Kinetic-thermodynamic coupling enables efficient low-temperature hydrogen storage through lattice and electronic-structure regulation

V-based hydrides offer high reversible hydrogen capacities near room temperature, but their low-temperature operation remains limited by sluggish dehydrogenation kinetics and excessive hydride stability. Here we show that Mn and Al co-substitution is an effective strategy for tuning the structure, thermodynamics, and kinetics of V-based hydrogen-storage alloys. A series of V₆₀Ti_15-x-γCr₂₅Mn_xAl_γ (x, γ = 0 or 2) alloys were synthesized by partially replacing Ti with Mn and Al. Rietveld refinement confirmed single-phase BCC solid solutions, while SEM-EDS revealed a broadly homogeneous distribution of the substituent elements. Mn and Al co-substitution also reduced lattice distortion, dislocation density and microstrain. Importantly, the co-substitution induced unit-cell contraction and electronic-structure redistribution, which jointly contributed to an increase in the low-temperature plateau pressure and a reduction in hydride stability. As a result, V₆₀Ti₁₁Cr₂₅Mn₂Al₂ delivered an effective storage capacity of 2.30 wt% at −25 °C upon desorption to 0.1 MPa, with the apparent dehydrogenation activation energy reduced from 21.46 to 10.63 kJ·mol⁻¹ and the desorption enthalpy from 42.15 to 33.67 kJ·mol⁻¹. Capacity retention after 100 cycles increased from 85.26% to 90.86%. Density functional theory calculations using partially hydrogenated models showed a lower calculated hydrogenation enthalpy for Mn₂Al₂. Separate single-H models revealed local charge redistribution around H and neighboring V atoms, an increased H-V distance, and changes in the energetic overlap between the H-s and metal states; together, these results are consistent with weakened local H-V interactions and provide an electronic-structure interpretation of the reduced hydride stability.