Towards dendrite-free Zn metal batteries via formation of fluorinated interfacial layer with functional additive

Abstract

Rechargeable aqueous zinc metal batteries are considered as an alternative in grid-scale energy storage since they offer several intrinsic merits that make them a promising choice including absolute safety, abundant reservoir, cost-effectiveness and sustainability, whereas the Zn anode sustained poor reversibility induced by active water-related parasitic reaction and uncontrollable Zn dendrite growth. In this work, we employed fluorophosphate ester (FEP) as functional additive for ZnSO4 aqueous electrolyte, which not only participated in the formation of protective fluorinated layer on surface of Zn electrode to facilitate the Zn2+ diffusion, but also preferentially adsorb on the Zn surface to manipulate the Zn deposition orientation. Consequently, dendrite-free Zn anode was achieved with extended cycling span of over 1800 h at 10 mA cm−2, 10 mAh cm−2 in Zn symmetric cell and appealing Coulombic efficiency up to 98.9% after 500 times of zinc plating/stripping in Zn||Cu asymmetric cell. Additionally, the FEP contained electrolyte supports full cells work when paired with MnO2 and commercial LiFePO4 cathode. This feasible strategy with electrolyte functional additive provides insightful direction in the design of interfacial layers to harvest stable Zn anodes in aqueous metal-based battery technology.