Trifluoracetic Acid-Driven (002) Facet Engineering of Zn Metal Powder Anodes for High-Performance Aqueous Zinc-Ion Batteries

Abstract

Zinc metal powder (ZnMP) anodes present significant advantages over conventional zinc foil anodes in aqueous zinc-ion batteries (AZIBs), offering higher electrochemically active surface area and improved mass utilization. However, the 3D morphology of ZnMP particles poses challenges for crystallographic control, as their random orientations and large surface areas intensify hydrogen evolution reactions (HER), corrosion, and dendritic growth. Here, a dual-functional etching strategy using trifluoroacetic acid (TFA) is reported to selectively modify ZnMP surfaces and enrich thermodynamically stable (002) crystal planes. Upon dissociation, TFA releases H+ ions that preferentially etch high-energy facets, while CF3COO− anions selectively adsorb onto (002) planes, forming protective layers that stabilize the etching process. This treatment produces a distinctive stepped hexagonal morphology enriched in (002) planes that mitigates parasitic reactions and promotes uniform zinc deposition. The TFA-modified ZnMP (TFA@ZnMP) electrodes exhibit remarkable stability, operating for over 1000 h in symmetric cells. In practical 4 × 3 cm2 pouch cells paired with V2O5 cathodes, the electrodes retain 79.8% of their capacity after 1000 cycles at 10 A g−1. Density functional theory calculations and phase-field modeling confirm the preferential ion adsorption mechanism and its contribution to enhanced electrochemical performance. These findings establish this surface-engineering strategy as a scalable pathway for high-performance AZIBs.