Crystalline-amorphous heterostructure on the phosphatized P-CoS2/CNT for augmenting the catalytic conversion kinetics of Li-S batteries

Abstract

Crystalline-amorphous heterostructure catalyst is employed to conquer the notorious shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) intermediates of lithium-sulfur (Li-S) batteries. Herein, crystalline-amorphous heterostructure on the phosphatized cobalt disulfide/carbon nanotube (designated as P-CoS2/CNT) are served as the functional interlayer for Li-S batteries. Crystalline-amorphous heterostructure of P-CoS2/CNT is composed of high crystalline CoS2 core and amorphous Co(PO3)2 (a-Co(PO3)2) shell along with abundant active Co-O-P bonds. The crystalline CoS2 core and grain boundary defects on the heterostructure can prop up the well-pleasing electron conductivity when a-Co(PO3)2 accelerates the catalytic conversion kinetics of the polysulfides through the comprehensive survey in terms of chemical anchoring capability, nucleation barrier for Li2S, In-situ Raman for monitoring the shuttle case of polysulfides, and the analysis of inactive sulfur species on Li anode. In consequence, the Li-S battery using the P-CoS2/CNT functional separator delivers an outstanding low-capacity decay of only 0.048 % per cycle for 1000 cycles at 2C, and the LiPSs's shuttle effect is efficaciously restrained. Even with a high sulfur loading of 3.6 mg cm−2, the cell still maintains an outstanding areal capacity of 1.75 mAh cm−2 after 200 cycles at 1C. This work develops a scalable crystalline-amorphous heterostructure strategy using the conventional heteroatom modulation in aspire of accurately guiding the high-efficiency electrocatalyst served for the Li-S electrochemistry.