Performance of a hydrogen uranyl phosphate—carbon double-layer solid capacitor

Abstract
A mixture of commercially available carbon black powders and hydrogen uranyl phosphate (HUP) precipitate can be used as the electrode material for miniaturized double‐layer capacitors. A solid cell of C‐HUP‖HUP‖C‐HUP has a capacitance of 1 F which, given the device area and thickness of 0.8 cm2 and 0.2 cm respectively, corresponds to an energy density of more than 5 J/cm3. The charge×voltage factor is higher than 5×106 s and the working voltage is over 1.6 V. The leakage current is lower than 3 μA at room temperature. The electrolyte can be operated up to about 120 °C if the device is hermetically sealed.