In situ sol-gel synthesis of ultrafine ZnO nanocrystals anchored on graphene as anode material for lithium-ion batteries

Ultrafine ZnO nanocrystals anchored on graphene were synthesized by a facile and highly efficient in situ sol-gel method. Uniform ZnO nanocrystals with an average size of 9.3 nm were well dispersed on graphene nanosheets forming two-dimensional nanostructured ZnO/Graphene hybrids. Due to the intimate integration and strong synergistic effects between the ZnO nanocrystals and graphene nanosheets these hybrids exhibited a stable electrochemical performance. Along with this the graphene anchoring provides to the system high conductivity and large surface area and buffers the ZnO volume change during cycling. Furthermore, ultrafine ZnO nanocrystals provide a short diffusion path for Li + upon insertion/deinsertion. These structure and property advantages allow the as-prepared ZnO/graphene composite to exhibit a high reversible operation as an anode for lithium batteries with a stable specific discharge capacity of 516 mAh g −1 after 100 cycles at a current density of 200 mA g −1 and a good rate capability with a discharge capacity of 304 mAhg −1 even at a cycling rate of 1500 mA g −1 .