LAUSR

Aqueous zinc-ion batteries (ZIBs) with low-cost and high-safety are promising energy storage devices. However, the ZIBs with metal Zn anodes usually suffer from low coulombic efficiency and poor cycling performance due to the occurence of side reactions on Zn anodes. Here, a binary hydrate-melt ZnCl2 /Zn(OAc)2 electrolyte was designed to suppress hydrogen evolution reaction and byproduct formation on Zn anodes by adjusting Zn2+ solvation structure. In the solvation structure of hydrate-melt ZnCl2 /Zn(OAc)2 electrolyte, carboxylate group in OAc- will coordinate with the Zn2+ , which will weaken the interaction between Zn2+ and H2 O molecules to achieve higher ionization energy of H2 O molecules. Simultaneously, these carboxylate groups of OAc- can serve as H-bond acceptor to construct H-bonds with H2 O molecules in their neighbouring solvation structures, forming cross-linking H-bond network. Such cross-linking H-bond network further suppresses the water activity in ZnCl2 /Zn(OAc)2 electrolyte. As a result, in such electrolyte, the side reactions are effectively restricted on Zn anodes and thus Zn anodes could achieve a high coulombic efficiency of 99.59% even after cycling. To illustrate the feasibility of the ZnCl2 /Zn(OAc)2 electrolyte in aqueous ZIBs, Zn||p-chloranil cells were assembled based on ZnCl2 /Zn(OAc)2 electrolyte. The resultant Zn||p-chloranil cells exhibit enhanced cycling performance compared with the cases with conventional ZnSO4 electrolyte. This article is protected by copyright. All rights reserved.