Facile Synthesis of Birnessite δ-MnO2and Carbon Nanotube Composites as Effective Catalysts for Li-CO2Batteries

Li-CO2 batteries are one type of promising energy storage and conversion devices to capture and utilize the greenhouse gas CO2, mitigating global temperature rise and climate change. Catalysts that could effectively decompose the discharge product, Li2CO3, are essential for high-performance Li-CO2 batteries. Benefiting from the interconnected porous structure, favorable oxygen vacancy, and the synergistic effects between the carbon nanotube (CNT) and layered birnessite δ-MnO2, our Li-CO2 cathodes with the as-prepared CNT@δ-MnO2 catalyst can efficiently afford a large reaction surface area and abundant active sites, provide sufficient electron/Li+ transport pathways, and facilitate electrolyte infiltration and CO2 diffusion, demonstrating low overpotential and superior cycling stability, which have been proven by both experimental characterization and theoretical computation. It is expected that this work can provide guidance for the design and synthesis of high-performance electrochemical catalysts for Li-CO2 batteries.