A parametric open circuit voltage model for lithium ion batteries
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We present an open circuit voltage (OCV) model for lithium ion (Li-ion) cells, which can be parameterized by measurements of the OCV of positive and negative electrode half-cells and a full cell. No prior knowledge of physical parameters related to particular cell chemistries is required. The OCV of the full cell is calculated from two electrode sub-models, which are comprised of additive terms that represent the phase transitions of the active electrode materials. The model structure is flexible and can be applied to any Li-ion cell chemistry. The model can account for temperature dependence and voltage hysteresis of the OCV. Fitting the model to OCV data recorded from a Li-ion cell at 0°C, 10°C, 20°C, 30°C and 40°C yielded high accuracies with errors (RMS) of less than 5 mV. The model can be used to maintain the accuracy of dynamic Li-ion cell models in battery management systems by accounting for the effects of capacity fade on the OCV. Moreover, the model provides a means to separate the cell's OCV into its constituent electrode potentials, which allows the electrodes’ capacities to be tracked separately over time, providing an insight into prevalent degradation mechanisms acting on the individual electrodes.
Birkl , C R , McTurk , E , Roberts , M R , Bruce , P G & Howey , D A 2015 , ' A parametric open circuit voltage model for lithium ion batteries ' Journal of The Electrochemical Society , vol 162 , no. 12 , pp. A2271-A2280 . DOI: 10.1149/2.0331512jes
Journal of The Electrochemical Society
© The Author(s) 2015. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited.
The financial support of EPSRC UK and Jaguar Land Rover Ltd is gratefully acknowledged.
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