Degradation Behavior of Lithium-Ion Batteries Based on Lifetime Models and Field Measured Frequency Regulation Mission Profile

Energy storage systems based on Lithium-ion (Liion) batteries have been proposed as an environmentally friendly alternative to traditional conventional generating units for providing grid frequency regulation. One major challenge regarding the use of Lithium-ion batteries in such applications is their higher cost-in comparison with other storage technologies or with the traditional frequency regulationmethods-combinedwith performance-degradation uncertainties. In order to surpass this challenge and to allow for optimal sizing and proper operation of the battery, accurate knowledge about the lifetime of the Li-ion battery and its degradation behavior is required. Thus, this paper aims to investigate, based on a laboratory developed lifetime model, the degradation behavior of the performance parameters(i.e., capacity and power capability) of a Li-ion battery cell when it is subjected to a field measured mission profile, which is characteristic for the primary frequency regulation service.