Designing an Anionic Layer in Low-Concentration Electrolytes to Promote In-Plane Ion Diffusion for Dendrite-Free Zinc-Ion Batteries.

Abstract

In contrast to high-concentration electrolyte systems, low-concentration electrolytes provide a cost-effective strategy to advance the commercialization of aqueous zinc-ion batteries (AZIBs). However, such electrolytes frequently exhibit severe dendrite formation caused by localized Zn²⁺ concentration gradients, which critically compromise the cycling stability and operational safety of AZIBs. In this work, an innovative approach is proposed that involves the in situ construction of a fluoride-ion (F^-) enriched interfacial layer on zinc anodes. This method facilitates in-plane diffusion of zinc ions at the anode interface, resulting in accelerated lateral growth of zinc deposits rather than dendritic formation. The results indicate that this orientated growth is closely associated with an anionic layer that effectively reduces random and irregular deposition as well as undesirable side reactions. The proposed system exhibits exceptional electrochemical performance within a low-concentration electrolyte framework, achieving a battery lifespan exceeding 1500 h at a current density of 2 mA cm^-2. Furthermore, it maintains Coulombic efficiency above 99% after 800 h of cycling. Additionally, the Na₂V₆O₁₆·3H₂O (NVO)//Zn full battery incorporating this additive showcases enhanced long-term cycling performance and improved capacity retention, further confirming the excellent reversibility of the plating/stripping processes for zinc anode.