Si-on-Graphite fabricated by fluidized bed process for high-capacity anodes of Li-ion batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-03, Vol.407, p.126603, Article 126603
• Main Authors: Müller, Jannes, Abdollahifar, Mozaffar, Vinograd, Andrey, Nöske, Markus, Nowak, Christine, Chang, Shu-Jui, Placke, Tobias, Haselrieder, Wolfgang, Winter, Martin, Kwade, Arno, Wu, Nae-Lih
• Format: Article
• Language: English
• Subjects: Fluidized bed process; High capacity anode; Pitch coating; Silicon-on-graphite composite
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.126603

[Display omitted] •Preparation of silicon-graphite composites via fluidized bed for lithium-ion anodes.•High capacity silicon-on-graphite composites with ≈600mAh g−1.•Ethyl cellulose enables strong adhesion of silicon nanoparticles on graphite.•Pitch coating improves electrical conductivity and stability of composite particles.•Pitch coated composites retain >70% of specific capacity after 400 cycles. Composites consisting of graphite and silicon have been considered as potential high-capacity anode materials for the next-generation Li-ion batteries (LIBs). The synthesis method is critical for determining the microstructure, which is directly related to the material performance and the cost-efficiency for making commercial electrode materials. Herein, we report the fabrication of silicon-on-graphite (Si@Gr) composites by fluidized bed granulation (FBG) for the first time. The FBG process is shown to produce composite powders comprising a uniform layer of nano-sized Si particles lodged onto the surface of micron-sized graphite particles to possess a core-shell microstructure. Adopting a suitable binder during the FBG process enables a firm adhesion of the Si nanoparticles on graphite surface during subsequent carbon-coating, where the composite particles are coated with pitch and then carbonised to form a highly electronically conductive and mechanical stabilizing layer of amorphous carbon. These carbon-coated composites exhibit a high capacity reaching over 600 mAh g−1, high rate capability and illustrates the potential of long-cycle stability in Si@Gr || Li metal cells, showing more than 70% capacity retention after 400 charge-discharge cycles even without electrolyte optimization. Furthermore, a significantly improved cycling stability is found for the carbon-coated Si@Gr materials in LiNi0.6Co0.2Mn0.2O2 (NCM-622) || Si@Gr full-cells.