Accelerated Life Testing of Double‐Layer Capacitors: Reliability and Safety under Excess Voltage and Temperature

Commercial 50 F double‐layer capacitors from leading international manufactures were tested with respect to fire protection regulations and general safety hazards in technical pulse–power applications at temperatures of up to 120 °C and voltages up to 4 V. Diagnostic criteria were gathered during a decade of lifetime testing concerning the destruction of the electrode materials and the evaporation of electrolyte. The aging behavior of supercapacitors is quantified on the basis of capacitance loss, parasitic side reactions, and the chemical analysis of decomposition products. Amines, amides, and oligomers of acetonitrile are formed in the electrolyte. The carbon composite electrodes are destroyed by continual stress at high temperatures and operating voltages.