Nuclear quantum confinement enables robust deuterium bonds for highly reversible aluminum anodes

The hydrogen evolution reaction (HER) fundamentally limits aluminum electroreduction in aqueous electrolytes by dominating interfacial charge transfer. Here, we suppress HER by engineering deuterium bonds (D‐bonds) through nuclear quantum effects, confining D between D₂O and DMF molecules. This quantum confinement weakens hydrogen delocalization and restructures the Al3+ solvation sheath, reducing water activity kinetically and thermodynamically. The regulated electrolyte enables uniform aluminum nucleation and dense plating layers, achieving 569 h (0.05 mA cm‐2) and 379 h (0.1 mA cm‐2) cycling stability in the 2D2O/1DMF electrolyte, which outperforms traditional sulfate electrolytes by 3.6 and 6.1 times, respectively. Our work uniquely leverages nuclear quantum confinement to engineer robust D‐bonds, simultaneously suppressing HER and enabling atomic‐level control over aluminum solvation structures for unprecedented Al redox reversibility in sulfate electrolytes. This exemplification pushes the electrolyte engineering from extensive component adjustment to quantum precision engineering, which provides an innovative solution for the high‐activity water‐based battery system.