Unique three-dimensional Co3O4@N-CNFs derived from ZIFs and bacterial cellulose as advanced anode for sodium-ion batteries
A novel strategy is exploited herein to fabricate zeolitic-imidazolate frameworks (ZIFs) and bacterial cellulose-derived Co3O4 nanoparticles anchored on three-dimensional nitrogen-doped carbon nanofibers (Co3O4@N-CNFs) network by simply growing ZIFs on bacterial cellulose and then applying a two-step annealing process. When utilized as an anode for sodium ion batteries, the as-fabricated Co3O4@N-CNFs electrode exhibits a high capacity (864.2 mA h g-1 for the first discharge and 450.2 mA h g-1 after 50 cycles at 100 mA g-1), excellent rate performance, and an ultralong cycling life stability (220.1 mA h g-1 at 1.6 A g-1 after 1000 cycles), which are better than those of other ZIF-derived cobalt-based oxide composites. The excellent capability can be ascribed to the synergistic effect between the Co3O4 polyhedrons and carbon nanofibers network, in which the unique interconnected nanostructures can decrease the ion diffusion route and enhance the conductivity and structural stability. These results indicate that the as-fabricated Co3O4@N-CNFs can be a promising anode material for high-performance sodium ion batteries. The present strategy for Co3O4@N-CNFs architectures can provide a promising approach for other metal-organic framework-derived materials for high-performance energy storage equipment.