Over 7500 Cycles Achieved in Platinum‐Group‐Metal‐Free Ni–H 2 Battery Through Reversible Hydrogen Spillover

ABSTRACT Traditional Ni–H 2 batteries employing platinum‐group metal (PGM) catalysts exhibit ultralong lifetimes (> 10 000 cycles), yet comparable durability has not been achieved in recently developed PGM‐free systems, mainly due to sluggish hydrogen evolution and oxidation reactions (HER/HOR) in alkaline media. Herein, we employ reaction‐dependent hydrogen spillover across a metal‐support interface to decouple the physical and electrochemical hydrogen steps onto distinct active sites, thereby accelerating HER/HOR kinetics and markedly extending battery lifetime. As a proof of concept, we develop a low‐cost catalyst consisting of Ni nanoclusters supported on oxygen‐deficient TiO 2–x . Owing to the difference in *H adsorption strength, hydrogen species migrate from Ni to TiO 2–x during HOR and in the reverse direction during HER, enabling physical hydrogen processes on Ni and electrochemical steps on TiO 2–x . The resulting electrode exhibits polarization performance surpassing that of Pt/C and outstanding durability for both HER and HOR, sustaining 3000 h operation at 15 mA cm −2 . Moreover, the assembled Ni–H 2 battery delivers excellent wide‐temperature performance (−20°C to 55°C) and achieves over 7500 cycles at a practical capacity of 15 mAh cm −2 . This work demonstrates that hydrogen spillover‐enabled decoupling of HER/HOR steps provides an effective route toward ultralong‐life PGM‐free Ni–H 2 batteries.