Formation of a robust SEI through covalent binding nitrile to silicon toward stabilized micron-sized silicon anodes

Abstract

Constructing robust solid electrolyte interface (SEI) has long been regarded as an effective strategy for stabilizing silicon anodes and still remains a great challenge. In this work, we experimentally demonstrate that the covalent binding of polyacrylonitrile (PAN) binder to silicon results in the formation of robust bilayer SEI containing a Li₃N-rich inner layer and an organic-components-rich outer layer. The in situ generated N-rich SEI is mechanically stable and ion-conductive. As a result, the stability and adhesion of silicon electrodes are greatly enhanced. Specifically, silicon electrodes utilizing PAN binder exhibit remarkable improvements in terms of Coulombic efficiency (CE), rate performance, and cycling stability (1290 mAh g⁻¹ after over 800 cycles at 0.5 C) compared to the electrodes utilizing other binders. The silicon surface functionalization strategy offers a potential approach paving the way toward the development of stable and high-energy silicon-based lithium-ion batteries.