The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composite has been synthesized by heating a mixture of elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure. The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature. It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test. The initial discharge specific capacity was 1180.8 mAh g-1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li2S. The specific capacity still kept as high as 720.4 mAh g^-1 after 60 cycles retaining 61% of the initial discharge capacity.
Feng WuSheng Xian WuRen Jie ChenShi ChenGuo Qing Wang
Composite polymer electrolytes based on mixing soft-segment waterborne polyurethane （WPU） and 1-butyl-3-methylimidazolium bis[（trifluoromethyl）sulfonyl]imide （BMImTFSI） have been prepared and characterized. The addition of BMImTFSI results in an increase of the ionic conductivity. At high BMImTFSI concentration （BMImTFSI/WPU = 3 in weight ratio）, the ionic conductivity reaches 4.27 × 10^-3 S/cm at 30 ℃. These composite polymer electrolytes exhibit good thermal and electrochemical stability, which are high enough to be applied in lithium batteries.
The mixing soft-segment WPU （waterborne polyurethane） polymer electrolytes were synthesized by using PEO （poly（ethylene oxide）） and PDMS （polydimethylsiloxane） as the soft segments. These polymer electrolytes exhibit good thermal and electrochemical stabilit）＇. The conductivity of the gel polymer electrolyte is 2.52 × 10^-3 S/cm at 25 ℃ with the LiTFSI/（DMC ＋ EC） content of 130%.
