Quantum-chemical calculations on borate and aluminate esters have been performed to study the effect of a Lewis acid center on the ion complexation in a poly(ethylene oxide)-based solid electrolyte. The preferred conformations of the investigated model molecules have been determined. Stabilization energies for Li+ and ClO4- ions complexed at the boron or aluminum center have been calculated. The results reveal that the stabilization of the perchlorate ion at the boron center is mainly due to the interactions with CH2 and CH3 groups and suggest much stronger binding of the anion to the aluminum atom.