In-situ fabrication of dense structure nitrogen-doped carbon nanotube embedded Co/Co2P accelerating the electrochemical kinetics of lithium-sulfur battery

Abstract

Accelerating the sluggish electrochemical kinetics of polysulfide conversion using electrocatalysis is an effective strategy to enhance the electrochemical performance of lithium-sulfur (Li-S) battery. A rational catalyst needs to maximize its ability to capture and catalyze the polysulfide. Herein, we report a novel catalyst that exhibits a network structure of dense nitrogen-doped carbon nanotube (CNT) embedded with Co/Co2P. The dense nitrogen-doped CNT plays the role of “tentacles” to capture and confine the polysulfide via physical and chemical interactions, and the embedded Co/Co2P that wrapped by the dense CNT acts as an electrocatalyst to catalyze the sulfur redox. As a result, the Li-S battery using Co/Co2P@N-CNT modified separator can deliver a capacity of 1405 mAh g−1 at 0.1C. It can also maintain a capacity of 647 mAh g−1 after 500 cycles, with a very low decay rate of 0.07% per cycle at 1C. Importantly, a high reversible areal capacity of 3.2 mAh cm−2 can be obtained over 60 cycles, even under a raised sulfur content of 4.8 mg cm−2. This work provides a deep understanding of the architecture design of a highly efficient electrocatalyst for high-performance Li-S battery.