A simple and effective approach to relieve stress and enhance cyclability of Si-based materials toward high-energy lithium-ion batteries

[Display omitted] •A high Si content of 66.8% is achieved.•Both SiOx and BNCNTs can alleviate the volume expansion of Si during cycling.•Finite element analysis confirms the stress relief effect of Si@SiOx@BNCNT.•Si@SiOx@BNCNT exhibits desirable electrochemical properties. Silicon-based materials are promising anodes to keep up with the demands for next-generation lithium-ion batteries in the coming decades owing to their ultrahigh theoretical capacities. However, the severe volume changes and mechanical fractures during cycling greatly hinder their way to commercialization. So far, it still remains a great challenge to develop advanced Si-based electrodes with high mechanical stability and remarkable electrochemical properties. In this work, we propose a simple and effective strategy to encapsulate Si@SiOx particles into B, N co-doped carbon nanotubes (BNCNTs) to develop Si@SiOx@BNCNT electrode for enhanced lithium storage. The SiOx layer upon Si particle is designed to mitigate the volume expansion of Si and maintain the particle integrity. Finite element analysis demonstrates that BNCNTs with high mechanical strength can further relieve the internal stress induced by Si expansion upon lithiation. The double restraint effect from SiOx layers and BNCNTs on the Si particles contributes to excellent resistance to structural degradation, enabling high stability and desirable electrochemical performance of Si@SiOx@BNCNT electrode. This strategy provides great opportunities for the practical application of Si-based anodes in high-energy lithium-ion batteries.