郑州大学崔鑫炜团队报道了提高硅基阳极性能的单壁碳纳米管的机制。相关研究成果发表在2024年6月12日出版的《美国化学会杂志》。

在硅基阳极中大量储存锂离子可以保证高能量密度，但也会导致大的体积膨胀，导致循环性和导电性受损。

该文中，研究人员公开了单壁碳纳米管（SWNT）可以利用体积膨胀并诱导界面反应，从而原位稳定粉碎的硅基团簇，而不是限制硅基颗粒的粉碎。操作拉曼光谱和密度泛函理论计算表明，硅基颗粒锂化引起的体积膨胀在单壁碳纳米管中产生了～14%的拉伸应变，这反过来加强了Li和C之间的化学相互作用。

这种化学机械耦合效应促进了单壁碳管缺陷处的sp²-C通过sp³杂化转化为Li–C键，这也启动了界面处新的Si–C化学键的形成。随着这一过程的进行，单壁碳纳米管还可以诱导阳极3D结构的原位重建，形成具有高电导率和离子电导率的机械强化网络。因此，仅添加1wt%的单壁碳纳米管，石墨/SiOx复合阳极就可以提供远远超过商业石墨阳极的实际性能。

这些发现丰富了人们对应变诱导的界面反应的理解，为减缓基于合金化或转化反应的电极的降解提供了通用原理。

附：英文原文

Title: What Is the Real Origin of Single-Walled Carbon Nanotubes for the Performance Enhancement of Si-Based Anodes

Author: Haolin Wang, Yunfeng Chao, Jinzhao Li, Qi Qi, Junfeng Lu, Pengfei Yan, Yanyan Nie, Liu Wang, Jiafu Chen, Xinwei Cui

Issue&Volume: June 12, 2024

Abstract: A large amount of lithium-ion storage in Si-based anodes promises high energy density yet also results in large volume expansion, causing impaired cyclability and conductivity. Instead of restricting pulverization of Si-based particles, herein, we disclose that single-walled carbon nanotubes (SWNTs) can take advantage of volume expansion and induce interfacial reactions that stabilize the pulverized Si-based clusters in situ. Operando Raman spectroscopy and density functional theory calculations reveal that the volume expansion by the lithiation of Si-based particles generates ～14% tensile strains in SWNTs, which, in turn, strengthens the chemical interaction between Li and C. This chemomechanical coupling effect facilitates the transformation of sp2-C at the defect of SWNTs to Li–C bonds with sp3 hybridization, which also initiates the formation of new Si–C chemical bonds at the interface. Along with this process, SWNTs can also induce in situ reconstruction of the 3D architecture of the anode, forming mechanically strengthened networks with high electrical and ionic conductivities. As such, with the addition of only 1 wt % of SWNTs, graphite/SiOx composite anodes can deliver practical performance well surpassing that of commercial graphite anodes. These findings enrich our understanding of strain-induced interfacial reactions, providing a general principle for mitigating the degradation of alloying or conversion-reaction-based electrodes.

DOI: 10.1021/jacs.4c01677

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c01677