(Invited) New Electrolyte Solvents and Additives Designed for Li Ion and Beyond Chemistries

Ever since the birth of Li ion chemistry, carbonate esters have been the main solvents used as the skeleton composition of the electrolytes. This class of polar organic compounds, ethylene carbonate in particular, brings both their merits of supporting reversible intercalation of Li+ at electrodes of potential differences as wide as 4.2 V, and their intrinsic limits of narrow temperature range, chemical reactivity toward conducting salts, and inflammability. Numerous efforts were made during the past decades in an attempt to replace these carbonate, either partially or entirely, but little change has occurred as the result.

The emergence of new chemistries such as the high voltage (>4.5 V) cathode intercalation materials and the beyond-Li-ion concepts −− most of which resort to conversion-reaction concepts to maximize the specific capacities −− presents unprecedented challenges to these carbonate esters that have been widely used by Li-ion industry, and activities resumed in seeking new alternatives. This presentation will summarize our recent efforts of designing, synthesizing and characterizing such new electrolyte solvents in both high voltage and Li-ion as well as beyond-Li-ion chemistries.