Conductive bridging effect of TiN nanoparticles on the electrochemical performance of TiN@CNT-S composite cathode

Improving the reaction kinetics of cathode and preventing the dissolution of polysulfides are two of the key strategies of developing the high-performance lithium-sulfur (Li-S) batteries. Herein, we propose a multi-porous conductive architecture through bridging conductive TiN nanoparticle over the surface of CNT-S composite. The as-prepared TiN@CNT-S composite cathode delivers the superior initial specific capacity of 1269 mAh g−1 at 0.05C and as high as 586 mAh g−1 at 2C. The reversible capacity of the TiN@CNT-S composite cathode is about two times higher than the bare cathode without TiN conductive bridging at 1C over 400 cycles. A high areal capacity of 4.0 mAh cm−2 was realized for the TiN@CNT-S composite cathode with a high areal sulfur loading of 5.4 mg cm−2 at a current rate of 0.5C over 50 cycles. The enhancements in the electrochemical performances are mainly ascribed to the TiN bridged highly conductive structure; the formation of the strong chemical interaction of S-N-Ti bond for polysulfides trapping provided by the chemically polar TiN, which is verified by the ultraviolet visible (UV) spectra and X-ray photoelectron spectroscopy (XPS) analyses.