Fluorine-free salts for aqueous lithium-ion and sodium-ion battery electrolytes

A first generation of fluorine-free lithium and sodium salts based on the concept of pseudo-delocalized anions has been synthesized with both high purity and yield using water as the solvent in the reaction medium. The salts have been fully characterized by Raman and FT-IR spectroscopies, thermogravimetry, and X-ray crystallography to reveal both basic properties in terms of thermal stability and solubility as well as the local, mainly ion-ion interaction dictated, coordination details and by ionic conductivity and electrochemical stability window measurements as aqueous electrolytes. Together a picture is created of the salts' promise as components in electrolytes - primarily aiming at application in low voltage fluorine-free aqueous lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs).