Subnanometer MoP clusters confined in mesoporous carbon (CMK-3) as superior electrocatalytic sulfur hosts for high-performance lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries are promising high-energy–density storage devices but severe shuttling of lithium polysulfides (LPSs), low sulfur utilization and sluggish reaction kinetics impede the practical applications. Herein, we report MoP clusters embedded in CMK-3 (cMoP-CMK-3) as a lightweight, conductive, and catalytic cathodic host with large sulfur mass loading for high energy Li-S batteries. The electronically conductive CMK-3 with ordered mesoporous channels could accommodate high loading and expansion of the active sulfur material and facilitate fast ionic/electronic transportation. The strong interaction between cMoP and CMK-3 results in concentrated Li ions inside the channels due to enhanced local electric field, significantly eliminating dead sulfur and improving sulfur utilization to over 90% due to confined catalytic effect. Moreover, the cMoP embedded into channels provide rich adsorptive and catalytic sites to effectively trap LPSs, and catalytically accelerate reaction kinetics. The resulting S@cMoP-CMK-3 cathode shows a large capacity of 1100 mAh g−1 at 0.5C (1C = 1675 mA g−1) based on the total mass of cathode, high-rate capacity of 767.8 mAh g−1 at 5C, and excellent cycle stability with 0.02% capacity fade per cycle over 500 cycles at 2C. This work demonstrates a confined catalytic strategy to improve the sulfur utilization for high-energy Li-S batteries.