Ultrathin δ-MnO 2 nanoflakes with Na + intercalation as a high-capacity cathode for aqueous zinc-ion batteries

Pristine δ-MnO as the typical cathode for rechargeable zinc-ion batteries (ZIBs) suffers from sluggish reaction kinetics, which is the key issue to prepare high-performance manganese-based materials. In this work, Na incorporated into layered δ-MnO (NMO) was prepared for ZIB cathodes with high capacity, high energy density, and excellent durable stability. By an effective fabricated strategy of hydrothermal synthesis, a three-dimensional interconnected δ-MnO nanoflake network with Na intercalation showed a uniform array arrangement and high conductivity. Also, the H insertion contribution in the NMO cathode to the discharge capacity confirmed the fast electrochemical charge transfer kinetics due to the enhanced ion conductivity from the insertion of Na into the interlayers of the host material. Consequently, a neutral aqueous NMO-based ZIB revealed a superior reversible capacity of 335 mA h g , and an impressive durability over 1000 cycles, and a peak gravimetric energy output of 459 W h kg . As a proof of concept, the as-fabricated quasi-solid-state ZIB exhibited a remarkable capacity of 284 mA h g at a current density of 0.5 A g , and good practicability. This research demonstrated a significant enhancement of the electrochemical performance of MnO -based ZIBs by the intercalation of Na to regulate the microstructure and boost the electrochemical kinetics of the δ-MnO cathode, thus providing a new insight for high-performance aqueous ZIBs.