An Industrially Applicable Passivation Strategy for Significantly Improving Cyclability of Zinc Metal Anodes in Aqueous Batteries

The cycling instability of metallic Zn anodes hinders the practicability of aqueous Zn-ion batteries, though aqueous Zn-ion batteries may be the most credible alternative technology for future electrochemical energy storage applications. Commercially available trivalent chromium conversion films (TCCF) are successfully employed as robust artificial interphases on Zn metal anodes (ZMAs). Fabricated through a simple immersion method, the TCCF-protected Zn (TCCF@Zn) electrode enables a superlow nucleation overpotential for Zn plating of 6.9 mV under 1 mA cm-2, outstanding Coulombic efficiency of 99.7% at 3 mA cm-2 for 1600 cycles in Zn||Cu asymmetric cells and superior cyclability in symmetric Zn||Zn batteries at 0.2, 2, and 5 mA cm-2 for 2500 h and 10 mA cm-2 for 1200 h. More importantly, the TCCF@Zn||V2O5 full cell exhibits a specific capacity of 118.5 mAh g-1 with a retention of 53.4% at 3 A g-1 for 3000 cycles, which is considerably larger than that of the pristine Zn||V2O5 full cell (59.7 mAh g-1 with a retention of 25.7%). This study demonstrates a highly efficient and low-cost surface modification strategy derived from an industrially applicable trivalent chromium passivation technique aimed at obtaining dendrite-free ZMAs with high reversibility for practical Zn batteries in the near future. An industrially applicable passivation strategy of zinc plating by a simple dipping treatment is adopted to grow trivalent chromium conversion films (TCCF) as artificial interphases for Zn metal anodes. The facile preparation process and superior electrochemical performance of TCCF@Zn offer an exciting possibility for the practicability of metallic zinc anodes in aqueous zinc batteries.image