Discharge behavior of MmNi3.66(CoAlMn)1.34 hydrogen storage alloys

Abstract

Discharge behaviors of MmNi3.66(CoAlMn)1.34 alloy electrodes at different discharge current (DC) have been investigated by simulated battery tests. The results indicate that discharge capacity is dependant on its DC adopted in the tests, in which discharge capacities decrease with increasing discharge current. More than 80% of capacity retention has been observed where DC is less than 1C, and 21.91% of capacity retention for DC = 3C. A second (additional) "activation process" is required in order to fully activate the MmNi3.66(CoAlMn)1.34 alloy electrodes to reach its active charge/discharge states again, when discharged at a higher DC above 0.2C. In addition to normal discharge step, an extra low-current discharge process indeed can effectively discharge the retained capacity; however such act damages the quality of MmNi3.66(CoAlMn)1.34 alloy electrodes, thereby resulting in an apparent decline in cycle life. © 2006 Elsevier B.V. All rights reserved.