The solvent-free hybrid solid electrolytes composed of lithium aluminum germanium phosphate (LAGP) and poly (ethylene oxide)(PEO) were prepared in the form of flexible film, and their electrochemical characteristics were investigated. The addition of ion-conductive LAGP powder into PEO-based solid polymer electrolyte improved the electrical and mechanical properties of solid electrolytes. For the hybrid solid electrolytes examined in this study, the optimum composition of LAGP was found to be about 60∼ 80 wt% in consideration of ionic conductivity, mechanical stability and formability for flexible thin film. The all solid-state Li/LiFePO 4 cell assembled with hybrid solid electrolyte delivered an initial discharge capacity of 137.6 mAh g− 1 and exhibited good cycling stability at 55 C.