Lithium-ion batteries (LIBs) has been broadly applied in electric vehicles (EVs) and the market adoption of EVs can be further improved with enhanced fast charging capabilities. The state-of-the-art chemistries, such as LiNi_xMn_yCo_1-x-yO₂ (NMC) and graphite, are capable for fast charging. However, the electrodes are limited to thin coating due to mass transport limitation, which results in low energy density and high cost [1]. For example, the United States Department of Energy (DOE) issued a call for proposal in 2017 to enable extreme fast charging with a target of cell energy density higher than 180 Wh/kg which is much lower than that under normal application.

The energy density of LIBs depends on the materials properties and cell engineering. In this presentation, the impact of cell design on energy density under fast charging will be discussed. Specifically, design in electrodes, current collectors, electrolyte, and separator will be elaborated to show their correlation to fast charging application [2-3].

Acknowledgment

This research at Oak Ridge National Laboratory (ORNL), managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office (VTO) and Advanced Manufacturing Office (AMO).

References

[1] Colclasure, A. M.; Dunlop, A. R.; Trask, S. E.; Polzin, B. J.; Jansen, A. N.; Smith, K. Requirements for Enabling Extreme Fast Charging of High Energy Density Li-Ion Cells while Avoiding Lithium Plating. J. Electrochem. Soc. 2019, 166, A1412-A1424.

[2] Parikh, D.; Christensen, T.; Li, J.; Elucidation of separator effect on energy density of lithium-ion batteries, J. Electrochem. Soc. 2019, 166 (14), A3377.

[3] Parikh, D.; Christensen, T.; Li, J.; Correlating the influence of porosity, tortuosity, and mass loading on the energy density of LiNi_{0. 6}Mn_0.2Co_0.2O₂ cathodes under extreme fast charging (XFC) conditions, Journal of Power Sources, 2020, 474, 228601.