Wang Wentao, Tan Chuan, He Lu, Yu Fengjiao, Gao Xiangwen, Chen Yuhui
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, People's Republic of China.
Future Battery Research Center, Global Institute of Future Technology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
J Phys Chem Lett. 2024 Jan 18;15(2):583-589. doi: 10.1021/acs.jpclett.3c03568. Epub 2024 Jan 10.
Lithium-oxygen batteries have one of the highest theoretical capacities and specific energies, but several challenges remain. One of them is premature death caused by a passivation layer with poor conductivities (both electronic and ionic) on the electrode surface during the discharge process. Once this thin layer forms on the surface of the catalyst and substrate, the overpotential significantly increases and causes early cell death. Therefore, understanding this thin layer is crucial to achieving high specific energy lithium-oxygen batteries. Herein, we quantitatively compared the ratio of lithium carbonate to lithium peroxide during the discharge process in a flow cell at different potentials. We found that the ratio rapidly increased at low potential and high flow rates. The surface route led to significant byproducts on the Au electrodes, and consequently, a 3 nm thick discharge product film passivates the electrode surface in a flow cell.
锂氧电池具有极高的理论容量和比能量之一，但仍存在一些挑战。其中之一是在放电过程中，电极表面形成了具有低电导率（电子和离子）的钝化层，导致电池过早失效。一旦这层薄膜在催化剂和基底表面形成，过电位会显著增加，并导致电池过早失效。因此，了解这层薄膜对于实现高比能锂氧电池至关重要。在此，我们定量比较了在不同电位下流动池中放电过程中碳酸锂与过氧化锂的比例。我们发现，在低电位和高流速下，该比例迅速增加。表面路径导致金电极上产生大量副产物，因此，在流动池中，一层3纳米厚的放电产物膜会使电极表面钝化。
