3D-Structured Metal Oxide/Sulfur Composites for High Performance Lithium-Sulfur Batteries

Abstract

The lithium-sulfur (Li-S) system is one of the promising rechargeable battery systems for energy storages and electrification of vehicles due to a high theoretical capacity and energy density, as well as the low cost and availability of non-toxic sulfur. However, polysulfide dissolution is the main limitation to the stability of the Li-S system. Here, we tackle this challenge by synthesizing 3D-structured graphene and porous silica materials with a pomegranate-like architecture through a simple chemical reactions, which is subsequently loaded with sulfur to form a 3D-graphene-sulfur composite (denoted as S@G composite). Furthermore, a thin layer (~100 nm) of tungsten oxide (WO3) on the S@G composite dramatically improves the cycling performance of the Li-S system with an initial capacity of 1425 mAh/g and approximately 95% capacity retention after 500 cycles. The porous silica/sulfur composite cathodes exhibit excellent electrochemical performances including a high specific capacity of 1450 mAh g-1, a reversible capacity of 82.9 % after 100 cycles at a rate of C/2 (1 C = 1672 mA g-1) and an extended cyclability over 300 cycles at 1 C-rate. Through the analysis and the theoretical calculation, results provide a novel material and approach to enhance the electrochemical performance of rechargeable Li-S batteries and sheds light on developing high-performance energy storage devices for a variety of applications.