Yu Hao, Li Yuan, Liu Fang, Wang Li, Song Yonghai
National Engineering Research Center for Carbohydrate Synthesis/Key Lab of Fluorine and Silicon for Energy Materials and Chemistry of Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, 99 Ziyang Road, Nanchang 330022, China.
National Engineering Research Center for Carbohydrate Synthesis/Key Lab of Fluorine and Silicon for Energy Materials and Chemistry of Ministry of Education, College of Chemistry and Chemical Engineering, Jiangxi Normal University, 99 Ziyang Road, Nanchang 330022, China.
J Colloid Interface Sci. 2024 May 15;662:313-321. doi: 10.1016/j.jcis.2024.02.071. Epub 2024 Feb 10.
Silicon (Si) has ultra-high theoretical capacity (4200 mAh g) and accordingly is widely studied as anode materials for lithium-ion batteries (LIBs). However, its huge volume expansion during charging/discharging is a fatal challenge. The preparation of Si-based composite materials with yolk shell structure is the key to solving the Si volume expansion. Here, N-doped carbon-coated Si nanoparticles (SiNPs) nanocomposites (YS-Si@NC-60) with yolk shell structure derived from covalent organic frameworks (COFs) was prepared. N-doped carbon shells derived from COFs not only maintain the well-ordered nanosized pores of COFs, which facilitates the transport of Li to contact with internal SiNPs, but also provide more extra active sites for Li storage. Most importantly, the internal void can effectively alleviate the damage effect of SiNPs volume expansion. The obtained YS-Si@NC-60 as a LIBs anode show high cyclic stability and Li storage performances. At 0.1 A g, the capacity is 1446 mAh g after 110 cycles, and initial coulomb efficiency is as high as 82.2 %. The excellent performance can be attributed to the unique yolk shell structure. This simple and template-free strategy provides a new idea for preparing Si-C nanocomposites with yolk shell structure.
硅（Si）具有超高的理论容量（4200 mAh g），因此作为锂离子电池（LIBs）的负极材料被广泛研究。然而，其在充放电过程中的巨大体积膨胀是一个致命挑战。制备具有蛋黄壳结构的硅基复合材料是解决硅体积膨胀问题的关键。在此，制备了一种由共价有机框架（COFs）衍生而来的具有蛋黄壳结构的氮掺杂碳包覆硅纳米颗粒（SiNPs）纳米复合材料（YS-Si@NC-60）。由COFs衍生的氮掺杂碳壳不仅保留了COFs有序的纳米尺寸孔隙，这有利于锂的传输以与内部的SiNPs接触，而且还为锂存储提供了更多额外的活性位点。最重要的是，内部空隙可以有效减轻SiNPs体积膨胀的破坏作用。所制备的YS-Si@NC-60作为LIBs的负极表现出高循环稳定性和锂存储性能。在0.1 A g的电流密度下，110次循环后容量为1446 mAh g，初始库仑效率高达82.2%。这种优异的性能可归因于独特的蛋黄壳结构。这种简单且无模板的策略为制备具有蛋黄壳结构的Si-C纳米复合材料提供了新思路。
