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In this thesis， as mentioned above， the area of electrolytes is chosen．Different components of solid and liquid electrolyte systems and their advantages and disadvantages will be discussed． The major focus of the work is to develop a better electrolyte system for rechargeable lithium batteries．
In lithium-ion battery chemistry， the important issues for SPE systems are associated with the polymer matrix． Although PEO is undoubtedly the best system still on hand for the base matrix in SPEs， the high crystallinity of PEO matrix is clearly not suitable for ambient temperature ionic conductivity at the desired level． On the way to overcome this difficulty， a series of novel lithium salts were synthesized and incorporated into a conventional PEO based SPE system， include three novel NPLS and four novel fluorinated dilithium salts with low lattice energy， and excellent thermal stability was presented．The ionic conductivity of these PEO-based SPEs was observed noteworthy，due to the decrease in the glass transition temperature of the polymer． These jobs are shown in Chapters 2 and 3．
Another main problem of the current liquid electrolyte system is the safe concern due to the existing of volatile and flammable organic carbonates， and poor low-temperature performance． A novel electrolyte solvent system should present an excellent ionic conductivity without volatile solvents． Varieties of non-volatile polar solvents with very low freezing point should be designed and studied for the liquid electrolyte systems． The approach involves the strategic design and synthesis of a series of RTILs to address the PSS problem． i） TFSI-based ILs are non-flammable， ease of synthesis， excellent thermal stability， but in general， cannot dissolve enough lithium salt （typically ＜ 0. 5M） to form the relatively high concentration． ii） DCA-based ILs have much lower viscosity than TFSI-based ILs and tend to display much better ionic conductivity， by using DCA as the counter anion for the ILs． DCA anion is usually unusable for LIB applications （4V electrochemical window）， but can perhaps be used for LSB as a result of the much lower operating voltage． iii） Asymmetric fluoro-based RTILs may exhibit good ionic conductivity， excellent electrochemical ＆ thermal stabilities， but need further measurements． Higher lithium ion density， excellent thermal property， and lower cost will demand the development of new RTILs． This area is discussed in Chapters 4 ＆5．
Thus， the goal of this thesis will be to create new electrolyte systems，which would meet the demands of automotive manufacturers， leading to the commercial production of rechargeable lithium batteries．