A polymer electrolyte was successfully fabricated for a room temperature operation lithium battery by cross-linking the mixture of oligomeric poly (ethylene glycol) dimethylether (PEGDME) and poly (ethylene glycol) diacrylate (PEGDA) with Li(CF3SO2)2N using electron beam irradiation. The maximum ionic conductivity achieved for the cross-linked solid polymer electrolyte (c-SPE) at room temperature was 2.1×10−4 Scm−1 and the lithium transport number of the electrolyte was around 0.2. The c-SPE showed no reaction heat with lithium metal up to 300°C. The interface resistance of Li/c-SPE/Li at room temperature was about 45Ωcm2, which is considerable lower than that of 210Ωcm2 for Li/PEO10Li(CF3SO2)2N/Li. The electrochemical window of the polymer electrolyte was above 4V (versus Li+/Li). The initial discharge capacity for the Li/SPE/LiFePO4-C cell was approximately 90mAhg−1 for LiFePO4-C at 1/10°C rate at room temperature and showed a good cyclability and a high coulombic efficiency of 99.2%.