Electrochemical Capacitors Based on Sol-Gel Derived, Ionically Conducting Composite Solid Electrolytes

Electrochemical capacitors have been devised using hybrid electrolytes containing either lithium or magnesium salt and high-density graphite (HDG) electrodes. The cells exhibit single-electrode discharge capacitance of 355 $\mu$ $F/cm^2$ at $1\hspace{2mm} mA/cm^2$ discharge rate for magnesium-containing ormolytes at 80°C. Typical response times have been calculated to be of the order of 0.28 s for magnesium ion and 0.73 s for lithium ion containing ormolytes. A typical coin-type cell exhibits excellent cyclability of more than $10^3$ cycles at a discharge current density of $1\hspace{2mm}mA/cm^2$.