Benefits of the Mixtures of Ionic Liquid and Organic Electrolytes for Sodium-ion Batteries

Abstract

The successful commercialization of sodium-ion batteries is heavily contingent on the development of suitable electrolytes marked with economic feasibility and stable electrochemical performance. To this end, we present a group of hybrid electrolytes made from the [C₃C₁pyrr][FSA] (C₃C₁pyrr = N-methyl-N-propylpyrrolidinium) ionic liquid (IL) and propylene carbonate organic liquid (OL) electrolytes with Na[FSA] (FSA = bis(fluorosulfonyl)amide) and Na[ClO₄] salts are mixed with exploring the possibilities of cost reduction, high performance and inhibited flammability. The thermal stability tests reveal that the addition of IL can effectively suppress flammability. Herein, the physicochemical and electrochemical properties of the various mixing ratios of the aforementioned hybrid electrolytes (ILOL) are investigated for sodium-ion batteries. Furthermore, full cell tests using hard carbon (HC) negative and NaCrO2 (NCO) positive electrodes using the ILOL systems improve electrochemical performance and enable battery operation at 363 K.