Li Yang, Dong Shanmu, Chen Bingbing, Lu Chenglong, Liu Kailiang, Zhang Zhonghua, Du Huiping, Wang Xiaogang, Chen Xiao, Zhou Xinhong, Cui Guanglei
Qingdao Industrial Energy Storage Research Institute, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , No. 189 Songling Road, 266101 Qingdao, China.
University of Chinese Academy of Sciences , No. 19A Yuquan Road, 100049 Beijing, China.
J Phys Chem Lett. 2017 Sep 7;8(17):4218-4225. doi: 10.1021/acs.jpclett.7b01497. Epub 2017 Aug 23.
Redox mediators (RMs) have been widely applied to reduce the charge overpotential of nonaqueous lithium-oxygen (Li-O) batteries. Among the reported RMs, LiI is under hot debate with lots of controversial reports. However, there is a limited understanding of the charge mechanism of I in anhydrous Li-O batteries. Here, we study the chemical reactivity between the oxidized state of I and LiO. We confirm that the LiO particles could be chemically oxidized by I rather than I species. Furthermore, our work demonstrates that the generated I from LiO oxidation would combine with I to give I species, hindering further oxidation of LiO by I. To improve the working efficiency of I RMs, we introduce a compound LiI(3-hydroxypropionitrile) (LiI(HPN)) with a high binding ability of I. Compared with LiI, the cell that contained LiI(HPN) shows a significantly increased amount of I species during charge and enhanced LiO oxidation efficiency under the same working conditions.
氧化还原介质（RMs）已被广泛应用于降低非水锂氧（Li-O）电池的电荷过电位。在已报道的氧化还原介质中，碘化锂（LiI）存在诸多争议报道，引发了激烈讨论。然而，对于无水Li-O电池中碘（I）的电荷机制，人们的了解还很有限。在此，我们研究了碘的氧化态与LiO之间的化学反应性。我们证实，LiO颗粒可被I而非I物种化学氧化。此外，我们的研究表明，LiO氧化生成的I会与I结合形成I物种，从而阻碍I对LiO的进一步氧化。为提高I氧化还原介质的工作效率，我们引入了一种对I具有高结合能力的化合物碘化锂（3-羟基丙腈）（LiI(HPN)）。与LiI相比，含有LiI(HPN)的电池在充电过程中显示出显著增加的I物种量，并且在相同工作条件下提高了LiO的氧化效率。
