Defect modulation of ZnMn2O4 nanotube arrays as high-rate and durable cathode for flexible quasi-solid-state zinc ion battery

The exploration of a stable and high-rate cathode is very important for rechargeable Zn ion batteries (ZIBs). With unique merits of rich abundance, low price, and environmental friendliness, spinel ZnMn 2 O 4 (ZMO) hold great promise as a cathode material for ZIBs. However, its inherent low electronic conductivity and large volume variation in the process of charge/discharge severely restrict the rate capability and durability. Herein, the novel N-doping coupled oxygen vacancies modulated ZMO nanotube arrays (NTAs) (N-ZMO NTAs) are fabricated as high-performance cathode for rechargeable ZIBs. Taking advantages of high electrical conductivity, fast ion diffusion, high surface area, sufficient active sites, and stable hollow nanotubular architecture, the N-ZMO NTAs show an admirable capacity (223 mA h g −1 at 0.1 A g −1 ), decent rate capability (133.3 mA h g −1 at 4 A g −1 ) and distinguished long-term durability (92.1% after 1500 cycles). Furthermore, a flexible quasi-solid-state ZIBs is fabricated with N-ZMO NTAs cathode, which achieves favorable energy density (214.6 W h kg −1 ), superb power density (4 kW kg −1 ), and impressive long-term stability (88.6% after 1500 cycles), outperforming most state-of-the-art ZIBs. This study may shed light on designing advanced cathodes for advanced ZIBs.