Nanomicellar Electrolyte To Control Release Ions and Reconstruct Hydrogen Bonding Network for Ultrastable High-Energy-Density Zn–Mn Battery

Abstract

Zn-Mn batteries with two-electron conversion reactions simultaneously on the cathode and anode harvest a high voltage plateau and high energy density. However, the zinc anode faces dendrite growth and parasitic side reactions while the Mn²⁺/MnO₂ reaction on the cathode involves oxygen evolution and possesses poor reversibility. Herein, a novel nanomicellar electrolyte using methylurea (Mu) has been developed that can encapsulate ions in the nanodomain structure to guide the homogeneous deposition of Zn²⁺/Mn²⁺ in the form of controlled release under an external electric field. Consecutive hydrogen bonding network is broken and a favorable local hydrogen bonding system is established, thus inhibiting the water-splitting-derived side reactions. Concomitantly, the solid-electrolyte interface protective layer is in situ generated on the Zn anode, further circumventing the corrosion issue resulting from the penetration of water molecules. The reversibility of the Mn²⁺/MnO₂ conversion reaction is also significantly enhanced by regulating interfacial wettability and improving nucleation kinetics. Accordingly, the modified electrolyte endows the symmetric Zn∥Zn cell with extended cyclic stability of 800 h with suppressed dendrites growth at an areal capacity of 1 mAh cm^-2. The assembled Zn-Mn electrolytic battery also demonstrates an exceptional capacity retention of nearly 100% after 800 cycles and a superior energy density of 800 Wh kg^-1 at an areal capacity of 0.5 mAh cm^-2.