Resolving the Capacity-Stability-Cost Trilemma in Multi-Principal-Element Hydrogen Storage Alloys Through...

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_0.8Zr_0.22Mn_1.22Cr_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.