Larger cations can move faster in solid polymer electrolytes
Abstract Poly[(ω-carboxy)-oligo(oxyethylene)methacrylate] alkali metal salts (P(CME n M)s) are synthesized as solid polymer electrolytes which can transfer only cations. The conductivity of a series of alkali metal ions such as Li + , Na + , K + , Rb + , and Cs + is measured, and the results are summarized with the reduced temperature ( T - T g: T g= glass transition temperature ) to neutralize the effect of segmental motion on the relative conductivity. They show a linear relation between the logarithm of conductivity at T - T g=60° C and the logarithm of radius of the carrier cations. The ion-dipole interaction is suggested to be the most effective factor to control the mobility in the solid polymer electrolytes. Cations having larger ionic radius such as Rb + or Cs + are suggested to have weaker interaction force with ether oxygens, reflecting the faster ion exchange between possible adjacent sites in the polymer matrix.