Stable anode performance of an Sb-carbon nanocomposite in lithium-ion batteries and the effect of ball milling mode in the course of its preparation

摘要

Materials that alloy with lithium (Si, Ge, Sn, Sb, and P) are considered as alternatives to graphitic anodes in lithium-ion batteries. Their practical use is precluded by large volume changes (200-370%) during cycling. Embedding nanoparticles into carbon is being investigated as a way to tackle that, and ball milling is emerging as a technique to prepare nanocomposites with enhanced capacity and cyclic stability. Using Sb as a model system, we investigate the preparation of Sb-carbon nanocomposites using a reconfigurable ball mill. Four distinctive milling modes are compared. The structure of the composites varies depending on the mode. Frequent strong ball impacts are required for the optimal electrochemical performance of the nanocomposite. An outstanding stable capacity of 550 mA h g~(-1) for 250 cycles at a current rate of 230 mA g~(-1) is demonstrated in a thin electrode (1 mg cm~(-2)) and a capacity of ～400 mA h g~(-1) can be retained at 1.15 A g~(-1). Some capacity fade is observed in a thicker electrode (2.5 mg cm~(-2)), i.e. the performance is sensitive to mass loading. The electrochemical stability originates from the nanocomposite structure containing Sb nanoparticles (5-15 nm) dispersed in a carbon component.