锂硫电池自放电特性的研究

Research on Self-Discharge of Lithium-Sulfur Batteries

锂硫电池是目前已知的比能量最高的以固态材料为活性物质的二次电池。然而,多硫化物"穿梭"效应导致的容量衰减快、库仑效率低和自放电率高等问题限制了锂硫电池的实用化进程。通过测试电池搁置前后的放电容量,分析了锂硫软包电池的放电深度(DOD)、环境温度和搁置时间对电池自放电特性的影响。研究结果表明,不同DOD下锂硫电池具有不同的自放电特性,自放电与环境温度、搁置时间呈正相关性。采用原位四电极法考察了不同DOD时内部电解液电导率的变化情况,推测锂硫电池的自放电特性与锂硫电池的电化学反应机制和过程产物密切相关。

Lithium-sulfur batteries have the highest specific energy among those secondary battery systemsthat use solid materials as active substance.However,problems of fast capacity fade,low coulomb efficiencyand high self-discharge rate caused by polysulfide shuttle effects limit its practical applications.In this paper,effects of depth of discharge(DOD),temperature and idling time on self-discharge characteristics wereinvestigated by testing the extent of capacity fade of lithium-sulfur pouch cells.Experimental results show thatself-discharge has a positive correlation with temperature and idling time.Variation of electrolyte conductivityin lithium sulfur battery was also investigated with an in-situ four-electrode method.It is speculated that theself-discharge characteristics of the lithium-sulfur battery are closely related to electrochemical reactionprocesses and intermediate products of lithium-sulfur battery.