Yu Jing,Guangchao Li,Zhixing Wang,Xinhai Li,Wenjie Peng,Huajun Guo,Hui Duan,Guochun Yan,Jiexi Wang
Silicon (Si) is considered as one of the most promising candidates for next-generation lithium-ion batteries with high energy density. The main problems are the severe volume expansion and continuous interfacial side reaction of Si that hinder its further application. It can be an effective way by constructing a robust coating layer outside of Si to impede/alleviate the above effect. SiOx with high mechanical strength can largely promote the electrochemical performance of Si. Herein, Si@SiOx material with high specific surface area, high porosity, and controllable coating was synthesized via a simple solid–liquid reaction by LiOH solution etching effect. The etching/oxidation mechanism of Si under alkaline conditions was thoroughly investigated. The surface oxide layer of Si was beneficial to the formation of a solid electrolyte interphase (SEI) with excellent stability and high Li+ conductivity, while its high-porosity structure reduces the volume expansion of the material by approximately 110%. Under the synergistic effect of etching-oxidation, the modified material exhibited superior electrochemical properties. When employed as anode materials, the specific capacity was as high as 3101.5 mAh g–1 and maintained at 841.0 mAh g–1 after 500 cycles at 1 A g–1.
Zongwei Tong,Baojie Zhang,Huijun Yu,Xiangjie Yan,Hui Xu,Xiaolei Li,Huiming Ji
Nanofibrous aerogels constructed by ceramic fiber components (CNFAs) feature lightweight, compressibility, and high-temperature resistance, which are superior to brittle ceramic aerogels assembled from nanoparticles. Up to now, in order to obtain CNFAs with stable framework and multifunctionality such as hydrophobicity and gas absorption, it is necessary to perform binding and surface modification processes, respectively. However, the microstructure as well as properties of CNFAs are deteriorated by the direct addition of binders and modifiers. To tackle these problems, we introduced a unique low-temperature (100 °C) chemical vapor deposition method (LTCVD) to achieve the cross-linking and hydrophobization of Si3N4 CNFA in only one step. More importantly, during the LTCVD process, SiOx coatings and nanowire arrays were in situ formed via vapor–solid (VS) and vapor–liquid–solid (VLS) mechanisms on the surface and intersection of Si3N4 nanofibers, which cemented the aerogel framework, endowed it with hydrophobicity, and improved its oxidation resistance at high temperature. Compared to most of its counterparts, the Si3N4/SiOx CNFA exhibited better mechanical properties, higher capability of oil/water separation (33–76 g·g–1), lower thermal conductivity (0.0157 W/m·K–1), and superior structural stability in a wide temperature range of −196–1200 °C. This work not only presents an excellent Si3N4/SiOx CNFA for the first time but also provides fresh insights for the exquisite preparation strategy of CNFAs.
危险品化学品经营许可证（带存储）