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

Abstract

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(O_x) 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 GeO_x. 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.