In this paper we report on the preparation, mechanical/thermal properties and electrochemical performances of polyethylene terephthalate (PET) based on fibrous membranes and their use as separator in lithium ion battery. The preparation of PET fibrous membrane was performed by an electrospinning method. The morphology, mechanical/thermal properties and electrochemical performances of electrospun PET membrane were investigated by scanning electron microscopy (SEM), stress-strain test, thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), and charge-discharge techniques. The results show that the PET membrane has high tensile strength, good elongation, and excellent thermal stability. The cell assembled with PET membrane show better electrochemical stability and higher discharge capacity than that assembled with Celgard membrane. The obtained results suggest that PET membrane can be used as candidate separator for high performance rechargeable lithium ion battery. (C) 2012 Elsevier B.V. All rights reserved.