Anchoring ultrafine Ru nanoparticles on cotton-derived self-standing carbon fibers as efficient cathode catalyst for Li-CO2 battery

Li-CO 2 batteries could capture and convert CO 2 into a valuable energy storage medium. The slow kinetics and high activation barrier associated with the breakdown cleavage of discharge products pose a significant hurdle in the advancement of reversible Li-CO 2 batteries. Herein, cotton-derived self-standing carbon fibers were utilized to disperse Ru nanoparticles which could avoid depletion of active sites caused by stacking of graphite-based supports. Consequently, CBRu cathode presents small voltage polarization of 1.41 V at high current density of 200 μA cm −2 , and high energy efficiency of 76.0 % at 20 μA cm −2 as well as long-term cyclability over 1000 h. According to in/ex-situ characterizations and theoretical calculations, the unique cross-linked structure of the carbon fibers offers ample space for the deposition of discharge products while these ultrafine Ru nanoparticles regulate the growth path of Li 2 CO 3 and accelerate reaction kinetics. This study offers a novel perspective on the selection of self-standing cathode carbon matrix for Li-CO 2 batteries.