Abstract: A lithium or lithium alloy cathode, instead of the cathode foils of commercial electrolytic capacitors, can substantially increase the volumetric energy density of a valve metal/metal oxide capacitor. The capacitors exhibit a voltage capability unexpectedly higher than the voltage supported by the anode alone. This unexpected advantage is achieved by constructing a capacitor including (1) a negative electrode comprising lithium or a lithium alloy; (2) a positive electrode comprising a relatively high surface area valve metal having a relatively thin oxide surface film; (3) a separator material disposed between the positive and negative electrodes to physically separate the electrodes and capable of allowing the passage of ions through the material between the electrodes and (4) an organic, non-aqueous electrolyte containing lithium ions and compatible with both electrodes.

Abstract: An electrical capacitor is described which comprises a housing, a pair of electrodes in said housing, one of said electrodes being composed of a mixture of carbon particles and an electrolyte and the other electrode being composed of a mixture of lead metal and the same electrolyte, and an ionically conductive separator means between and in contact with said pair of electrodes, electronically separating said electrodes from each other, wherein the electrolyte comprises an acidic solution of soluble sulfate salts.

Abstract: A method of etching aluminum by applying an alternating electric current to aluminum which is in contact with an electrolyte containing hydrochloric acid, in which the alternating current has a symmetrical waveform wherein the current rises rapidly from zero to a maximum, then subsequently decreases rapidly in a first stage to an intermediate value which is about one-third to about one-half of the maximum, and thereafter decreases more slowly to zero in a second stage. Thereafter the current rises and falls in the opposite direction with the same waveform. The ratio of time of the second stage to time of the first stage of the waveform is in the range from 1 to 6. By this procedure higher capacitance values of the etched aluminum are obtained in comparison to prior procedures.

Abstract: An electrolytic capacitor containing a novel electrolyte comprising solute selected from ammonium pentaborate and its mixture with boric acid and solvent comprising ethylene glycol, at least one ketone selected from 2,4-pentanedione, 2,4-hexanedione, 5-hydroxy-2-pentanone, and cyclohexanone, and their mixtures with other polar organic solvents. The electrolyte may also contain added water.

Abstract: An electrolyte composition for electrolytic capacitors consisting essentially of a salt of a slilcotungstatic or silicomolybdic acid in a polar organic solvent and having a pH of from about 5.0 to about 7.2; and a capacitor containing said composition.