Lifetime Degradation Cost Analysis for Li-ion Batteries in the Capacity Market Using Accurate Physics-based Models

Energy storage devices provide services in the capacity market (CM). Li-ion batteries are a popular type of energy storage devices used in CM. Battery lifetime is a key factor in determining the economic viability of Li-ion batteries and current approaches to estimating this are limited. This paper explores the potential of a lithium-ion battery to provide CM services with four de-rating factors (0.5h,1h,2h and 4h). During the CM contract, the battery experiences both calendar and cycle degradation which reduces the overall profit. Physics-based battery and degradation models are used to quantify degradation cost for the battery in the CM to enhance earlier research results. The degradation model quantifies capacity losses related to solid-electrolyte interphase (SEI) layer, active material loss and SEI crack growth. Results show that the physics-based degradation model can accurately predict degradation cost at different operating conditions thus can substantiate the business case of the battery in the CM. The simulated CM profit can be higher by 60% and 75% at 5C and 25 respectively compared to empirical and semi-empirical degradation models. A sensitivity analysis for a range of parameters are given to show their effects on batteries’ overall profit.