TiN synergetic with micro-/mesoporous carbon for enhanced performance lithium–sulfur batteries

Porous carbon has high specific area and total pore volume but weak interaction with dissolved polysulfides. Conductive polar metal compound has strong chemical adsorption of polysulfides but difficult to attain high porosity to encapsulate sulfur series. Instead of efforts on the cathode, we prepared a composite made up of titanium nitride and three-dimensional micro-/mesoporous carbon by a facile and economic way. This composite was coated on the commercial Celgard separator as a polysulfide interceptor to enhance the performances of lithium – sulfur battery. The strategy exerts the synergetic merits of porosity, chemical adsorption, physical interception, and benign conductivity. The hierarchical carbon possesses a high specific surface area of 1571 m 2 /g and total pore volume of 1.56 cm 3 /g with the pore size centered at 1.27 and 5.30 nm. TiN can immobilize sulfur intermediates by strong chemical interaction. In addition, excellent electrical conductivity of TiN facilitates redox kinetics. The pure sulfur cathode with the modified separator delivers high initial capacity of 1130 mAh/g at 1 C (1 C = 1675 mAh/g) and retains 500 mAh/g after 400 cycles, demonstrating superior cycling stability, rate capabilities. Discharge-charge profiles, electrochemical impedance spectrum, and cyclic voltammetry curves of batteries were investigated to support the prominent electrochemistry of the material. Further analysis and observation on the modified separator disassembled from the coin cells after cycling were conducted to probe the evolution and reaction mechanism of the coating.