Phase-separated silicon-tin nanocomposites for high capacity negative electrodes in lithium ion batteries

► A phase separation-induced nanostructure (amorphous Si nanoparticles uniformly embedded in Sn matrix) was reported. ► The unique nanostructure improved fracture toughness and prevented the microcrack propagation during the cycling. ► The composite electrode showed excellent cycling stability and high capacity. ► The proposed concept can be generalized for material design to improve mechanical properties.