A practical Li ion battery anode material with high gravimetric/volumetric capacities based on T-Nb₂O₅/graphite composite

Much progress has been made in developing high capacity, high rate capability and long life lithium ion batteries with nanomaterials, however, nanomaterials have two major issues to be addressed, including low tap density and severe side reactions due to active surface. Herein, we present a solution by forming layered micrometer-sized secondary architecture with a nanostructured building block. A composite of orthorhombic Nb₂O₅ (T-Nb₂O₅) inserted mesocarbon microbeads (MCMB) is prepared. Electron microscope images demonstrate the T-Nb₂O₅ nanoparticles distributing in gaps of graphitic layers homogenously. The layered structure endows the composite good electron conductivity and facilitated ion transport channels when using it as Li ion battery anode material, which possesses capacities of more than 1000 and 100 mAh g⁻¹ at 0.06 and 90 A g⁻¹ (discharge in 4.0 s), respectively, much better than raw MCMB. Furthermore, stable surface leads the composite a small initial irreversible capacity (8.7%) and good durability (2500 cycles) at high rate currents. More attractively, a reasonable tap density (0.58 g cm⁻³) of the composite results in large volumetric capacity densities (e.g. 120 Ah L⁻¹ at a rate current of 30 A g⁻¹), making it more practical than traditional nanostructured materials.