Tailoring Li2CO3 configuration and orbital structure of CoS to improve catalytic activity and stability for Li-CO2 batteries

The sluggish reaction kinetics has greatly hampered the development of reversible Li-CO₂ batteries. Especially during charge, high charge voltage and possible side reactions during Li₂CO₃ decomposition require both high activity and strong durability of catalysts. Herein, a strategy of introducing rich sulfur vacancies is proposed, which tailors the configuration of Li₂CO₃ and the orbital structure of CoS to realize the dual enhancement. The calculation results show that charge redistribution by sulfur vacancies on the catalyst stretches the adsorbed Li₂CO₃ and consequently facilitates its decomposition. Moreover, the induced vacancies lower the S 2p band center, promoting the electrochemical stability of sulfides. Therefore, Li-CO₂ batteries with sulfur vacancy-rich CoS exhibit a low overpotential of 1.07 V after 400 h cycling, while batteries with pristine CoS have a short lifespan that the overpotential exceeds 1.75 V after cycling for 200 h. This study not only proposes a strategy to improve both catalytic activity and stability but also paves new avenues for designing advanced catalysts for Li-CO₂ batteries and beyond.