Cycle aging and physico-chemical characterization of commercial cells of automotive interest
2022-01-0324
03/29/2022
- Event
- Content
- Nowadays, the reduction of greenhouse gases and air pollutants, largely produced by vehicles with internal combustion engines, is of primary importance. The usage of energy storage systems could represent a smart opportunity for cleaner transportation. Lithium ion batteries have emerged as the most suitable technology available on the market to reach this challenging goal. To make Li-ion battery technologies a competitive solution for the automotive industry, costs, performances and safety must be improved. A deep understanding of Li-ion battery materials and their response under real-use conditions is mandatory to achieve these targets. From a full characterization of the electrochemical performances, it is possible to specifically design the charge and discharge conditions for maximizing the battery performances while optimizing its life. In this study the thorough characterization of commercial 18650 cells is carried out over their full life. First, the fresh cells have been characterized in their capacity and internal resistance. To gain understanding on the chemistry and material composition the cells have been torn down. The characterization of the electrodes, separator and electrolyte, applying techniques such as SEM, XRF, XRD, GC and IC, provides a wide panorama of the physico-chemical behaviour. In order to simulate real driving conditions, a set of cells has been aged in such a way as to reproduce the stress the battery pack will experience during its life. The experiments are performed by means of WTLC (Worldwide Harmonized Light Vehicles Test Cycle)-based profiles and by applying various charging, driving conditions, and ambient temperatures in order to trigger different aging phenomena in the cells. At end of life the teardown of the aged cells is exploited for the detection of aging effects on electrodes, electrolytes and other components. This allows to gain a deep understanding of the degradation phenomena occuring during the cell life at laboratory scale and in the vehicle.
- Citation
- Dotoli, M., Rocca, R., Giuliano, M., Sgroi, M. et al., "Cycle aging and physico-chemical characterization of commercial cells of automotive interest," SAE Technical Paper 2022-01-0324, 2022, .