New Tailored Sodium Salts for Battery Applications

Abstract

This article describes synthesis and basic electrochemical and structural properties of newly designed sodium salts for application in liquid nonaqueous sodium electrolytes. There has been two imidazole fluorine derivative sodium salts synthesized: sodium 4,5-dicyano-2-(trifluoromethyl)­imidazolate (NaTDI) and sodium 4,5-dicyano-2-(pentafluoroethyl)­imidazolate (NaPDI). The structure of the salts has been confirmed by means of Raman spectroscopy, nuclear magnetic resonance (¹³C NMR and ¹⁹F NMR), X-ray diffraction, thermogravimetry (TGA), and differential scanning calorimetry (DSC). Electrochemical characterization included ionic conductivity measurements, dynamic viscosity, and electrochemical stability of solutions of the salts in propylene carbonate (PC) at different temperatures. Raman spectra of the electrolytes have been performed to carefully monitor the degree of ionic associations specially ion pairing tendencies