폴리설파이드 용출을 억제할 수 있는 이중 층 구조의 탄소-황 양극을 이용한 리튬-황 전지의 성능향상 연구

Abstract

Li-S batteries have many advantages such as high theoretical capacity, high energy density and abundant of sulfur. However, commercialization of Li-S batteries has been impeded because of low loading amount of active materials and poor cycle performance. Herein, we report a free-standing bilayer carbon-sulfur (FBCS) electrode with superior electrochemical performance at high sulfur loading level (3 mg cm-2). Top part of the FBCS cathode is composed of interlacing multiwall carbon nanotube (MWCNT) and bottom part is made up of mixed layer, MWCNT including sulfur and N-doped porous carbon (NPC). MWCNT layer (top part of FBCS cathode) blocks polysulfide dissolution from cathode to anode and, NPC in bottom part of FBCS cathode not only provides spacious active site but also absorbs polysulfide by the functional group of nitrogen. The novel designed FBCS cathode delivered a high initial discharge capacity of 963.6 and 900.0 mAh g-1 at 0.5 and 1 C, respectively. Also, it displays excellent cycle retention of 83.1% at 0.5 C and 83.4% at 1 C after 300 cycles.