Modelling of current and temperature effects on supercapacitors ageing. Part II: State-of-Health assessment

This second part of the paper proposes a model for predicting the State-of-Health (SOH) of electrochemical double layers supercapacitors (SCs) during combined high-pulsed power cycling and high-temperature life endurance stresses. The evolutions of the SC capacitance, CSC, during these specific types of stresses have been discussed in part I and, based on the phenomenological observations we made, we here predict the CSC evolution by means of a dedicated model. The inputs of the proposed model are the SC delivered charge and the duration of the temperature stress above the rated one; the output is the CSC. The main virtue of the model is its capability to take into account the presence of the CSC recovering and accelerated ageing that cannot be represented by other models available in the literature. The validation of the proposed SC ageing model is carried out by means of experimental results, other than those used to infer the model, obtained on a 365 F SC stressed by combined life-endurance and power-cycling stresses over a time window of 35 days.