Hybrid Aqueous/Organic Electrolytes Enable the High-Performance Zn-Ion Batteries

Abstract

Rechargeable aqueous zinc ion batteries (ZIBs) are considered as one of the most promising systems for large-scale energy storage due to their merits of low cost, environmental friendliness, and high safety. The utilization of aqueous electrolyte also brings about some problems such as low energy density, fast self-discharge, and capacity fading associated with the dissolution of metals in water. To combat the issues, we utilize a freestanding vanadium oxide hydrate/carbon nanotube (V 2 O 5 ·nH 2 O/CNT) film as the cathode and probe the performance in aqueous/organic hybrid electrolytes. The corresponding structural and morphological evolution of both V 2 O 5 ·nH 2 O/CNT cathode and Zn anode in different electrolytes is explored. The integrity of electrodes and the suppression of zinc dendrites during cycles are largely improved in the hybrid electrolytes. Accordingly, the battery in hybrid electrolyte exhibits high capacities of 549 mAh g -1 at 0.5 A g -1 after 100 cycles and 282 mAh g -1 at 4 A g -1 after 1000 cycles, demonstrating an excellent energy density of 102 Wh kg -1 at a high power of 1500 W kg -1 based on the cathode.