New insights on lithium storage in silicon oxycarbide/carbon composites: Impact of microstructure on electrochemical properties. (15th November 2021)

• Record Type: Journal Article
• Authors: Knozowski, Dominik; Graczyk-Zając, Magdalena; Vrankovic, Dragoljub; Trykowski, Grzegorz; Sawczak, Mirosław; De Carolis, Dario M.; Wilamowska-Zawłocka, Monika
• Is Part Of: Composites. Number 225(2021)
• Publication Date: 2021-11-15
• Subjects: Polymer derived ceramics -- Composites -- Graphite -- Li-ion battery -- Sol-gel synthesis; Composite materials -- Periodicals; Materials science -- Periodicals; Composite materials; Periodicals; Electronic journals; 620.118
• DOI: 10.1016/j.compositesb.2021.109302
• Languages: English
• ISSNs: 1359-8368

Abstract

Abstract: In this work, we study the impact of the preceramic precursor vinyltriethoxysilane (VTES) on the electrochemical performance of silicon oxycarbide (SiOC) glass/graphite composites. We apply an innovative approach based on high-power ultrasounds in order to obtain highly homogenous composites with a uniform distribution of small graphitic flakes. This procedure enhances gelation and drying of VTES-based preceramic polymer/graphite blends. The SiOC/graphite composites reveal stable capacities (up to 520 mAh g −1 after 270 cycles), which are much higher than the sum derived from the ratio of the components. Additionally, the first cycle Coulombic efficiencies obtained for the composites are 15% higher than that of the pristine VTES-based SiOC ceramic. These properties are identified as the synergistic effect, originated from the addition of graphite to VTES-based SiOCs. Interestingly, such improvement in electrochemical performance is not noticed in the case of analogous SiOC/graphite composites based on phenyltriethoxysilane (PhTES) precursor. The microstructural investigation of the composites based on two different preceramic precursors using solid-state 29 Si NMR and Raman Spectroscopy unveils the reason for such discrepancy in their electrochemical behaviour. Graphical abstract: Image 1 Highlights: SiOC/C composites are prepared by a novel high-power ultrasounds-assisted synthesis Graphitic flakes are uniformly distributed and partially exfoliated within the ceramic Microstructural dissimilarities of SiOC/C based on various precursors are discussed Synergistic effect on electrochemical properties of SiOC/C depends on microstructure SiOC/C electrodes exhibit improved first cycle Coulombic efficiency and high capacity