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

Abstract

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 100mAhg−1 at 0.06 and 90Ag−1 (discharge in 4.0s), 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 (0.58gcm−3) of the composite results in large volumetric capacity densities (e.g. 120AhL−1 at a rate current of 30Ag−1), making it more practical than traditional nanostructured materials.