Study on the Cathode Reaction Mechanism and Performance of Hybrid Electrolyte Lithium-Air Batteries

Abstract Hybrid electrolyte lithium-air batteries are noteworthy for their elevated theoretical energy density but the slow kinetic rate, low redox efficiency, and inadequate cathodic catalytic performance of the cell lead to a reduced service life. Molybdenum carbide (MoC) has been utilized as an effective catalyst or catalyst support for several reaction systems. Nonetheless, MoC possesses intrinsic deficiencies, including low conductivity and sluggish redox kinetics. Here, three-dimensional porous nanocomposites of Ru-MoC with dual active sites were successfully synthesized based on the coordination anchoring technique of melamine-tricyanuric acid framework, combined with carbon nanotubes, and utilized in hybrid electrolyte lithium-air batteries, with their electrochemical performance and catalytic reaction mechanisms examined by density functional theory (DFT). Experimental results reveal that Ru-doped MoC has outstanding cycle stability and high discharge capacity in hybrid electrolyte lithium-air batteries. At 0.1 mA current (i.e., 0.05 mA·cm⁻² current density), the battery has a life up to 2,740 h and an initial maximum discharge capacity of up to 22,500 mAh·g⁻¹. DFT calculations suggest that the overpotential of Ru-MoC as a hybrid electrolyte Li-air battery catalyst is 0.28 V; a good fit with the experimental data. The complete results tillustrate that Ru-MoC is a suitable cathode catalyst material for hybrid electrolyte lithium-air batteries