Aqueous Na-ion batteries are promising candidates for sustainable energy storage due to the high abundance of Na, the ready availability of water, and the improved safety of aqueous electrolytes. However, aqueous batteries are often limited in their energy storage capability because of the narrow electrochemical stability window of water. We designed a sustainable and safe aqueous Na-ion full cell containing only vanadium as transition metal ion for improved recyclability and sustainability, employing V 3 O 7 ·H 2 O as positive and VO 2 as negative electrode material. After screening several electrolyte compositions by varying Na-salts, Na-salt concentrations, and additives via galvanostatic cycling, cyclic voltammetry and electrical impedance spectroscopy in half-cell configurations, we identified 17.1 m NaClO 4 with 5.5 m glucose as suitable electrolyte. Its water-in-salt and crowding properties were experimentally verified via Fourier Transform Infrared Spectroscopy and ionic conductivity measurements. The corresponding full cell achieved a superior potential window of 2 V and a competitive initial specific capacity of 83.6 mA·h∙g -1 at a current density of 30 mA∙g -1 . Moreover, it showed excellent stability with a capacity retention of 89% and a coulombic efficiency above 98% after 1000 cycles. This study demonstrates that the design of competitive battery cells is possible while respecting sustainability criteria. • Crowded WiSE with NaClO 4 and glucose unlocks a potential window of 2 V. • The full ASIB delivered 83.6 mA·h∙g -1 with 92% capacity retention after 50 cycles. • After 1000 cycles, the battery shows capacity retention of 89% and a CE >98%. • All-vanadium battery chemistry improves recyclability and sustainability.
Lam-Chen et al. (Fri,) studied this question.