Surface modification and characterisation of LaNi5 metal hydride powders with Cu and Cu/Ag coatings

Abstract

The low thermal conductivity of LaNi₅-based metal hydride powders limits efficient heat removal during hydrogen charging and discharging, thereby reducing overall system efficiency. This study examines the application of a Cu/Ag duplex coating on LaNi₅ metal hydride particles to minimize interparticle thermal resistance and improve thermal conductivity. LaNi₅ particles were first ground in a ball mill for one hour, then coated with Cu via a chemical reduction method in a copper sulfate-containing solution. The Cu/Ag duplex coating was subsequently formed by reducing the Cu-coated surfaces with [Ag(NH₃)₂]⁺ complex ions in a solution containing potassium sodium tartrate (KNaC₄H₄O₆·4H₂O). The structural, morphological, and thermal properties of the coatings were characterized using several techniques. Scanning electron microscopy (SEM) was used to analyze the surface morphology, while energy dispersive X-Ray spectroscopy (EDX) confirmed the elemental composition. X-ray diffraction (XRD) was used to determine the phase structure. Differential scanning calorimetry (DSC) was performed to evaluate thermal stability and potential structural transformations. The results show that a uniform and stable Cu/Ag duplex coating can be successfully applied to LaNi5 powders. DSC analysis further reveals that the duplex coating improves the thermal behavior of metal hydrides, offering a promising method for enhancing heat transfer in hydrogen storage systems.

Keywords

• LaNi5
• Metal hydride
• Cu/Ag
• Coating
• Characterisation

Kaynakça

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