Experimental studies of lithium-ion batteries are very often based only on deep charge and discharge cycles. However, these test profiles do not fully reflect the actual operation of the battery in an electric vehicle or in stationary applications, where the battery is not only loaded during the main charging and discharging profiles, but it is also stressed by the current throughput caused by renewable power fluctuations or by auxiliary services. These cycles, which are superimposed to the main charge and discharge processes and have a depth of discharge not exceeding 2%, are called micro-cycles. Although there are several simulation studies that attempt to capture this issue, there is still no comprehensive experimental study that has the phenomena that occur during micro-cycling. This paper presents an experimental analysis of micro-cycles, providing a detailed view of the different processes taking place in the battery during aging, by means of a detailed analysis of the results from electrochemical impedance spectroscopy (EIS). By studying the single electrochemical processes in detail, this paper explains the benefits of micro-cycling in terms of extending the lifetime of the battery.

This research was funded by the Czech Technical University student's grant project number SGS24/136/OHK3/3T/13 and by the project 'The Energy Conversion and Storage', funded as project No. CZ.02.01.01/00/22-008/0004617 by Programme Johannes Amos Comenius, call Excellent Research. Moreover, this work is part of the projects PID2022-139914OB-I00, funded by MCIN/AEI/10.13039/501100011033/FEDER, UE, TED2021-132457B-I00, funded by MCIN/AEI/10.13039/501100011033/ and by the European Union NextGenerationEU/PRTR, and HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre.

Publicado 2024-07-30