Representing polyether-salt systems by chains of interacting coordination shells, each of which defined by a cation and by its nearest ligands (ether-oxygens and eventually anions), the interaction potential between a given coordination shell and all the others closest to it-the inter-shells potential-is derived in terms of two-electron polarization effects. Values are presented for crystalline monovalent-based poly(ethylene oxide), PEO , complexes, while for non-crystalline divalent electrolytes only an upper limit is estimated. For the eutectic concentration of PEO/Eu3+ electrolytes, the inter-shells energy epsilon is also evaluated by relating the;empirical value of the nearest-ligands local-field potential with the variation of Eu3+ concentration. The value obtained by this procedure was epsilon = 554.2 cm(-1), while by the two-electron polarization potential they were epsilon = 520.3 cm(-1) for 10 nearest oxygens and epsilon = 572.4 cm(-1), for 11 oxygens, for a mean radius of the first coordination shell (R) over bar=2.4 Angstrom and a minimum distance between nearest shells R-0=5.3 Angstrom. This last method also permits the determination of the number of Eu3+-nearest oxygens.