Porous Coconut Shell Carbon Offering High Retention and Deep Lithiation of Sulfur for Lithium-Sulfur Batteries.

ABSTRACT

Retaining soluble polysulfides in the sulfur cathodes and allowing for deep redox are essential to develop high-performance lithium-sulfur batteries. The versatile textures and physicochemical characteristics of abundant biomass offer a great opportunity to prepare biochar materials that can enhance the performance of Li-S batteries in sustainable mode. Here, we exploit micro-/mesoporous coconut shell carbon (CSC) with high specific surface areas as a sulfur host for Li-S batteries. The sulfur-infiltrated CSC materials show superior discharge-charge capacity, cycling stability, and high rate capability. High discharge capacities of 1599 and 1500 mA h g-1 were achieved at current rates of 0.5 and 2.0 C, respectively. A high reversible capacity of 517 mA h g-1 was retained at 2.0 C even after 400 cycles. The results demonstrate a high retention and a deep lithiation of the CSC-confined sulfur. The success of this strategy provides insights into seeking high-performance biochar materials for Li-S batteries from abundant bioresources.