Zhou Yin, Yin Kun, Gu Qianfeng, Tao Lu, Li Yiju, Tan Hao, Zhou Jinhui, Zhang Wenshu, Li Hongbo, Guo Shaojun
School of Materials Science and Engineering, Peking University, Beijing, 100871, China.
Beijing Key Laboratory of Construction-Tailorable Advanced Functional Materials and Green Applications, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, 10081, China.
Angew Chem Int Ed Engl. 2021 Dec 13;60(51):26592-26598. doi: 10.1002/anie.202114067. Epub 2021 Nov 17.
The sluggish oxygen reaction kinetics concomitant with the high overpotentials and parasitic reactions from cathodes and solvents is the major challenge in aprotic lithium-oxygen (Li-O ) batteries. Herein, PtIr multipods with a low Lewis acidity of the Pt atoms are reported as an advanced cathode for improving overpotentials and stabilities. DFT calculations disclose that electrons have a strong disposition to transfer from Ir to Pt, since Pt has a higher electronegativity than Ir, resulting in a lower Lewis acidity of the Pt atoms than that on the pure Pt surface. The low Lewis acidity of Pt atoms on the PtIr surface entails a high electron density and a down-shifting of the d-band center, thereby weakening the binding energy towards intermediates (LiO ), which is the key in achieving low oxygen-reduction-reaction (ORR) and oxygen-evolution-reaction (OER) overpotentials. The Li-O cell based on PtIr electrodes exhibits a very low overall discharge/charge overpotential (0.44 V) and an excellent cycle life (180 cycles), outperforming the bulk of reported noble-metal-based cathodes.
与高过电位以及来自阴极和溶剂的寄生反应相伴的缓慢氧反应动力学是非质子锂氧（Li-O₂）电池的主要挑战。在此，具有低路易斯酸度的铂原子的铂铱多脚架被报道为一种用于改善过电位和稳定性的先进阴极。密度泛函理论计算表明，由于铂的电负性高于铱，电子有很强的从铱转移到铂的倾向，导致铂原子的路易斯酸度低于纯铂表面上的路易斯酸度。铂铱表面上铂原子的低路易斯酸度导致高电子密度和d带中心下移，从而削弱了对中间体（LiO₂）的结合能，这是实现低氧还原反应（ORR）和析氧反应（OER）过电位的关键。基于铂铱电极的锂氧电池表现出非常低的总放电/充电过电位（0.44 V）和优异的循环寿命（180次循环），优于大多数已报道的基于贵金属的阴极。
