| This manuscript introduces the studies in solid polymer electrolytes and gives the background needed to appreciate the potential benefits of the research conducted thus far. The motivation for developing solid polymer electrolytes came about from the desire of applying lithium metal, the highest of energy density metal, as the anode of batteries in the most efficient and safe manner. A comprehensive matrix of composite Polyethylene oxide-based solid-state electrolytes developed in order to systematically study a number of variables and their impact upon the electrochemical properties of the resulting materials. Solid state NMR characterization was performed to determine lithium diffusion rates. A novel type of poly(ethyleneoxide) (PEO) with a star-shaped architecture has been synthesized and investigated. The higher chain mobility and lower Tg of the star-shaped PEO has been observed to result in slightly higher conductivity compared to the commonly used linear PEO in solid composite polymer electrolytes (CPEs). In an effort to maximize conductivities, a number of plasticizers were incorporated into the CPEs. The results were evaluated using electrochemical impedance spectroscopy (EIS) and differential scanning calorimetry. Single-ion-conducting polymers that can be used in lithium cells have long been sought. Single-ion conductors are preferred to multiple-ion conductors because concentration gradients associated with multiple-ion conduction lead to concentration polarization. Norbornene sufonic acid esters have been synthesized by a ring-opening metathesis polymerization technique, using ruthenium-based catalysts. In addition to solid polymer electrolytes, development of lithium-ion electrolytes containing partially and fully fluorinated carbonate solvents was also investigated. The advantage of using such solvents is that they possess the requisite stability demonstrated by the hydrocarbon-based-carbonates, while also possessing more desirable physical properties imparted by the presence of the fluorine substituents, such as lower melting points, increased stability toward oxidation, and favorable SEI film forming characteristics on carbon. A number of electrochemical techniques were employed (i.e., Tafel polarization measurements, linear polarization measurements, and electrochemical impedance spectroscopy (EIS)) to further characterize the performance of these electrolytes, including the SEI formation characteristics and lithium intercalation/de-intercalation kinetics. |
