Development of new pyrazole-based lithium salts for battery applications – Do established basic design concepts really work?

Abstract This work is focused on applying structural concepts and basic chemical principles to model two N -heterocyclic lithium salts, based on trifluoromethyl substituted pyrazolide anions. An easily upscalable preparation method without difficult purification steps was also developed. In a comparative study, the physicochemical properties of the two new lithium salts were investigated, particularly the effect of an additional BF 3 -group at the nitrogen atom. In comparison to non-substituted lithium pyrazolide, the BF 3 -addition led to a strong improvement of thermal and electrochemical stability, ionic conductivity, as well as better C-rate and cycling performance. Furthermore, the anodic stability of Al current collectors was investigated and compared to commercial lithium salts, namely LiPF 6 and lithium bis((trifluoromethyl)sulfonyl)imide (LiTFSI). Possible mechanisms that lead to the presented improvements are discussed. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]