ABSTRACTRechargeable electrical energy storage cells, especially lithium-ion cells, are the critical technology that realized the great... Show moreABSTRACTRechargeable electrical energy storage cells, especially lithium-ion cells, are the critical technology that realized the great development of the portable electronic devices, such as laptop computers and cell phones. But in some other areas, such as the renewable energy industries and electrical vehicles, which are developing fast and more and more important for environment protection, the current rechargeable energy storage cells cannot meet their requirements, because of their limited energy density.Two types of cells, lithium sulfur batteries (LSBs) and supercapacitors, are attracting peoples’ attention for their potential to be developed as the future high-energy-density rechargeable cells. However, Li-S batteries are suffering from the fast discharging capacity fading, which is still a barrier for the large-scale commercialization. Although supercapacitors have been widely used in various areas, their energy density is much lower than current lithium-ion batteries, which limited their application only in assistant systems, such as regenerative brakes.To solve these problems, novel design for both the electrode material and electrolytes are required. In this thesis work, we focused our study in four areas: (1) New electrolytes for LSBs; (2) Cathode material for LSBs; (3) Activated carbon electrodes for electrical double layer capacitors (EDLCs); and (4) Electrolyte formulations for EDLCs. We investigated three types of new compounds as a co-solvent for the electrolyte of LSBs: fluorinated ethers, fluoroether sulfones and sulfonium ILs, which have improved the discharging capacity and cycling stability of LSBs. A novel S@HCN@MnO2 cathode material was designed and synthesized, which performed excellent long-term performance. A novel porous AC material with very high SSA was synthesized, and EDLCs with new electrolyte formulations were tested, which showed wide electrochemical potential window and high energy density. Show less
