.Poly （ vinylidene fluoride） （PVDF）/poly （ vinylidene fluoridehexafluoropylene ） （PVDF-HFP） monolayer nanofibrous membrane and PVDF/PVDF-HFP/A1203 multilayer composite nanofibrous membranes were successfully prepared by the electrospinning method. The surface morphology, crystallinity, dimensional thermal stability,and electrochemical properties of the composite nanofibrous membranes were characterized by scanning electron microscopy （SEM）, differential scanning calorimetry （DSC）, thermal shrinkage and alternating current （AC） impedance. The smooth surface and uniform distribution fibers morphology were obtained for the PVDF/PVDF-HFP monolayer nanofibrous membrane. This membrane are made of fibers of 2 ixm diameter. The coarse surface and thinner fiber diameter were observed for the composite membrane. Moreover,the composite membrane exhibits lower crystallinity and higher electrolyte uptake than PVDF/PVDF- HFP monolayer nanofibrous membrane. The dimensional shrinkage of PVDF/PVDF-HFP/A1203 bilayer composite membrane is 3% at 170μ for 1 h. Polymer electrolytes were prepared by immobilizing 1 mol/L LiPF6 in ethylene carbonate （EC）/dimethyl carbonate （DMC）/diethyl carbonate （ DEC ） in the membranes. The PVDF/PVDF-HFP/A1203 bilayer composite membranes exhibit a high electrolyte uptake of 497 wt%. The ion conductivity of the bilayer composite polymer electrolyte is 5.04×10^-3 S/cm at 25 ℃. Meanwhile, it has electrochemical stability at potentials higher than 4.6 V versus Li/Li＋. The three types of membranes were assembled with lithium iron phosphate （LiFePO4）/Li coin cells. The cell based on the PVDF/PVDF-HFP/ A1203 bilayer composite electrolyte presents good rate capabilities over various discharge current densities. The PVDF/PVDF-HFP/AI203 bilayer composite electrolyte has better compatibility and interface stability with lithium metal.

关 键 词：静电纺丝 复合纳米纤维膜 锂离子电池 界面稳定性 

分 类 号：TM912[电气工程—电力电子与电力传动]