| This dissertation describes new electrolyte systems designed, synthesized and developed for applications in lithium-ion batteries.;With the increasingly needs for creating new clean and sustainable energy sources to substitute traditional fossil fuel at present, the improvements of energy storage devices like lithium-ion batteries have shown the significance in this strategy. As a necessary and important component in a battery system, the varieties of electrolytes need to be expanded according to the cell's requirements for application and usage of electrodes materials. Especially nowadays, researches for safe, environmentally benign and cost effective battery electrolyte systems are very challenging and active all around the world.;This work presents our efforts in developing better electrolytes for both solid and liquid systems. For a solid electrolyte system, two new amorphous PEO based solvent free polymer electrolytes were synthesized and characterized by functionalization of a commercially available epichlorohydrin-ethylene oxide copolymer. To further improve their room temperature ionic conductivities, which were about 10--6 magnitude with the obtained solvent free polymer electrolyte membrane materials, a cross-linked gelled system was designed and prepared. The obtained gel membrane electrolyte materials were tested with ionic conductivity of 1.826x10-3 S/cm, comparable to the commercialized liquid counterparts. This type of gel membrane materials' morphology, electrochemical windows, cycling properties and thermal stabilities were also determined through SEM, Solartron electrochemical analyzer and TGA/DSC etc. Meanwhile, a series of tri-lithium salts and a poly-lithium salt used as dissociable lithium ion sources in lithium-ion batteries were designed and prepared through facile routes. These unusual non-fluorinated salts offer the potential for significant cost savings over the current battery standard, while exhibiting superior performance characteristics, including ionic conductivities as high as 2.86x10--3S/cm, electrochemical stabilities from OV to > 4.5V, good solubilities in DMF, DMSO, and sulfolane, and compatibility to standard Li-ion cell electrode materials. Very good thermostability, measured by TGA and DSC, is also observed. Furthermore, some future plans of studies in lithium-ion battery electrolyte field were also discussed. |
