High performance rechargeable Li-S batteries using binder-free large sulfur-loaded three-dimensional carbon nanotubes

The increasing demand for clean and efficient energy storage in portable electronics, electric vehicles, and smart energy grid has spurred attention to develop advanced battery systems. Complementing the high theoretical specific capacity of sulfur cathode (∼1672 mAh/g), environmentally benign, and low-cost, Li-S batteries can meet the myriad needs of inexpensive and high energy density energy storage. However, the intrinsic drawbacks of poor cycle life and low charge efficiency in conventional Li-S batteries hinder the advancement of this alluring technology. Here, we propose a novel and facile synthesis of binder-free three-dimensional carbon nanotubes (3D CNTs)/sulfur (S) hybrid composite as an electrode material, where 3D CNTs provide a high conduction path and short diffusion length for Li-ions, while confining soluble poly-sulfides within the structure for high cycling performance. The unique binder free cathode design results in one of the highest sulfur loading of 8.33 mg/cm2 (∼55 wt% S in the cathode electrode) with excellent areal and specific capacity of 8.89 mAh/cm2 and 1068 mAh/g at 0.1C rate (∼1.4 mA/cm2) offering coulombic efficiency of greater than 95% for 150 cycles. The novel cell exhibits maximum specific energy of ∼1233 Wh/kg with a specific power of ∼476 W/kg, with respect to the mass of the cathode.

241