All-Solid-State battery pack design: simply exchanging the cells?

Authors

M. Stapelbroek, M. Teuber, A. Averberg, R. Beykirch, A. Neumann - FEV Europe GmbH, M. Demirci - FEV Turkey GmbH, F. Pampel - TME, RWTH Aachen University

Summary

The global trend toward electrification of vehicle powertrains is leading to challenging development targets for battery storage systems. To improve the driving range, the aim is to further increase the energy density. At the same time, the thermal safety behavior must be maintained or even improved. In addition, the power density must also be further increased with a focus on fast charging capability in order to store as much energy as possible for a long driving range in a short time.

A promising future concept is the use of solid-state battery cells in which the electrolyte also acts as a separator. A breakthrough would be the safe and reversible use of lithium metal anodes with inorganic solid electrolytes to enable significantly higher energy densities at the cell level. Other benefits may include improved high power capability, increased thermal stability, and extended cyclic as well as service lifetimes. These are offset by technical challenges such as limited chemical stability relative to other cell components, processing difficulties, and high interfacial resistances. Cell manufacturers aim to meet the targets set by the industry. However, it is not yet clear how the improved cell properties can be exploited on pack level.

In this paper, the properties of current solid state cells (prototypes and near-series cells) are investigated. From the results, challenges for a pack design in terms of swelling, safety, production, and cell temperatures are derived. For example, a larger volume change is to be expected, which must be compensated with a significantly higher compression. In addition, it is not conclusively determined whether the implemented safety mechanisms could be reduced when switching to all solid-state battery cells. Although there is no liquid electrolyte, there is a risk of hydrogen sulfide formation and lithium metal fire....