Nano-pit corrosion of the tabs in aluminum electrolytic capacitor: Polarization characteristics of the tabs in ethyleneglycol–borate solution with chloride ions

To evaluate the corrosion behavior of the anode tab in aluminum electrolytic capacitor, we performed some electrochemical and morphology analysis using the polarization curves in conjunction with atomic force microscope (AFM), scanning electronic microscope (SEM) and optical microscope (OM). The results suggest that the current oscillation was found to be associated with nano-pit, which is defined as the rectangular pit (β) with a depth less than 55 nm and a width no more than 100 nm. Furthermore, elevation of Cl− concentration widened the crevices caused by electrolytic tension, enlarged the nano-pit area, and accelerated the electrochemical reaction rate of the anode tab in ethyleneglycol–borate solution. These findings may have implications for the failure of aluminum electrolytic capacitor.