LIBquiv: An open-source MATLAB class for time-domain simulation of physics-informed equivalent circuit models of lithium-ion batteries

Abstract

Lithium-ion battery technology is today the most important electrical energy storage technology. Equivalent circuit models (ECMs) are widely used in battery research and development, and for diagnostics as part of battery management systems. The present article introduces LIBquiv, a MATLAB class for time-domain simulation of battery equivalent circuit models. LIBquiv features physics-informed models, including dual-electrode, hysteresis, and diffusion models; degradation mode models for aging simulation and lifetime prediction; and voltage-controlled models for innovative state diagnostics. LIBquiv allows intuitive use through object-oriented implementation and simple user commands. LIBquiv combines the low computational complexity of ECMs with physics-informed descriptions of electrode behavior, thermal effects, aging, and state diagnostics within a single framework. Its capabilities are demonstrated for thermo-electrical cell simulation, where the battery temperature change is predicted during charge and discharge operation; for long-term aging prediction, where the model allows to predict the nonlinear aging (“knee” formation); and for voltage-controlled state-of-charge diagnosis, where LIBquiv is able to estimate the state of charge during diverse cycling protocols based on voltage only as input. The illustrative examples are taken directly from the GitHub repository.