The Influence of Impurities in Room Temperature Ionic Liquid Electrolyte for Lithium Ion Batteries Containing High Potential Cathode

Abstract

We report the effect of the impurities including water and bromide in the propylmethylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PMPyr-TFSI) on the electrochemical performance of lithium ion batteries. The several kinds of PMPyr-TFSI electrolytes with different amount of impurities are applied as the electrolyte to the cell with the high potential electrode, LiNi0.5Mn1.5O4 spinel. It is found that the impurities in the electrolytes cause the detrimental effect on the cell performance by tracing the cycleability, voltage profile and Coulombic efficiency. Especially, the polarization and Coulombic efficiency go to worse by both impurities of water and bromide, but the cycleability was not highly influenced by bromide impurity unlike the water impurity.