In-situ coating of metal fluoride/polymer bi-layer protection for dendrite-free, anti-corrosive Zn-metal anode

Abstract

To pursue a highly safe, sustainable energy storage system, aqueous Zn metal batteries (AZBs) have emerged due to their great promises of non-flammability and cost-effective energy storage. However, the growth of Zn dendrites and the parasitic hydrogen evolution reaction (HER) in Zn metal anodes (ZMAs) have resulted in the failure of AZBs to meet commercial requirements. This study presents bi-layer-structured ZMA protection via a one-step coating of a hydrophilic polymeric outer layer and a zincophilic Ag-decorated inner layer (Ag0/ZnF2) through an in-situ displacement reaction by a silver fluoride (AgF) additive to synergistically suppress Zn dendrites and the HER. The AgF-guided bi-layered Zn protective layer (BSPL@Zn) plays a synergistic role in suppressing HER and ZMA corrosion but facilitating uniform Zn deposition, largely extending the short-circuiting time with a three-fold reduction in H2 gas evolution. BSPL@Zn demonstrates a robust Zn||Zn cell cycling over 1800 h at 5 mAh cm−2 of Zn plating capacity. The Zn||NH4V4O10 cell with BSPL@Zn exhibited stable cycling over 1000 cycles with 80% capacity retention. Crafting a bi-layered protection framework with an optimal material selection could offer a promising pathway for deploying ZMA in AZBs.