A novel sandwiched composite membrane(SCM) was prepared by depositing alumina micro. particles between two layers of electrospun poly(vinylidene fluoride. co. hexafluor. opropylene) [P (VDF-HFP)] nanofibers through electrostatic spray deposition. The morphologies, thermal shrinkage, tensile properties and electrochemical properties of the separator and battery performance for cells made with the SCM were investigated. The results show a higher uptake of electrolyte for the SCM than the pure P(VDF-HFP) membrane(PHM). SCM can easily absorb the electrolyte to form gel polymer electrolytes(GPEs). The tensile strength of the SCM membrane is about 4.00 MPa when the elongation at break is 261.57%. The ionic conductivity of SCM GPEs is 1.61 x 10(-3) S/cm at room temperature and GPE shows a high electrochemical stability potential of 5.4 V. With LiCoCO2 as the cathode, the cell with SCM GPEs exhibits a high initial discharge capacity of 145 mA . h . g(-1).