Regulating Solvent Co-Intercalation in Bi-Layered Vanadium Oxides for Zinc Batteries by Nanoconfinement Chemistry

Electrochemical intercalation typically involves ion desolvation at the electrolyte-electrode interface, incurring kinetic limitations and strong ion-host interactions. The emerging mechanism of solvent co-intercalation, where ions intercalate together with a (partially) intact solvation shell, can mitigate these drawbacks, but has thus far been primarily explored from the viewpoint of electrolyte design. Herein, we demonstrate the feasibility of regulating solvent co-intercalation by electrode nanoconfinement design. By tuning the nanoconfining interlayer environment of bi-layered vanadium oxides from hydrophilic to hydrophobic, the Zn2+ intercalation properties in aqueous electrolyte are modified. Comprehensive experiments and simulations reveal progressively reduced solvation/hydration of intercalating Zn2+ with decreasing interlayer hydrophilicity, affecting maximum capacity, redox potential, and kinetics of the electrochemical intercalation reactions. Similar electrochemical trends are observed in non-aqueous electrolytes, indicating the potential of nanoconfinement design as a universal strategy for regulating ion-solvent (co-)intercalation in various battery chemistries.