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Magnesium hydride (MgH2) is a promising hydrogen storage material for its high hydrogen capacity of 7.6 wt.%. However, the further application is severely hampered by the sluggish reaction kinetics and stable thermodynamics. Introducing catalysts is an effective method to improve the reaction rate, but the catalytic activity tends to decrease with an increasing number of reaction cycles, due to the highly reductive Mg and H species. Herein, the spring effect has been observed in the P doped Li3VO4, in which both V─P and V─V bonds undergo compression and elongation during hydrogen absorption and desorption, respectively. Such a unique self‐regulation spring effect not only improves the reaction kinetics of MgH2, but also maintains the high activity of P doped Li3VO4, thereby ensuring the hydrogen capacity of MgH2 even after 100 loops. This spring effect of chemical bonding, stretched‐recovered‐stretched with the motion between the highly reductive Mg and H species, will provide insight into catalyst design for hydrogen‐related industries. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (PIBs) have been considered as potential alternatives for lithium‐ion batteries since there is a demand for better anode with superior energy, excellent rate capability, and long cyclability. The high‐capacity zinc selenide (ZnSe) anode, which combines the merits of conversion and alloying reactions, is promising for PIBs but suffers from poor cyclability and low electronic conductivity. To effectively boost electrochemical performance of ZnSe, a "dual‐carbon‐confined" structure is constructed, in which an inner N‐doped microporous carbon (NMC)‐coated ZnSe wrapped by outer‐rGO (ZnSe@i‐NMC@o‐rGO) is synthesized. Combining finite element simulation, dynamic analysis, and density functional theory calculations, the respective roles of inner‐ and outer‐carbon in boosting performance are revealed. The inner‐NMC increased the reactivity of ZnSe with K+ and alleviated the volume expansion of ZnSe, while outer‐rGO further stabilized the structure and promoted the reaction kinetics. Benefiting from the synergistic effect of dual‐carbon, ZnSe@i‐NMC@o‐rGO exhibited a high specific capacity 233.4 mAh g−1 after 1500 cycles at 2.0 A g−1. Coupled with activated carbon, a potassium‐ion hybrid capacitor displayed a high energy density of 176.6 Wh kg−1 at 1800 W kg−1 and a superior capacity retention of 82.51% at 2.0 A g−1 after 11000 cycles. [ABSTRACT FROM AUTHOR]