Lithium-salt-free polyoxovanadates/cellulose acetate-poly(ethylene glycol) nanocomposite solid electrolytes with enhanced electrochemical properties

Solid polymer electrolytes (SPEs) have been regarded as one of the most encouraging choices for lithium-based cells of the future generation as they further boost battery energy density and do away with any potential safety risks associated with liquid organic electrolytes. Nevertheless, solid electrolytes' restricted ion conductivity hinders their hands-on applications. In this work, lithium-ion conductor SPEs based on polymer/polyoxovanadates nanocomposites are fabricated by a facile cast solution method. Polyoxovanadate Li₇[V₁₅O₃₆(CO₃)] (LVC) possesses a high diffusion coefficient which acts as lithium salt. The dual function role of polyoxovanadates in the diffusion of Li⁺ cations and reducing the crystallinity of polymer leads to high ion conductivity of 4.1 × 10^-4 S cm^-1 at room temperature. Moreover, compared to the routine CA-PEG1000-LiPF₆ electrolyte, the SPE with LVC had a broader electrochemical voltage window of more than 5 V. The excellent performance as lithium salt and inorganic filler and its role in reducing the crystallinity of polymers and providing mobile cations in polymer matrix, and acceptable electrochemical properties, including considerable transference number (t⁺) 0.59, good stability of electrode/electrolye interface after 100 h Li plating/stripping without short-circuiting, and good specific capacity (226 mAh g^-1 of LiCoO₂/CA-PEG1000-LVC/Gr at 0.1 C) suggest LVC as lithium salt and also as inorganic fillers for designing new SPEs with high performance for next-generation lithium-based batteries.