Cobalt-embedded 3D conductive honeycomb architecture to enable high-sulphur-loading Li-S batteries under lean electrolyte conditions
Hui Pan, Zhibin Cheng, Jan Fransaer, Jiangshui Luo, Michael Wübbenhorst
Abstract
High sulphur loading and lean electrolyte conditions are important to achieve the high theoretical energy density of lithium-sulphur (Li-S) batteries. However, serious problems such as low sulphur utilization and fast capacity fade are typically experienced under low electrolyte/sulphur (E/S) ratios and high sulphur loading conditions. To address these issues, a cobalt-containing three-dimensional conductive honeycomb (Co@N-HPC) is proposed in this work as a material for sulphur cathodes. The good electrical conductivity and high density of catalytic sites of (Co@N-HPC) allow fast redox kinetics of lithium polysulfide (LiPS) in high-sulphur-loading electrodes. In addition, the hierarchical structure and good wettability by the electrolyte of Co@N-HPC facilitates electrolyte penetration and LiPS conversion, leading to a high utilization of sulphur under lean electrolyte conditions. Therefore, at a current density of 0.2 C, a volumetric capacity of 1,410 mAh·cm−3 was attained with a sulphur loading of 5.1 mg·cm−2 and an E/S ratio of 5 µL·mg−1. This work provides ideas for the development of lean electrolyte Li-S batteries with a high sulphur loading.