One-step targeted treatment for Zn flatting and protection

Aqueous zinc metal batteries (AZMBs) have shown great promise as the advanced energy storage systems. Unfortunately, the common Zn foil anode suffers from severe Zn dendrites growth and electrolyte corrosion, leading to limited application of AZMBs. Here, we prove that the Zn dendrites formation is bound up with the processing-induced step-edge structure on Zn foil anodes. Targeting to the high activity of the step-edge Zn, we design a solvent-controlled replacement reaction (Zn + SnF2 → Sn + ZnF2) to chemically flatten the step edges. Such treatment inhibits Zn nucleation along the step edges and guarantees uniform electric field distribution on Zn foil anode, thus enabling uniform Zn deposition without dendrites growth. In addition, the generated ZnF2 is embedded in polyvinylidene fluoride (PVDF) to work as an anticorrosion protective layer on Zn foil surface. The as-designed Zn anodes (Zn-SP) maintain dendrite-free and corrosion-free electrochemical Zn plating/stripping over 1500 h at 2 mA cm−2 and 2 mA h cm−2 in the symmetric cells. The Zn-SP‖CNT@MnO2 full cells also deliver high capacity retention of 98.6% at 1 A g−1 after 1600 cycles. This work provides a facile method as well as a new perspective of targeted surface treatment for developing stable metal anodes, such as Li, Na, K and Al.