Vertical graphene growth on uniformly dispersed sub-nanoscale SiOx/N-doped carbon composite microspheres with a 3D conductive network and an ultra-low volume deformation for fast and stable lithium-ion storage†
Silicon suboxide (SiOx, x < 2) is a promising candidate anode material, which has been widely used in lithium-ion batteries (LIBs) due to its high lithium-ion storage capacity. However, SiOx has poor conductivity and undergoes large volume change, resulting in poor rate capability and stability during cycling. Herein, a vertical graphene@SiOx/N-doped carbon (VG@SiOx/NC) composite is easily prepared by the radially oriented growth of VG on SiOCN microspheres obtained by the pyrolysis of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in a sealed vessel under thermal chemical vapor deposition (CVD) conditions. The SiOCN microspheres are transformed into SiOx/NC microspheres with homogeneously dispersed SiOx and NC at the sub-nanoscale in the CVD process. The uniformly dispersed sub-nanoscale NC in the spheres of SiOx/NC and the surface VG construct a 3D conductive and robust network, resulting in fast and stable lithium ion intercalation/deintercalation. As an LIB anode, the VG@SiOx/NC composite shows a high reversible capacity of 1323.8 mA h g−1, excellent rate performance (265.5 mA h g−1 at 20 A g−1), and long cycling life (over 500 cycles with 84.2% of capacity retention at 2 A g−1).