Rational Fe–4d dual-atom pairing for stabilizing redox mediators in lithium–oxygen batteries

초록

Lithium–oxygen batteries (LOBs) offer exceptionally high energy density but are limited by poor reversibility and large charging overpotentials owing to sluggish lithium oxide decomposition. We propose a rational Fe–4d dual-atom catalyst (DAC) strategy to regulate oxygen evolution and stabilize NO2− redox mediation. Fe–Zr/Nb/Mo pairs are atomically dispersed onto defect-rich nitrogen-doped carbon nanotubes (NCNTs) and evaluated as oxygen-electrode catalysts. Among these, Nb–Fe–NCNT exhibits a superior performance, enabling excellent cycling for over 290 cycles with significantly reduced polarization. Electrochemical analysis reveals that Nb-Fe enhances charge-transfer kinetics and sustains low-voltage redox-mediated oxygen evolution while suppressing high-voltage direct Li2O2 oxidation. Ex situ characterization confirms highly reversible Li2O2 formation and decomposition. Density functional theory shows favorable reaction energetics and enhanced electron redistribution, which strengthens mediator interaction. These results demonstrate that metal-dependent electronic synergy in Fe–4d DACs governs oxygen-evolution pathways and provide practical design guidelines for durable, nonprecious catalysts for high-performance LOBs.

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