Sodium-Ion/Crystal Water Cointercalated δ-MnO2 with Improved Performance for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) have gained much attention because of their high theoretical capacity, low cost, and high level of safety merits. Nevertheless, the progress of their practical applications is often restricted by the poor structural degradation in cathodes and inherently sluggish transport kinetics. Herein, we developed layered Na0.08MnO2<middle dot>0.57H(2)O nanoflowers by a simple and effective hydrothermal method for the cathode of AZIBs. Na0.08MnO2<middle dot>0.57H(2)O was obtained by the cointercalated sodium ion and minimal water in crystalline delta-MnO2. Consequently, the Na0.08MnO2<middle dot>0.57H(2)O cathode delivers a high capacity (368 mA h g(-1 )at 0.1 A g(-1)) and a satisfactory cycle stability above 250 cycles at 0.5 A g(-1). Our research could provide some ideas for the enhanced electrochemical performance of rechargeable AZIBs.