Accelerated ageing testing and cycle life prediction of supercapacitors for alternative battery applications

Since supercapacitors (SCs) have inherently long life, they can be an alternative energy storage source to traditional secondary batteries in long-life applications where the batteries are cycled with shallow depth of discharge to extend their cycle life. Cycle life performance tests were conducted under various cycling conditions in order to evaluate the feasibility of the accelerated ageing testing and cycle life prediction for SCs in alternative battery applications. The resultant capacitance retention trends could be extrapolated linearly with the square root of the number of cycles as the x-axis. Capacitance degradation ratios were mainly dependent on temperature, implying that ageing can be accelerated by elevating temperature. An ageing acceleration factor was determined from activation energies obtained from the Arrhenius equation. A cycle life prediction model for SCs was established by combining extrapolation and acceleration factor. The experimental and predicted capacitance retention trends were in good agreement, and the derived prediction model was verified to be appropriate for SCs in alternative battery applications.