Si@nitrogen-doped porous carbon derived from covalent organic framework for enhanced Li-storage

• Published in: Journal of colloid and interface science 2023-03, Vol.634, p.176-184
• Main Authors: Chen, Kaixiang, Xiong, Jinyong, Yu, Hao, Wang, Li, Song, Yonghai
• Format: Article
• Language: English
• Subjects: Anode; Core-shell structure; Covalent organic frameworks; Lithium-ion batteries; Nano-Si; Nitrogen-doped carbon
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2022.12.058

Flexible nitrogen-doped porous carbon-encapsulated silicon nanoparticles (Si@NC) were successfully prepared using covalent organic framework as precursor, and showed good performance when applied to the anode of lithium-ion batteries. [Display omitted] •A Si@nitrogen-doped porous carbon (NC) was prepared by using covalent organic framework (COFs).•The NC derived from COFs has well-ordered pores, which facilitates the transport of Li+.•The flexible ordered NC framework can effectively overcome the effect of huge volume expansion of Si.•The nano-Si is decomposed into smaller Si nanoparticles, which improve the Li+ storage greatly.•The Si@NC composite exhibits high Li+ storage capacity and good cyclic stability. Due to ultra-high theoretical capacity (4200 mAh g−1), silicon (Si) is an excellent candidate for the anode of lithium-ion batteries (LIBs). However, the application of Si is severely limited by its volume expansion of approximately 300% during the charge/discharge process. Herein, nitrogen-doped porous carbon (NC) capped nano-Si particles (Si@NC) composites with a core-shell structure were obtained by calcination of covalent organic frameworks (COFs) encapsulated nano-Si. COFs is a crystalline material with well-ordered structures, adjustable and ordered pores and abundant N atoms. After carbonization, the well-ordered pores and frameworks were kept well. Compared with other Si@NC composites, the well-ordered NC framework shell derived from COFs possesses high elasticity and well-ordered pores, which provides space for the volume expansion of nano-Si, and a channel to transfer Li+. The core-shell Si@NC composite exhibited good performances when applied as the anode of LIBs. At a current density of 100 mA g−1, it exhibited a discharge-specific capacity of 1534.8 mAh g−1 after 100 cycles with a first-coulomb efficiency of 69.7%. The combination of COFs with nano-Si is a better strategy for the preparation of anode materials of LIBs.