Defect-Rich, Mesoporous Cobalt Sulfide Hexagonal Nanosheets as Superior Sulfur Hosts for High-Rate, Long-Cycle Rechargeable Lithium-Sulfur Batteries

摘要

The performance of lithium-sulfur (Li-S) batteries is strongly limited by the sluggish lithium polysulfides (LiPSs) conversion kinetics and LiPSs shuttling. Herein, mesoporous Co3S4 hexagonal nanosheets with sulfur-atom vacancy defects (Co3S4-DHS) are synthesized via hydrothermally treating the Co-3(VO4)(2) hexagonal nanosheet parent in the presense of Na2S. The sulfur-atom vacancy defects endow Co3S4-DHS with a significantly enhanced electronic conductivity and superior LiPSs adsorbability. Moreover, the abundant mesoporous textures of Co3S4-DHS help to maximize the exposure of catalytically active sites toward LiPSs conversion and buffer the negative effects of large volume fluctuation of loaded sulfur during cycling. Benefiting from these aspects, the Li-S batteries employing Co3S4-DHS/S-based cathodes exhibit a reversible specific capacity of 1090 mA h g(-1) at 0.1 C and 750 mA h g(-1) at 1 C, as well as a high capacity of 699 mA h g(-1) after 400 charge-discharge cycles at 0.1 C, corresponding to a low capacity fade rate of 0.17% per cycle. This work enriches the way to fabricate defect-rich transition metal sulfides as efficient sulfur host materials for high-rate, long-lifespan rechargeable Li-S batteries.