Hysteresis and loss of cyclic capacity of multicomponent alloys for hydrogen storage: Thermodynamic modeling and advanced structural characterization

• Grant number: 25/06227-4
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2025
• End date: August 31, 2028
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Guilherme Zepon
• Grantee: Guilherme Zepon
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated researchers: Daniel Rodrigo Leiva ; Walter José Botta Filho

Abstract

Hydrogen plays a key role in the transition from a fossil fuel-based energy matrix to a low-carbon, renewable-based energy matrix. Brazil has enormous potential to produce clean energy from renewable sources and, therefore, potential to produce low-carbon H2. One of the major bottlenecks for the wide use of H2 as an efficient energy vector lies in its storage and transportation, which is limited by the low density of this gas even at high pressures. The storage of hydrogen in solid state in metal hydride (HM) forming metallic materials is one of the most promising ways to solve this problem. The applicability of an HM-forming alloy is directly linked to its pressure-composition-temperature (PCT) diagram. Significant advances in the design of multicomponent HM-forming alloys have been achieved thanks to the development and implementation of computational thermodynamics models for PCT diagram calculations [1-5]. However, two characteristics that are detrimental to its application persist and are not completely understood: hysteresis in the pressure-composition-isotherm (PCI) curves and the loss of storage capacity throughout the absorption and desorption cycles. This project has two complementary objectives. The first is to incorporate the phenomenon of hysteresis into existing thermodynamic models. The second is to elucidate the causes of hysteresis and loss of capacity during the cycling of multicomponent alloys by combining different advanced structural characterization techniques in samples with different hydrogenation conditions. The techniques employed will be ex-situ and in-situ XRD, SEM with chemical microanalysis by EDS and crystallographic orientation analysis by EBSD, and TEM with EDS and automatic analysis of crystallographic orientation using the ASTAR system from samples produced by Focused Ion Beam (FIB). Understanding these phenomena will bring benefits to the design of materials with optimized properties for applications involving hydrogen absorption and desorption. (AU)