Ordered Dual-Channel carbon embedded with molybdenum nitride catalytically induced High-Performance Lithium-Sulfur battery

Abstract

• MoN@CMK-5 with a bimodal pore was employed as polar host for sulfur cathode. • MoN@CMK-5/S shows an excellent inhibition effect for LiPSs. • The electrochemical reaction kinetics is effectively enhanced. • MoN@CMK-5/S delivers superior durability and a high charge capacity. Lithium-sulfur batteries (LSBs) have attracted considerable research attention because of their high theoretical capacity and energy density, low cost and environmental friendliness. However, the shuttle effect of lithium polysulfides hinders the commercialization of LSBs. Effectively improving the electrochemical reaction kinetics of the sulfur cathode still represents a significant challenge. Here, a MoN@CMK-5 composite with a bimodal pore system was designed to electrocatalytically mediate Li/S conversion chemistry. MoN@CMK-5 presents a large specific surface area (1012 m 2 g −1 ) and two sets of tunnels with pore sizes of 3.63 and 3.47 nm, which efficiently adsorb polysulfides and accelerate the mass transfer of electrolytes. Furthermore, MoN has high intrinsic catalytic activity and enables the rapid conversion of polysulfides. Owing to the synergistic “adsorption-conversion-mass transfer” effect, the electrochemical reaction kinetics are effectively enhanced. Consequently, the MoN@CMK-5/S electrode achieves excellent performance with an initial capacity of 1582 mAh g −1 at 0.1C and retains a reversible capacity of 658.4 mAh g −1 after 200 cycles at 1C. The cathode delivers a specific capacity of 475.8 mAh g −1 at a high current density of 5C, with a capacity decay as low as 0.027% per cycle during 1000 cycles. In addition, theoretical calculations reveal that MoN@CMK-5/S exhibits low activation energy for Li 2 S decomposition and effectively inhibits the shuttling of polysulfides. This work provides a new avenue for the development of high-performance LSBs.