Lithium Difluoro(dioxalato) Phosphate as an Electrolyte Additive for NMC811/Graphite Li-ion Pouch Cells

• Published in: Journal of the Electrochemical Society 2022-11, Vol.169 (11), p.110513
• Main Authors: Song, Wentao, Gauthier, Roby, Taskovic, Tina, Ouyang, Dongxu, Ingham, Harrison A., Eldesoky, Ahmed, Azam, Saad M., Zsoldos, Eniko S., Deng, Zhe, Heino, Dylan H., Geng, Chenxi, Sidebottom, Rowan, Dahn, J. R.
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ac96aa

Lithium difluoro(dioxalato)phosphate (LiDFDOP) has been systemically studied as an electrolyte additive singly and in combination with co-additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) in LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811)/artificial graphite (AG) pouch cells. Long-term cycling tests at room and elevated temperatures (20 °C, 40 °C, and 55 °C) with different upper cutoff voltages (4.06 V and 4.20 V) were performed. These results were combined with ultra-high precision coulometry (UHPC), ex-situ gas measurements, and automatic cell storage tests to reveal multiple aspects of cell performance. A density functional theory (DFT) calculation has also been performed and compared to formation data to reveal the mechanistic aspects of LiDFDOP reduction. Radar plots and a figure-of-merit (FOM) approach were further utilized to summarize results and rank additive and additive combination performance for the NMC811/AG cells. This work highlights an effective additive and suitable co-additives for use in NMC811/graphite cells and gives important insights for future electrolyte additive studies.