Advances in Carbon Nanotubes and Carbon Coatings as Conductive Networks in Silicon-based Anodes

Abstract

Silicon-based anode has high theoretical capacity but suffers from poor electrical conductivity, large volume expansion, and unstable solid electrolyte interphase (SEI). Adding carbon nanotubes (CNTs) and carbon coatings are both very effective methods for addressing the above issues. The intrinsic sp² covalent structure endows CNTs with excellent electrical conductivity, mechanical strength, and chemical stability, which makes them suitable for various energy storage applications, such as in lithium-ion batteries (LIBs). Apart from the conductive network, CNTs can serve as current collectors, mechanical probes, and mechanical frameworks, and they have potential in the construction of next-generation battery architectures. Carbon coatings are mixed ionic-electronic conductors with good chemical stability that provide mechanical support and mitigate the volume expansion of Si-based materials. This review outlines the advances in CNTs and carbon coatings as conductive networks in Si-based anodes, as well as insights into their future development. It provides an in-depth analysis of the percolation and mechanical mechanism of conductive networks, highlights the importance of flexible long-range conductivity, and decouples the relationships between stress, interface stability, and electron/ion transfer.