Studies On Some Metal Antimonides As Anode Materials Of Lithium-ion Batteries

Lithium ion cells represent the state-of-the-art in the small rechargeable batteries due to their high voltage, high energy density and long life. The present work is aimed to develop and study new materials based on metal antimonides as the candidate anodes for lithium ion batteries.In this thesis, the electrochemical properties of CoSb3 were investigated. The lithium ion insertion and extraction capacities of the annealed CoSb3 alloy reach about 630 and 470mAh/g respectively in the first cycle, and those of the as-melted CoSb3 are some what lower (550 and 364mAh/g in the first cycle). Experiments showed that the cycle life could be improved after anneal when a single skutterudite phase was obtained. The electrochemical mechanism of Li+ reaction with the anode materials could be explained as the formation and decomposition of Li3Sb. The results illustrated that the addition of meso-carbon micro-beads (MCMB) can significantly improve the reversible capacities and cycle life of the CoSb3 electrodes, with the reversible capacity 586mAh/g in the first cycle. However, the addition of carbon nano-tubes (CNT) does not show any obvious effects on the improvement of the electrochemical behaviors of CoSb3. It was found that the electrochemical properties of the alloy can be improved also with the reducing the particle sizes of the active materials.Other metal antimonides, such as CoFe3Sb12, CoSb2 and FeSb2 have been also prepared and studied as anode materials in the present work. The insertion and extraction capacities of the CoFe3Sb12 in the first cycle could reach 636 and 396mAh/g respectively. It was found that the behaviors of CoFe3Sb12 at the large current could be improved with the addition of graphite. The electrcochemical properties of CoSb2, FeSb2 and nano-sized FeSi2 were also studied in the present work.