A Comparative Study of Redox Mediators for Improved Performance of Li–Oxygen Batteries
A Comparative Study of Redox Mediators for Improved Performance of Li–Oxygen Batteries
复制标题
DOI：
10.1002/aenm.202000201
复制
发表时间：
2020-06
影响因子：
27.8
通讯作者：
Chengji Zhang;Naveen K. Dandu;Sina Rastegar;Saurabh N. Misal;Z. Hemmat;A. Ngo;L. Curtiss;A. Salehi‐khoji
中科院分区：
文献类型：
--
作者：
Chengji Zhang;Naveen K. Dandu;Sina Rastegar;Saurabh N. Misal;Z. Hemmat;A. Ngo;L. Curtiss;A. Salehi‐khoji
氧化还原沉降器(RMS)是一种位于电解液中的可溶性催化剂，可以提高锂氧(Li-O2)电池的能量效率(降低过电位)和循环性能。本文研究了以二甲基亚砜和四乙二醇二甲醚为电解液的Li-O2体系中20rms的电化学性质，并用循环伏安(CV)实验测量了它们的氧化还原电位、阴阳极峰分离和电流强度等电化学特性。根据它们的电化学性能，选择六种有效值作为主要选择，然后进行稳定性测试，以检查连续循环后的电化学响应。此外，在一个由选定的六个有效值组装的锂-O2电池系统中进行了恒流循环测试，以进行实际情况的一致性调查。结果表明，循环伏安与恒流循环测试结果对卤化物和有机金属均方根是一致的，前者表现出更高的稳定性。然而，有机均方根在循环伏安中表现出较高的可逆性，但在电池循环结果中表现出较低的可逆性。为了更好地理解RMS的稳定性和氧化还原势，进行了密度泛函理论计算。这项研究为选择最可靠的Li-O2电池均方根提供了比较信息，并对其电化学活性和稳定性有了新的基本理解。
Redox meditators (RMs) are soluble catalysts located in an electrolyte that can improve the energy efficiency (reduced overpotential) and cyclability of Li–oxygen (Li–O2) batteries. In this work, 20 RMs within a Li–O2 system with dimethyl sulfoxide and tetraethylene glycol dimethyl ether electrolytes are studied and their electrochemical features such as redox potential, the separation of cathodic and anodic peaks, and their current intensities are measured using cyclic voltammetry (CV) experiments. Six RMs are selected as “primary” choices based on their electrochemical performance, and stability tests are then performed to examine their electrochemical responses after consecutive cycles. Moreover, galvanostatic cycling tests are performed within a Li–O2 battery system assembled with selected six RMs for real case consistency investigations. It is found that results from CV to galvanostatic cycling tests are consistent for halides and organometallic RMs, where the former exhibit much higher stability. However, the organic RMs show high reversibility in CV but low in battery cycling results. Density functional theory calculations are carried out to gain more understanding of the stability and redox potentials of the RMs. This study provides comparative information to select the most reliable RMs for Li–O2 batteries along with new fundamental understanding of their electrochemical activity and stability.