Si/Si–O–C composite materials with nano-silicons uniformly distributed in an amorphous Si–O–C matrix are prepared using a sol–gel method. The resulting materials exhibit a large initial coulombic efficiency of 78%, and deliver a capacity of 715.9 mA h g⁻¹ after 30 cycles at 3900 mA g⁻¹. The high capacity originates from lithium storage in nanosilicons and the Si–O–C matrix, and the excellent C-rate performances are related to the buffering of the Si–O–C matrix.