2010 Volume 78 Issue 12 Pages 982-987
Two types of polyacrylonitrile (PAN) nano-fiber based nonwovens as separator for lithium ion battery, which consist of different fiber diameters, have been developed by an electrospinning technique. SEM observation exhibited that the electrospun PAN nano-fibers had homogeneous thicknesses, and their diameters were around 250 and 380 nm. The physical, electrochemical and thermal properties of the PAN nonwovens were characterized. The nonwovens possessed homogeneous pore size distribution with similar pore sizes to a polyolefin membrane separator. Moreover, they showed higher porosities, lower Gurley values than that of the polyolefin one. Cyclic voltammetry revealed that they were electrochemically stable in the voltage range of −0.5 to 4.5 V vs. Li0/Li+. They showed higher ionic conductivities than that of the polyolefin one in the temperature range of −10 to 60°C. Any internal short circuit was not observed for cells using them during charge-discharge tests. Cells using them showed better cycleabilities than that with the polyolefin one at −10 and 30°C. Besides, they showed better rate capabilities than a cell with the polyolefin one.