Microstructure Analysis and Hydrolysis Mechanism of AlLi Alloys Activated by Metal Additives for Hydrogen Generation

Microstructure analysis and hydrolytic mechanism of activated Al-Li alloys including low melting point metal additives X (X:indicated as Bi, Sn, In and Ga) are explained for their good hydrogen generation performance in this paper. It is demonstrated that the presence of these metals has a double effect. The metals are helpful to reduce the grain size of Al-Li alloys due to the formation of new intermetallic compounds such as BiLi3, Sn5Li13, AlLiIn2, etc., preventing the connection of Al-Al and Li-Li atoms. The metals strongly improved hydrogen generation performance because the metals deposited on the surface of Al and Li metals act as cathodic centers for hydrogen generation. There were dual micro galvantic cells between Al (Li) and metal additives created in the hydrolysis process which stimulated the electrochemical corrosion of Al and Li. The LiX alloy acts as the initial hydrolysis centers due to its low standard potential and its hydrolysis byproduct LiOH further accelerates the micro galvantic cell between Al and X. Therefore, hydrogen generation performance is linked to standard potential of metal additives, increased Li and X amounts, uniform distribution of Li and X in the Al matrix in the longer milling time. Our results show that the potential good hydrogen generation performance can be obtained via the design and preparation technology of Al alloys.