Bridging the Safety-Performance Gap: A Comparative Study of Graphite Versus Niobium Tungsten Oxide Anodes and Carbonate Versus Ether Electrolytes for Lithium-Ion Batteries

Abstract Niobium tungsten oxides (NbWOs) have been reported to have excellent performance in fast-charging and low-temperature conditions, especially with a cyclopentyl methyl ether (CPME)-based electrolyte, though its safety profile remains uncharacterized compared to standard graphite anodes and carbonate-based commercial electrolytes (CommLEs). Herein, differential scanning calorimetry (DSC) is employed to probe the heat release of cycled graphite and NbWO anodes using the CommLE and CPME electrolytes in both the lithiated and delithiated states with a 2 × 2 × 2 factorial experimental design. Cell combinations utilizing the CPME electrolyte tended to release more exothermic heat than the equivalent systems using the CommLE electrolyte (ex. lithiated NbWO released 56.6 J g−1 with CommLE but 354.4 J g−1 with CPME). However, the cycled NbWO anodes released less heat than the graphite anodes (ex. 200.2 J g−1 for NbWO compared to 327.2 J g−1 for graphite for delithiated anodes with CPME). This is attributed to the lack of a conventional solid-electrolyte interphase (SEI) on the NbWO anodes due to their cycling voltage window. Comparing the tailored NbWO/CPME and conventional graphite/CommLE systems, the exothermic heat released decreased to 354.4 J g−1 for NbWO/CPME from 615.2 J g−1 for graphite/CommLE, verifying the safety of this system from a heat-release perspective.