Fabrication of porous carbon-coated ZnO nanoparticles on electrochemical exfoliated graphene as an anode material for lithium-ion batteries

As a high-quality graphene, electrochemical exfoliated graphene exhibits higher electrical conductivity and stronger mechanical strength than reduced graphene oxide, and thereby is suitable to replace reduced graphene oxide as a great carbon substrate. Herein porous carbon-coated ZnO nanoparticles are fabricated on electrochemical exfoliated graphene by direct growth of ZIF-8 on electrochemical exfoliated graphene and subsequent carbonization of ZIF-8. ZnO nanocrystals are formed and homogeneously dispersed in the pores of porous carbon derived from ZIF-8. The graphene substrate not only prevents the aggregation of porous carbon polyhedrons to open more channels for lithium-ion diffusion, but also enhances the electron conductivity of the hybrid electrode. Therefore, as an anode material for lithium-ion batteries, this graphene hybrid exhibits extraordinary reversible capacity and remarkable cycle stability, such as a reversible capacity of 736 mA h g(-1) at 0.1C after 100 cycles. The growth mechanism of ZIF-8 on electrochemical exfoliated graphene is also studied, and the results show that the growth is conspicuously suppressed on electrochemical exfoliated graphene. This novel graphene hybrid opens a new gate for the synthesis design of high-performance graphene hybrids as electrode materials for lithium-ion batteries and other energy storage devices. (C) 2019 Elsevier B.V. All rights reserved.