Alternative energy storage system research has recently undergone a paradigm shift toward inherently safer and more sustainable design, causing the adoption of lithium iron phosphate (LFP) batteries as a global alternative to many nickel or cobalt based battery cathodes. LFP cathodes demonstrate improved stability at the cost of decreased capacity and energy density in comparison to high energy NMC cathodes. Additionally, most state-of-the-art batteries require the use of flammable liquid electrolytes which pose significant safety risks during battery failure involving pressurization of battery cells and potential risk of thermal runaway reactions. Many research efforts have unified in identifying less flammable electrolyte alternatives to both mitigate the safety hazards of liquid electrolytes and enhance the energy density of battery systems. Among these alternatives, solid polymer electrolytes (SPEs) are at the forefront of research due to their mechanical, chemical, and electrochemical stability; ease of processability; and low-cost alternative to other solid electrolytes. Poly (ethylene glycol) diacrylate (PEGDA), for example, is a highly promising cross-linkable polymer that is liquid at room temperature, which allows for facile incorporation of lithium salts and filler materials for electrolyte preparation without the addition of flammable solvents. Through the addition of 8% vanadium pentoxide (V2O5) and 40% succinonitrile (SN), this SPE achieves a high room temperature ionic conductivity of 6.7x10-4 S/cm. Half cells with an LFP cathode demonstrated remarkable initial capacities nearing 160 mAh/g at C/20 and show promising cycle life and rate capability. This SPE was further characterized using XRD, SEM/EDS, and FTIR to support the synergistic effects observed of the combined V2O5 and SN filler materials. The correlation of electrochemical performance and ionic conductivity will be discussed. This work demonstrates the efficacy of combining filler materials for solid state battery electrolytes and further explores the role of ionic conductivity in electrochemical performance of SPEs.
