Compatibility of LiMn2O4 cathode with electrolyte based on low-viscosity ether-functionalized pyrazolium ionic liquid

One new ether-functionalized ionic liquid (IL) composed of pyrazolium cation with one 2-ethoxyethyl group and bis(trifluoromethylsulfonyl)imide anion was synthesized and characterized. The IL showed the lowest viscosity among all the reported pyrazolium ILs, and the value was 38.9 mPa s at room temperature. The conductivity of the IL was 3.48 mS cm(-1) at 25 A degrees C, and its electrochemical window was 4.4 V. Cycling performance of symmetric lithium cell was investigated for the IL electrolyte with 0.6 mol kg(-1) of LiTFSI. Li/LiMn2O4 cell using the IL electrolyte owned good cycling and rate performances, and it was found for the first time that LiMn2O4 cathode was compatible with electrolyte based on ether-functionalized IL. By the characterizations of X-ray diffraction and scanning electron microscopy for fresh and cycled LiMn2O4 electrodes, it was inferred that the slow dissolution of LiMn2O4 in the IL electrolyte might happen during the charge-discharge processes.