Spontaneous grain refinement effect of rare earth zinc alloy anodes enables stable zinc batteries.

Abstract

Irreversible interfacial reactions at the anodes pose a significant challenge to the long-term stability and lifespan of zinc (Zn) metal batteries, impeding their practical application as energy storage devices. The plating and stripping behavior of Zn ions on polycrystalline surfaces is inherently influenced by the microscopic structure of Zn anodes, a comprehensive understanding of which is crucial but often overlooked. Herein, commercial Zn foils were remodeled through the incorporation of cerium (Ce) elements via the 'pinning effect' during the electrodeposition process. By leveraging the electron-donating effect of Ce atoms segregated at grain boundaries (GBs), the electronic configuration of Zn is restructured to increase active sites for Zn nucleation. This facilitates continuous nucleation throughout the growth stage, leading to a high-rate instantaneous-progressive composite nucleation model that achieves a spatially uniform distribution of Zn nuclei and induces spontaneous grain refinement. Moreover, the incorporation of Ce elements elevates the site energy of GBs, mitigating detrimental parasitic reactions by enhancing the GB stability. Consequently, the remodeled ZnCe electrode exhibits highly reversible Zn plating/stripping with an accumulated capacity of up to 4.0Ah cm-2 in a Zn symmetric cell over 4000h without short-circuit behavior. Notably, a ∼0.4Ah Zn||NH4V4O10 pouch cell runs over 110 cycles with 83% capacity retention with the high-areal-loading cathode (≈20mg cm-2). This refining-grains strategy offers new insights into designing dendrite-free metal anodes in rechargeable batteries.