Polymer electrolytes based on electrospun polyimide (PI) membranes are incorporated with electrolyte solution containing 1 mol L-1 LiPF6/ethylene carbonate/ethylmethyl carbonate/dimethyl carbonate to examine their potential application for lithium ion batteries. The as-electrospun non-woven membranes demonstrate a uniformly interconnected structure with an average fiber diameter of 800 nm. The membranes, showing superior thermal stability and flame retardant property compared to the commercial Celgard (R) membranes, exhibit high porosity and high uptake when activated with the liquid electrolyte. The resulting PI electrolytes (PIs) have a high ionic conductivity up to 2.0 x 10(-3) S cm(-1) at 25 degrees C, and exhibit a high electrochemical stability potential more than 5.0 V (vs. Li/Li+). They also possess excellent charge/discharge performance and capacity retention. The initial discharge capacities of the Li/PIs/Li4Ti5O12 cells are 178.4, 167.4, 160.3, 148.3 and 135.9 mAh g(-1) at the charge/discharge rates of 0.2 C, 1C, 2C, 5C and 10C, respectively. After 200 cycles at 5C, a capacity around 146.8 mAh g-1 can be still achieved. The PI-based polymer electrolytes with strong mechanical properties and good electrochemical performance are proved to be promising electrolytes for lithium ion batteries. (C) 2014 Elsevier Ltd. All rights reserved.