Abstract
Overcoming the capacity-stability-cost trilemma in hydrogen storage materials represents a fundamental Pareto-type challenge for practical metal hydride applications. Current research efforts remain fragmented, typically pursuing single-parameter optimization while lacking holistic approaches that concurrently satisfy all three criteria. Here, a novel design paradigm is proposed by orchestrating A/B-side multi-principal-element alloys (MPEAs) in C14 Laves phases, enabling concurrent optimization of interstitial hydrogen storage environments and thermodynamics. Through three consecutive elemental screening and precise composition engineering, the optimized Ti(0.8)Zr(0.22)Mn(1.22)Cr(0.53)(VFe)(0.25) MPEA achieves a breakthrough saturation capacity of 2.06 wt.% at 20 °C with merely 1.6 MPa electrolysis-derived hydrogen pressure. More significantly, this material maintains an exceptional reversible capacity of 1.93 wt.% at 80 °C (against 0.1 MPa back pressure), achieving an 93.7% capacity utilization efficiency. Such outstanding performance under limited operating conditions surpasses the vast majority of known C14 Laves-phase materials. Equally noteworthy is the superior structural-property robustness enabled by local strain release through timely pulverization during repeated hydrogen insertion/extraction, which results in negligible influence in hydrogen storage properties, crystallographic structure, or elemental distribution throughout extended cycling. These findings establish new design guidelines for high-capacity, long-cycle-life, low-cost hydrogen storage materials operating under energy-efficient conditions.