Modeling current-rate effects in lithium-ion batteries based on a distributed, multi-particle equivalent circuit model

Due to the wide range of operating conditions under which a lithium-ion battery operates, it is essential to develop models that are able to replicate experimental behavior in a variety of temperature and current-rate scenarios. However, there are some complex effects in the range of moderate to high current rates that are difficult to justify with current formulations of both equivalent circuit and electrochemical models, due to model shortcomings or a challenging parameterization process. For this reason, in this article we present a discretely distributed, multi-particle equivalent circuit model capable of addressing said limitations. By obtaining quasi-static characteristics from thermodynamic tests and making informed assumptions about particle size distributions, the model is only dependent on three parameters that are directly correlated to those determined from experimental impedance data. The proposed model is able to provide accurate results in a current range from C/10 to 2C (RMS≤12 mV at 40 °C) as well as dynamic operation (RMS≤7 mV at 40 °C), and ensures consistent behavior at ambient temperatures in the range from 10 °C to 40 °C. For all the reasons above, the proposed model constitutes a suitable alternative for modeling complex behavior in lithium-ion batteries with a reduced computational cost and a well-defined parameterization process.