Si@Si3N4@C composite with egg-like structure as high-performance anode material for lithium ion batteries

By Xiao Zhexi, L. Chao, Yu Chunhui, Xiao Chen, Zhenxing Zhu, Hairong Jiang, F. Wei. 2020

157 citations recorded by the source corpus.

Abstract Si-based anode materials in lithium-ion batteries (LIB) suffer huge volume changes during the charge–discharge cycling. Employing buffer materials to restrain the volume effect is important for these alloy-mechanism materials. In this work, we present a composite with an egg-like structure (denoted as Si@Si3N4@C) prepared by a two-step gas–solid reaction. The nanosized Si core exhibits high capacity. The highly strong and tough Si3N4 intermediate layer acts as a structural buffer, and the Li+ conductive layer accommodates volume variations and facilitates ion transport. The highly graphitized carbon shell enhances the integral conductivity. Consequently, the proposed composite can deliver a high first discharge capacity of 3093.8 mAh g−1 with an initial coulombic efficiency (ICE) of 91.51%. More than 80% capacity retention (vs. 2nd discharge) is observed after 200 cycles; when discharged at 10 A g−1, a capacity of 881 mAh g−1 is still displayed. The influence of the Si3N4 intermediate layer on Li+ diffusion is studied first, and the overall lithium-ion solid diffusion coefficient (DLi+) of the egg-like structure composite is found to be 8.111 × 10−11 cm2 s−1, which is approximately 300 times higher than that of Si, indicating a significant increase in Li+ diffusion. The probable reason is discussed and presented.

Subfields: Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/2ab661288c0b2279675e56b0294b998523c0a938