Email: fengs [at] mit . edu
Designing stable electrolyte materials for Lithium-air battery
Lithium-oxygen (Li-O2) batteries offer great potential in transportation applications due to their high theoretical specific energies, with a tenfold increase over the state-of-the-art Li-ion batteries. Currently, the practical development of rechargeable aprotic Li-O2 batteries is hindered by a number of challenges, amongst which electrolyte instability has been recognized by many researchers as the most challenging impediment. Several families of organic solvents, polymers, and ionic liquids have been evaluated as electrolyte candidates for Li-O2 batteries, but none are stable against the oxygen electrode in Li-O2 batteries. To develop Li-O2 batteries with long cycle life, organic electrolytes that are stable against oxygen and oxygen reduction products in a basic and oxidizing environment are needed. We developed a comprehensive framework for the assessment of chemical and electrochemical oxidative stability of organic molecules in the oxygen electrode of typical aprotic Li-O2 batteries. We applied this framework to a library of organic molecules, including solvents and sulfonimide salts. A number of chemically stable molecules with promising electrochemical stability were identified, from which we obtained valuable structure-property relationships that will guide the design of stable organic electrolytes for aprotic Li-O2 batteries.