One‐Pot Synthesis of Antimony‐Embedded Silicon Oxycarbide Materials for High‐Performance Sodium‐Ion Batteries

• Published in: Advanced functional materials Vol. 27; no. 43
• Main Authors: Lee, Yongho, Lee, Kwan Young, Choi, Wonchang
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 17.11.2017
• Subjects: Additives; Amorphous materials; Anodes; Antimony; Chemical synthesis; Composite materials; Low cost; Materials science; Nanoparticles; Oxycarbides; Particulate composites; Pyrolysis; Reaction kinetics; Rechargeable batteries; Silicon; silicon oxycarbide; silicone oils; Sodium-ion batteries
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201702607

Sodium‐ion batteries have recently attracted intensive attention due to their natural abundance and low cost. Antimony is a desirable candidate for an anode material for sodium‐ion batteries due to its high theoretical capacity (660 mA h g−1). However, the utilization of alloy‐based anodes is still limited by their inherent huge volume changes and sluggish kinetics. The Sb‐embedded silicon oxycarbide (SiOC) composites are simply synthesized via a one‐pot pyrolysis process at 900 °C without any additives or surfactants, taking advantage of the superior self‐dispersion properties of antimony acetate powders in silicone oil. The structural and morphological characterizations confirm that Sb nanoparticles are homogeneously embedded into the amorphous SiOC matrix. The composite materials exhibit an initial desodiation capacity of around 510 mA h g−1 and maintained an excellent capacity retention above 97% after 250 cycles. The rate capability test reveals that the composites deliver capacity greater than 453 mA h g−1, even at the high current density of 20 C rate, owing to the free‐carbon domain of SiOC material. The electrochemical and postmortem analyses confirm that the SiOC matrix with a uniform distribution of Sb nanoparticles provides the mechanical strength without degradation in conductive characteristics, suppressing the agglomeration of Sb particles during the electrochemical reaction. Sb‐embedded SiOC composites are synthesized by direct one‐pot pyrolysis without any additional surfactants or chemicals. The crystalline Sb nanoparticles are homogeneously embedded into the amorphous SiOC. The mechanical strength of SiOC enhances its long‐term performance. The free‐carbon domain in SiOC provides the superior rate capability of the composite electrode.