POLYPHOSPHAZENE-BASED SOLID ELECTROLYTES: SYNTHESIS, COMPLEX FORMATION, CONDUCTIVITY, AND ION TRANSPORT (POLYMER, CONDUCTIVITY)

The focus of this thesis is the design, synthesis, and characterization of new phosphazene polymers as solid electrolyte host materials. A series of poly(alkoxy) phosphazenes, NP O(C(,2)H(,4)O)(,x)CH(,3) (,2) (,n) (x = 1, 2, 7, 12, 17; n (GREATERTHEQ) 15,000), were prepared and formed homogeneous complexes with a wide range of salts. The ionic nature of the conductivity was determined by AC complex impedance and DC potentiostatic polarization methods. The results, presented in three chapters, demonstrate that phosphazenes with short-chain polyethers, as sidegroups, are extremely good host materials.; Chapter One describes the wide range of mono-, di-, and trivalent salts which will form solvent-free, amorphous complexes with MEEP (x = 2). Also included is the characterization of the polymer-salt complexes and the effects of different cations, anions, and salt concentrations on the ionic conductivity and physical properties, such as the glass transition temperature.; Chapter Two deals with lithium salt complexes of MEEP, with emphasis on the effects of different anions on ionic conductivity and the relative contributions of the ions to the conductivity (transference numbers).; Chapter Three depicts the effects of varying the sidechain length on the ionic conductivity and physical properties of the polymers.; The phosphazene polymers exhibited ionic conductivities that were 2-3 orders of magnitude better than the corresponding poly(ethylene oxide) complexes at ambient temperatures ((LESSTHEQ) 60(DEGREES)C). Alkali-metal salt complexes were completely amorphous, single phase systems and the parent polymers exhibited chemical, thermal, and electrochemical stabilities desirable for electrolytes in high energy density batteries and other electrochemical devices.