Oxygen-doped TiN entrapped in N-doped porous graphitic carbon promotes sulfur cathode kinetics

Abstract

The hybridization of carbon materials with metal compounds is a promising approach for designing advanced composites. However, the standard methodologies are often limited in practical terms by the complicated syn-thetic routes and/or an inability to control the structures of the resulting materials. Herein, we describe a one-pot strategy for synthesizing a N-doped porous graphitic carbon that is hybridized with oxygen-doped titanium nitride (designated O-TiN@N-PGC) and show that the composite displays outstanding chemisorption and electrocatalytic effects in sulfur cathodes. The method employs urea as nitrogen source and thus avoids the use of dangerous and toxic ammonia gas. The unique structure of O-TiN promotes the electrocatalytic conversion of sulfur species found in sulfur cathodes. Li-S cells that are prepared using the O-TiN@N-PGC as a sulfur host exhibit remarkable performance in terms of specific capacity (1408 mA h g-1 at 0.1 C), rate capacity (604 mA h g-1 at 4 C), and cycling stability (513 mA h g-1 after 1000 cycles at 0.5 C). Moreover, an areal capacity of 7.6 mA h cm-2 is achieved under a high sulfur loading of 5.7 mg cm-2. The results establish a facile and efficient strategy for integrating metal nitrides in porous carbons, particularly for use in contemporary energy technologies.