Spin-Orchestrated Lithium Diffusion in Reforged Ferromagnetic Fe@C Anodes

This reports a dual-functional approach in which Fe catalysts, initially employed for methane pyrolysis to generate COx-free hydrogen, are directly repurposed as anode materials following in situ carbon deposition. During methane splitting, catalytic decomposition of CH₄ at 900 °C forms onion-like graphitic carbon shells (≈280 layers) around Fe cores (≈50 nm), producing a structurally stable and electrically conductive Fe@C900 composite without post-treatment. This carbon-enriched catalyst demonstrates exceptional electrochemical behavior when transitioned into a battery context. Without any conductive additives, Fe@C900 delivers a reversible capacity of 380 mAh g⁻¹ with 98% retention over 1000 cycles at 1 C. Under a 5000 G magnetic field, spin alignment within the Fe cores triggers directional lithium-ion migration, enhancing rate performance by 150%. Multimodal characterization reveals accelerated lithium kinetics, stable SEI evolution, and deep lithiation behavior. DFT calculations further confirm strong lithium adsorption (-24.14 eV) and low insertion barriers (-22.85 eV), validating the spin-guided diffusion mechanism. This work introduces a new class of hydrogen-derived ferromagnetic anodes, where the byproduct of a clean hydrogen process is re-engineered into a high-rate, conductor-free lithium storage platform. By coupling hydrogen generation with energy storage through shared material intermediates, this strategy offers a scalable path to carbon-efficient, magnetically enhanced battery systems.