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. Through the combined effects of decreasing interlayer water of bi-layered vanadium oxides and introducing molecules that tune the nanoconfining interlayer environment 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 nonaqueous electrolytes, indicating the potential of nanoconfinement design as a universal strategy for regulating ion-solvent (co-)intercalation in various battery chemistries.