Toward Low-Cost Metal Hydrides: Ferrovanadium as a Viable Feedstock for TiZrVFeNi-Based Stationary Hydrogen Storage

Abstract

Abstract

Abstract Metal hydride-based hydrogen storage systems are promising for stationary applications; however, the high capital expenditure (CAPEX), largely driven by refined alloying elements, remains a barrier to large-scale deployment. This work investigates substituting high-purity V and Fe with industrial ferrovanadium (FeV80) in dual-phase C14/BCC Ti21Zr21VxFeyNiz alloys. Two representative compositions were produced using high-purity (HP) and low-cost (LC) precursors: a low-vanadium alloy (5 V) and a high-vanadium alloy (14 V). Microstructural and crystallographic characterization confirmed that the LC alloys fully preserved the target dendritic dual-phase configuration and phase balance, proving that industrial impurities below 0.7 wt % do not alter the core metallurgy. At room temperature, the LC alloys exhibited reversible capacities (1.1 wt % for 5 V and 0.7 wt % for 14 V) and cycling stability virtually identical to their HP counterparts, while FeV80 successfully halved the activation incubation time of the 14 V alloy from 1000 to 500 s. Economically, the FeV80 substitution achieved a substantial raw material cost reduction of up to 61.1%, slashing the 14 V alloy price from 66.79 to 25.99 USD/kg. Projecting these experimental values onto a commercial stationary storage case study with a 7.6 kg H2 target demonstrates that under an optimized maximum capacity scenario, the 14 V-LC alloy requires only 481 kg of active material, which represents a 12.5% mass reduction compared to the 550 kg commercial benchmark active bed and a 60.6% reduction in active material cost compared to the HP counterpart. Ultimately, this study establishes industrial-grade ferrovanadium as a strategic, scalable feedstock capable of drastically reducing storage system CAPEX while completely decoupling production costs from functional performance.