Preparation of mg-si and nitrogen-doped graphene nanocomposites for use as lithium-ion anode

• Main Authors: Parinya Jinai, Thanapat Autthawong, Theeraporn Promanan, Viratchara Laokawee, Thapanee Sarakonsri
• Format: Book Series
• Published: 2020
• Subjects: Materials Science
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85088211407&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/70687
• Institution: Chiang Mai University

© 2020 Trans Tech Publications Ltd, Switzerland. Si and Mg are good candidates for anode lithium-ion batteries because Si and Mg have high theoretical capacity of 4200 mAh g-1 and 994 mAh g-1, respectively. However, these elements generate high-volume expansion during the charge-discharge process, which can cause the electrode to crack after being used for a few cycles. To solve this problem, the active materials are prepared in a nanosize and composited with a 2D-sheet of nitrogen-doped graphene, as the high mechanical stability and flexibility of nitrogen-doped graphene can support the volume expansion. Preparation of Si-Mg and nitrogen-doped graphene includes two steps. First, the reduction of Mg2+ ions with NaBH4 in ethylene glycol solution and reflux at 350-400 °C for 3 hr and Si nanoparticles, which were prepared by magnesiothermic reduction, was conducted. Second, Si and Mg nanoparticles and nitrogen-doped graphene were mixed in ethylene glycol solution and then collected by centrifugation. The obtained Si-Mg nanocomposite particles were well distributed on the nitrogen-doped graphene. The phases were indexed as Si, Mg and nitrogen-doped graphene. The particle sizes were small (approx 21-56 nm) with good dispersion on the nitrogen-doped graphene which observed by transmission electron microscopy and scanning electron microscopy techniques. Energy dispersive spectrometry results confirmed the existence of Si-Mg. Therefore, Si-Mg and nitrogen-doped graphene nanocomposite materials are expected to contain promising properties that can be used as high-performance anode materials in lithium-ion batteries in the future.