Tandem Chemistry with Janus Mesopores Accelerator for Efficient Aqueous Batteries.

A reliable solid electrolyte interphase (SEI) on the metallic Zn anode is imperative for stable Zn-based aqueous batteries. However, the incompatible Zn-ion reduction processes, scilicet simultaneous adsorption (capture) and desolvation (repulsion) of Zn(HO), raise kinetics and stability challenges for the design of SEI. Here, we demonstrate a tandem chemistry strategy to decouple and accelerate the concurrent adsorption and desolvation processes of the Zn cluster at the inner Helmholtz layer. An electrochemically assembled perforative mesopore SiO interphase with tandem hydrophilic -OH and hydrophobic -F groups serves as a Janus mesopores accelerator to boost a fast and stable Zn reduction reaction. Combining electrochemical digital holography, molecular dynamics simulations, and spectroscopic characterizations reveals that -OH groups capture Zn clusters from the bulk electrolyte and then -F groups repulse coordinated HO molecules in the solvation shell to achieve the tandem ion reduction process. The resultant symmetric batteries exhibit reversible cycles over 8000 and 2000 h under high current densities of 4 and 10 mA cm, respectively. The feasibility of the tandem chemistry is further evidenced in both Zn//VO and Zn//I batteries, and it might be universal to other aqueous metal-ion batteries.