Jiang Zhuoliang, Huang Yaohui, Zhu Zhuo, Gao Suning, Lv Qingliang, Li Fujun
Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin, 300071, China.
Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China.
Proc Natl Acad Sci U S A. 2022 Aug 23;119(34):e2202835119. doi: 10.1073/pnas.2202835119. Epub 2022 Aug 15.
Aprotic Li-O batteries are a promising energy storage technology, however severe side reactions during cycles lead to their poor rechargeability. Herein, highly reactive singlet oxygen (O) is revealed to generate in both the discharging and charging processes and is deterimental to battery stability. Electron-rich triphenylamine (TPA) is demonstrated as an effective quencher in the electrolyte to mitigate O and its associated parasitic reactions, which has the tertiary amine and phenyl groups to manifest excellent electrochemical stability and chemical reversibility. It reacts with electrophilic O to form a singlet complex during cycles, and it then quickly transforms to a triplet complex through nonradiative intersystem crossing (ISC). This efficiently accelerates the conversion of O to the ground-state triplet oxygen to eliminate its derived side reactions, and the regeneration of TPA. These enable the Li-O battery with obviously reduced overvoltages and prolonged lifetime for over 310 cycles when coupled with a RuO catalyst. This work highlights the ISC mechanism to quench O in Li-O battery.
非质子锂氧电池是一种很有前途的储能技术，然而循环过程中的严重副反应导致其充电性能不佳。在此，研究发现高活性单线态氧（O）在放电和充电过程中均会产生，并且对电池稳定性有害。富电子的三苯胺（TPA）被证明是电解液中一种有效的猝灭剂，可减轻O及其相关的寄生反应，其叔胺和苯基表现出优异的电化学稳定性和化学可逆性。在循环过程中，它与亲电O反应形成单线态络合物，然后通过非辐射系间窜越（ISC）迅速转变为三线态络合物。这有效地加速了O向基态三线态氧的转化，以消除其衍生的副反应以及TPA的再生。当与RuO催化剂结合使用时，这些使得锂氧电池的过电压明显降低，寿命延长至超过310次循环。这项工作突出了在锂氧电池中通过系间窜越机制猝灭O的方法。
