Ti4O7 coating creates a highly stable Zn anode for aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) are one of the most promising energy storage devices owing to their high capacity, low cost, high safety, and environmental friendliness. However, the corrosion of the zinc metal and dendrite growth hinder the commercialization of AZIBs. To solve these problems, a hydrophilic titanium suboxide (Ti₄O₇)-coating method was proposed for the formation of a protective layer on the zinc foil surface through a scraping technique. Experimental studies and DFT calculations were performed to verify its effects on Zn anode protection. The growth of dendrites was inhibited by the Ti₄O₇-coating layer because of the merits of high conductivity, hydrophilicity, and high affinity for Zn through accelerating the transport of zinc ions, providing more nucleation sites and uniform electric field distribution. The Ti₄O₇ coating also provides physical protection against the direct contact between the electrolyte and zinc to effectively inhibit the occurrence of hydrogen evolution and corrosion. The Ti₄O₇@Zn anode exhibits an ultra-long cycling life of over 5900 h at 1 mA cm⁻² and a stable cycle of up to 3200 h even at 5 mA cm⁻². Based on the above results, the Ti₄O₇@Zn//MnO₂ battery shows good cycling stability and rate performance. This work provides a convenient and practical strategy to achieve a high-performance Zn anode for AZIBs.