Strain-Induced Magnetic Ordering Unlocks Spin-Conserved Catalysis in Lithium-Oxygen Batteries.

Abstract

Designing advanced ferromagnetic catalysts with robust intrinsic magnetism and efficient spin polarization is critical for enabling spin-selective electron transfer between triplet O₂ and singlet Li₂O₂ in lithium-oxygen batteries (LOBs), yet controlling magnetic ordering and spin states at the atomic scale remains a fundamental challenge. Here, we present a lattice tensile strain engineering to construct strained CoS₂ anchored on reduced graphene oxide (s-CoS₂/rGO), achieving significantly enhanced ferromagnetic exchange interactions and spin polarization. Experimental and theoretical analyses reveal that a ∼4% tensile strain along the (111) plane induces spontaneous parallel alignment of atomic magnetic moments, generating intrinsic magnetic anisotropy and coherent single-domain architectures. This lattice distortion enhances d-p orbital hybridization and establishes spin-polarized conduction channels at Co─S active sites, enabling parallel-spin electron transfer to adsorbed O₂ and effectively bypassing the spin-flip energy barrier associated with O₂/Li₂O₂ conversion. As a result, the s-CoS₂/rGO catalyst exhibits elevated spin-polarized current densities, a markedly reduced O₂ dissociation barrier, and superior catalytic kinetics, delivering ultra-long cycling exceeding 2000 h at 200 mA g^-1. This work offers a general approach for designing high-performance ferromagnetic catalysts and highlights the critical role of spin-state engineering in advancing next-generation LOB technologies.