Self-regulating shielding layer induces (002) plane directional deposition of zinc metal anode

Abstract

Rechargeable aqueous zinc batteries (AZIBs) are ideal for grid-scale energy storage due to their safety and economic characteristics. However, uncontrollable side reactions and dendrite growth severely affect the reversibility of zinc anodes. In the interfacial reaction, inducing smooth deposition of dominant planes is crucial for stabilizing the zinc anodes. Herein, we report a highly concentrated 1‑butyl‑3-methylimidazolium ion (BMIM+) modified electrolyte to improve the diffusion and deposition behavior of Zn2+. Thanks to the strong adsorption effect of BMIM+ at the zinc anode interface, the self-regulating shielding layer inhibits water-induced parasitic reactions. Under the action of BMIM+, Zn2+ has the lowest diffusion energy barrier towards the (002) plane, thus transforming the electrodeposition from a randomly stacked sheet to a dense deposited layer in the Zn(002) plane. The results showed that the symmetric cell composed of the modified electrolyte had a cycle life of 3200 h at 1 mA cm−2, and the average coulombic efficiency (CE) of the asymmetric cell was as high as 99.8 %. The full cell assembled with ZnxV2O5·nH2O still provided 86 % capacity retention at 2 A g−1 after 500 cycles. This electrolyte modification strategy provides a promising option for modulating the anode/electrolyte interface chemistry to achieve high-performance AZIBs.