All-temperature batteries enabled by fluorinated electrolytes with non- polar solvents

XL Fan and X Ji and L Chen and J Chen and T Deng and FD Han and J Yue and N Piao and RX Wang and XQ Zhou and XZ Xiao and LX Chen and CS Wang, NATURE ENERGY, 4, 882-890 (2019).

DOI: 10.1038/s41560-019-0474-3

Carbonate electrolytes are commonly used in commercial non-aqueous Li- ion batteries. However, the high affinity between the solvents and the ions and high flammability of the carbonate electrolytes limits the battery operation temperature window to -20 to + 50 degrees C and the voltage window to 0.0 to 4.3 V. Here, we tame the affinity between solvents and Li ions by dissolving fluorinated electrolytes into highly fluorinated non-polar solvents. In addition to their non-flammable characteristic, our electrolytes enable high electrochemical stability in a wide voltage window of 0.0 to 5.6 V, and high ionic conductivities in a wide temperature range from -125 to + 70 degrees C. We show that between -95 and + 70 degrees C, the electrolytes enable LiNi0.8Co0.15Al0.05O2 cathodes to achieve high Coulombic efficiencies of >99.9%, and the aggressive Li anodes and the high-voltage (5.4 V) LiCoMnO4 to achieve Coulombic efficiencies of >99.4% and 99%, respectively. Even at -85 degrees C, the LiNi0.8Co0.15Al0.05O2 parallel to Li battery can still deliver similar to 50% of its room-temperature capacity.

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