Multifunctional Optimization Enabled by the Space Design of a Non-Toxic Fluoride Protective Layer for Dendrites-Free and Corrosion-Resistance Zinc Anodes

Aqueous zinc-ion batteries (AZIBs) are among those of focus in the research realm of next-generation electric energy storage, benefiting from their intrinsic safety, high volumetric capacity and low cost. Nonetheless, the problems of lifespan and reversibility caused by dendrites, hydrogen evolution and corrosion reactions restrict the large-scale commercialization of AZIBs. Herein, a multifunctional strategy has been explored in this research, of which the porous submicron-CaF₂ layer with uniform channels is applied to the zinc anode by employing a straightforward, low-cost method. Moreover, the submicron-CaF₂ coating can provide abundant submicron channels, restricting the free diffusion of Zn²⁺ and effectively preventing the growth of zinc dendrites. Additionally, a series of characterizations reveal that the Zn@CaF₂ anode has a high cycle reversibility due to the marked suppression of the corrosion and hydrogen evolution reactions provided for the desolvation effects of CaF₂. Consequently, the Zn@CaF₂ symmetrical cell afforded a long cycling lifespan for more than 1850 h at 1 mA cm^-2. Importantly, even at a high current of 8 mA cm^-2, the symmetrical cell can stably maintain for 2000 cycles. As a proof of the strategy, the entire Zn@CaF₂//Zn₃V₂O₈∙1.85H₂O cell outperformed the full cell with bare Zn anode through superior capacity retention.