Rechargeable Aqueous Zinc-Ion Batteries in MgSO4/ZnSO4 Hybrid Electrolytes.

MgSO4 is chosen as an additive to address the capacity fading issue in the rechargeable zinc-ion battery system of MgxV2O5·nH2O//ZnSO4//zinc. Electrolytes with different concentration ratios of ZnSO4 and MgSO4 are investigated. The batteries measured in the 1 M ZnSO4-1 M MgSO4 electrolyte outplay other competitors, which deliver a high specific capacity of 374 mAh g-1 at a current density of 100 mA g-1 and exhibit a competitive rate performance with the reversible capacity of 175 mAh g-1 at 5 A g-1. This study provides a promising route to improve the performance of vanadium-based cathodes for aqueous zinc-ion batteries with electrolyte optimization in cost-effective electrolytes.