Barbital-derived chelating ligands for interface regulation and stabilization of Zn metal anodes for aqueous zinc-ion batteries.

Aqueous zinc-ion batteries (AZIBs) have inherent merits, such as a low price, good safety and high volumetric capacity, and have promising potential for widespread applications. However, the unexpected issues posed by both water-induced side reactions and the uncontrollable growth of zinc dendrites on the zinc anode-electrolyte interface have significantly hindered the widespread application of AZIBs. In this work, barbital (Bb), which has two amide groups, was introduced into a ZnSO electrolyte to create a Bb@ZnSO electrolyte. The hydrolysis of the amide groups resulted in the formation of strong polar groups (carboxyl and amino), which could efficiently anchor zinc ions. Specifically, through the derivation of Bb, it was possible to adjust the Zn solvation structure, decreasing the coordinated active SO/HO and promoting the anchoring of these species on the surface of the zinc anode. This process provided electrostatic shielding and isolates the SO/HO, demonstrating an interface regulating effect and synergistic solvation. Therefore, Bb could mitigate electrochemical corrosion and facilitate dendrite-free homogeneous zinc deposition. As a consequence, the assembled asymmetric Zn∥VO full cell utilizing the Bb@ZnSO electrolyte showed highest specific capacities of 294.9 and 92.7 mA h g at 0.1 and 1 A g, much higher than the Zn∥VO full cell with the ZnSO electrolyte, which delivered specific capacities of 161.1 and 3.0 mA h g at the same current densities. These findings promise to realize the practical application of Bb as an efficient additive in high-performance AZIBs.