“Nano-Skeleton” Si-SiOx@C Anodes towards Highly Stable Lithium-ion Batteries

A fragile solid-electrolyte interphase (SEI) layer due to the volume expansion of silicon cannot sufficiently prevent side reactions and electrolyte consumption and restricts the application of silicon anodes in lithium-ion batteries with high cycling stability. Herein, a carbon nanotube (CNT) supported “nano-skeleton” structure with high mechanical property and improved conductive pathways is designed by twining CNTs with in-situ grown SiOx@C and carbon-wrapped Si nanoparticles. The CNT “nano-skeleton” can improve electrical contact between particles, promoting the formation of a denser and more homogenous SEI layer. Moreover, the buffer region granted by the CNTs can tolerate the volume expansions of Si avoiding the repeated destruction of the SEI layer during continuous lithiation and delithiation processes. Combined with these advantages, the anode with optimal CNT content can deliver a high capacity (918 mAh·g-1 at 200 mA·g-1) and high capacity retention (74% after 300 cycles) with relieved volume expansion (71.4%). The capacity of the NMC111 full cell retains about 70 mAh·g-1 after 500 cycles at 100 mAh·g-1 with capacity retention of 72%.