Mitigating HF in Quasi-solid State Electrolytes via Cerium Oxide Functionalized Nanoparticles

The growing shift toward renewable energy sources has intensified the need for more efficient energy storage technologies. Quasi-solid-state electrolytes (QSSEs) present a promising route by enabling the substitution of graphite anodes with lithium metal, thereby enhancing both energy density and overall performance. One strategy for fabricating QSSEs involves employing a polymer matrix that retains a small amount of solvent, combined with a lithium salt to facilitate Li-ion transport. Fluorinated anion-based salts are typically used; however, their susceptibility to hydrolysis under humid conditions leads to the formation of HF, which contributes to cathode degradation. This work investigates the incorporation of functionalized cerium oxide nanoparticles as HF scavengers in the electrolyte , with the goal of mitigating cathode damage and improving long-term electrochemical stability. Following surface modification of the nanoparticles with a tailored silane compound, membranes comprising PVdF-HFP and varying concentrations of CeO₂ were prepared via solvent casting, and their physical and electrochemical properties were systematically evaluated. After determining the optimal formulation, the HF scavenging ability was assessed by introducing water and observing corresponding changes in the electrolyte's behavior. Cells incorporating the nanofiller-enhanced membrane demonstrated improved longevity, even under humid conditions, when compared to those based on the unmodified polymer. Overall, the integration of functional nanofillers into QSSEs not only preserves the expected electrochemical performance but also enhances moisture tolerance by effectively scavenging residual water in the system.