Fluoroethylene Carbonate-Based Electrolyte with 1 M Sodium Bis(fluorosulfonyl)imide Enables High-Performance Sodium Metal Electrodes

Yongwon Lee; Jaegi Lee; Jeongmin Lee; Koeun Kim; Aming Cha; Sujin Kang; Taeung Wi; Seok Ju Kang; Hyun-Wook Lee; Nam-Soon Choi

doi:10.1021/acsami.8b02446

Fluoroethylene Carbonate-Based Electrolyte with 1 M Sodium Bis(fluorosulfonyl)imide Enables High-Performance Sodium Metal Electrodes

ACS Appl Mater Interfaces. 2018 May 2;10(17):15270-15280. doi: 10.1021/acsami.8b02446. Epub 2018 Apr 23.

Authors

Affiliation

¹ School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Ulsan 44919 , Republic of Korea.

PMID: 29648435
DOI: 10.1021/acsami.8b02446

Abstract

Sodium (Na) metal anodes with stable electrochemical cycling have attracted widespread attention because of their highest specific capacity and lowest potential among anode materials for Na batteries. The main challenges associated with Na metal anodes are dendritic formation and the low density of deposited Na during electrochemical plating. Here, we demonstrate a fluoroethylene carbonate (FEC)-based electrolyte with 1 M sodium bis(fluorosulfonyl)imide (NaFSI) salt for the stable and dense deposition of the Na metal during electrochemical cycling. The novel electrolyte combination developed here circumvents the dendritic Na deposition that is one of the primary concerns for battery safety and constructs the uniform ionic interlayer achieving highly reversible Na plating/stripping reactions. The FEC-NaFSI constructs the mechanically strong and ion-permeable interlayer containing NaF and ionic compounds such as Na₂CO₃ and sodium alkylcarbonates.

Keywords: fluoroethylene carbonate; in situ differential electrochemical mass spectrometry; in situ optical microscopy; interface; sodium metal electrode.