Rational Design of a Cost-Effective Biomass Carbon Framework for High-Performance Lithium Sulfur Batteries

Abstract

Lithium–sulfur (Li-S) batteries are the most attractive candidates for next-generation large-scale energy storage because of their high theoretical energy density and the affordability of sulfur. However, most of the reported research primarily concentrates on low sulfur loading (below 2 mgs cm−2) cathodes using binders and traditional collectors, thus undermining the expected energy density. Herein, a N, O co-doped carbon nanotube (N, O-CNT) decorated wood framework (WF), denoted as WF-CNT, was designed as a free-standing sulfur host, achieving high sulfur loading of 10 mgs cm−2. This unique cathode featured low tortuosity microchannels and a conductive framework, reducing the diffusion paths for both ions and electrons and accommodating the volume changes associated with sulfur. Moreover, the internal CNT forests effectively captured soluble lithium polysulfides (LiPSs) and catalyze their redox kinetic. Consequently, the S@WF-CNT-800 sample exhibited a high initial discharge capacity of 1438.2 mAh g−1 at a high current density of 0.5 A g−1. Furthermore, a reversible capacity of 404.5 mAh g−1 was obtained after 500 cycles with sulfur loading of 5 mgs cm−2 at 0.5 A g−1. This work may support the development of high sulfur loading cathodes utilizing cost-effective and sustainable biomass materials for Li-S batteries.

Keywords

• lithium sulfur batteries
• wood framework
• high sulfur loading
• low-tortuosity microchannel