Face-to-face conducting mechanism enabled by Si-C bonds for binder free Si@CNTs electrode

Abstract

The three-dimensional conductive network has been developed, creating a continuous pathway for Si anodes. Nonetheless, the weak physical contact between Si particles and the conducting network is prone to separation due to expansion stress and the solid electrolyte interface. This results in a rapid decline in cell cycling performance. Herein, we have developed a binder free Si@CNTs fibrous thin film structure using carbon nanotube (CNT) conducting networks through a high vacuum magnetic sputtering process of molecular reorganization. With Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS) tests and density functional theory (DFT) calculations, we propose a strong “face-to-face” contact configuration based on Si-C bonds. The Si@CNTs film demonstrated stable mechanical and electrical properties even after repeated bending and stretching of up to 6%. In-situ transmission electron microscopy confirmed that the initial cycling volume expansion of the Si@CNTs fibers with Si-C bonds was only 58.33%. Furthermore, the full cell using Si@CNTs anode enabled stable high-rate cycling performance at 6C after 500 cycles. This innovative strategy redefines the conductive mode of CNTs with Si anodes.