Studies on Electroless Cobalt Coatings for Microencapsulation of Hydrogen Storage Alloys

Abstract

LaNi4 275n,24 alloy was microencapsulated with cobalt by electroless deposition from an alkaline hypophosphite bath. Discharge curves of the encapsulated alloy indicate an additional contribution to the capacity arising from the cobalt on the surface. Studies on cobalt thin films reveal the presence of adsorbed hydrogen in cobalt. The amount of hydrogen adsorbed was observed to increase with time of cathodic polarization and to reach a maximum. Polarization techniques have been used to characterize the cobalt-plated alloy as a function of state of charge. The equilibrium potential of the microencapsulated electrode at low hydrogen concentration is determined by the potential of the cobalt coating on the surface. InfroductionNickel hydride batteries (MH) with reversible hydrogen storage alloys have recently attracted great attention. For Recently, we studied the shape evolution of copper bumps with photoresist angles.9This investigation discusses the cavity shapes and the current distributions for deep cavities. The role of convection and diffusion within the cavities is discussed. The current distributions at diffusion limited overpotentials were calculated by the numerical fluid dynamics computations.

Synthesis and Characterization of Hydrous Ruthenium Oxide-Carbon Supercapacitors

“…This agrees with the results shown by McKeown et al 9 Similar behavior ͑increased discharge currents at lower scan rates͒ has also been observed for metal hydride electrodes where the transport of hydrogen within the particle is rate limiting. 16 Charge-discharge studies.-The capacitance obtained from CVs was confirmed by chronopotentiometric studies at various applied currents. Figure 8A presents the galvanostatic charge-discharge curves for the RuO 2 -carbon composite heated at 100°C.…”

Electrochemical energy storage of Co powders in alkaline electrolyte

“…This may relate to the dissolution and precipitation of Co(OH) 2 in alkaline electrolyte. Haran et al [24] mentioned that the Co(OH) 2 could be oxidized to HCoO 2 − in alkaline solution, which could be subsequently precipitated into Co(OH) 2 in the solution. It is fortunate that the formed HCoO 2 − is only fractional [24].…”

“…Haran et al [24] mentioned that the Co(OH) 2 could be oxidized to HCoO 2 − in alkaline solution, which could be subsequently precipitated into Co(OH) 2 in the solution. It is fortunate that the formed HCoO 2 − is only fractional [24]. We found that the KOH solution exhibits a sky-blue color after the first cycle, followed by an apparent light brown color on the inner surface of the glass pipe of the half-cell.…”

Shrinking Core Model for the Discharge of a Metal Hydride Electrode

“…Equation 15 can be used to modify Eq. 12 [16] The boundary condition at x ϭ 1 is not homogeneous and suggests a transformation of the form 15 …”