Corrosion behaviour of Cu-plate current collector under ex-situ cyclic stability testing for energy storage application

Abstract

This study compares the corrosion behaviour of a copper plate current collector subjected to an ex-situ cyclic stability test in a 6 M KOH and a 6 M Na₂SO₄ electrolyte solution for an electrochemical supercapacitor cell. Through experimental analysis, the change in microstructures resulting from the corrosion behaviour of the copper plate current collector samples are examined by employing various analytical techniques, including microscopy, spectroscopy, and surface roughness analyzer. The corrosion behaviour was studied by employing potentiodynamic polarization and electrochemical impedance spectroscopy analyses. The copper plate current collector samples analysed in 6 M KOH and 6 M Na₂SO₄ electrolyte solution showed uniform and localized corrosion product formation, respectively. The CU-72HRS sample recorded a corrosion potential of −608.6 mV, −628.87 mV, and −89.5 mV, −87.588 mV using both Tafel and resistance polarization data fitting analysis, respectively, for both 6 M KOH and 6 M Na₂SO₄ electrolyte solution using a scan rate of 5 mV/s at a voltage window of −1–1 V. Comparing the microstructural changes under various cyclic conditions provides valuable insights into the durability and reliability of copper plates as current collectors in energy storage systems. The results of this study help improve our understanding of the supercapacitor cell performance in ex-situ cyclic stability tests, assisting in the development of more efficient and durable energy storage technologies.