钯催化剂对锂空气电池氧析出和氧还原反应的催化机理的研究

Catalytic Mechanism of Palladium Catalyst for the Oxidation Reduction and Evolution Reaction of Lithium-air Battery

锂空气电池以其超高的能量密度而备受关注,然而充、放电过电位高等问题严重限制了其实际应用。金属钯作为催化剂可而降低锂空气电池的充、放电过电位,但其充、放电反应催化机制尚不完善。本研究运用第一原理计算方法,建立了钯/氧气/过氧化锂(Pd/O_2/Li_2O_2)的三相界面催化模型,从微观角度揭示钯催化剂在锂空气电池充、放电反应中的催化机制。研究表明, Pd/O基底通过促进Li_2O_2在界面处的电荷转移提高自身对LiO_2吸附作用,从而加速放电产物在电极表面的形成,有效降低了充电过电位0.43 V。

Rechargeable lithium-oxygen （Li-O2） batteries have recently attracted great attention due to their superior energy storage density. However, its practical application is seriously limited by some problems such as high charging and discharging overpotential. Metal palladium as a catalyst can simultaneously reduce the charging and dis- charging overpotential in Li-O2 batteries by enhancing catalytic activity of air electrode, but its catalytical mechanism is insufficient. Here, using first-principles calculations, a three-phase interface model which consists of Pd/O2/Li2O2 is constructed to explore the mechanism of charge and discharge reaction. The result indicates that the Pd/O substrate enhances its adsorption of LiO2 by promoting charge transfer between substrate and Li2O2, thereby accelerating discharge product formed on the electrode surface, and effectively reducing the charging overpotential by 0.43 V.