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.