Construction of Novel Hierarchical Honeycomb-Like Mn 3 O 4 MnO 2 Core-Shell Architecture with High Voltage for Advanced Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are considered as potential secondary battery technology for grid-scale energy storage system due to its reliable safety and low cost. However, limited cathode materials with superior rate capability and cyclic performance is still the main bottleneck restricting its further development. Herein, a hierarchical honeycomb-like Mn 3 O 4 @MnO 2 core–shell architecture is proposed as the robust cathode material for ZIBs for the first time. The electrochemically active MnO 2 and the honeycomb-like nanocomposite particles are beneficial to fast ion transport and storage, moreover, the encapsulated MnO 2 shell can function as the buffer to suppress the volume expansion of the active material, ultimately enhancing the reaction kinetics and electrochemical performance of the Mn 3 O 4 @MnO 2 . Significantly, the Mn 3 O 4 @MnO 2 nanocomposite delivers a high discharge capacity of 165 mAh g −1 at a high current density of 2 A g −1 , which is almost two times as high as the pure Mn 3 O 4 (87 mAh g −1 ). The capacity retention (76.3% after 600 cycles at 1 A g −1 ) is also superior to the Mn 3 O 4 cathode (48.7%). Furthermore, the Zn//Mn 3 O 4 @MnO 2 battery possesses a 1.83V-high open-circuit voltage. These ideal results suggest that the hierarchical honeycomb-like Mn 3 O 4 @MnO 2 core–shell composite is a promising cathode material for high-performance aqueous ZIBs.