Solvation structure regulation via combined H2O-polar molecule and H2O-anion interactions toward stable zinc metal electrodes in aqueous batteries

Aqueous zinc (Zn) batteries (AZBs) possessing low cost and high safety offer a prominent solution for large-scale energy storage. However, the application of AZBs is still plagued by the corrosion of Zn electrode due to hydrogen evolution reactions (HERs) in aqueous electrolytes. Herein, the combination of H 2 O-polar molecule and H 2 O-anion interactions is proposed as an efficient approach to alter the solvation structure of aqueous electrolyte for stable AZBs. Using dimethyl sulfoxide (DMSO) with a high polarity as a model molecule, its interaction with H 2 O can weaken the Zn 2+ -H 2 O interaction in Zn 2+ solvation sheath, thereby suppressing HERs while at the expense of Zn 2+ mobility. By fixing the DMSO content at a compromising value to balance the Zn 2+ transport and HER suppression, a supplementary H 2 O-anion interaction is further experienced in the solvation structure by using bis(fluorosulfonyl)imide anion (FSI − ), where the interaction between FSI − and the bipolar H 2 O molecules enables additional force to reduce the H 2 O number of the Zn 2+ solvation sheath. Based on the combined H 2 O-DMSO and H 2 O-FSI − interactions, the HERs and Zn corrosions are significantly suppressed for stable AZBs.