Enhanced Lithium Storage Properties of High Sulfur Doped Hard Carbon Derived from Thiophene-Containing Conjugated Microporous Polymer

The development of hard carbon with high capacity and long cycling stability is a significant issue for lithium ion batteries. Herein, thiophene-containing conjugated microporous polymer (SCMP) was synthesized using 1,3,5-triethynylbenzene 2,5-dibromothiophene by Sonogashira-Hagihara crosscoupling reactions. Then, high sulfur doped hard carbon (SHC) and KOH activated SHC (SHC-K) are prepared by direct carbonization and KOH-assisted carbonization of SCMP, respectively. Both samples were then investigated by SEM, elemental analysis, FTIR, XPS and Nitrogen adsorption/desorption. Taking advantages of sulfur content and abundant porosity, SHC-K delivers a first charge specific capacity of 842.2 mAh g(-1) at 0.1 A g(-1) and a specific charge capacity of 565.9 mAh g(-1) after 500 cycles at 0.6 A g(-1).