Magnetron sputtering of platinum on nitrogen-doped polypyrrole carbon nanotubes as an efficient and stable cathode for lithium-carbon dioxide batteries

As an emerging green energy storage and conversion system, rechargeable Li-CO 2 batteries have undergone extensive research due to their ultra-high energy density and their significant role in greenhouse gas CO 2 conversion. However, current Li-CO 2 batteries have some shortcomings that severely limit their large-scale application. The most critical problems involve the insulation of the discharge product Li 2 CO 3 and the slow decomposition kinetics, meaning that the battery generates a large overpotential and has a low cycle life, so the rational design of an efficient cathode catalyst is imperative. Here, we prepared a composite material via the magnetron sputtering of Pt onto nitrogen-doped polypyrrole carbon nanotubes (NPPy-CNTs) as a high-efficiency cathode catalyst for Li-CO 2 batteries. The three-dimensional hollow tubular NPPy-CNTs can provide efficient channels for CO 2 diffusion and enough space for the uniform deposition and decomposition of Li 2 CO 3 . Benefiting from the doping of nitrogen, more defects and active sites are introduced into the polypyrrole carbon nanotubes. Furthermore, the introduction of a small amount of the precious metal Pt effectively improves the catalytic activity of the CO 2 reduction reaction (CO 2 RR) and the CO 2 release reaction (CO 2 ER), greatly improving the cycle life of the battery. The Pt-NPPy-CNT-based battery shows a much improved electrochemical performance. The overpotential of the battery is reduced to 0.75 V, and the battery shows a specific discharge capacity of up to 29 614 mA h g −1 . An efficient cathode catalyst for Li-CO 2 batteries is fabricated by magnetron sputtering Pt on hollow N-doped carbon nanotubes, which demonstrate an ultrahigh discharge capacity of 29 614 mA h g −1 and a low cut-off overpotential of 0.75 V.