Dual-layer carbon protected coaxial cable-like Si-based composites as high-performance anodes for lithium-ion batteries

•The NC@Si@CNTs electrode has coaxial cable structure.•The N doping into the carbon framework can be synchronized with the preparation procedure, which not only generate more defects and active sites, but also introduce porous microstructures and increase the specific surface area.•The double-layer carbon structure not only provides high conductivity, but also acts as a buffer to reduce volume expansion during cycling and stabilize the structure.•The composites have high capacity and good cyclic.