화학공학소재연구정보센터
Electrochimica Acta, Vol.47, No.28, 4433-4440, 2002
Poly(ethylene oxide)-LiX rubbery electrolytes with X--X-disulfonamide anions having two or three ether groups in their structures
This work deals with poly(ethylene oxide), PEO-MX (M=Li, K and Cs) amorphous electrolytes with X--X-, [CF3SO2NCH2(CH2OCH2)(2)CH2NSO2CF3](2-) (EDSA) and [CF3SO2NCH2CH2(CH2OCH2)(3)CH2CH2NSO2CF3](2-) (TTSA) disulfonamide anions. These dianions have X- end-groups identical to anions [CF3SO2N(CH2)(2)OCH3](_) (MESA) and [CF3SO2N(CH2)(3)OCH3](_) (MPSA), one of which (MPSA) was reported to yield chelate-like associated species (presumably LiX2- triplets) at concentrations above EO/Li = 20 in PEO. This feature of LiMPSA, evidenced through glass transition temperature (T,) measurements, does not apply to Li(2)EDSA and Li(2)TTSA. Though none of these lithium salts form crystalline intermediate compounds with PEO, the limit of solubility of LiMESA (EO/Li = 16) does not allow a clarification of this point for this salt. At lower concentrations, however, a conductivity comparison with the potassium and caesium salts shows that the apparent degree of dissociation (alpha = C-Li+/C-Li) of LiMESA is comparable to that of LiMPSA. As opposed to both these salts and to some extent to Li(2)EDSA, a much greater dissociation takes place for Li(2)TTSA, the anion of which contains an inner, third ether group in its structure.