Regulating SEI Components of Sodium Anode via Capturing Organic-Molecule Intermediates in Ester-Based Electrolyte

Xin Li; Pan Xu; Hongbin Ni; Xiaodong Lin; Yajing Wang; Jingmin Fan; Mingsen Zheng; Ruming Yuan; Quanfeng Dong

doi:10.1002/smtd.202300388

Regulating SEI Components of Sodium Anode via Capturing Organic-Molecule Intermediates in Ester-Based Electrolyte

Small Methods. 2023 Oct;7(10):e2300388. doi: 10.1002/smtd.202300388. Epub 2023 Jun 14.

Authors

Xin Li^{1

2}, Pan Xu^{1

2}, Hongbin Ni^{1

2}, Xiaodong Lin^{1

2}, Yajing Wang^{1

2}, Jingmin Fan^{1

2}, Mingsen Zheng^{1

2}, Ruming Yuan^{1

2}, Quanfeng Dong^{1

2}

Affiliations

¹ State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Xiamen University, Engineering Research Centre of Electrochemical Technologies of Ministry of Education, Xiamen, Fujian, 361005, China.
² Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Materials, Xiamen University, Xiamen, 361005, China.

PMID: 37316995
DOI: 10.1002/smtd.202300388

Abstract

Highly reversible sodium metal anodes are still regarded as a stubborn hurdle in ester-based electrolytes due to the issue of uncontrollable dendrites and incredibly unstable interphase. Evidently, a strong protective film on sodium is decisive, while the quality of the protective film is mainly determined by its components. However, it is challenging to actively adjust the expected components. This work can regulate the solid electrolyte interphase (SEI) components by introducing a functional electrolyte additive (2-chloro-1,3-dimethylimidazoline hexafluorophosphate (CDIH, namely CDI⁺ +PF₆ ^- )) into FEC/PC ester-based electrolyte. Specifically, the chloride element in the CDI⁺ can easily react to form a NaF/NaCl-rich SEI together with the decomposition products of FEC; then the CDI⁺ without chlorine as a gripper to capture the organic-molecule intermediates generated during FEC decomposition to greatly reduce the content of unstable organic components in SEI, which can be confirmed by molecular dynamic simulation and experiment. Eventually, a highly reversible Na deposition behavior can be delivered. As expected, under the action of CDIH additives, the Na||Na symmetrical cell performs an excellent long-term cycling (>800 h, 0.5 mA cm^-2 -0.5 mAh cm^-2 ) and rate performance (0.5-4 mA cm^-2 ). Furthermore, the Na||PB full cell exhibits the outstanding electrochemical performance with small polarization.

Keywords: Na metal anodes; SEI components; ester-based electrolytes; organic-molecule intermediates.

Abstract

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