Analysis of Polysulfide Dissolved in Electrolyte in Discharge-Charge Process of Li-S Battery
Analysis of Polysulfide Dissolved in Electrolyte in Discharge-Charge Process of Li-S Battery
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DOI：
10.1149/2.060204jes
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发表时间：
2012-01-01
影响因子：
3.9
通讯作者：
Hong, Xiaobin
中科院分区：
文献类型：
--
作者：
Diao, Yan;Xie, Kai;Hong, Xiaobin
本文报道了锂硫电池充放电和循环过程中溶解在电解液中的多硫化物的定性和半定量分析方法。使用ICP-OES（电感耦合等离子体-光发射光谱仪）测量来估计溶解在电解质中的总硫含量。通过LC-MS（液相色谱-质谱联用）分离并确认了不同顺序的多硫化锂。Li 2S 4和Li 2S 6被证明是多硫化锂物种的最稳定形式。在放电过程结束时，以Li 2S 4和Li 2S 6形式保留在电解质中的总硫含量约为初始阴极中活性材料的20%。在充电过程结束时，45%的总硫含量主要以Li 2S 6的形式保留在电解质中。活性物质从液相到固相的部分转化导致实际比容量比理论比容量相对较低。在循环过程中，活性物质在液相和固相之间的转移保持平衡，总硫、Li 2S 4和Li 2S 6的含量在循环结束时变化不大。因此，溶解在电解液中的多硫化物仅对Li-S电池的容量随循环而衰减承担有限的责任。(C)2012年电化学学会。[DOI：10.1149/2.060204jes]版权所有。
In this paper, the qualitative and semi-quantitative analysis of polysulfide species dissolved in electrolyte during the discharge-charge process and cycling of Li-S batteries was reported. ICP-OES (Inductively coupled plasma- Optical emission spectrometer) measurement was used to estimate the total sulfur content dissolved in electrolyte. Lithium polysulfide with different order were separated and confirmed by LC-MS (Liquid chromatography coupled with mass spectrometry). Li2S4 and Li2S6 were proved to be the most stable form of lithium polysulfide species. At the end of discharge process, total sulfur content in the form of Li2S4 and Li2S6 remained in electrolyte was about 20% of the active material in initial cathode. At the end of charge process, 45% total sulfur content was preserved in electrolyte mainly in the form of Li2S6. The partial transformation of active material from liquid phase to solid phase resulted in relatively low practical specific capacity than the theoretical. In cycles, active material transferred between liquid and solid phase kept a balance, and the content of total sulfur, Li2S4 and Li2S6 were changed slightly at the end. Consequently, polysulfide dissolved in electrolyte just took limited responsibility for the capacity fading with cycles of Li-S batteries. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.060204jes] All rights reserved.