5V-Class Electrolytes Based on Fluorinated Solvents for Li-Ion Batteries with Excellent Cyclability

A novel electrochemically compatible, high-voltage, and nonflammable electrolyte has been prepared based on a fluorinated ether with no flash point, that is, 1,1,1,3,3,3-hexafluoroisopropyl methyl ether (HFPM). Our experimental results demonstrate that this F-electrolyte is not only totally nonflammable in fire burning tests, but it also exhibits a remarkably high anodic stability of at least 5.5V (vs. Li+/Li). In particular, this F-electrolyte has good compatibility with graphite anodes. Mesocarbon microbeads/LiNi0.5Mn1.5O4 18650 batteries made with this F-electrolyte display an excellent cycling stability with 82% capacity retention after 200 cycles at a high cutoff voltage of 4.9V, confirming their potential as high-voltage lithium-ion batteries with enhanced safety and longevity.