Electrothermal impedance spectroscopy measurement on high power LiMO2/Li4Ti5O12 battery cell with low bandwidth test setup

Abstract

Modern lithium-ion batteries, like LiMO2/Li4Ti5O12 chemistry, are having very high power capability, which drives the need for precise thermal modelling of the battery. Battery thermal models are required to avoid possible safety issues (thermal runaways, high-temperature gradients) but also for the optimal battery pack design and for predicting battery electrical performance during operation (especially at low temperatures). Equivalent electrical circuit battery models (thermal and electro-thermal) are able to offer relatively good performance with relatively low computational efforts and may be executed on-line (e.g. in the electric vehicle Battery Management System). The Electrothermal Impedance Spectroscopy (ETIS) can be used as a relatively simple and fast method for non-destructive parametrization of the battery thermal models. However, the ETIS requires expensive galvanostat with high-bandwidth and high-current capability for large format battery cells. Thus, this paper evaluates the possibility and accuracy of performing ETIS measurements with a standard battery test station (or bidirectional power supply) with low-bandwidth.