Co-loading of sulfur/silicon oxides in self-supporting binder/collector free CNT sheets delivers enhanced electrochemical storage capacity of 830 mAh g⁻¹ and 368 mAh g⁻¹ at 1 A g⁻¹ current density after 250 cycles in LIB and SIB mode, respectively.

Abstract

Sulfur and silicon oxides loaded self-supporting binder and collector free CNT sheets have been synthesized using floating catalyst chemical vapor deposition technique and investigated for their application as anodes in lithium/sodium ion battery. The CNT sheets have been characterized thoroughly using various microscopic and spectroscopic techniques. The addition of sulfur improves the interplanar spacing in the lattice and also generated abundant defects. The silicon oxides help in enhancing the specific capacity of the CNT sheet via conversion reactions. These features lead to enhanced electrochemical properties and the best performance has been demonstrated by the co-loaded CNT/S/silicon oxide electrode. As anode in LIB, it delivers 830 mAh g⁻¹ at 1 A g⁻¹ current density after 250 cycles. More importantly, the kinetic analysis confirms that sulfur/silicon oxide co-loading can improve the Li⁺ diffusion coefficient in CNT anode and enhance the metal ion storage. The structural modifications also enhance Na⁺ ion storage and the CNT/S/Silicon oxide anode delivers 368 mAh g⁻¹ after 250 cycles at a current rate of 1 A g⁻¹ with a superior initial coulombic efficiency of 77.5 %.