Covalently Bonded Si−SiOC−C Heterostructural Nanocomposites as Durable Anode Materials for High-Energy Lithium-Ion Batteries

Abstract

Enhancing electrical conductivities and structural stabilities of Si-based anodes is critical to achieve efficient and stable capacity output, promoting their practical implications. Here, we design a covalently bonded heterostructural Si−SiOC−Cnanocomposite to improve the above properties.Covalentlybonded Si−polyvinylalcohol (Si−PVA) nanocomposites are first fabricated via high-energy ball-milling of the mixture of micronsized Si and PVA, then dual-layered SiOC−Cwrappersarein-situ formedon Si surfacebylow-temperatureannealing. The obtained compositeis thusa Si−SiOC−C heterostructurewith good mechanical resiliency to accommodate Si volumetric expansion and also good mixed conductivity. Such composite anode design enables excellent electrochemical performance, including high specific capacity and good cycle stability (2130 mAh g−1 after 100 cycles at 0.2 A g−1, and 1068 mAh g−1 after 300 cycles at 1.0 A g−1). Notably, Si−SiOC−C anode demonstrates a great potential for Li-ion batteries, where Si−SiOC−C-graphite//NCM811full-cell exhibitsefficient and stablecapacityoutput (initial capacity of 195 mAh g−1 and retain capacity of 160 mAh g−1 after 300 cycles at 1.0C).The simpleand scalable manufacturing makes Si−SiOC−C anode materialpotentially viable for commercialization.