Electrochemical Characterization of Carbon Anode Performance

Coke used in the manufacturing of anodes is commonly a mix of cokes from several suppliers to meet the customer’s specifications. This variation in coke composition from suppliers may lead to considerable deviation in anode performance. The present work, still in its early phase, aims to develop a method with which to characterize electrochemical performance of anodes and relate this to the anode material properties. To verify the experimental approach, laboratory anodes were produced from various single cokes with different impurity levels. Voltammetry was performed and polarization curves were recorded to investigate current-voltage characteristics of these anodes. Gas analysis was also executed in order to study the CO2:CO ratio and calculate Pearson-Waddington current efficiencies. The reaction overpotential from polarization curves was found to decrease with increasing total metallic and sulphur impurities, indicating that blended cokes may behave differently on a microscopic scale and between individual anodes in a cell if the anodes come from different production batches. Contrary to the polarization curves, metallic and sulphur impurities were found to not significantly change the CO2:CO ratio or Pearson Waddington current efficiency. Experiments of this type aim to develop fundamental understanding of how single coke properties affect electrochemical performance.