Promoting polysulfide conversion by catalytic ternary Fe3O4/carbon/graphene composites with ordered microchannels for ultrahigh-rate lithium–sulfur batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (43), p.25078-25087
• Main Authors: Ding, Meng, Huang, Shaozhuan, Wang, Ye, Hu, Junping, Mei Er Pam, Fan, Shuang, Shi, Yumeng, Ge, Qi, Yang, Hui Ying
• Format: Article
• Language: English
• Subjects: Aerogels; Anchoring; Batteries; Carbon; Catalytic converters; Conversion; Crystals; Density functional theory; Energy storage; Graphene; Iron oxides; Kinetics; Lithium; Lithium sulfur batteries; Microchannels; Nanocrystals; Organic chemistry; Polysulfides; Reaction kinetics; Storage batteries; Sulfur; X-ray diffraction
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta06489c

As a promising energy storage system, lithium–sulfur (Li–S) batteries are attracting increasing attention but still limited by the sluggish reaction kinetics and shuttle effect caused by the dissolution of lithium polysulfides. Herein, a significant improvement of conversion kinetics and areal sulfur loading is achieved using an ordered microchannel graphene scaffold with incorporated catalytic Fe3O4 nanocrystals and porous carbon as a multifunctional sulfur host. The synergy between the polar catalytic Fe3O4 nanocrystals and porous carbon frameworks enables a strong polysulfide anchoring effect and a fast polysulfide conversion rate. Thus, the 3D ternary Fe3O4/porous carbon/graphene aerogel demonstrates an ultrahigh rate performance of 755 mA h g−1 at 3C and a high areal capacity of 6.24 mA h cm−2 at a sulfur loading of 7.7 mg cm−2. Moreover, the promoted reaction kinetics and reliable cyclability are revealed by the visible evolution of polysulfides using in situ X-ray diffraction (XRD), and the enhanced chemical anchoring of polysulfides is disclosed by density functional theory (DFT) calculations. This work provides a promising approach to develop multifunctional ordered porous aerogels with metal oxide nanocrystals for high-performance Li–S batteries, especially those which suffer from low sulfur loading and inferior rate performance.