Hierarchical porous Mo-Co3O4-CNTc nanosheets for aqueous rechargeable zinc ion batteries with ultralong life

Aqueous rechargeable zinc ion batteries (ZIBs) are a promising next-generation energy storage device, which suffers from poor capacity and limited cycle life. In this work, a ZIB cathode material was reported, consisting of a composite of Co3O4 doped with Mo and carboxylic carbon nanotubes (Mo-Co3O4-CNTc), with a hierarchical porous structure arising from ultrathin nanosheets. The composite was prepared via a sol-gel method in an emulsion system. The experimental electrochemical data and density-functional first-principles calculations showed that the as-prepared Mo-Co3O4-CNTc composites with 152.9 mAh g−1 showed superior electrochemical performance compared to pure Co3O4 (as 107.3 mAh g−1) and Mo-Co3O4 (as 112.0 mAh g−1) electrode materials. Furthermore, the as-prepared MoCo-Zn batteries, with zinc metal foil anode and Mo-Co3O4-CNTc cathode, exhibited a specific capacity of 195.7 mAh g−1 at 0.5 A g−1, energy density of 237.6 Wh kg−1 at 1692.4 W kg−1, and a remarkable ultralong cycling life of over 10,000 cycles with 85.1% capacity retention. The superior performance can be attributed to the hierarchical porous structures with open spaces acting as “ion-buffering reservoirs.” The summary of zinc ion storage mechanism in the MoCo-Zn batteries was investigated during the charge-discharge process. Therefore, this work promotes the development of innovative strategies to synthesize carbon-modified composites with hierarchical porous nanosheets as cathode materials, for the ultra-long cycle-life aqueous rechargeable ZIBs. The cathode materials of Mo-doped in hierarchical porous Mo-Co3O4-CNTc composites were fabricated for aqueous rechargeable zinc ions batteries with ultra-long cycle life.