A robust hierarchical 3D Si/CNTs composite with void and carbon shell as Li-ion battery anodes

To target the low conductance and expansion issues of Si based anodes for Li-ion batteries, a 3D structural composite constructed by CNTs framework distributedly anchored with double-carbon coated silicon nanoparticles has been designed, fabricated and characterized. The crosslinked CNT framework provided electrical conductive pathway as well as void-space to accommodate the expansion of silicon nanoparticles. The double layered carbon coating was formed under the assistance of the sulfur sacrificing agent giving protection on the silicon particle surface. The Si/CNTs@(S)-C electrodes exhibited a high reversible capacity of 943 mAhg−1 after 1000 cycles at a C/5 rate. The excellent cycling performance is attributed to the unique structure which can stabilize the silicon particle during volume expansion and keep the electrical connection at the same time.