The stability of organic solvents and carbon electrode in nonaqueous Li-O₂ batteries

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• 作者：Wu Xu ; Jianzhi Hu ; Mark H. Engelhard ; Silas A. Towne ; John S. Hardy ; Jie Xiao ; Ju Feng ; Mary Y. Hu ; Jian Zhang ; Fei Ding ; Mark E. Gross ; Ji-Guang Zhang
• 关键词：Li-O2 battery ; Lithium peroxide ; Electrolyte ; Organic solvent ; Discharge product
• 刊名：Journal of Power Sources
• 出版年：2012
• 出版时间：1 October, 2012
• 年：2012
• 卷：215
• 期：Complete
• 页码：240-247
• 全文大小：765 K

文摘

The effects of six types of aprotic organic solvents on the discharge performance and discharge products in Li-O₂ batteries are systematically investigated. A large amount of Li₂O₂ is identified in the air electrodes discharged in glyme-based electrolytes, while only a small amount of Li₂O₂ is detected in the air electrodes discharged in the electrolytes of nitrile, ionic liquid, phosphate, and sulfoxide. Li₂CO₃ and LiF are also found as byproducts whose compositions are related to the solvents. Li₂CO₃ is produced from oxidation and decomposition of the solvent, not from the oxidation of the carbon-based air electrode, as revealed by using a ¹³C-labeled carbon electrode and the solid-state ¹³C-magic angle spinning nuclear magnetic resonance technique. LiF in the discharge products can be attributed to the attack of superoxide radical anions to the Teflon binder and/or the F-containing imide salt. The formation of these byproducts will significantly reduce the Coulombic efficiency and cycle life of the Li-air batteries. Among the studied solvents, dibutyl diglyme is the suitable solvent for Li-O₂ batteries based on its overall properties. However, better electrolytes that can ensure the formation of Li₂O₂ but minimize other reaction products need to be further investigated for long cycling rechargeable Li-air batteries.