Thermolytically grafted silicon particles with ultrathin carbonaceous coating rich of phenyl moieties as lithium-storage anode material

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-09, Vol.395, p.125169, Article 125169
• Main Authors: Xuan Tran, Minh, Woo, Jae-Young, Nguyen, Thuy-An, Lee, Sang-Wha, Kee Lee, Joong
• Format: Article
• Language: English
• Subjects: Bundle-like porous Si; Low temperature thermolytic grafting; Phenyl moieties; Ultrathin carbonaceous film
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.125169

•Styrenic carbon fragments were grafted on the porous silicon (por-Si) particles via thermolysis of polystyrene.•The Si-C grafted species rich of phenyl moieties were uniformly coated on the por-Si surface.•Ultrathin carbonaceous coating prevents the rapid pulverization of Si nanostructure as a strong passivation layer.•Thermolytically grafted por-Si plays as an excellent lithium-storage anode material. The most critical bottleneck of Si anode materials is an inevitable cracking and pulverization of Si nanostructure during electrochemical cycling process, resulting in a significant loss of electrical contact and rapid capacity fading. The low-temperature thermolytic grafting process at 360–400 °C was employed to produce a conformal carbon coating on a bundle-like porous silicon (por-Si) prepared by silver-assisted chemical etching. During the thermolytic grafting process, polystyrene infiltrated in the por-Si was depolymerized into styrenic carbon fragments rich of phenyl moieties. The styrenic carbon fragments were subsequently grafted uniformly on the por-Si surface as an ultrathin carbonaceous film of 5 nm, which was confirmed by transmission electronic microscope, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The polystyrene grafted por-Si (por-Si@PS) was employed as a lithium-storage anode material. After 100 cycles at a current rate of 0.5C, the por-Si@PS anode exhibited an excellent reversible capacity of 1938.82 mAh g−1, when compared to those of por-Si and pristine Si anodes with 1228.57 mAh g−1 and 117.43 mAh g−1. The por-Si@PS exhibited a good recovery capability of 93.1% in the C-rate test. The ultrathin carbonaceous coating rich of phenyl moieties not only prevents the rapid pulverization of nanostructured Si, but also enhances the interfacial properties of por-Si@PS as lithium-storage anode material. Notably, the thermolytically grafted Si-C species rich of phenyl moieties played as a strong adhesive passivation layer against the corrosive electrochemical agents during cycling.