In-situ CNT-reinforced double-layer carbon Si/C anodes for Li-ion batteries with low volume expansion and high cyclability

A new approach is proposed for in-situ growth of carbon nanotubes on the surface of ZIF-8 particles. • The double-layer carbon encasing effectively suppresses the volume expansion of silicon nanoparticles. • The silicon carbon composite exhibits excellent cycling performance for lithium-ion battery anodes. • Abundant CNT-containing carbon framework boosts conductivity and lithium ion diffusion kinetics. Silicon-based materials as anode materials for lithium-ion batteries, face critical challenges including significant volume expansion during charge/discharge cycles and low electronic conductivity. Carbon-coated silicon particles represent a promising approach, and their cycling stability falls short of the need in practical applications. Here, a novel method to in-situ synthesize dual-layered carbon-coated silicon nanoparticles rich in carbon nanotubes has been reported as an anode material for lithium-ion batteries. It exhibits outstanding lithium storage performance, maintaining a discharge capacity of 1007.1 mAh g −1 after 1000 charge/discharge cycles at current density of 0.5 A g −1 , demonstrating a capacity retention rate of 99.9%, while maintaining a low volumetric expansion rate of only 40% after 1000 cycles as compared to the value of 155% for the bare Si electrode investigated by the top-view digital photographs and cross-sectional SEM image. Even at 1 A g −1 high current density, the composite maintains a high reversible capacity of 705.4 mAh g −1 with 92.1% capacity retention rate after 1000 charge/discharge cycles. It is found that the better electric performance above is closely related with the carbon nanotubes outside the unique dual-layered carbon-coated silicon nanoparticles, which significantly enhances the electrode electrical conductivity and lithium-ion diffusion coefficient (≈10 −10  cm 2  s −1 ). This work provides a valuable technical route to develop silicon-based anode materials with high electrical conductivity and reactivity. Download: Download high-res image (143KB) Download: Download full-size image