Carbon Yarn-Ball-Entangled SiO2 Anode with Excellent Electrochemical Performance for Lithium-Ion Batteries

Various nanoscale SiO2 and their composites have demonstrated superior electrochemical performance as anodes for lithium-ion batteries. However, both the battery production and real applications require the integration of nanoscale SiO2 into micrometer-sized secondary particles while preserving their excellent stability and conductivity, which remains a great challenge. In this work, a unique carbon yarn-ball structure is successfully synthesized that entangles nanoscale SiO2 together to build a micrometer-sized secondary particle. The hook-like carbon wires closely adhere to individual SiO2 nanoparticles, which constitute the basic unit of the yarn-ball structure. The entangled carbon wires create a network of electron conduction highways for SiO2, and the yarn-ball structure provides a resilient 3D matrix that can effectively buffer the anisotropic volume changes of SiO2 during Li ion insertion/extraction. Under 0.1 A g(-1), the carbon yarn-ball-entangled SiO2 can deliver a 1297 mAh g(-1) discharge capacity with a small irreversible capacity of 82 mAh g(-1). The entangled carbon yarn ball firmly maintains its structural integrity during high-rate cycling (1 A g(-1)), which gives rise to a large accessible capacity (709 mAh g(-1), 90.7% retention for 500 cycles), superior coulombic efficiency (>99.9%), and excellent structural stability.