Reversible electrochemical mirror (rem) with improved electrolytic

Abstract

A reversible electrochemical mirror (REM) includes a first electrode and a second electrode, one of which is substantially transparent to at least a portion of the spectrum of electromagnetic radiation. An electrolytic solution, disposed between the first and second electrodes, contains ions of a metal which can electrodeposit on the electrodes. The electrolytic solution also contains halide and/or pseudohalide anions having a total molar concentration ratio of at least 6:1 compared to that of the electrodepositable metal. A negative electrical potential applied to the first electrode causes deposited metal to be dissolved from the second electrode into the electrolytic solution and to be electrodeposited from the solution onto the first electrode to form a mirror deposit, thereby affecting the reflectivity of the REM device for electromagnetic radiation. A positive electrical potential applied to the first electrode causes deposited metal to be dissolved from the first electrode into the solution and electrodeposited from the solution onto the second electrode, thereby decreasing the reflectivity of the REM mirror. It is usually necessary to apply a surface modification layer to the first electrode to ensure uniform nucleation so that a mirror electrodeposit having high reflectivity is obtained. The high molar concentration ratio of halide and/or pseudohalide anions to electrodepositable metal ions in the electrolyte provides the inherent electrolyte stability, high deposit quality, good deposit erasure and long cycle life needed for practical applications.