南京工业大学陈宇辉团队研究了Li-O₂电池放电时的真实反应部位。相关研究成果于2022年1月7日发表在国际顶尖学术期刊《美国化学会杂志》。

在追求先进的Li-O₂电池时，阴极中的真实反应部位决定了电池性能和催化剂设计。当第一层绝缘Li₂O2固体在放电过程中沉积在电极基板上时，以下O₂还原为Li₂O₂可能发生在电极| Li₂O₂界面或Li₂O₂ |电解质界面。机理决定了催化剂的设计策略；然而，它仍然是神秘的。

该文中，研究人员使用旋转环-盘电极沉积一层致密的Li₂O₂膜，并用¹⁶O/¹8O同位素标记Li₂O₂产物。通过使用Li₂¹⁶O₂和Li₂¹⁸O₂的新特征信号确定Li₂¹⁶O₂和Li₂¹⁸O₂在Li₂O₂薄膜中的分布，结果表明，O₂在两个界面处都被还原为Li₂O₂。当电极在¹⁶O₂和¹⁸O₂下放电时，在电极表面发现了Li₂¹⁸O₂ | Li₂¹⁶O₂ | Li₂¹⁸O₂的三明治结构。电极| Li₂O₂界面是主要反应部位，占整个反应的75%。该新机制为锂氧电池的催化剂设计提出了新的挑战和新的策略。

附：英文原文

Title: True Reaction Sites on Discharge in Li–O2 Batteries

Author: Chuan Tan, Deqing Cao, Lei Zheng, Yanbin Shen, Liwei Chen, Yuhui Chen

Issue&Volume: January 7, 2022

Abstract: In the pursuit of an advanced Li–O2 battery, the true reaction sites in the cathode determined its cell performance and the catalyst design. When the first layer of insulating Li2O2 solid is deposited on the electrode substrate during discharging, the following O2 reduction to Li2O2 could take place either at the electrode|Li2O2 interface or at the Li2O2|electrolyte interface. The mechanism decides the strategies of catalyst design; however, it is still mysterious. Here, we used rotate ring-disk electrode to deposit a dense Li2O2 film and labeled the Li2O2 product with 16O/18O isotope. By identification of the distribution of the Li216O2 and Li218O2 in the Li2O2 film using new characteristic signals of Li216O2 and Li218O2, our results show that O2 is reduced to Li2O2 at both interfaces. A sandwich structure of Li218O2|Li216O2|Li218O2 was identified at the electrode surface when the electrode was discharged under 16O2 and then 18O2. The electrode|Li2O2 interface is the major reaction site, and it contributes to 75% of the overall reaction. This new mechanism raises new challenges and new strategies for the catalyst design of Li–O2 batteries.

DOI: 10.1021/jacs.1c09916

Source: https://pubs.acs.org/doi/10.1021/jacs.1c09916