Appoication of Oxalate Inorganic Filler to Impove Ionic Conductivity of Solid Polymer Electrolyte

초록

All-Solid-State Batteries (ASSBs) are proposed as the next-generation energy storage systems to overcome the safety issues associated with existing lithium-ion batteries (LIBs). LIBs suffer from flammability, corrosiveness, electrolyte leakage, and other safety concerns. Therefore, ASSBs, which replace liquid electrolytes with solid-state materials, are gaining attention for their enhanced safety and energy density. Depending on the electrolyte material, ASSBs can be categorized into sulfide-based, oxide-based, and polymer-based systems. The polymer-based electrolyte used in this study offers excellent flexibility and formability, leading to high adhesion to electrodes and compatibility with existing roll-to-roll manufacturing processes. However, it suffers from the drawback of low ionic conductivity at room temperature. Accordingly, strategies are being attempted to increase ionic conductivity by reducing the crystallinity of the polymer and adding inorganic fillers to the solid polymer electrolyte. In this study, nickel mesh coated with oxalate was electrochemically treated to produce an inorganic filler for composite solid polymer electrolyte (CSPE), enhancing the ionic conductivity of poly(ethylene oxide). A comparative analysis was conducted between the solid polymer electrolyte (SPE) without fillers and CSPE with inorganic fillers. Basic physical properties were evaluated by examining the surface shape of SPE through a scanning electron microscope, glass transition temperature, and degree of crystallinity through differential scanning calorimetry. Additionally, the ionic conductivity of SPE and CSPE was compared using electrochemical impedance spectroscopy, which confirmed an increase in ionic conductivity in CSPE. Subsequently, complete cells with LiFePO4 as the cathode were assembled to evaluate their electrochemical performance.