期刊
CHEMICAL ENGINEERING JOURNAL
卷 443, 期 -, 页码 -出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2022.136257
关键词
Room temperature sodium-sulfur battery; Covalent-bonded sulfur; Graphene; N-doped carbon matrix; Vapor-infiltration method
资金
- Fundamental Research Funds for the Central Universities [xtr042019013]
- State Key Laboratory of Electrical Insulation and Power Equipment of Xi?an Jiaotong University [EIPE19127, EIPE21203]
- National Natural Science Foundation of China [52077175]
In this study, a novel nitrogen-doped graphene/sulfur cathode material was developed. Sulfur was homogeneously incorporated into the graphene-based host through a vapor-infiltration method, and a polydopamine-derived nitrogen-doped carbon layer was coated to improve the sulfur content. The obtained cathode material showed excellent cycle stability in room temperature sodium-sulfur battery.
Application of emerging room temperature sodium-sulfur (RT Na-S) battery is restrained by the poor conductivity, volume expansion of sulfur cathode and the shuttle effect of soluble polysulfides in electrolytes. Herein, an N-doped two-dimensional (2D) carbon host was derived from the polydopamine coated graphene for sulfur storage. Different from the conventional used melt-diffusion method to integrate sulfur on graphene layer physically, we employed a vapor-infiltration method to realize the homogenous incorporation of sulfur in the graphene-based host via C-Sx-C bond. A polydopamine-derived N-doped carbon layer was further coated on graphene to confine the high-temperature-induced gas-phase sulfur, which effectively increase the covalently bonded sulfur content in the host. Moreover, based on Time-of-Flight Secondary Ion Mass Spectrometry (TOFSIMS) measurement, the C-S bonds are mainly formed beside N-doped carbon, being well explained by the stronger interaction between N-doped carbon and S4 (sulfur vapor) than that of pure carbon from density functional theory (DFT) calculation results. When tested as a cathode for RT Na-S battery, the obtained N-doped graphene/sulfur cathode shows superior cycle stability.
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