Journal
CHEMICAL ENGINEERING JOURNAL
Volume 415, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2021.129001
Keywords
Li-S batteries; Functional separator; Chemical adsorption; Catalytic conversion; Synergistic effect
Categories
Funding
- National Natural Science Foundation of China-Hong Kong Research Grant Council (NSFC-RGC) Joint Research Scheme [21661162002, N_HKUST601/16]
- National Natural Science Foundation of China [21875071]
- Guangdong key R&D Program of China [2019B090908001]
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The novel Fe3C/Fe@NC/G nanocomposite effectively addresses the sluggish conversion and shuttle effect of soluble polysulfides in lithium-sulfur cells, leading to improved performance. A modified Li-S cell using this functional separator demonstrates high discharge capacity and good cycling stability, especially under high sulfur loading.
The sluggish conversion and severe shuttle effect of soluble polysulfides in lithium-sulfur (Li-S) cells are still the urgent problems for boosting their practical application, although they have been considered as one of the most promising candidates for the advanced energy storage devices in the near future. Herein, a heterostructural Fe3C/Fe@NC/G nanocomposite, in which the Fe3C and Fe nanoparticles are well-embedded in the N-doped porous carbon nanosheets and graphene substrate, is firstly prepared by a novel two-steps temperaturecontrolled calcination, and then it is used to modify the conventional PP separator. The thin Fe3C/Fe@NC/G coating layer can not only effectively block the diffusion of dissolved polysulfides through the physical barrier and chemical binding, but also accelerates the redox conversion of polysulfides as a functional catalyst. As a result, a Li-S cell prepared by this modified separator and a S/KB composite with a high sulfur content of 70 wt% in the final cathode displays high discharge capacity and good cycling capability, with a high specific capacity of - 1489 mAh g-1 at 0.1C and a capacity decline rate of - 0.062% per cycle during 500 cycles at 1.0C, respectively. Furthermore, this functional separator can enable a Li-S cell with a high sulfur areal loading of 5.0 mg cm-2 to perform well, with a high specific capacity of 618 mAh g-1 at 0.1C and a good cycling stability. This facile and effective strategy will provide better insight to develop high-energy Li-S batteries, from the perspective of improvement of kinetics conversion and decrease of shuttle effect of the polysulfides simultaneously.
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