S Doped Carbon Nanotubes Scaffolded Silicon Anode Toward Splendid High-Temperature Performance

Abstract

The poor electronical conductivity and large volume change of nano-silicon anode has seriously hander its further application. To overcome these drawbacks, we employed the S-doped multiwalled carbon nanotubes (SCNTs) as the conductive additive to fabricating a scaffolded framework for the first time. The as-assembled Si anode with 5 wt% SCNTs (Si@C-5SCNTs) shows a large specific capacity of 939 mA h g-1 at 2 A g-1, within 0-1 V, significantly higher than that of Si@C (466 mA h g-1) and Si@C-5CNTs (720 mA h g-1), showing a superior rate performance. Besides, it shows higher initial coulombic efficiency, Li-ion diffusion coefficient, cycling performance, and smaller volume change than that of Si@C and Si@C-CNTs at room temperature. Even at 40 ℃, the Si@C-5SCNTs anode still show a superior rate performance (1842 and 819 mAh g-1 at 0.05 and 2 A g-1, respectively) and cycling stability (83.6% capacity retention) than that of Si@C and Si@C-5CNTs. To better explain the significantly enhanced electrochemical performance of Si anode both room and high temperature conditions, both the chemo-mechanical coupling and internal temperature distribution models have been rational constructed, and further demonstrated that the SCNTs can effectively buffer the volume expansion and reduce the internal local temperature rise.

Keywords: Si anode, SCNTs conductive additive, Volume change, High-temperature performance, Internal temperature distribution