An all-electrochem-active silicon anode enabled by spontaneous Li–Si alloying for ultra-high performance solid-state batteries

An all-electrochem-active Si/Li 21 Si 5 anode was designed, in which the Li 21 Si 5 served as efficient ionic/electronic channel and expansion buffer. It achieved an ultra-high ICE of 97.8% and a low expansion rate of 18.8% at a capacity of 17.9 mA h cm −2 .