A composite polymer membrane is prepared by coating poly(vinylidene fluoride) (PVDF) on the surface of a membrane based on methyl cellulose (MC) which is environmentally friendly and cheap. Its characteristics are investigated by scanning electron microscopy, FT-IR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The outer PVDF layers are porous which results in high electrolyte uptake and the lithium ion transference number is much larger than that of the pure MC. Moreover, the cell based on Li//LiFePO4 delivers high discharge capacity and good rate behavior in the range of 4.2–2.5 V when the composite membrane is used as the separator and the host of a gel polymer electrolyte, lithium as the counter and reference electrode, and LiFePO4 as cathode. The obtained results suggest that this unique composite membrane shows great attraction in the lithium ion batteries with high safety and low cost. A composite membrane, PVDF/MC/PVDF, is successfully made. As a host for gel polymer electrolyte, it delivers high lithium ion transference number and good mechanical performance. When used as separator in lithium ion batteries, it shows excellent rate behaviour and cycling performance. Display omitted •Methyl cellulose (MC) is environmentally friendly and cheap.•A composite polymer membrane is prepared by coating PVDF on the surface of a membrane from MC.•The composite membrane is used as the separator and the host of a gel polymer electrolyte.•The prepared gel polymer electrolyte shows excellent electrochemical performance.