Systematic study on group 14 elements and their oxides for high-capacity anode active materials of lithium-ion secondary battery

For the purpose of use as anode active materials of lithium-ion secondary batteries, the group 14 elements (Si, Ge, Sn and Pb) and their oxides were investigated systematically. Ge(Ox) actually showed high capacity of around 1,200 mAh/g. This is corresponding to the fact that more than four moles of Li ions react to one mole of GeOx. Except for SiO2, the oxides of these elements generally showed relatively higher capacity and good cycle performance when compared to simple bodies. It is due to a conversion reaction to form Li2O. Vinylene carbonate (VC) addition and capacity limitation were effective on improvement of cycle performance for not only Si but also other elements and oxides. A summation factor of irreversible capacity shows that the quantities of solid-electrolyte interface formation are almost same in the case of PbO2-derived anode with/without the VC addition or the capacity limitation.