摘要
锂硫电池体系因其超高理论能量密度,被认为是极具发展前景的下一代电池体系.但是,现阶段锂硫电池体系特别是正极部分仍然存在诸多技术难题,开发高性能正极材料成为锂硫电池体系的重要研究内容.总结了多孔碳、碳纳米管、石墨烯等复合碳基载硫材料以及其他类型非碳载硫材料,分析了上述材料在锂硫电池体系中的作用机理.重点介绍了正极部分存在的多硫化物"穿梭效应"导致循环性能差、单质硫及其化合物绝缘性引起导电性差和硫利用率低、载硫低引起的体积能量密度小以及单质硫放电过程体积膨胀等技术难题,并综述了针对各类问题提出的相应策略和研究成果.最后展望了高性能碳基材料以其低廉的价格和优异的性能将继续成为锂硫电池正极材料商业化发展的研究重点.
Abstract
The lithium-sulfur battery system is considered to be a promising next-generation battery system due to its ultra-high theoretical energy density.However,there are still many technical challenges in the lithium-sulfur battery system,especially in the positive electrode part,and the development of high-performance positive electrode materials has become an important research direction for the lithium-sulfur battery system.This article briefly introduces carbon-based sulfur-carrying composite materials such as porous carbon,carbon nanotubes and graphene,and other types of non-carbon-based sulfur-carrying materials,and analyzes the action mechanisms of these materials in lithium-sulfur battery systems.At the same time,the technical challenges in cathode parts of lithium-sulfur batteries are discussed,such as poor cycle performance caused by the shuttle effect of polysulfides,poor conductivity and low sulfur utilization due to the insulation of elemental sul-fur and its compounds,low volume energy density caused by low sulfur loading,and volume expansion in elemental sulfur discharge,and the corresponding strategies and research progress are summarized.Finally,it is expected that high-performance carbon-based materials will continue to be the research focus of the commercial development of lithium-sulfur battery cathode materials due to their low price and excellent performance.
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