Metal-Organic Framework-Derived NiO@C as a Host for MnO2 Cathode of Stable Zinc-Ion Batteries

MnO2 has been regarded as one of the mostpromisingcathode materials for safe and inexpensive aqueous Zn-ion batteries(AZIBs). However, the severe Mn dissolution upon cycling is a majorchallenge for their practical application. Herein, we prepared a flexibleand carbonaceous host for the MnO2 cathode in the formof metal-organic framework-derived nanoporous carbon decoratedwith NiO nanoparticles. The NiO nanoparticle-encapsulated carbon asa helpful additive led to a synergistic effect with MnO2. The MnO2 hosted on the flexible support allowed theconstruction of AZIB with a high capacity (330 mAh/g after 250 cyclesat 0.625 A/g) and good cyclic performance (74.4% retention after 1500cycles at 3.75 A/g). It is believed that the structural transformationof & beta;-MnO2 (MnO2 & RARR; Mn2+ & RARR; birnessite MnO (x) ) and the reversible(de)-insertion of Zn2+ into NiO (NiO & LRARR; Zn (x) NiO) play a key role in the high capacity andcyclic stability of the prepared AZIBs. Our approach holds great promiseto design various hosts for MnO2-based cathodes of AZIBs.