Investigation of the Roles of Functional Solvents in Performance Stability of High Voltage Lithium Batteries

Abstract

Li-ion batteries (LIBs) have become prevalent for portable and large-scale applications, such as personal electronic devices, unmanned aircraft systems, electric vehicles, and power grids.1 However, LIBs are approaching an asymptotic limit in specific energy (~250 Wh kg-1 at cell level); therefore, they are insufficient to meet future applications that require higher battery specific energies.2 Ni-rich cathodes, such as LiNi0.8Co0.1Mn0.1O2 (NMC811), have the potential to provide much higher specific energies for next-generation LIBs (e.g., >350 Wh kg-1) and, therefore, are considered the most promising low-cost cathode materials.3 Nevertheless, Ni-rich cathode based LIBs with conventional carbonate solvent based electrolytes face severe technical challenges, especially when cycled at high upper cutoff voltages, due to electrolyte decomposition, parasitic oxidation reactions at the electrolyte/cathode interface, irreversible phase changes in the cathodes, and dissolution of transition metals into electrolytes.4 Therefore, R&D efforts are needed to tackle the above technical challenges of Ni-rich cathode based LIBs before they become commercially viable.In our previous study,5 a ternary of fluorinated solvents was used to formulate a high voltage stable electrolyte (HVE) which was used in Ni-rich cathode based, high-voltage lithium batteries. These HVE-based batteries demonstrated a significant improvement in cycle stability when operated at a charge cutoff voltage of 4.5 V (vs Li/Li+). In this study, we investigated the roles of single-solvents and co-solvents in the cycle stability of the high-voltage lithium batteries. Several families of organic solvents, such as fluorinated carbonates and organosilicon based solvents were investigated. Our preliminary data showed that some unique combinations of the functional solvents could lead to exceptionally stable cycle performance in the high-voltage lithium batteries. We will discuss possible fundamental mechanisms responsible for the observed performance stability of the high-voltage lithium batteries using ex-situ XPS, density functional theory calculations, and other characterization techniques. References (1) Li, J.; Fleetwood, J.; Hawley, W. B.; Kays, W. From materials to cell: state-of-the-art and prospective technologies for lithium-ion battery electrode processing. Chemical Reviews 2021, 122 (1), 903-956.(2) Khan, F. N. U.; Rasul, M. G.; Sayem, A.; Mandal, N. K. Design and optimization of lithium-ion battery as an efficient energy storage device for electric vehicles: A comprehensive review. Journal of Energy Storage 2023, 71, 108033.(3) Xue, W.; Huang, M.; Li, Y.; Zhu, Y. G.; Gao, R.; Xiao, X.; Zhang, W.; Li, S.; Xu, G.; Yu, Y. Ultra-high-voltage Ni-rich layered cathodes in practical Li metal batteries enabled by a sulfonamide-based electrolyte. Nature Energy 2021, 6 (5), 495-505.(4) Yang, J.; Liang, X.; Ryu, H.-H.; Yoon, C. S.; Sun, Y.-K. Ni-Rich Layered Cathodes for Lithium-Ion Batteries: From Challenges to the Future. Energy Storage Materials 2023, 102969.(5) Poches, C.; Razzaq, A. A.; Studer, H.; Ogilvie, R.; Lama, B.; Paudel, T. R.; Li, X.; Pupek, K.; Xing, W. Fluorinated High-Voltage Electrolytes To Stabilize Nickel-Rich Lithium Batteries. ACS Applied Materials & Interfaces 2023, 15 (37), 43648-43655. Acknowledgement This work was supported by the following funding sources. The Larry and Linda Pearson Endowed Chair at the Department of Mechanical Engineering, South Dakoda School of Mines and Technology. The Naval Air Warfare Center Weapons Division, China Lake, CA under Contract No N6893622C0017. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Naval Air Warfare Center Weapons Division, China Lake, CA. TP acknowledges the support from the SDBOR Governor Research Center for the Electrochemical Energy Storage and NASA EPSCOR-80NSSC23M0072.