Cathode-electrolyte interface modification by electrolyte engineering for vanadium-based zinc-ion batteries

The vanadium (V)-based cathode of aqueous zinc-ion batteries (ZIBs) faces the problem of rapid capacity decay due to material dissolution and structural collapse during the continuous cycling process. Here, we present a strategy to convert the irreversible cathode-electrolyte interphase (CEI) layer of the NH 4 V 4 O 10 (NVO) cathode into a protective layer by incorporating alkali metal sulfate as an additive. After the introduction of Na + , the dynamic consumption and replenishment of OH – during the conversion of Zn 3 (OH) 2 V 2 O 7 ·2H 2 O and Na 2 ZnV 2 O 7 regulates the pH value on the surface of the NVO cathode and inhibits the occurrence of side reactions. The NVO cathode exhibits a higher specific capacity (from 371.8 to 407.8mAh g −1 at 0.1 A g −1 ), better capacity retention (from 30.5 % to 65.9 % after 150 cycles), and superior rate capability after Na + introduction. Additionally, the Na + additives could be also applied for other V-based materials (e.g., V 2 O 5 and VO 2 ) to significantly improve the capacity retention rate. This strategy of incorporating alkali metal sulfate electrolyte additives to fortify cathode cycling stability serves to expedite the transition of aqueous ZIBs from the realm of academia to the industrial sector.