Publication | Closed Access
Characterization of Corrosion Products of AB[sub 5]-Type Hydrogen Storage Alloys for Nickel-Metal Hydride Batteries
70
Citations
0
References
2000
Year
EngineeringCorrosion ProductsChemistryNickel-metal Hydride BatteriesChemical EngineeringElectron MicroscopyCorrosionSodium BatteryCorrosion ResistanceMaterials ScienceBattery Electrode MaterialsAdvanced Electrode MaterialEnergy StorageHydrogenElectrochemistryLi-ion Battery MaterialsCorrosion KineticsElectrochemical Energy StorageBatteriesHydrogen EmbrittlementStorage Capacity
To better understand the decrease in storage capacity of alloys in rechargeable Ni/MH batteries undergoing repeated charge/discharge cycles, the corrosion of a alloy in aqueous KOH electrolyte was studied. The crystal structure, chemical composition, and distribution of corrosion products were characterized by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Hollow and filled needles of a mixed rare earth hydroxide were found to cover a continuous nanocrystalline corrosion scale composed of metal (Ni,Co) solid solution, oxide (Ni,Co)O solid solution and rare earth hydroxide, and a Mm‐depleted alloy subscale. Corrosion kinetics were measured for three different temperatures. Growth kinetics of the continuous corrosion scale and of the needles obeyed linear and parabolic rate laws, respectively. Models for the corrosion mechanism were developed on the basis of diffusional transport of Mm and OH through the hydroxide needles and subsequent diffusion along grain boundaries through the nanocrystalline scale. © 2000 The Electrochemical Society. All rights reserved.