Mesoporous Tubes Composed of Graphitic Carbon-Doped Co₃O₄ Nanoparticles for Lithium Storage

The cheap biomass-derived carbon-encapsulated strategy has recently attracted much attention in enhancing the properties of metal oxide-based anodes for lithium-ion batteries (LIBs). Herein, graphitic carbon (GC)-encapsulated Co3O4 material with mesoporous hierarchical structure was prepared by immersion, carbonization, and air calcination with poplar branch as a biotemplate and carbon source. We also investigated the impact of different carbon contents on the nanostructure and electrochemical performance of composites. The microtube wall of Co3O4/GC350 oxidized at 350 °C is assembled by cross-linking Co3O4 nanoparticles and graphitic carbon, making Co3O4/GC350 possess a large specific surface area of 70.4 m2 g–1 and a concentrated mesopore size distribution of 3.75 nm. As an anode for LIBs, Co3O4/GC350 exhibits better lithium storage performance than the product oxidized at 450 °C. At 1 A g–1, it delivers a stable capacity of 665.7 mA h g–1 after long cycling 1200 times and even retains a capacity of 294.1 mA h g–1 at 5 A g–1, indicating that Co3O4/GC350 nanomaterial has good rate performance and long-cycling stability. The excellent electrochemical performance is primarily ascribed to the unique mesoporous nanostructure, large specific surface area, encapsulated GC in Co3O4/GC350, and the synergism of pseudocapacitive behavior arising from oxygen vacancy defects and the mesoporous structure. Therefore, the simple, eco-friendly, and large-scale poplar branch-templated strategy in this work can offer a beneficial experience for synthesizing other transition-metal oxide anodes.