Tuning electronic and composition effects in ruthenium-copper alloy nanoparticles anchored on carbon nanofibers for rechargeable Li-CO2 batteries

Rechargeable Li-CO2 batteries are attracting increasing attention due to their high energy density and ability to capture greenhouse gas CO2. However, the difficulty in decomposing electronically insulating and electrochemically sluggish Li2CO3 discharge products under low charge voltages is still a major challenge. Herein, for the first time, a composite of intermixed ruthenium-copper alloy nanoparticles uniformly anchored on carbon nanofibers (i-RuCu/CNFs) as efficient cathode electrocatalysts for Li-CO2 batteries is well designed. Remarkably, the Li-CO2 batteries with i-Ru4Cu1/CNFs cathodes can be steadily cycled for over 110 cycles without capacity decay. And they show record-high rate capability along with much decreased overpotentials of 1.45 and 1.56 V even at current densities of 1000 and 2000 mA g(-1), respectively. Moreover, a high discharge capacity of 15,753 mAh g(-1) is obtained for Li-CO2 batteries based on i-Ru4Cu1/CNFs, and 99.3% of discharged capacity could be reversibly charged, giving the significant Coulombic efficiency. This work demonstrates the powerfully catalytic activity of intermixed RuCu nanoalloys for easily decomposing discharge products in Li-CO2 batteries and provides more insights to design more highly efficient cathode electrocatalysts for Li-CO2 batteries and beyond.