How is hydrogen stored?

The traditional method is liquefaction, but this method is expensive and difficult to use. At present, the most advanced method is to use some hydrogen storage materials, which can reversibly absorb and release hydrogen. Metal palladium was first discovered. 1 volume palladium can dissolve hundreds of volumes of hydrogen, but palladium is expensive and lacks practical value. Since 1970s, the research and development of hydrogen energy has become more and more important. The first thing to be solved is the safe storage and transportation of hydrogen. The range of hydrogen storage materials has been increasingly extended to transition metal alloys. For example, La-Ni intermetallic compounds can reversibly absorb and release hydrogen:

Each gram of La-Ni alloy can store 0. 157 liters of hydrogen, which can be released again with a little heating. LaNi5 is a nickel-based alloy. Iron-based alloy can be used as hydrogen storage material together with TiFe, which can absorb and store 0. 18 liter of hydrogen per gram. Other magnesium-based alloys, such as Mg2Cu and Mg2Ni, are relatively cheap.