Aqueous rechargeable zinc/sodium vanadate batteries with enhanced performance from simultaneous insertion of dual carriers

TLDR

Rechargeable aqueous zinc‑ion batteries promise high safety and low cost, yet progress is limited by scarce high‑capacity positive electrodes and poorly understood mechanisms. This work presents a highly reversible zinc/sodium vanadate battery, employing sodium vanadate hydrate nanobelts as the cathode and a zinc sulfate/sodium sulfate aqueous electrolyte. Its superior performance stems from a simultaneous proton and zinc‑ion insertion/extraction process, delivering a reversible capacity of 380 mAh g⁻¹.

Abstract

Rechargeable aqueous zinc-ion batteries are promising energy storage devices due to their high safety and low cost. However, they remain in their infancy because of the limited choice of positive electrodes with high capacity and satisfactory cycling performance. Furthermore, their energy storage mechanisms are not well established yet. Here we report a highly reversible zinc/sodium vanadate system, where sodium vanadate hydrate nanobelts serve as positive electrode and zinc sulfate aqueous solution with sodium sulfate additive is used as electrolyte. Different from conventional energy release/storage in zinc-ion batteries with only zinc-ion insertion/extraction, zinc/sodium vanadate hydrate batteries possess a simultaneous proton, and zinc-ion insertion/extraction process that is mainly responsible for their excellent performance, such as a high reversible capacity of 380 mAh g