Facile Preparation of High-Content N-Doped CNT Microspheres for High-Performance Lithium Storage

Herein, high-content N-doped carbon nanotube (CNT) microspheres (HNCMs) are successfully synthesized through simple spray drying and one-step pyrolysis. HNCM possesses a hierarchically porous architecture and high-content N-doping. In particular, HNCM800 (HNCM pyrolyzed at 800 degrees C) shows high nitrogen content of 12.43 at%. The porous structure derived from well-interconnected CNTs not only offers a highly conductive network and blocks diffusion of soluble lithium polysulfides (LiPSs) in physical adsorption, but also allows sufficient sulfur infiltration. The incorporation of N-rich CNTs provides strong chemical immobilization for LiPSs. As a sulfur host for lithium-sulfur batteries, good rate capability and high cycling stability is achieved for HNCM/S cathodes. Particularly, the HNCM800/S cathode delivers a high capacity of 804 mA h g(-1) at 0.5 C after 1000 cycles corresponding to low fading rate (FR) of only 0.011% per cycle. Remarkably, the cathode with high sulfur loading of 6 mg cm(-2) still maintains high cyclic stability (capacity of 555 mA h g(-1) after 1000 cycles, FR 0.038%). Additionally, CNT/Co3O4 microspheres are obtained by the oxidation of CNTs/Co in the air. The as-prepared CNT/Co3O4 microspheres are employed as an anode for lithium-ion batteries and present excellent cycling performance.