In situ construction of a hydrophobic channel interconnecting zincophilic planes on the Zn surface for enhanced stability of Zn metal anodes†

Abstract

The poor reversibility of Zn stripping/plating processes leads to unsatisfactory cycling stability of Zn anodes, limiting the practical application of aqueous zinc-ion batteries. Herein, sulfobutylether-β-cyclodextrin (SCD) was introduced into the electrolyte as a multi-functional additive. The zincophilic sulfonate groups were found to interact with Zn²⁺ to modulate the solvation structure, enhance adsorption and govern the adsorption configuration of SCD on the Zn surface. This specific adsorption configuration could in situ construct two planes on the Zn surface with progressively improved affinity to Zn²⁺, which could drive the diffusion of Zn²⁺ through the hydrophobic toroidal inner channel, enable the uniform dispersion of Zn²⁺ flux and facilitate the de-solvation process. The synergistic promotional effect of the functional groups and specific structural features remarkably improved the stability of the Zn anode. With the addition of SCD, the Zn//Cu cell exhibited an extended cycle life of over 3000 cycles with an average CE exceeding 99.7%. The Zn//Zn symmetric cell also demonstrated superior cycling stability of over 3900 h at 2 mA cm⁻². The corresponding Zn//NH₄V₄O₁₀ full cells delivered a higher specific capacity and better cycling stability than cells using bare electrolytes. The assembled pouch cells were also stable for over 300 cycles, demonstrating the practical application potential of this electrolyte in high-performance AZIBs.