Enhanced cycling performance of SiOx microparticles uniformly coated with graphene sheets

• Published in: Electrochimica acta Vol. 421; p. 140469
• Main Authors: Li, Zhaolin, Tao, Xin, Yang, Yaozong, Yao, Nana, Yang, Zhao, Luo, Dawei, Wang, Jie, Zhao, Hailei
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.07.2022; Elsevier BV
• Subjects: Anode; Anodes; Carbon; Coated electrodes; Cycles; Electrochemical performance; Electrode materials; Electrodes; Graphene; Graphene-coating; Heat treatment; Hydrogen bonds; Lithium ion battery; Lithium-ion batteries; Microparticles; Rechargeable batteries; Sheets; Silicon suboxide; Structural integrity; Electrochemical performance; Lithium ion battery; Silicon suboxide; Graphene-coating; Anode
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.140469

•A conformally graphene-coated SiOx material is achieved through surface engineering.•PVP avoids the oxidation and thus capacity loss of SiOx during hydrothermal process.•Excellent cycling performance and superior rate capability were delivered. Microsized silicon suboxide (SiOx, 0<x<2) materials promise less interfacial side reactions and higher volumetric capacity than those of nanosized couterpart when used as anode materials for high energy density lithium ion batteries. However, its poorer mechanical stability during charge/discharge process severely frustrates the cycling performance. Here we successfully achieved a conformally graphene-coated microsized SiOx material through surface engineering by a facile PVP-assisted hydrothermal method. PVP connects SiOx and graphene oxide (GO) sheets via hydrogen bonds in hydrothermal process and then in-situ carbonizes to form an amorphous carbon layer between SiOx core and graphene sheets after heat-treatment. The inner amorphous carbon layer and outer graphene sheets together evenly and conformally coat on SiOx particles, forming a double-layer coated SiOx/C@graphene composite. The well-encapsulation of SiOx by the double coating layers guarantees the uniform occurrence of electrode reactions on SiOx surface, which reduces the structural stress and homogenizes the volume variation, thus enabling excellent structural integrity of electrode during lithiation/delithiation process. Owing to the well-engineered structure, the SiOx/C@graphene electrode delivers an excellent cyclic performance (1076 mAh g−1 at 0.5C after 120 cycles with a capacity retention of 88.7%) and superior rate capability (785 mAh g−1 at 3C). The well-encapsulated SiOx by a double-coating-layer of amorphous carbon and graphene sheets is prepared by a PVP-assisted hydrothermal approach. Benefiting from the well-elaborated structure, the SiOx/C@Graphene anode material presents an ultrahigh cyclic stability and excellent rate performance. This work provides an effective way for the design and preparation of high-performance SiOx anode materials. [Display omitted]