US 12,266,483 B2
Cathode and electrolytic capacitor
Kazuhiro Nagahara, Tokyo (JP); Tatsuru Hatae, Kanagawa (JP); Kazuya Koseki, Kanagawa (JP); Atsushi Yoshida, Fukushima (JP); and Makoto Tominaga, Fukushima (JP)
Assigned to Nippon Chemi-Con Corporation, Tokyo (JP)
Appl. No. 17/765,427
Filed by Nippon Chemi-Con Corporation, Tokyo (JP)
PCT Filed Sep. 29, 2021, PCT No. PCT/JP2021/035889
§ 371(c)(1), (2) Date Mar. 30, 2022,
PCT Pub. No. WO2022/071403, PCT Pub. Date Apr. 7, 2022.
Claims priority of application No. 2020-165933 (JP), filed on Sep. 30, 2020.
Prior Publication US 2022/0367122 A1, Nov. 17, 2022
Int. Cl. H01G 9/055 (2006.01); H01G 9/035 (2006.01); H01G 9/042 (2006.01); H01G 9/145 (2006.01)
CPC H01G 9/055 (2013.01) [H01G 9/035 (2013.01); H01G 9/0425 (2013.01); H01G 9/145 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A cathode of an electrolytic capacitor which has only electrolyte solution as an electrolyte, comprising:
a cathode foil formed of aluminum;
an enlarged surface layer and oxide film formed on the cathode foil; and
a conductive layer formed on a surface of the cathode foil, the conductive layer being a deposition from a slurry having entered into the enlarged surface layer and including carbon black as carbon material, a binder, and a solvent, and being free of activated carbon,
wherein:
the conductive layer has a configuration such that when current in a range of current density of leakage current of the electrolytic capacitor flows by electrochemical polarization, and when a reference electrolyte solution of the electrolytic capacitor includes ethylene glycol and azelaic acid, and does not include a nitro compound, the cathode potential corresponding to said current is higher than the natural immersion potential of a reference cathode foil formed of aluminum with a purity of 99.9% by 0.3 V or more,
a polarization curve by the electrochemical polarization has a first potential range in which current produced by cathode reaction which reduces dissolved oxygen in the reference electrolyte solution is larger than current produced by cathode reaction which reduces hydrogen ions, and a second potential range in which the current produced by cathode reaction which reduces dissolved oxygen in the reference electrolyte solution is smaller than the current produced by cathode reaction which reduces hydrogen ions, and
in the polarization curve, the range of the current density of the leakage current of the electrolytic capacitor corresponds to the first potential range in which the current produced by cathode reaction which reduces dissolved oxygen in the reference electrolyte solution is larger than current produced by cathode reaction which reduces hydrogen ions.