Hierarchically Hollow and Porous NiO/NiCo2O4 Nanoprisms Encapsulated in Graphene Oxide for Lithium Storage.

Engineering materials nanostructures is key for developing renewable energy technologies for lithium-ion batteries (LIBs) but remains a long-term research challenge. In this paper, heterostructured NiO/NiCo2O4 nanoprisms with a hierarchically hollow cavity and porous framework are rationally designed and further encapsulated in graphene oxide (NiO/NiCo2O4@GO) as a highly efficient anode nanomaterial for LIBs. Heterostructured NiO/NiCo2O4 hollow/porous nanoprisms are derived by the ionic exchange of Ni precursors with [Co(CN)6]3- (CoNi-metal-organic framework (MOF)) and then annealed under air. The encapsulation is achieved by fast assembly of GO and NiO/NiCo2O4. Thanks to hierarchically hollow and porous nanostructure, heterostructured NiO/NiCo2O4, and overcoated GO, the NiO/NiCo2O4 electrode shows excellent electrochemical performance toward lithium storage, disclosing a large rate capacity of 468 mA h g-1 at 3.0 A g-1 and a good capacity retention of 561 mA h g-1 at 1 A g-1 after 800 cycles. This work paves a facile ionic exchange method for the controllable construction of hierarchically hollow MOFs and their derived composite nanomaterials for various energy-related applications.