Spin regulation and magnetohydrodynamic effects driven novel magnetic field-assisted LiO2 battery

Abstract

Lithium‑oxygen battery (LOB) has attracted great interest due to its ultra-high theoretical specific capacity. However, the practical application of the LOB is obstructed by the high kinetic barriers and large overpotentials. Hence, a novel magnetic field assisted LOB (MF-LOB) is developed with ferromagnetic FeCo₂O₄ nanowires as catalyst that can improve the ORR and OER kinetics through the application of a moderate magnetic field. The FeCo₂O₄ nanowires are magnetized into nanomagnets with high spin polarization under a magnetic field, which is beneficial to the adsorption of O₂-intermediates and transfer of electrons. Equally, the MHD effect contributes to the mass transport and diffusion including O₂ and Li⁺. The generation and oxidation of Li₂O₂ are promoted for the MF-LOB based on FeCo₂O₄ nanowires due to the high spin polarization and MHD effect. The MF-LOB based on FeCo₂O₄ nanowires shows a lower overpotential of 0.89 V and longer cycle life of 150 cycles than those (1.22 V and 53 cycles) of the LOB without the magnetic field. This unique in-situ magnetic enhancement strategy for optimizing catalyst performance provides a new idea for the development of high-performance external field assisted LOBs.