Abstract:

This study addresses the severe volume expansion and poor conductivity issues of silicon-based anode materials during the charge-discharge process in lithium-ion batteries. To improve structural stability and electrochemical performance, a Si@Void@C composite material with a hollow structure was designed. In this study, Sb₂S₃ was used as a hard template and nano-sized Si/Sb₂S₃ particles were prepared via mechanical ball milling. Subsequently, resorcinol-formaldehyde was used as the carbon source, and a hollow structure with internal voids was constructed using the carbothermal reduction method. During this process, the carbon shell coating the silicon nanoparticles prevented direct contact between silicon and the electrolyte while considerably enhancing the material's conductivity. Additionally, the voids between the silicon nanoparticles and the carbon shell buffered the mechanical stress caused by volume changes during charge-discharge cycles, further improving cycle stability. As an anode material for lithium-ion batteries, the Si@Void@C composite exhibited excellent electrochemical performance, achieving an initial discharge capacity of 1691 mAh/g at a current density of 0.5 A/g. Even after 500 cycles, it maintained a high reversible capacity of 735.9 mAh/g, demonstrating exceptional cycling stability and capacity retention.

Key words: lithium-ion batteries, anode materials, Si, Si/C composites, buffering matrix