A holistic approach for simulation and evaluation of electrical and thermal loads in lithium-ion battery systems

Lithium-ion batteries (LIBs) exhibit a complex electrical and thermal behavior during operation. This is amplified at the system level, where the LIBs are arranged in a serial and parallel connection and phenomena such as parameter variations and heat transport effects exert additional influences that must be acknowledged and understood. Therefore, to reliably design battery systems with regard to safety and service life, a profound understanding of the exact behavior of each individual cell in the battery system is required. In this paper, the authors propose a holistic approach to model and simulate the complete electrical and thermal behavior of battery systems and a novel strategy to comparatively evaluate the load on individual cells. The modular design of the simulation framework allows fast adaptation to different battery interconnections and thermal properties. An analytic computation of the electrical and thermal effects ensures efficient computation. This enables investigations at both the cell and the system level, making it feasible to compare different system layouts systematically, including the consideration of additional influences like temperature sensors, cell balancing, and cooling systems or the environment. The electrical part of simulation framework is validated on the cell and the system level and an optimization-based approach for the parameterization of the thermal submodel is presented.