Toolchain for advanced modeling of rechargeable lithium-ion batteries

Summary:

Battery electrical and thermal modeling is a fundamental task in understanding cell and system performance and degradation during the development of battery system for application. This is generally accomplished by i) cell and system test analysis and evaluation, ii) model selection, iii) parameterization, and iv) validation. In the frame of this work, a flexible toolchain able to achieve all these tasks in a systematic manner is presented. This means that test data in whichever structure can be processed by the tool to extract useful information and dependencies (e.g. open circuit voltage, impedance etc.) and to parameterize customized electrical and thermal models, both in time and frequency domain. Moreover, different additional advanced features, such as low state-of-charge electric behavior and corresponding power limitation strategy for application can be parameterized, designed, and tested. The user is guided in the use of the toolchains by a simple and intuitive Graphical User (friendly) Interface: this avoids multiple time programming of same operation for each new selected and tested cell or newly designed battery system. The toolchain is completely implemented in Matlab environment and can be also used as standalone program. Examples of possible usage of the toolchain are reported. Firstly, approach and exemplary battery equivalent electric circuit model parameterizations on different cell types by means of constant current pulses and of electrochemical impedance spectroscopy are presented, together with validation based on application profiles (e.g., driving profiles of electric vehicles). Moreover, preliminary results concerning advanced model parameterization for battery low state-of-charge behavior are presented and discussed. The exemplary results demonstrate the versatility of the developed battery model toolchain and its flexibility to be used in a systematic manner for parameterizing basic or advanced cell models based on different approaches.