期刊
ADVANCED SCIENCE
卷 9, 期 3, 页码 -出版社
WILEY
DOI: 10.1002/advs.202104205
关键词
biomimetic catalysts; covalent amide bonds; FeN5 coordination structures; lithium-sulfur batteries; multiple Li-bond networks
资金
- National Natural Science Foundation of China [22109119, 51972238, 21875166]
- Natural Science Foundation of Zhejiang Province [LR18E020001, LQ19B030006]
- Basic Scientific Research Projects of Wenzhou City [G2020002]
- Major Scientific and Technological Innovation Project of Wenzhou City [ZG2021013]
In this study, a biomimetic enzyme catalyst was designed to efficiently convert polysulfides in lithium-sulfur batteries, leading to a high capacity retention even after a large number of cycles. The synergistic mechanism of the catalyst enabled rapid sulfur reaction kinetics, alleviated polysulfide shuttling, and minimal loss of active sites, contributing to the battery's superior performance.
Lithium-sulfur batteries possess high theoretical energy density but suffer from rapid capacity fade due to the shuttling and sluggish conversion of polysulfides. Aiming at these problems, a biomimetic design of cofactor-assisted artificial enzyme catalyst, melamine (MM) crosslinked hemin on carboxylated carbon nanotubes (CNTs) (i.e., [CNTs-MM-hemin]), is presented to efficiently convert polysulfides. The MM cofactors bind with the hemin artificial enzymes and CNT conductive substrates through FeN5 coordination and/or covalent amide bonds to provide high and durable catalytic activity for polysulfide conversions, while pi-pi conjugations between hemin and CNTs and multiple Li-bond networks offered by MM endow the cathode with good electronic/Li+ transmission ability. This synergistic mechanism enables rapid sulfur reaction kinetics, alleviated polysulfide shuttling, and an ultralow (<1.3%) loss of hemin active sites in electrolyte, which is approximate to 60 times lower than those of noncovalent crosslinked samples. As a result, the Li-S battery using [CNTs-MM-hemin] cathode retains a capacity of 571 mAh g(-1) after 900 cycles at 1C with an ultralow capacity decay rate of 0.046% per cycle. Even under raising sulfur loadings up to 7.5 mg cm(-2), the cathode still can steadily run 110 cycles with a capacity retention of 83%.
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