Abstract
The rational design of advanced catalysts for sodium-sulfur (Na-S) batteries is important but remains challenging due to the limited understanding of sulfur catalytic mechanisms. Here, we propose an efficient sulfur host consisting of atomic low-coordinated Zn-N2 sites dispersed on N-rich microporous graphene (Zn-N2@NG), which realizes state-of-the-art sodium-storage performance with a high sulfur content of 66 wt %, high-rate capability (467 mA h g-1 at 5 A g-1), and long cycling stability for 6500 cycles with an ultralow capacity decay rate of 0.0062% per cycle. Ex situ methods combined with theoretical calculations demonstrate the superior bidirectional catalysis of Zn-N2 sites on sulfur conversion (S8 ↔ Na2S). Furthermore, in situ transmission electron microscopy was applied to visualize the microscopic S redox evolution under the catalysis of Zn-N2 sites without liquid electrolytes. During the sodiation process, both surface S nanoparticles and S molecules in the mircopores of Zn-N2@NG quickly convert into Na2S nanograins. During the following desodiation process, only a small part of the above Na2S can be oxidized into Na2Sx. These results reveal that, without liquid electrolytes, Na2S is difficult to be decomposed even with the assistance of Zn-N2 sites. This conclusion emphasizes the critical role of liquid electrolytes in the catalytic oxidation of Na2S, which was usually ignored by previous works.
Original language | English |
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Pages (from-to) | 26650-26659 |
Number of pages | 10 |
Journal | ACS Applied Materials and Interfaces |
Volume | 15 |
Issue number | 22 |
DOIs | |
State | Published - Jun 7 2023 |
Externally published | Yes |
Funding
This research/project is supported by the Ministry of Education, Singapore, under its SUTD Kickstarter Initiative (SKI 2021_02_16). S. Huang gratefully acknowledges financial support from the National Natural Science Foundation of China (22109183).
Funders | Funder number |
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Ministry of Education - Singapore | SKI 2021_02_16 |
National Natural Science Foundation of China | 22109183 |
Keywords
- Zn single atom
- bidirectional catalysis
- low-coordination number
- sodium−sulfur batteries