Reactivity of Electrolytes for Lithium-Oxygen Batteries with Li2O2

The stability of electrolytes is a significant limitation for cycle life performance in Li-O-2 batteries. Since Li2O2 is generated at the cathode surface during cycling, an investigation of the thermal stability of common electrolytes with Li2O2 was conducted. All of the solvents investigated, including ethylene carbonate (EC), propylene carbonate (PC), dialkyl carbonates, dimethoxyethane (DME), tetraethylene glycol dimethyl ether, and acetonitrile, have good thermal stability in the presence of Li2O2. Many salts, including LiBF4, lithium bis(oxalaoto)borate (LiBOB), and lithium Bis(trifluoromethanesulfonyl)imide (LiTFSI), also have good stability in the presence of Li2O2. However, LiPF6 reacts rapidly with Li2O2 to generate OPF2OLi and LiF. (c) 2012 The Electrochemical Society. All rights reserved.