A novel binder-free cathode catalyst Cu@NCNF/CP with three-dimensional self-supporting structure for Li-CO2 battery

The Li-CO2 battery is an emerging energy storage device that has garnered significant attention due to its high theoretical energy density and remarkable CO2 capture ability. However, the low reaction activity of Li2CO3 formation and decomposition may result in large overpotentials and poor cycling performance. In this work, a novel three-dimensional self-supporting high-performance cathode catalyst (Cu@NCNF/CP) was prepared. The Cu@NCNF/CP cathode catalyst is composed of Cu nanoparticles loaded on nitrogen-doped carbon nanotube fibers (NCNF) deposited on carbon paper (CP). The three-dimensional interconnected self-supporting structure of Cu@NCNF/CP eliminates the need for binders and can facilitate efficient electrolyte diffusion and electron transfer. Moreover, the nitrogen doping introduces enrichment active sites, and boosts the CO2 reduction reaction (CO2RR) activity, while the uniformly loaded Cu nanoparticles facilitate the adsorption and precipitation of CO2 molecules, thereby playing a crucial role in enhancing the electrocatalytic activity of the CO2 evolution reaction (CO2ER). Importantly, the Li-CO2 battery utilizing Cu@NCNF/CP as a cathode catalyst exhibits a large discharge capacity of 10.59 mAh cm -2 at a current density of 0.05 mA cm -2. When the cutoff capacity is limited to 0.15 mAh cm -2, the first-cycle overpotential is merely 1.28 V, and the cycle life can reach 1140 h due to the high reversibility of the Li2CO3 formation and decomposition. The successful application of a three-dimensional self-supporting Cu@NCNF/CP cathode catalyst in Li-CO2 battery systems introduces a novel concept for developing high-performance transition metal-based catalysts.