Metal-free Si-doped graphene: A new and enhanced anode material for Li ion battery

Anode materials with large reversible capacity, small volume expansion, high mobility and low cost are urgently demanded in portable electronics. Herein, we have tried to seek a new and excellent material for Li ion batteries. Because of the synergetic effect of Si and graphene, Si-doped graphene with divacancy structure has been found to be the best candidate. On the one hand Si component can improve the storage capacity and facilitate the Li atom diffusion, on the other hand, the stable frame structure of graphene can reduce the expansion effect simultaneously, contributing to its long-time stability. The reversible capacity can be increased to 1171 mA h/g or even more just by one Si atom doping, with only 0.4% volume expansion. Simultaneously, the foreign Si impurity can decrease the barrier of Li diffusing compared to its counter-part pristine graphene. Therefore, it is reasonable to design Si-doped graphene serving as a new and promising Li ion battery anode.