Corrosion as the origin of limited lifetime of vanadium oxide-based aqueous zinc ion batteries

Aqueous zinc ion batteries are receiving increasing attention for large-scale energy storage systems owing to their attractive features with respect to safety, cost, and scalability. Although vanadium oxides with various compositions have been demonstrated to store zinc ions reversibly, their limited cyclability especially at low current densities and their poor calendar life impede their widespread practical adoption. Herein, we reveal that the electrochemically inactive zinc pyrovanadate (ZVO) phase formed on the cathode surface is the main cause of the limited sustainability. Moreover, the formation of ZVO is closely related to the corrosion of the zinc metal counter electrode by perturbing the pH of the electrolyte. Thus, the dissolution of VO2(OH)(2)(-), the source of the vanadium in the ZVO, is no longer prevented. The proposed amalgamated Zn anode improves the cyclability drastically by blocking the corrosion at the anode, verifying the importance of pH control and the interplay between both electrodes. Aqueous zinc ion batteries are good systems for large-scale energy storage. Here, the authors report that the corrosion of zinc metal anode is the origin of limited lifetime of vanadium oxide-based aqueous zinc ion batteries, and supressing corrosion improves the calendar and cycle lifetime markedly.

Automated summary

Aqueous zinc ion batteries are gaining popularity for large-scale energy storage due to their safety, cost, and scalability. However, the limited cyclability and poor calendar life of vanadium oxide-based batteries hinder their practical adoption. This study reveals that the formation of an inactive zinc pyrovanadate phase on the cathode surface is the main cause of limited sustainability and is correlated with the corrosion of the zinc metal anode. By controlling the pH and using an amalgamated zinc anode, the cyclability and lifetime of the batteries can be significantly improved.