Impedance studies on poly(ethylene oxide)-Cu(CF3SO3)2-sulfolane solid electrolyte
Abstract The ionic conductivity of a solid polymer electrolyte based on copper(II) trifluoromethanesulfonate dissolved in poly(ethylene oxide) (PEO) was significantly improved by addition of a non-volatile solvent sulfolane (tetramethylene sulfone, TMS). The bulk conductivity of (PEO) 15 Cu(CF 3 SO 3 ) 2 thin-film electrolyte can be increased from ∼10 −5 Ω −1 cm −1 at ambient temperature to almost 5×10 −4 Ω −1 cm −1 for (PEO) 15 Cu(CF 3 SO 3 ) 2 TMS 20wt.% composite electrolyte. The charge transfer resistance of a Cu|electrolyte|Cu symmetrical cell decreases after addition of the solvent from ∼2.9 kΩ cm 2 (at ambient temperature) to ∼0.2 kΩ cm 2 . The activation energy of ionic conductivity obtained from ln σ= f ( T −1 ) plot was 98.9 kJ mol −1 for the (PEO) 15 Cu(CF 3 SO 3 ) 2 and 79.5 kJ mol −1 for the (PEO) 15 Cu(CF 3 SO 3 ) 2 TMS 20wt.% electrolyte.