Exposure of functional group from hyperbranched precursor to arrange SiOC phase for lithium-ion batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2025-01, Vol.503, Article 158270
• Main Authors: Wu, Quanhui, Wu, Pengfei, Tu, Huibin, Mi, Sen, Zhang, Zhenpu, Song, Keyan, Liu, Anhua
• Format: Article
• Language: English
• Subjects: Hyperbranched polymers; Lithium-ion batteries; Rearrangement reactions; SiOC ceramics
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.158270

•This article achieves the regulation of the reversible phase composition (SiO2C2 and SiO3C) in SiOC materials through the molecular structure design of the precursor.•Hyperbranched precursors exposed to different amounts of Si-OH are synthesized by the Grignard reaction, in which Si-OH can regulate the Si-C/Si-O rearrangement during pyrolysis, providing a new method for customized SiOC ceramics.•The introduction of phenolic resin builds a conductive network, improves the conductivity of SiOC anode, and increases its application potential. The SiOC anode still has a capacity of 775.5mAh/g at 0.5A/g after 300 cycles. Polymer-derived silicon oxycarbide (SiOC) ceramics are promising anode materials for lithium-ion batteries due to their high theoretical capacity. However, controlling their structure and composition during pyrolysis is challenging. This study employs chemical methods to construct hyperbranched polysiloxane precursors, exposing varying amounts of Si–OH groups to regulate Si–C and Si–O rearrangement. The resulting SiOC ceramics exhibit high reversible phase contents and improved electrical conductivity with added phenolic resin. The optimized SiOC ceramic M1-PF delivers a reversible capacity of 775.5 mAh g−1 after 300 cycles at 0.5 A g−1, and 344 mAh g−1 at 4 A g−1. A full cell with M1-PF and LiFePO4 retains 89.7 % capacity after 100 cycles at 0.2 A g−1. This work provides new insights for customizing SiOC ceramics for advanced battery applications.