Developments of electrolytes have been progressed in various fields with increasing demand for electrical energy storage devices. In particular, gel polymer electrolytes (GPEs) can improve safety and cycle life due to excellent physical properties, attempts to replace the organic liquid electrolyte are ongoing. However, intrinsic poor electrochemical properties of GPE restrict the commercialization of all-solid-state energy storage devices. Poly(ethylene glycol oxide) (PEO) chain-based electrolyte is representative of polymer electrolytes owing to good salt solvation ability and ion conduction characteristics, but it has a problem with weak physical properties. In an attempt to solve this problem, it was reported that forming an interpenetrating polymer network (IPN) by adding different kinds of polymer network/linear polymer can supplement the deficient electrochemical/physical characteristics of a single polymer network electrolyte. We researched on designing two different IPN electrolytes and applying energy storage devices. First, we fabricated enhanced ion-conducting GPE that poly(ethylene glycol) type hetero-network form IPN with high strength epoxy network electrolyte (~ 6.5 × 10-4 S/cm σ_DC, 5.3 × 106 Pa Gʹ at room temperature). Then, an all-solid-state supercapacitor using the electrolyte has improved specific capacitance and energy density (~ 209.4 F/g, 851.4 W/kg) compared to a non-IPN electrolyte supercapacitor. Second, we researched strengthening poly(methyl methacrylate) based electrolytes by forming semi-IPN with thermoplastic polyurethane. The mechanical strength of the produced semi-IPN GPE was improved by 388%, and it was applied to lithium metal battery that has excellent lithium-ion diffusion properties ( ~ 5.7 × 10-11 cm2/s DLi+) at cathode-electrolyte interface.