Nishioka Kiho, Morimoto Kota, Kusumoto Takayoshi, Harada Takashi, Kamiya Kazuhide, Mukouyama Yoshiharu, Nakanishi Shuji
Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
J Am Chem Soc. 2021 May 19;143(19):7394-7401. doi: 10.1021/jacs.1c00868. Epub 2021 May 4.
Prior to the practical application of rechargeable aprotic Li-O batteries, the high charging overpotentials of these devices (which inevitably cause irreversible parasitic reactions) must be addressed. The use of redox mediators (RMs) that oxidatively decompose the discharge product, LiO, is one promising solution to this problem. However, the mitigating effect of RMs is currently insufficient, and so it would be beneficial to clarify the LiO reductive growth and oxidative decomposition mechanisms. In the present work, Nanoscale secondary ion mass spectrometry (Nano-SIMS) isotopic three-dimensional imaging and differential electrochemical mass spectrometry (DEMS) analyses of individual LiO particles established that both growth and decomposition proceeded at the LiO/electrolyte interface in a system containing the Br/Br redox couple as the RM. The results of this study also indicated that the degree of oxidative decomposition of LiO was highly dependent on the cell voltage. These data show that increasing the RM reaction rate at the LiO/electrolyte interface is critical to improve the cycle life of Li-O batteries.
在可充电非质子锂氧电池实际应用之前，必须解决这些装置高充电过电位的问题（这不可避免地会导致不可逆的寄生反应）。使用氧化还原介质（RM）氧化分解放电产物LiO是解决该问题的一个有前景的方案。然而，目前RM的缓解效果不足，因此阐明LiO的还原生长和氧化分解机制将是有益的。在本工作中，通过对单个LiO颗粒进行纳米级二次离子质谱（Nano-SIMS）同位素三维成像和差分电化学质谱（DEMS）分析，确定在含有Br/Br氧化还原对作为RM的体系中，LiO的生长和分解均在LiO/电解质界面处进行。该研究结果还表明，LiO的氧化分解程度高度依赖于电池电压。这些数据表明，提高LiO/电解质界面处的RM反应速率对于提高锂氧电池的循环寿命至关重要。
