Si-SiOx@C-2.5 (19.4 m 2 •g -1 ) and Si-SiOx@C-5 (16.2 m 2 •g -1 ). With the introduction of CNTs, the twined CNTs skeleton led to a more stacked structure and reduced the surface area slightly. The relatively low specific surface areas could reduce the side reactions and SEI formation compared to the nanoparticles and porous composites with high specific surface area .