Toward reliable values of electrochemical stability limits for electrolytes

Electrolyte is an indispensable component of any electrochemical cell. Among the properties of an electrolyte, its inertness toward electrochemically induced electronation (reduction at negatively charged electrode) and de-electronation (oxidation at positively charged electrode) has the most direct influence over the operation of the cell. As an ionic conductor in contact with the electrodes at different potentials, electrolyte in most cases is expected to maintain this inertness against both oxidation and reduction while the desired electrochemical process is in progress at the electrodes. The authors scrutinized the conventional practice of measuring an electrolyte stability window. It is shown that misleading values might be generated by this practice. Thus, the authors recommend that to obtain a real stability window, the working electrode material should simulate the electrodes used in a real device. Further, in applications that have a high-surface-area electrode, a new quantification of a stability window is proposed. The electrochemical stability values of various nonaqueous electrolytes that are derived this way should reflect the actual operation limits of these electrolytes in real-life devices.