Overcoming the Spin Barrier of Oxygen Redox Chemistry in Lithium-Oxygen Batteries via Metal-Support Magnetic Interaction.

Abstract

A major bottleneck for the practical application of lithium-oxygen (Li-O2) batteries is the high overpotential resulting from sluggish kinetics of oxygen redox chemistry. This kinetic limitation can rise in part from the spin-state transition barriers in converting triplet oxygen (3O2) into peroxide species, alongside the parasitic generation of singlet oxygen (1O2). Here, we demonstrate that metal-support magnetic interactions can effectively overcome this spin barrier. Using palladium (Pd) nanoparticles anchored on ferrimagnetic CoFe2O4 (CFO) substrates as a model catalyst, we reveal that interfacial magnetic coupling restructures the spin and electronic states of Pd sites, generating spin-polarized active ensembles with optimized adsorption toward oxygen intermediates. This interfacial spin-electronic effect promotes the conversion of 3O2 into peroxide species while suppressing parasitic 1O2 evolution during charging, thereby improving the reversibility of oxygen redox chemistry. As a result, the Pd/CFO catalyst achieves a low charging overpotential of 0.05 V and remarkable energy efficiency (91.2%) under spin alignment. This finding establishes metal-support magnetic interaction as a powerful strategy for controlling spin-dependent oxygen electrocatalysis, providing a general design principle for catalysts involving multi-site interactions.