Controls-oriented models of lithium-ion cells having blend electrodes. Part 1: Equivalent circuits

- Battery management systems need models of cell dynamics to predict performance.
- Cells having composite electrodes motivate specialized models.
- We consider two equivalent-circuit-style models of composite-electrode cells.
- We give parameter-identification procedures for both model structures.
- Simulation results show that parallel equivalent circuit model gives best results.

Battery-management systems rely on mathematical sets of equations known as models when implementing battery controls procedures. Models are used in state-of-charge, state-of-health, available-energy, and available-power estimation tasks. These models should be high fidelity for good estimates but also computationally lightweight for inexpensive implementation.This paper and its Part-2 companion concern themselves with simple but accurate models of lithium-ion cells having composite electrodes, which are composed of a blend of multiple active materials. In this paper, we develop two forms of equivalent-circuit model (ECM): the series ECM and the parallel ECM-and show how to find values for the model parameters using current-voltage input-output data. We compare simulations of the ECMs to truth data from simulations of a full-order model and show that an ECM designed with knowledge of the material blend can outperform a standard ECM of similar complexity. In the companion paper, we show that it is further possible to create physics-based reduced-order models that have greater predictive power.