A self-assembled carbon nanotube/silicon composite battery anode stabilized with chemically reduced graphene oxide sheets

Abstract

This study presents a streamlined fabrication process for lithium-ion battery (LIB) electrodes, involving the dispersion of carbon nanotubes (CNT), silicon (Si), and graphene oxide (GO) in an aqueous solution, followed by vacuum filtration to produce self-standing composite electrodes. Two reduction routes are employed to form reduced graphene oxide (rGO). The chemically reduced CNT/Si/rGO-5 %-Chem anode exhibits superior mechanical resilience compared to thermally reduced counterparts, which suffer from reduced strength and structural integrity. Chemical reduction also enhances electrochemical performance, increasing the initial capacity of the non-reduced CNT/Si/GO-5 % composite anode from 1,461 to 2,342 mAh g−1, with improved long-term cycling performance. Electrochemical impedance spectroscopy shows lower pre-cycle charge transfer resistance (148 Ω) and superior solid electrolyte interphase (SEI) resistance (43 Ω) for chemically reduced anodes compared to thermally reduced ones. After cycling, the chemically reduced composite anode exhibits reduced electrolyte resistance and charge transfer resistance, indicating stable electrochemical reactions. The composite structure undergoes adaptive rearrangements during cycling, optimizing active material utilization. In summary, CNTs accommodate silicon swelling, while chemically reduced rGO promotes stable SEI formation, highlighting the benefits of chemical reduction in enhancing mechanical durability and electrochemical performance, making the self-standing CNT/Si/rGO composite film a promising LIB anode.

Keywords

• Silicon anode
• Graphene oxide
• Carbon nanotube current collector
• Chemical reduction
• Thermal reduction
• Lithium-ion batteries