Using redox electrolytes to extend the charge storage capacity in an aqueous hybrid ion battery

Aqueous hybrid Zn2+/Na+ ion batteries (AHZSIBs) have gained considerable attention for stationary energy storage applications because of their outstanding safety, sustainability, abundance, and low raw material costs. However, the capacity values (<100 mAh/g) Na+ deinsertion/insertion cathodes limit overall AHZSIBs. Herein, we propose a novel concept to extend charge performance AHZSIBs using electrolyte with redox characteristics. The benefits aqueous electrolytes such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) sodium ferrocyanide (Na4[Fe(CN)6]) were investigated in an AHZSB, which consists Zn metal anode nickel hexacyanoferrate (Na-NiHCF) cathode. proposed AHZSB Na4[Fe(CN)6] provided (144 that was ~2.94 times higher than AHZSIB conventional Na2SO4 (49 mAh/g). This enhancement emanated from faradaic contribution Fe2+(CN)64−/Fe3+(CN)63− pair present Fe2+/Fe3+ lattice Na-NiHCF. In addition, TEMPOL-based also improved (from 49 120 through combined TEMPOL/TEMPOL+ dissolved Na-NiHCF lattice. These results confirm competence enhancing capacity. We anticipate this proof-of-concept study will provide new direction developing high-capacity More importantly, approach can be used any aqueous/non-aqueous batteries.