Overview over common degradation pathways and failure mechanisms in supercapacitors. Electrolyte decomposition can occur due to factors such as high temperatures, high voltages, and prolonged cycling, resulting in the formation of gases, solids, or other degradation products that can clog the pores of the electrode or lead to the formation of a passivating layer on the electrode surface. The active materials used in supercapacitors can undergo structural and chemical changes during charge/discharge cycles, leading to a decrease in their capacitance and/or stability. The performance and stability of supercapacitors can also be affected by the operating conditions such as temperature, humidity, and voltage. Elevated temperatures can cause chemical reactions in the supercapacitor, leading to electrolyte decomposition and a decrease in capacitance. Conversely, low temperatures can cause the electrolyte to freeze, resulting in mechanical stress and possible damage to the supercapacitor. The interphase between the electrode and electrolyte can also degrade over time due to factors such as electrochemical reactions, charge/discharge cycling, and mechanical stress. When exposed to the electrolyte the metal current collectors can undergo corrosion upon cell operation, which is a significant failure mechanism in supercapacitors.
