Regulating the solvation sheath of zinc ions by supramolecular coordination chemistry toward ultrastable zinc anodes

Abstract

Abstract Aqueous zinc‐ion batteries (ZIBs) have attracted extensive interest for the next‐generation batteries, which, however, are facing great challenges due to the poor reversibility of zinc (Zn) anodes and side reactions of water decomposition. Herein, we demonstrated a strategy that the solvation sheath of Zn ions could be facilely regulated by supramolecular coordination chemistry by adding small amounts of cyclodextrins (CDs) and, hence, inhibited the side reactions and side products, widened the electrochemical window, facilitated the homogenous deposition of Zn ions, refined the Zn grains, and enhanced the stability of Zn anodes. Importantly, we demonstrated that compared with α‐ and β‐CD, the γ‐CD showed the best regulation effect of the solvation sheath of Zn ions either at the same molar ratio or at the same mass concentration, which could be ascribed to their difference in supramolecular coordination chemistry and the strongest interaction of γ‐CD with Zn ions. As a result, with γ‐CD, the Zn//Zn symmetric cells showed ultrahigh stability with a cycling lifespan of over 2400 h at a current density of 1 mA/cm2. These results highlight the regulation of solvation sheath by supramolecular coordination chemistry for highly stable Zn anodes and pave a new way to realize high‐performance ZIBs.

Keywords

• aqueous zinc‐ion batteries
• electrolyte additives
• solvation
• supramolecular coordination chemistry
• Zn anodes