Robust electrical highway network for high mass loading sulfur cathode

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 1421 mA h g(-1), excellent rate performance of 750 mA h g(-1) at 2 C and 465 mA h g(-1) at 5 C, and a capacity fading rate as low as 0.037% per cycle at 2 C for 1400 cycles. At high areal sulfur loading up to 10.2 mg cm(-2), the cathode retains a high areal capacity of 5.43 mA h cm(-2) after 150 cycles at a high current rate (1 C). A large areal cathode (77 x 50 mm(2)) with sulfur loading of 8.5 mg cm(-2) delivers a record-high capacity of 9.04 mA h cm(-2) at 0.1 C, demonstrating its great potential for practical application in Li/S batteries.