Lithium-ion batteries have become essential energy storage systems in contemporary society, driving a diverse range of applications that span from portable electronics to electric vehicles. As reliance on these batteries grows, understanding and optimizing their performance becomes critically important. This study explores the effects of external pressure on the efficiency of high-capacity commercial pouch NMC/G lithium-ion cells, a chemistry that is often employed in automotive and industrial settings. We examine these effects in a pristine and in an aged battery cell, understanding the change in the performance along its lifetime.

Our research employs a comprehensive experimental approach to investigate how external pressure interacts with battery degradation, with a focus on characterizing both electrical performance and mechanical properties. We consider different pressure levels alongside varying states of charge (SOC), thereby simulating real-world scenarios such as the stacking of batteries within packs and the mechanical stresses experienced during operation.

The results indicate that external pressure is a significant factor that must be considered during the characterization of lithium-ion cells. Notably, we observed distinct variations in cell’s electrical characteristics when the external pressure changes. Furthermore, the mechanical properties of the lithium-ion cells exhibited variations dependent on both SOH and SOC, as reduction of reversible swelling with the degradation, and a stiffer mechanical response with high SOC, attributed to microstructural changes occurring within the cell over time.

This study highlights the need to account for external pressure effects when characterizing lithium-ion cells, as these factors are necessary to accurately understand battery performance. The insights obtained from this research are valuable for enhancing methodologies related to lithium-ion battery characterization and for improving the accuracy of the predictions of the behavior of lithium-ion batteries. Ultimately, this research contributes to the advancement of lithium-ion technology, bringing us closer to more reliable and efficient energy storage solutions for our increasingly electrified world.