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

Abstract

ABSTRACT A major bottleneck for the practical application of lithium–oxygen (Li–O 2 ) 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 ( 3 O 2 ) into peroxide species, alongside the parasitic generation of singlet oxygen ( 1 O 2 ). Here, we demonstrate that metal–support magnetic interactions can effectively overcome this spin barrier. Using palladium (Pd) nanoparticles anchored on ferrimagnetic CoFe 2 O 4 (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 3 O 2 into peroxide species while suppressing parasitic 1 O 2 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.