Considering the safety problem that is caused by liquid electrolytes and Li dendrites for lithium batteries, a new quasi-solid-state polymer electrolyte technology is presented in this work. A layer of 1,4-phenylene bridged polysilsesquioxane (PSiO) is synthesized by a sol-gel way and coated on the electrospun polyacrylonitrile (PAN) nanofiber to prepare a PAN@PSiO nanofiber composite membrane, which is then used as a quasi-solid-state electrolyte scaffold as well as separator for lithium batteries (LBs). This composite membrane, consisting of the three-dimensional network architecture of the PAN nanofiber matrix and a mesoporous PSiO coating layer, exhibited a high electrolyte intake level (297 wt%) and excellent mechanical properties. The electrochemical analysis results indicate that the ionic conductivity of the PAN@PSiO-based quasi-solid-state electrolyte membrane is 1.58 × 10-3 S cm-1 at room temperature and the electrochemical stability window reaches 4.8 V. The optimization of the electrode and the composite membrane interface leads the LiFePO4|PAN@PSiO|Li full cell to show superior cycling (capacity of 137.6 mAh g-1 at 0.2 C after 160 cycles) and excellent rate performances.
Keywords: electrospun polyacrylonitrile; lithium batteries; polysilsesquioxane; quasi-solid-state polymer electrolyte; separator; sol-gel preparation.