A facile coating strategy for high stability aqueous zinc ion batteries: Porous rutile nano-TiO2 coating on zinc anode

Abstract

Rechargeable aqueous zinc ion batteries have attracted significant attention because of their non-toxicity, high theoretical capacity, and low cost. However, many challenges regarding zinc anodes have hindered the development of zinc ion batteries, such as the growth of zinc dendrites, passivation and hydrogen evolution. In this study, a simple strategy based on porous rutile nano-TiO2 coating was used to guide uniform deposition of zinc ions to inhibit the formation of zinc dendrite. The TiO2 coated zinc anode shows excellent electrochemical performance. Therefore, for ZnZn symmetric cell, the zinc anode protected by TiO2 coating shows reduced voltage hysteresis (50 mV at 0.4 mA cm−2). Moreover, for Zn-MnO2 full cell, the cell with TiO2 coating also shows excellent cycling performance. The discharge capacity of Zn-MnO2 full cell is only 27.69 mAh g−1 after 500 cycles, while discharge capacity of Zn@TiO2-MnO2 full cell is up to 89.14 mAh g−1. This excellent electrochemical performance may be attributed to improved wettability of TiO2 coated zinc anode, the uniform deposition of Zn2+ and reduction of Zn dendrites. Overall, this study provides a simple and beneficial strategy for future development of rechargeable aqueous zinc ion batteries.