Enhanced Electrochemical Performance of Aprotic Li-CO2 Batteries with a Ruthenium-Complex-Based Mobile Catalyst

摘要

Li-CO2 batteries are regarded as next-generation high-energy-density electrochemical devices. However, the greatest challenge arises from the formation of the discharge product, Li2CO3, which would accumulate and deactivate heterogenous catalysts to cause huge polarization. Herein, Ru(bpy)(3)Cl-2 was employed as a solution-phase catalyst for Li-CO2 batteries and proved to be the most effective one screened so far. Spectroscopy and electrochemical analyses elucidate that the Ru-II center could interact with both CO2 and amorphous Li2C2O4 intermediate, thus promoting electroreduction process and delaying carbonate transformation. As a result, the charge potential is reduced to 3.86 V and over 60 discharge/charge cycles are achieved with a fixed capacity of 1000 mAh g(-1) at a current density of 300 mA g(-1). Our work provides a new avenue to improve the electrochemical performance of Li-CO2 batteries with efficient mobile catalysts.