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

Abstract

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, Li₂ CO₃ , which would accumulate and deactivate heterogenous catalysts to cause huge polarization. Herein, Ru(bpy)₃ Cl₂ 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 Li₂ C₂ O₄ 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.

Keywords: Li-CO2; batteries; mobile catalyst; oxalate; ruthenium complexes.