The performance as well as the lifetime of lithium-ion battery cells are strongly temperature-dependent. To achieve optimal results in both aspects, efficient thermal management systems are needed for the automotive application. However, manufacturers and suppliers face certain obstacles considering the validation of the thermal management systems along the development process of these systems. An extensive experimental infrastructure is required and high safety regulations have to be fulfilled for the investigation of lithium-ion battery cells. The thermal behavior of the cells changes as a result of cell degradation, which leads to a reduced reproducibility considering the experimental validation of the thermal management systems. Finally extreme situation tests are hardly possible because of the danger of cell damage or thermal runaway.

To overcome the mentioned obstacles this work focuses on the development of thermal substitute cells, which replicate the thermal cell behavior precisely but no longer contain any electrochemical storage function and therefore do not succumb to degradation or thermal runaway. They require no complex equipment, have low safety limitations and enable the possibility of extreme situation investigations. Furthermore, they provide the possibility of flexible design adaptations and are highly available even in early development stages. With these advantages they enable a reduction of development time and costs and help to improve the efficiency and quality of thermal management systems.

In this contribution, the development of the substitute cells as well as their performance to replicate the thermal cell behavior for different operating conditions will be shown. Additional to the simulative comparison between the real battery cell to the substitute cell the replication quality will also be shown with experimental validation based on developed substitute cell prototypes. Furthermore, central aspects of the development process of the substitute cell will be presented as well. This includes the thermal characterization of the chosen battery cell with an in-house methodology. The interaction of inner components and outer boundary conditions is evaluated in simulation studies and the critical heat transfer paths are identified. The possible applications of the developed validation tool “substitute cell” for the design of thermal management systems will be shown as an outlook.