Lithium batteries are plagued with safety concerns due to their use of conventional liquid electrolytes that typically consist of flammable organic solvents, which has galvanized research efforts into solid electrolyte alternatives. Among solid electrolytes, composite polymer electrolytes (CPEs) are poised to be one of the most promising alternatives to liquid electrolytes due to their mechanical stability, electrochemical stability, cost, and processability. While the ionic conductivities of most polymer electrolytes are several orders of magnitude lower than their liquid electrolyte counterparts, the integration of filler materials greatly enhance CPE ionic conductivities by promoting the amorphous phase of the polymer matrix and providing ionic transport pathways through the electrolyte. Poly (ethylene glycol) diacrylate (PEGDA) is an emerging polymer in the field of CPE research due to its high electrochemical stability window and simple preparation methods. PEGDA-based solid electrolyte can be cross-linked with ultraviolet light and avoid the addition of flammable solvents. Much of the research on PEGDA electrolytes have been focused on the incorporation of liquid electrolytes, incorporation of passive fillers, addition of active fillers, and the effects of plasticizers such as succinonitrile (SN), achieving ionic conductivities on the order of 10-4 S/cm. This study systematically examines the effects of passive filler (V2O5) and plasticizer (SN) on electrolyte ionic conductivity in a PEGDA electrolyte matrix at various concentrations. The synergistic effects of adding both V2O5 and SN promote a higher ionic conductivity of the electrolyte than electrolytes containing only SN. These effects were further inferred from morphological and chemical composition characterizations using x-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS). Through a combination of 45% SN and 8% V2O5, an ionic conductivity of 9.6x10-4 S/cm is achieved in an all-solid-state PEGDA electrolyte, which is nearly an order of magnitude higher than electrolytes containing only SN. This study demonstrates the effects of combining fillers with plasticizers to optimize electrolyte ionic conductivities and identifies methods to increase the conductivities of polymer electrolytes beyond the limits of individual filler materials.
