Abstract:

High-sulfur-loading is an important condition for the cathode of high energy density lithium-sulfur battery. However, with the increase of areal sulfur loading, the performance of Li-S battery presents a significant decay accompanied by poor electron conduction, slow transformation kinetics of polysulfide and the aggravation of the “shuttle effect”. Herein, we discussed the corresponding strategies to solve these problems with the focus on the mass transfer and reaction engineering to promote the development of high energy density batteries. Specifically, strategies are compared from four perspectives of enhancing electron conduction, improving lithium ion mass transfer, optimizing reaction kinetics and inhibiting polysulfide transfer. The analysis shows that the design of 3D highly conductive electrode with adsorption-catalysis dual functions is the most promising strategy. From the perspective of application, this paper also focuses on the safety problem which is often ignored in the design of high-loading cathode. We investigate the feasibility of weakening the positive electrode induction and reducing the risk of thermal failure at source, aiming to provide practical guidance for researchers to optimize the design scheme of high-loading sulfur cathode (≥4mg/cm²).

Key words: lithium-sulfur batteries, high sulfur-loading, composite cathodes, electrochemistry

摘要：

高载量硫正极是研发高能量密度锂硫电池的必要先决条件。然而，硫载量的提高不可避免地会引起正极导电性不良、多硫化物转化动力学缓慢，穿梭效应加剧等问题。本文从化学工程的角度出发，重点关注高载量硫正极中的传质和反应过程，综述了性能优良的高载量锂硫电池正极设计思路。具体而言，从增强电子传导、改善锂离子传质、优化反应动力学、抑制多硫化物穿梭这四种研究思路出发，对比了不同优化策略之间的优劣性，并提出下一代高硫载量硫正极设计的探索方向。分析表明，基于吸附-催化双重功能的三维高导电正极具有巨大发展前景。从应用层面考虑，本文还关注了高载量正极设计中常被忽视的安全性问题，探讨了削弱正极诱导并从源头降低热失效风险的可行性，旨在为研究人员优化高载量（≥4mg/cm²）正极设计方案时提供实用指导。

关键词: 锂硫电池, 高硫载量, 复合正极, 电化学