Understanding Side Reactions in K鈥揙2 Batteries for Improved Cycle Life

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• 作者：Xiaodi Ren ; Kah Chun Lau ; Mingzhe Yu ; Xuanxuan Bi ; Eric Kreidler ; Larry A. Curtiss ; Yiying Wu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：November 12, 2014
• 年：2014
• 卷：6
• 期：21
• 页码：19299-19307
• 全文大小：417K
• ISSN：1944-8252

文摘

Superoxide based metal鈥揳ir (or metal鈥搊xygen) batteries, including potassium and sodium鈥搊xygen batteries, have emerged as promising alternative chemistries in the metal鈥揳ir battery family because of much improved round-trip efficiencies (>90%). In order to improve the cycle life of these batteries, it is crucial to understand and control the side reactions between the electrodes and the electrolyte. For potassium鈥搊xygen batteries using ether-based electrolytes, the side reactions on the potassium anode have been identified as the main cause of battery failure. The composition of the side products formed on the anode, including some reaction intermediates, have been identified and quantified. Combined experimental studies and density functional theory (DFT) calculations show the side reactions are likely driven by the interaction of potassium with ether molecules and the crossover of oxygen from the cathode. To inhibit these side reactions, the incorporation of a polymeric potassium ion selective membrane (Nafion-K⁺) as a battery separator is demonstrated that significantly improves the battery cycle life. The K鈥揙₂ battery with the Nafion-K⁺ separator can be discharged and charged for more than 40 cycles without increases in charging overpotential.

Keywords:

metal鈭抋ir batteries; potassium鈭抩xygen battery; side reactions; O₂ crossover; ion selective separator