Hybrid Nano-Phase Ion/Electron Dual Pathways of Nickel/Cobalt–Boride Cathodes Boosting Intercalation Kinetics for Alkaline Batteries

Nickel-based hydroxides and their derivatives exhibit relatively low capacities and unsatisfactory durability as cathode materials for rechargeable alkaline batteries. In this work, a hybrid NiCo–B nanosheet cathode, integrating electrolyte ion-shuttling channels and electron-transferring networks into a metal–organic framework (MOF), was devised delicately. In the structure, the hybrid ion/electron dual pathways were constructed by NiCo-MOF frameworks and NiCo–B interpenetration networks. It revealed that nano-phase electron-transferring pathways in the MOF obviously boosted ion intercalation kinetics. The as-obtained hybrid NiCo–B nanosheets as cathode materials exhibited reversible capacity as high as 280 mA h g–1 at a current density of 1 A g–1 and excellent rate capability with a capacity retention of 78% from 1 to 10 A g–1. After 2000 charge/discharge cycles at 4 A g–1, the capacity still remained at 94% of the initial one. A full battery assembled with a hybrid NiCo–B cathode and a Fe2O3 anode showed a high capacity of 250 mA h g–1 and a considerable stability of 89% after 1000 cycles. Ragone plots indicated the highest energy density of 409 W h kg–1 and the lowest power density of 1.5 kW kg–1, outperforming other aqueous batteries. It revealed that a syngenetic structure of ion/electron hybrid dual pathways integrated into an MOF could be a potential strategy to optimize ion intercalation electrode materials for alkaline batteries.