COMPOSITE POLYETHER BASED SOLID ELECTROLYTES - THE LEWIS ACID-BASE APPROACH

The conductivity and phase structure of several composite polyether-al kali metal salt solid electrolytes are analysed and discussed. Species containing Lewis acid centres (AlCl3), Lewis base centres (poly(N,N d imethylacrylamide) as well as those of amphoteric Lewis acid-base char acter (alpha-Al2O3) are used as fillers. It is suggested that the comp etition between the Lewis base ether oxygens in the polyether chains a nd filler Lewis base centres in the complexation of alkali metal catio ns leads to the formation of different types of complexes and therefor e to the modification of the polymer electrolyte ultrastructure. On th e other hand acidic centres on the fillers compete with the Lewis acid metal cations in the formation of complexes with the polyether chain. The final ultrastructure and conductivity of composite electrolytes d epends on the equilibrium of these Lewis acid-base reactions.