Enhanced Silicon Anodes with Robust SEI Formation Enabled by Functional Conductive Binder

• Published in: Advanced functional materials 2024-08, Vol.34 (34), p.n/a
• Main Authors: Chen, Benqiang, Xu, Dongmin, Chai, Simin, Chang, Zhi, Pan, Anqiang
• Format: Article
• Language: English
• Subjects: Anodes; binder; Charge materials; Charge transfer; Chemical bonds; Citric acid; conductive polymer; Elastic properties; Electrodes; Isopropanol; lithium‐ion battery; Mechanical properties; Robustness; Silicon; silicon anode; solid electrolyte interface; Solid electrolytes; Structural stability; Sulfonic acid; Surface stability
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202401794

The application of silicon (Si) anode is limited by the drastic volume change of silicon in the lithiation/delithiation process, the repeated formation of the solid electrolyte interface (SEI), and the low intrinsic conductivity. In this work, a small amount of poly (3,4‐ethylenedioxythiophene):poly (styrene sulfonic acid) (PEDOT:PSS) (PP), citric acid (CA), isopropyl alcohol (IPA), and silicon nanoparticles (SiNPs) are mixed and vacuum treated at a specific temperature to obtain silicon‐based anode electrode composite Si@PP@CA. The interphase forms a robust elastic network with hydrogen and chemical bonds, which have good mechanical properties and self‐repairing characteristics. The modified PEDOT:PSS as the conductive medium significantly improves the charge transfer rate. Moreover, the rapid formation of SEI by CA on the surface of SiNPs enhances the structural stability of the material. The electrochemical results show that the capacity of Si@PP@CA composite electrode canretain more than 2200 mAh g−1 after 200 cycles at 0.2 A g−1. It still shows a high capacity retention of 89% even at the current density of 1.0 A g−1 after 2000 cycles. More importantly, such excellent performance can be obtained using an electrode with an active material content of up to 90 wt%, which is essential for practical applications. In this work, a functional conductive polymeric binder composed of poly(3,4‐ethylenedioxythiophene):poly (styrene sulfonic acid) (PEDOT:PSS) (PP) and citric acid (CA) is proposed. After co‐treatment with isopropanol (IPA) and CA, PEDOT changes from helical conformation to linear conformation, which can greatly improve the electrical conductivity. PSS, citric acid, and silicon particles cross‐link each other to form a 3D mechanical network and stable solid electrolyte interface (SEI) layer.