The typical structural evolution of silicon anode

Due to its high theoretical capacity, silicon is the most promising anode candidate for future lithium-ion batteries with high energy density and large power. Yet the low conductivity and poor structural stability resulting from huge volume expansion after full lithiation are still the critical issues impacting practical applications of silicon anodes. This review unveils how structural designs address these challenges and outlines the structural evolution of silicon anodes. Up to now, six generations of structural designs have been proposed for silicon anodes, encompassing solid nanostructures, porous structures, core-shell structures, yolk-shell structures, high-tap-density packed yolk-shell structures, and carbon-nanotube-improved yolk-shell structures. The evolution of structural improvement principles deployed for silicon anodes can provide valuable guidance for the rational structural design of other electrode materials that undergo large volume changes.