Development of a metal hydride hydrogen compressor with high-pressure hydrogen storage alloys

Single- and double-stage metal hydride hydrogen compressors (MHHC) were developed using two series of metal hydrides of AB₅-based La_0.5Ce_0.5Ni_5-xAl_x (x = 0, 0.1, 0.2) alloys and AB₂-based Ti_1-yZr_yMn_0.8Cr_1.2 (y = 0.05, 0.1, 0.2) alloys. In single-stage mode, La_0.5Ce_0.5Ni₅ and Ti_0.9Zr_0.1Mn_0.8Cr_1.2 alloys could produce hydrogen pressures of 117 atm and 132 atm, respectively, at 100 °C. When the temperature was raised to 140 °C, both alloys could produce hydrogen pressures of 200 atm. The Ti_0.9Zr_0.1Mn_0.8Cr_1.2 alloy exhibited higher hydrogen discharging pressure and faster kinetics than those of the La_0.5Ce_0.5Ni₅ alloy. A pair of alloys were used for a double-stage MHHC (first stage: Ti_0.9Zr_0.1Mn_0.8Cr_1.2; second stage: Ti_0.95Zr_0.05Mn_0.8Cr_1.2). The initial hydrogen pressure of 50 atm increased to 245 atm when the working temperature was raised from 25 °C to 100 °C, which provides an opportunity for designing a compact and simple MHHC.