A gel polymer electrolyte is prepared by soaking a polymer-coated separator in electrolyte solution that contains an inorganic additive. The porous polymer coated on the separator is gelled by soaking in an electrolyte solution to encapsulate a larger amount of electrolyte solution. By using the gel polymer electrolyte, lithium-metal–polymer cells composed of a lithium anode and V2O5 cathode are assembled and their cycling performances are evaluated. The effect of an inorganic additive (AlI3) on the cycling performance of Li/V2O5 polymer cells is investigated. The addition of AlI3 to the gel polymer electrolyte reduces the interfacial resistance and thus the cells exhibit a less capacity fading and better high rate performance.