Optimization of Nonaqueous Electrolytes for Primary Lithium/Air Batteries Operated in Ambient Environment

The selection and optimization of nonaqueous electrolytes for ambient operations of lithium/air batteries have been studied. Organic solvents with a low volatility and low moisture absorption are necessary to minimize the change in electrolyte compositions and the reaction between lithium anode and water during the discharge process. It is also critical to make the electrolyte with a high polarity so that it can reduce wetting and flooding of the carbon-based air electrode and lead to improved battery performance. For ambient operations, the polarity of solvents outweighs the viscosity, ion conductivity, and oxygen solubility once these latter properties attain a certain reasonable level. Hence, a propylene carbonate/ethylene carbonate (PC/EC) mixture is the most feasible solvent system and lithium bis(trifluoromethanesulfonyl)imide the best salt for ambient operations of Li/air batteries, whose performance is relatively insensitive to PC/EC ratio and salt concentration. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3168564] All rights reserved.