A comprehensive study on hydrolysis and electrochemistry of Li–Ca–Si alloys

Abstract

The hydrolysis of silicon and its compounds to produce hydrogen for fuel cell remains a major problem. In this work, the active metal calcium and lithium are introduced into the silicon system by preparing Li–Ca–Si ternary alloy. The preferential hydrolysis of active metal in the alloy led to the formation of weakly alkaline environment. It is proved that 25 % Li–CaSi₂ alloy (25 Li) with a large number of secondary nano-phase has the highest electrochemical activity through electrochemical tests, the presence of the secondary nano-phase optimizes the reaction kinetics. Then the 25 Li shows the rapidest kinetics and highest yield in 0.5 M NaF solution, delivering a hydrogen yield of 590 mL g⁻¹ in 20 min and maintain a long-term stable dehydrogenation. In addition, the system still reaches a retention rate of 89 % after exposing to air for 24 h. Furthermore, the above system achieves hydrogen-electric conversion in fuel cell tests. This work provides a novel idea for the research of Si-water system for hydrogen production, and provides a reference for the practical applications on fuel cells in the future.