Experimental and Theoretical Analysis of Products and Reaction Intermediates of Lithium鈥揝ulfur Batteries

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• 作者：Natalia A. Ca帽as ; David N. Fronczek ; Norbert Wagner ; Arnulf Latz ; K. Andreas Friedrich
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：June 12, 2014
• 年：2014
• 卷：118
• 期：23
• 页码：12106-12114
• 全文大小：667K
• 年卷期：v.118,no.23(June 12, 2014)
• ISSN：1932-7455

文摘

We investigated the reduction process of sulfur during cycling in a lithium鈥搒ulfur battery, correlating the output of ultraviolet鈥搗isible (UV鈥搗is) spectroscopy and further characterization techniques with a theoretical model. The experimental setup allows carrying out UV鈥搗is absorption measurements under argon atmosphere. The characteristic absorption bands (位_max) of sulfur and dilithium sulfide dissolved in tetra-ethylene glycol dimethyl ether (TEGDME) are determined to be at 265 and 255 nm, respectively. Reference solutions of polysulfides diminish the 位_max in the UV region with decrease of polysulfide order. The same tendency is observed in the range between 25鈥?5% depth of discharge (DOD), caused by a progressive reduction of polysulfides in the electrolyte. At 425 and 615 nm, absorption bands are identified in the reference polysulfide solutions and also in the electrolyte at different DOD. These bands are interpreted as the characteristic bands of S₄^{2鈥?/sup> and S₃鈥⑩€?/sup>, and concentration changes of these species are determined semiquantitatively. The highest concentration of polysulfides is found at around 37% DOD (450 Ah路kg_S鈥?). This was confirmed by the results of electrochemical impedance spectroscopy and computer simulations.}