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

Abstract 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 5.5 V (vs. Li + /Li). In particular, this F‐electrolyte has good compatibility with graphite anodes. Mesocarbon microbeads/LiNi 0.5 Mn 1.5 O 4 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 4.9 V, confirming their potential as high‐voltage lithium‐ion batteries with enhanced safety and longevity.