▎ 摘　　要

NH2-terminated Si nanoparticles with an ultrathin silica shell have been efficiently obtained by a one-step reaction in ammonia-water-ethanol solution. Graphene nanosheet (GNS) encapsulated Si@ultrathin SiOx has been fabricated by self-assembly and thermal treatment. Because of the uniform ultrathin SiOx shell and superior GNS encapsulation structure, this material shows a reversible capacity of 2391.3 mA h g(-1), maintaining 1844.9 mA h g(-1) after 50 cycles at a current density of 200 mA g(-1), and good rate and long cycle performance (similar to 700 mA h g(-1) at 2000 mA g(-1) after 350 cycles) as well.