How Cell Design Affects the Aging Behavior: Comparing Electrode-Individual Aging Processes of High-Energy and High-Power Lithium-Ion Batteries Using High Precision Coulometry

Abstract

The aging behavior of lithium-ion batteries is crucial for the development of electric vehicles and many other battery-powered devices. The cells can be generally classified into two types: high-energy (HE) and high-power (HP) cells. The cell type used depends on the field of application. As these cells differ in their electrical behavior, this work investigates whether both cell types also show different aging behavior. More precisely, the occurring capacity loss and internal side reactions are analyzed via the charge throughput. For comparison, aging tests are carried out with a high-precision battery tester, allowing the application of High Precision Coulometry (HPC). This enables early detection of aging effects and also allows us to break down the capacity loss into electrode-individual processes. A total of two sub-studies are performed: (1) a cyclic study focusing on lithium plating; and (2) an accelerated calendar aging study. It is found that HE cells exhibit stronger cyclic aging effects (lithium plating) and HP cells exhibit stronger calendar aging effects. The higher lithium plating can be explained by the higher diffusion resistance of the lithium ions within the electrodes of HE Cell. The higher calendar aging fits to the larger electrode surfaces of the HP cell. These results give deep insights into the proceeding aging in a novel way and are interesting for the selection of the appropriate cell type in the context of battery development. In a next step, the measured capacity losses could also be used for a simple parameterization of battery aging models.

Keywords

• electrode specific aging effects
• high precision coulometry
• high-energy cell
• high-power cell