Chitosan as a functional additive for high-performance lithium–sulfur batteries

Chitosan with abundant hydroxyl and amine groups as an additive for cathodes and separators has been proven to be an effective polysulfide trapping agent in lithium–sulfur batteries. Compared with common sulfur cathodes, the cathode with chitosan shows an enhanced initial discharge capacity from 950 to 1145 mA h g−1 at C/10. The reversible specific capacity after 100 cycles increases from 508 mA h g−1 to 680 mA h g−1 and 473 to 646 mA h g−1 at rates of C/2 and 1 C, respectively. In addition, batteries with separators that are coated with a carbon/chitosan layer can exhibit a high discharge capacity of 830 mA h g−1 at C/2 after 100 cycles and 675 mA h g−1 at 1 C after 200 cycles with the capacity fading to as low as 0.11% per cycle. This study demonstrates the benefits of using chitosan for not only lithium–sulfur batteries but also potentially other sulfur-based battery applications.