Chemical vs Electrochemical Formation of Li2CO3 as a Discharge Product in Li–O2/CO2 Batteries by Controlling the Superoxide Intermediate

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• 作者：Wei YinAlexis Grimaud ; Florent Lepoivre ; Chunzhen Yang ; Jean Marie Tarascon
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2017
• 出版时间：January 5, 2017
• 年：2017
• 卷：8
• 期：1
• 页码：214-222
• 全文大小：708K
• ISSN：1948-7185

文摘

The Li–O₂/CO₂ battery with high capacity has recently been proposed as a new protocol to convert CO₂. However, the fundamental mechanism for the reaction still remains hazy. Here, we investigated the discharge processes of Li–O₂/CO₂ (70%/30%) batteries in two solvents, dimethyl sulfoxide (DMSO) and 1,2-dimethoxyethane (DME). During discharge, both solvents initially show the reduction of oxygen. However, afterward, the solvent affects the reaction pathways of superoxide species by solvating Li⁺ with different strength, depending on the so-called donor number. More precisely, the initial formation of CO₄^•– is favored in DMSO at the expense of lithium superoxide formation that we observed in DME. Despite the different intermediate processes, X-ray diffraction showed that Li₂CO₃ was the final discharge product in both solvents. Moreover, we observed that CO₂ cannot be reduced within the electrochemical stability window of DMSO and DME.