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

ABSTRACT 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.