Self-assembled three-dimensional mesoporous ZnFe₂O₄-graphene composites for lithium ion batteries with significantly enhanced rate capability and cycling stability

We report a facile, one-pot hydrothermal strategy to prepare self-assembled three-dimensional mesoporous ZnFe₂O₄ submicron-sized spheres wrapped in graphene sheets as high-performance anode material for lithium ion batteries. The mesoporous submicron-sized spheres are composed of numerous nanoparticles where the void spaces between the neighboring nanoparticles provide a cushion to alleviate volume variation issues during the conversion/alloying process and also provide large contact areas with the electrolyte to facilitate lithium ion diffusion and electron transport during cycling. The synergistic effects between ZnFe₂O₄ submicron-sized spheres and graphene sheets are another positive effect to enhance the electrochemical performance. The electrochemical characterization of ZnFe₂O₄-graphene composites exhibits a high specific capacity of 1182 mAh g^-1 cycling at a specific current of 100 mA g^-1, and significantly enhanced rate capability and cycling stability after long-term testing resulting from their unique structure features.