Preparation And Properties Of Silicon-Based Anode Materials For Lithium Ion Batteries

In this paper, the development of lithium ion battery and anode materials were firstly discussed. Since the commercialization of lithium ion batteris, people want to find a safer and better anode material than that of graphite materials. Silicon based materials receive more concerns because of low cost, high safety and high capacity. In this work, we studied the Si-based composites used as the anode materials for Li-ion batteries. Si-based composites were prepared by ball milling and chemical reduction-oxidation methods, and X-ray diffraction(XRD), scanning electron microscope(SEM), Fourier Transform infrared spectroscopy(FTIR) analysis methods have been carried out to characterize the morphology and structure of these samples. In addition, we used electrochemical measurements to determine the electrochemical properties and lithium storage of silicon material. The effect of milling time on silicon material showed that the first delithiation capacity of20h milling material was778mAh/g, but the capacity decay was severe at the following cycling. After added graphite and carbon nanotube, the electrochemical properties and cycle performance of the samples have been improved, and the delithiation capacity of two composites maintained339.6mAh/g and381.3mAh/g after50cycles. We introduced Ag into the silicon/graphite composites by ball milling method. The electrode exhibited an initial reversible capacity of703.5mAh/g, and a modified cycleability having the capacity of500mAh/g at50th cycle. It found that the electrochemical performance and cycleability of the composite was effectively improved due to the buffering effect of carbon matrix and electrical contact of silver.The nanosilicon connected by polypyrrole (PPy) and silver (Ag) particles was synthesized by a chemical polymerization process in order to prepare Si-based anode materials for Li-ion batteries. The addition of appropriate of PPy and Ag particles could improve the electrochemical performance of Si materials to some extent. As high as capacity of more than823mAh/g was maintained after100cycles. The high stable cyclability of the composite electrode was attributed to the effect that the nanosilicon particles were electrically connected by the PPy and Ag particles. In the meantime, the PPy acted as an efficient host matrix to prevent cracking and pulverization of the Si electrode, thus improving the cyclability of the Si electrode.