Toward Safer Energy Storage Solution by Development of Fluorine-Free Battery Electrolyte

Abstract: Portable electronic devices such as mobile phones, laptops, cameras and electronic vehicles (EVs) which contain lithium-ion batteries (LIBs), are indispensable part of our modern society. The safety of conventional electrolytes of LIBs, composed of fluorinated lithium salts and organic solvents is the source of some concerns. While the former is meta-stable at room temperature, quite expensive to synthesis and unsafe in the presence of moisture, the latter have high vapor pressure and are also flammable. Therefore, development of more stable salts and electrolytes are highly desirable, especially in the light of increased use of battery technology in e.g. electric vehicles (EVs).In order to mitigate the challenges with current fluorine containing electrolytes, we set out to develop a new class of safer, fluorine-free anions based on the concept of pseudo-delocalized Mickey MouseTM anions. Their Lithium and sodium salts have been synthesized for the first time, and fully characterized by different analytical methods such as NMR, mass spectroscopy and elemental analysis. Thermogravimetry analysis and X-ray crystallography were conducted to reveal both basic properties in terms of thermal stability and solubility of the salts. To further assess their properties as electrolytes, ion conductivity and electrochemical stability windows (ESWs) were performed.