Facile synthesis of MOF-derived hollow NiO microspheres integrated with graphene foam for improved lithium-storage properties

In this work, Ni-based metal-organic framework (MOF) hollow microspheres were firstly grown on the substrate of graphene foam (GF) by a facile solvothermal method, and then the NiO/GF composites were obtained after the calcination of Ni-MOF/GF precursors. The resulting NiO/GF could be employed as freestanding anode electrodes of lithium-ion batteries, showing superior specific capacities and cycling stabilities to pure NiO and GF. In detail, the optimized composite exhibited a capacity of 640 mAh g(-1) after 50 cycles at 100 mA g(-1). Even at a high current of 1 A g(-1), the capacity still reached to similar to 330 mAh g(-1). The excellent electrochemical performance can be attributed to the synergistic effect between NiO and GF components. The GF matrix not only improves the conductivity of electrode, but also provides a flexible platform for the loading of active materials, preventing the escape and diffusion of NiO particles into the electrolyte during the cycling. Meanwhile, the well-defined hierarchical hollow structure of NiO in the composite effectively mitigates the volume change of metal oxides during the insertion/extraction reaction. (C) 2019 Elsevier B.V. All rights reserved.