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Magnesium‐based batteries have garnered significant attention due to their high energy density, excellent intrinsic safety, and low cost. However, the application process has been hindered by the high Mg2+ ions diffusion barrier in solid‐state structures and solid‐liquid interphase. To address this issue, a hybrid battery technology based on Mg anode and Fe‐based Prussian Blue Analogue cathode doped with functional transition metal ions and N═O bonds is proposed. Combined multiscale experimental characterizations with theoretical calculations, the subtle lattice distortion can create an asymmetric diffusion path for the active ions, which enables reversible extraction with significantly reduced diffusion barriers achieved by synergistic doping. The optimized cathode exhibits a working potential of 2.3 V and an initial discharge capacity of 152 mAh g−1 at 50 mA g−1. With the preferred electrolyte combined with equivalent concentration [Mg2(µ‐Cl)2(DME)4][AlCl4]2 and NaTFSI salt solution, the hybrid system demonstrates superior cycling performance over 200 cycles at a high current density of 200 mA g−1, maintaining ≈100% coulombic efficiency with superior ion dynamic. The findings are expected to be marked an important step in the further application of high‐voltage cathodes for Mg‐based hybrid batteries. [ABSTRACT FROM AUTHOR]

Conventional sodium‐based layered oxide cathodes are extremely air sensitive and possess poor electrochemical performance along with safety concerns when operating at high voltage. The polyanion phosphate, Na3V2(PO4)3 stands out as an excellent candidate due to its high nominal voltage, ambient air stability, and long cycle life. The caveat is that Na3V2(PO4)3 can only exhibit reversible capacities in the range of 100 mAh g−1, 20% below its theoretical capacity. Here, the synthesis and characterizations are reported for the first time of the sodium‐rich vanadium oxyfluorophosphate, Na3.2Ni0.2V1.8(PO4)2F2O, a tailored derivative compound of Na3V2(PO4)3, with extensive electrochemical and structural analyses. Na3.2Ni0.2V1.8(PO4)2F2O delivers an initial reversible capacity of 117 mAh g−1 between 2.5 and 4.5 V under the 1C rate at room temperature, with 85% capacity retention after 900 cycles. The cycling stability is further improved when the material is cycled at 50 °C within 2.8–4.3 V for 100 cycles. When paired with a presodiated hard carbon, Na3.2Ni0.2V1.8(PO4)2F2O cycled with a capacity retention of 85% after 500 cycles. Cosubstitution of the transition metal and fluorine in Na3.2Ni0.2V1.8(PO4)2F2O as well as the sodium‐rich structure are the major factors behind the improvement of specific capacity and cycling stability, which paves the way for this cathode in sodium‐ion batteries. [ABSTRACT FROM AUTHOR]