The development of Li-ion battery has attracted extensive efforts in the last three decades for its high energy density and long cycle life. The rapid growth of electric vehicle market has a demand for fast charging of Li-ion battery in order to increase the market penetration. The energy density of Li-ion battery has been increased to 225-250 Wh/Kg nowadays thanks to R&D of cell engineering development (mainly increasing electrode thickness). This high energy density ensures longer driving mileage, but also limits the fast charging capability compared to high power Li-ion cells with thinner electrodes.

The relationship between battery energy density, power density and areal capacity in thick electrodes has been studied by Du et al¹. and Gallagher et al². The results suggested that the rate capability is limited by both the Li-ions mass transport in liquid electrolytes and interfacial overpotential in graphite anodes ^2,3. The findings also implied that a significant portion of the available energy in thick electrodes cannot be accessed because of the depletion of Li-ions in the electrolyte phase ¹. Therefore, development of electrolyte that has the capability of fast mass transport in the cell is of great importance for fast charging of high energy density Li-ion cells.

The team at ORNL is developing electrolyte that can enable a fast charging of 15 minute for high energy density Li-ion cells. By developing suitable solvent, salt and additives, the Li ion transport properties can be increased by >20%. We will talk about the result in details during the meeting.

1. Z. Du, D. L. Wood, C. Daniel, S. Kalnaus, and J. Li, J. Appl. Electrochem., 47, 405–415 (2017).
2. K. G. Gallagher et al., J. Electrochem. Soc., 163, A138–A149 (2016).
3. S. Ahmed et al., J. Power Sources, 367, 250–262 (2017).