Constructing Wide‐Temperature‐Range Li–S Batteries Through Synergistic Boride Spin‐Polarization Coupling Regulation and Magnetohydrodynamic Effects

Lithium-sulfur batteries, despite their high specific capacity, high theoretical energy density, environmental benignity, and low cost-related unique advantages, face critical challenges including polysulfide shuttling, sluggish redox kinetics, and uncontrolled lithium dendrite growth. Here, we propose a magnetic field cooperative regulation strategy that concurrently optimizes both sulfur cathode and lithium via spin engineering and magnetohydrodynamic (MHD) effects. Bilayer-hollow FeNi boride bipyramids (FeNi─B) with nanoreactor architectures were designed, in which an external magnetic field triggers 3d-orbital electron spin rearrangement. Simultaneously, the uniform distribution of ions and dendrite-free deposition were achieved by driving lithium-ion spiral convection through MHD effects. It is worth noting that the optimized cells exhibit exceptional cycling stability under extreme conditions (-40°C). Density functional theory and multiphysics simulations jointly reveal two mechanisms: Spin-polarization-enhanced adsorption energy for sulfur species and lithium protection via Lorentz-force-mediated ion transport. This work establishes a novel paradigm for designing magnetic field-responsive electrocatalysts and manipulating spin-orbit coupling, offering broad implications for multiphysical-field strategies in next-generation batteries.