Network polymer electrolytes with free oligo(oxyethylene) chains as internal plasticizers were prepared by cross-linking poly(ethylene glycol) acrylates. The effects of salt concentration and properties of internal plasticizers on ionic conductivity were studied. Network polymer electrolytes with free oligo (oxyethylene) chains as internal plasticizers were prepared by cross-linking poly (ethylene glycol) acrylates. The effects of salt concentration and properties of internal plasticizers on ionic conductivity were studied.