State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry Jilin University, 2699 Qianjin Street, Changchun, 130012, P. R. China.
Northeast Normal University, 5268 Renmin Street, Changchun, 130012, P. R. China.
Chemistry. 2021 Jul 21;27(41):10749-10757. doi: 10.1002/chem.202100727. Epub 2021 Jun 14.
A N-enriched porous carbon/SiO (SiO /NC) composite from rice husks was prepared by ball milling and tested as a stable anode for lithium ion batteries (LIBs), in which the homogeneous dispersion of SiO nanoparticles and carbon matrix, and high level of N-doping can be realized simultaneously. The influence of N-doping on a series of SiO /NCs was systematically studied; this proved that the porosity, N-doping content, and electronic conductivity of SiO /NC can be controlled by adjusting common nitrogen sources (urea and melamine) and doping routes, including dry and wet milling, to reach a desirable balance of high capacity, long-term cyclability, and rate property. The optimized SiO /NC composite delivers a stably reversible capacity of 581 mA h g at the high current load of 1.0 A g at the 1000th cycle. The novel Li-storage mechanism of active silica in a composite was first proposed after observation of the N-doping effect that the redox reaction between SiO and Li is accelerated to transform into an alloying reaction of generated Si and Li , thus enhancing the reversible capacity. Moreover, kinetics analysis confirms that there is a combined Li-storage mechanism of battery-capacitive pattern in composite that contributes to fast charge transfer and ion diffusion during cycle.
以稻壳为原料，通过球磨法制备了一种富氮多孔碳/二氧化硅（SiO /NC）复合材料，并将其用作锂离子电池（LIBs）的稳定阳极。该复合材料中，SiO 纳米颗粒和碳基质均匀分散，且氮掺杂水平较高。系统研究了氮掺杂对一系列 SiO /NC 的影响，结果表明，通过调整常见氮源（尿素和三聚氰胺）和掺杂途径（包括干法和湿法球磨），可以控制 SiO /NC 的孔隙率、氮掺杂含量和电子电导率，从而达到高容量、长循环稳定性和倍率性能的理想平衡。优化后的 SiO /NC 复合材料在 1000 次循环时以 1.0 A g 的高电流负载下，可稳定提供 581 mA h g 的可逆容量。通过观察氮掺杂效应，提出了复合材料中活性二氧化硅的新型储锂机制，即 SiO 和 Li 之间的氧化还原反应加速转化为生成的 Si 和 Li 的合金化反应，从而提高了可逆容量。此外，动力学分析证实，复合材料中存在一种电池-电容混合的储锂机制，这有助于在循环过程中实现快速的电荷转移和离子扩散。
