Robust electrical “highway” network for high mass loading sulfur cathode

Abstract

High performance cathode with sufficiently high areal sulfur loading is still a major challenge for practical Li/S batteries. Herein, we propose a 3D nanocarbon architecture with robust electrical “highway” network for high sulfur mass loading and efficient sulfur utilization. The structure is constructed by “welding” highly conductive nitrogen-doped graphene (NG) and nitrogen-doped carbon nanotubes (NCNT) together through in-situ polymeric crosslinking and nitrogen-doped carbon shell (NCS) formation. The highly sulfur-absorptive NCS provides strong physical and chemical confinements to sulfur and polysulfides, which is confirmed by in-situ Raman and electrochemical analysis. At a moderate sulfur loading, the NG-NCNT@NCS@S cathode exhibits a high initial discharge capacity of 1421mAhg−1, excellent rate performance of 750mAhg−1 at 2C and 465mAhg−1 at 5C, and a capacity fading rate as low as 0.037% per cycle at 2C for 1400 cycles. At high areal sulfur loading up to 10.2mgcm−2, the cathode retains a high areal capacity of 5.43mAhcm−2 after 150 cycles at a high current rate (1C). A large areal cathode (77 × 50mm2) with sulfur loading of 8.5mgcm−2 delivers a record-high capacity of 9.04mAhcm−2 at 0.1C, demonstrating its great potential for practical application in Li/S batteries.