Trimetallic-Organic Framework-Derived Ni-Doped MnO/PC as cathodes for High-Performance aqueous zinc-ion batteries

Manganese-based materials are frequently employed as the cathodes of aqueous zinc ion batteries (AZIBs) due to the merits of low cost, eco-friendliness and high operating voltage. However, their inherent low conductivity and poor structural stability often lead to an insufficient rate capacity and therefore limit their application in AZIBs. Herein, we use the trimetallic-organic framework precursor to synthesize a Ni nanoparticle doped MnO composite uniformly anchored on porous carbon (Ni-MnO/PC) by a simple hydrothermal and annealing method. Electrochemical evaluation indicates that the Ni-MnO/PC composite electrode exhibits excellent zinc storage performance, mainly due to the synergistic effect of Ni nanoparticles doping and porous carbon, which enhances adsorption energy of zinc ions and also increases structure stability. The Zn || Ni-MnO/PC batteries represent not only an outstanding discharge capacity of 347.4 mAh/g at 100 mA g−1, but also an ultra-long cycle stability. Even in 3000 mA g−1, the Ni-MnO/PC electrode holds a high-capacity retention of 91.1 % after 6000 cycles. The various ex-situ tests reveal that co-intercalation of H+ and Zn2+ in Ni-MnO/PC electrode is the major mechanism for storing zinc. Finally, quasi solid-battery assembled with Ni-MnO/PC cathode can also withstand stress at different bending states. This work will promote the application of metal nanoparticles doping strategies for AZIBs and provide views for the development of durable flexible energy storage devices.