Institute of Technical Electrochemistry, Technische Universität München, Lichtenbergstr. 4, 22 D-85748, Garching, Germany.
Phys Chem Chem Phys. 2013 Jul 21;15(27):11478-93. doi: 10.1039/c3cp51112j. Epub 2013 Jun 10.
The instability of currently used electrolyte solutions and of the carbon support during charge-discharge in non-aqueous lithium-oxygen cells can lead to discharge products other than the desired Li2O2, such as Li2CO3, which is believed to reduce cycle-life. Similarly, discharge in an O2 atmosphere which contains H2O and CO2 impurities would lead to LiOH and Li2CO3 discharge products. In this work we therefore investigate the rechargeability of model cathodes pre-filled with four possible Li-air cell discharge products, namely Li2O2, Li2CO3, LiOH, and Li2O. Using Online Electrochemical Mass Spectrometry (OEMS), we determined the charge voltages and the gases evolved upon charge of pre-filled electrodes, thus determining the reversibility of the formation/electrooxidation reactions. We show that Li2O2 is the only reversible discharge product in ether-based electrolyte solutions, and that the formation of Li2CO3, LiOH, or Li2O is either irreversible and/or reacts with the electrolyte solution or the carbon during its oxidation.
在非水锂-氧电池中，目前使用的电解质溶液和碳载体在充放电过程中的不稳定性会导致除所需 Li2O2 以外的放电产物，例如 Li2CO3，据信这会降低循环寿命。同样，在含有 H2O 和 CO2 杂质的 O2 气氛中放电会导致 LiOH 和 Li2CO3 放电产物。因此，在这项工作中，我们研究了预先填充有四种可能的 Li-空气电池放电产物（即 Li2O2、Li2CO3、LiOH 和 Li2O）的模型阴极的可再充电性。使用在线电化学质谱 (OEMS)，我们确定了预先填充电极充电时的充电电压和释放的气体，从而确定了形成/电氧化反应的可逆性。我们表明，Li2O2 是醚基电解质溶液中唯一可逆的放电产物，而 Li2CO3、LiOH 或 Li2O 的形成要么是不可逆的，要么在其氧化过程中与电解质溶液或碳发生反应。
