Regioisomerism-guided interfacial design toward stable zinc metal anodes

Abstract

The interfacial instability of zinc metal anodes is one of the key obstacles limiting the practical commercialization of aqueous zinc-ion batteries (AZIBs). In recent years, the introduction of small organic molecule additives into electrolytes has demonstrated great potential for regulating the zinc/electrolyte interfacial behavior. However, the unique regioisomeric effects of these additives and the structure–function relationships underlying their adsorption configurations remain largely unexplored. In this work, pyridinecarboxamide molecules were selected as a model system to systematically investigate the interfacial regulation behavior of three regioisomers—picolinamide, nicotinamide, and isonicotinamide—at the zinc metal anode. Specifically, picolinamide (PA), with its amide group positioned ortho to the pyridine nitrogen, forms a stable bidentate coordination structure. This configuration facilitates Zn²⁺ desolvation at the electrode interface and induces a uniform and compact adsorption layer formation, thereby promoting uniform zinc deposition while suppressing side reactions and dendrite growth. Consequently, the PA-containing electrolyte significantly enhances the stability of zinc anodes, achieving a cycling lifespan exceeding 6000 h in Zn//Zn symmetric cells and an average coulombic efficiency of 99.87% over 6000 plating/stripping cycles in Zn//Cu half cells. This work underscores the crucial role of regioisomerism in electrolyte additive design and provides a viable molecular-level strategy for constructing stable zinc metal anodes.