LAUSR

Rechargeable magnesium batteries (RMBs) are emerging as compelling alternatives for next‐generation high‐energy‐density storage systems, owing to magnesium's abundance, safety, and high volumetric capacity. However, the divalent nature of magnesium ions (Mg2+) results in sluggish ion diffusion and severe polarization, significantly impeding their practical application. Here, it is reported the design and synthesis of boron‐doped molybdenum disulfide (B‐MoS2) cathodes via an in situ phase transformation of Boridene (Mo4/3B2‐xTz). Based on experimental results and theoretical calculations, it is confirmed that boron atoms are stably incorporated into the hexagonal lattice, yielding a thermodynamically stable boron‐doped structure that strengthens Mg2+ adsorption and facilitates rapid ion transport. The optimized B‐MoS2 cathodes deliver a high reversible capacity of up to 218.4 mAh g−1 and sustain a capacity above 100 mAh g−1 for over 400 cycles at 200 mA g−1, it overwhelms all similar 2H phase MoS2‐based materials reported so far. Benefiting from the unique surface chemistry and wide bandgap features inherent to Boridene‐derived materials, this work offers a new paradigm for engineering high‐performance cathode architectures for multivalent‐ion batteries.