Studies On Anode Materials For Lithium Ion Batteries

The lithium-storage behaviors of flower-like CeO2, gelatin-pyrolized porous carbon and black phosphorus have been comprehensively investigated as anode materials of lithium ion batteries.Flower-like CeO2 was synthesized successfully by hydrothermal method. The electrochemical properties of the flower-like CeO2 were investigated by galvanostatic tests between 0.0 and 4.2 V(vs.Li+/Li). The galvanostatic test reveals that the initial discharge and charge capacities of the Flower-like CeO2 are 140mAh/g and 80 mAh/g, respectively. It is found that the discharge and charge capacities of the material decrease in the first few cycles and then turn to increase with cycling. In addition, the specific capacities of the material decreases as the current density increases. X-ray diffraction and transmission electron microscopy analyses show that the flower-like CeO2 does not show any change during the discharge and charge processes. The decomposition of the electrolyte might be responsible for the increased capacity. Further analyses is required to confirm this suggestion.Porous carbon was obtained by pyrolyzing gelatin in nitrogen. Electrochemical evaluation shows that these porous materials have very good cycling performances. The reversible capacity of the porous carbon is more than 1000mAh/g. FTIR and XPS spectroscopic studies indicate that the nitrogen in the material exist in two forms, the amidogen nitrogen and the graphitic nitrogen. The former participates in the formation of the solid electrolyte interface (SEI) layers. Raman spectroscopic analysis shows that the porous carbon becomes more disordered during discharge but more ordered during recharge. The reversible structural variation ensures the high cyclic reversibility of the material. Black phosphorus was synthesized successfully by a fast low-pressure transport route. X-ray diffraction, scanning electron microscopy and Raman spectroscopy were employed to characterize the structure of the obtained black phosphorus. The Li-storage behavior of the black phosphorus was examined by galvanostatic cycling and cyclic voltammetry (CV) at room temperature. Charge–discharge test reveals that the initial discharge and charge capacities of the black phosphorus are 850mAh/g and 600 mAh/g, respectively. However, cycling performance of this black phosphorus is poor. Further efforts should be taken to improve its cycling stability...