Regulating Interfacial Molecular Configuration to Drive Facet-Selective Zn Metal Deposition

Abstract

The direct use of metal anode emerges as a key strategy in advancing high-energy-density batteries, applicable across non-protonic, aqueous, and solid-state battery systems. To enhance battery durability, one effective approach involves employing interfacial molecular modification to modulate metal's facet orientation, reducing the tendency of metals to form random and loose morphologies during deposition. Herein, we propose a model to elucidate how dicarboxylic acid molecules with varying alkyl chain lengths modulate their adsorption behavior and deposition rate on Zn surfaces, achieving facet-selective Zn deposition. Taking glutaric acid (GA) as an example, its medium alkyl chain length allows for a "flat-lying" adsorption configuration on Zn(002) surface, resulting in strong adsorption and Zn-GA metal-molecule bridging interface. This regulates Zn2+ diffusion process and restricts its accessibility to the Zn(002) facet, facilitating the selective exposure of Zn(002) facet. Due to this design, the Zn||Zn symmetric cell stably operates at a high current density of 20 mA·cm-2 and a high depth of discharge of 85%. The Zn||MnO2 pouch cell achieves a high capacity of 1.1 Ah with 90% capacity retention. This metal-molecule interface design can be extended to other metal anodes, with the potential for tailored molecular selections to regulate the selective growth of crystal facets.