Preparation of silicon oxycarbide (SiOC) anodes for high performance Li-ion batteries using competitive relationship between crosslinking and polymerization

SiOC anode is considered as a candidate for the next generation of lithium ion batteries, because of its appealing specific capacity and relative small volume expansion. However, the inherent inferior electron conductivity blocks its development. Recently, controlling the amount of free carbon domains is adopted to modify the performance, ignoring the influence of free C on the SiOC phases change and their synergistic effect on the performance. The crosslinking and polymerization competition between divinylbenzene and polymethylsilsesquioxane was coordinated to regulate the free carbon and phase composition of SiOC ceramics, and a durable SiOC anode with high ceramic yield was prepared. The result is that, keeping the proportion of free C about 10% and increasing the SiO3C and SiO2C2 phases ratios can obtain good anode within limited cycle life (440 cycle in this work), and increasing free C amount further is necessary for durable long cycle life. Herein, SDVB-2 anode with 12% free C delivers 698.7 mAh g-1 at a current density of 100 mA g-1 after 100 cycles, and SDVB-1 anode with 20.6% free C shows excellent stable long cycle performance at the current density of 0.5 A g-1, the remaining capacity is 476 mAh g-1 after 500 cycles.