Study of the causes of hysteresis in Pressure-Composition-Isotherm curves and the loss of hydrogen storage capacity during cycling in body-centered cubic multicomponent alloys

• Grant number: 24/16147-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2025
• End date: July 31, 2028
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Guilherme Zepon
• Grantee: Gabriela Chimello Mayer Dias
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Amid concerns about the finite reserves of fossil fuels and their environmental impacts, hydrogen emerges as a promising alternative. However, ensuring its safe and efficient storage remains a challenge. In this context, metal hydrides enable hydrogen storage in the solid state at low pressures. Body-centered cubic (BCC) multicomponent alloys are notable for their flexibility in varying properties through compositional adjustments. Despite advancements in optimizing operating conditions, two issues remain unresolved and not fully understood: hysteresis in the pressure-composition-isotherm (PCI) curves, which results in a higher absorption pressure compared to desorption and causes a loss in thermodynamic efficiency, and the reduction of hydrogen storage capacity with the number of absorption and desorption cycles. Both phenomena appear to be interrelated, with the magnitude of hysteresis decreasing as the number of cycles increases. This PhD project aims to investigate and understand the causes of hysteresis in PCI curves and the loss of hydrogen storage capacity during cycling in BCC multicomponent alloys through a combination of hydrogen absorption experiments and advanced structural characterization techniques. For this, the Ti-V-Nb-Cr system will be adopted as a model. Results obtained under different experimental cycling conditions, first hydrogenation measurements, and PCT diagrams will be correlated with observed structural changes.