Thesis

Performance and reliability studies of Atmospheric Plasma Spraying Raney nickel electrodes for alkaline electrolysers

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Awarding institution
  • University of Strathclyde
Date of award
  • 2014
Thesis identifier
  • T13948
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Abstract
  • This PhD main aim was the examination of the Atmospheric Plasma Spraying Raney nickel electrodes samples with strong emphasis on electrochemical characterisation and investigation of the degradation/deactivation mechanisms which occur within the electrodes structure. Nowadays research in alkaline electrolysis mainly aims to improve efficiency, extend durability and decrease the price of electrolyser units. One of the methods to achieve all of these goals is the development of novel electrode types. Raney nickel electrodes manufactured by Force Technology (Denmark) using a novel atmospheric plasma spraying method (APS), have been shown to exhibit good performance with low overpotential towards the hydrogen evolution reaction (HER). In comparison to the other electrode production methods APS is considered also to be relatively cheap. To our knowledge, this is the first time APS has been applied for the production of Raney nickel electrodes for water electrolysis. APS is cheaper and simpler than actually used vacuum plasma spraying, making it more suitable for mass production of the electrodes. For a purpose of experimental work the laboratory environment was set-up which consisted of the electrochemical cells and the data acquisition devices. The methods of Tafel extrapolation, cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy were applied, that allowed to estimate electrochemical parameters of the samples. Characterisation work concluded, that overall performance of the tested samples have been attributed to the very high electrochemical active area as well as enhanced kinetics obtained for these samples following the chemical and electrochemical activation procedures Investigation of degradation mechanisms work part identified hydrides impact as a main source of deactivation for cathodes. To prevent, this effect techniques of hydrides oxidation and activation of the electrolyte were tested however, neither of them was able to eliminate hydrides impact completely. The overall work is concluded that suppressing hydrides impact should be possible by improving electrodes manufacturing process for example by application of molybdenum coatings. The performed study is supplemented by two additional outcomes. First of them is electrochemical measurement device, which concept was created and initial prototype was built using cheap electronic components. Second one is feasibility study of application of hydrogen storage technologies to increase hybrid wind energy-diesel electricity generation system efficiencies.
Resource Type
DOI
Date Created
  • 2014
Former identifier
  • 1216870

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