S doped CNTs scaffolded Si@C spheres anode toward splendid High-Temperature performance in Lithium-ion Battery

The poor electronical conductivity and large volume change of nano-silicon anode has seriously hindered 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 celcius, 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.