Carbon nanotube doped active carbon coated separator for enhanced electrochemical performance of lithium-sulfur batteries

摘要

A thin coating layer composed of carbon nano-tubes (CNTs) and active carbon (AC) was introduced on one side of a pristine Celgard separator toward the cathode. Possessing superior physical adsorption capacity and electrical conductivity, this functional carbon coating can act as a barrier to effectively intercept polysulfides and further improve the utilization of sulfur. This functionality greatly improves rate capability and cycle life. The initial discharge specific capacity of a lithium-sulfur battery with CNT/AC-coated separator could reach 1495.6 mAh g~(-1) at 0.2 C. After 200 discharge/charge cycles, it can still deliver a reversible capacity of as high as 742 mAh g~(-1) with a low fading rate of 0.25% per cycle. When the rate is increased to 1 C, the S cathode can still deliver a discharge capacity of 988.4 mAh g~(-1) and retain the remaining capacity of 718 mAh g~(-1) over 50 cycles.