Electrochemical and Nanomechanical Properties of TiO2 Ceramic Filler Li-Ion Composite Gel Polymer Electrolytes for Li Metal Batteries

Ionically conductive polymers are a promising family of electrolytes for electrochemical devices, including batteries, and flexible electronics. The polymer electrolytes with an excellent mechanical property probably can inhibit the dendrites growth during charging/discharging. Herein, the mechanical properties of an N −methyl− N −propyl piperidinium bis(trifluoromethanesulfonyl)imide/poly(vinylidene fluoride-hexafluoropropylene) gel polymer electrolyte is improved through compositing with %TiO 2 nanoparticles. The gel polymer electrolyte shows increased loss modulus after compositing with 5 wt% TiO 2 , indicating that the inorganic nanoparticles can increase the viscous response of polymer electrolytes. The Li-ion conductivity shows a noticeable dependence on %TiO 2 and the highest ionic conductivity is obtained at 5 wt% TiO 2 . The presence of TiO 2 in the gel polymer electrolyte also allows for smaller interfacial resistance and a more stable Li−electrolyte interface upon long-term storage and battery cycling. As a result, when assembled with the LiFePO 4 and LiNi 0.6 Mn 0.2 Co 0.2 O 2 cathodes, the composite gel polymer electrolyte improves the full-cell performance, such as higher Coulombic efficiency, improved cycling stability, and more stable electrode–electrolyte interface.