A cathode and an electrolytic capacitor including the cathode which can suppress production of hydrogen gas are provided. The cathode of the electrolytic capacitor includes cathode foil formed of valve action metal and a conductive layer formed on a surface of the cathode foil. A natural immersion potential of the cathode foil when immersed in an electrolyte solution is at a higher side than a natural immersion potential of reference cathode foil formed of the valve action metal with purity of 99.9%.

An electrolytic capacitor includes an anode body having a dielectric layer; a solid electrolyte layer in contact with the dielectric layer of the anode body; and an electrolytic solution. The electrolytic solution contains a solvent and a solute. The solvent contains a glycol compound. The solute contains an acid component and a base component. A mass of the acid component in the solute is greater than a mass of the base component in the solute. The acid component contains a first aromatic compound having a hydroxyl group.

An electrolytic capacitor includes an anode body having a dielectric layer; a solid electrolyte layer in contact with the dielectric layer of the anode body; and an electrolytic solution. The electrolytic solution contains a solvent and a solute. The solvent contains a glycol compound. The solute contains an acid component and a base component. A mass of the acid component in the solute is greater than a mass of the base component in the solute. The acid component contains a first aromatic compound having a hydroxyl group.

A cathode and an electrolytic capacitor including the cathode which can suppress production of hydrogen gas are provided. The cathode of the electrolytic capacitor comprising cathode foil formed of valve action metal, and a conductive layer formed on a surface of the cathode foil. When current in a range of current density of leakage current of the electrolytic capacitor flows by electrochemical polarization, potential corresponding to said current is at a higher side than a natural immersion potential of reference cathode foil formed of the valve action metal with purity of 99.9%.

A cathode and an electrolytic capacitor including the cathode which can suppress production of hydrogen gas are provided. The cathode of the electrolytic capacitor comprising cathode foil formed of valve action metal, and a conductive layer formed on a surface of the cathode foil. When current in a range of current density of leakage current of the electrolytic capacitor flows by electrochemical polarization, potential corresponding to said current is at a higher side than a natural immersion potential of reference cathode foil formed of the valve action metal with purity of 99.9%.

A method for manufacturing an electrolytic capacitor includes a first connection step, a second connection step, a first insertion step, a housing step, and a sealing step. In the first connection step, a first internal lead having a foil shape is connected to a first electrode foil. In the second connection step, after the first connection step, a first external lead having a rod shape is connected to the first internal lead to obtain the first electrode. In the first insertion step, the first external lead is inserted into an insertion port of a sealing plate after the second connection step. In the housing step, the first electrode is housed in a container after the first insertion step. In the sealing step, an opening of the container is closed with the sealing plate after the housing step.

A method for manufacturing an electrolytic capacitor includes a first connection step, a second connection step, a first insertion step, a housing step, and a sealing step. In the first connection step, a first internal lead having a foil shape is connected to a first electrode foil. In the second connection step, after the first connection step, a first external lead having a rod shape is connected to the first internal lead to obtain the first electrode. In the first insertion step, the first external lead is inserted into an insertion port of a sealing plate after the second connection step. In the housing step, the first electrode is housed in a container after the first insertion step. In the sealing step, an opening of the container is closed with the sealing plate after the housing step.

A composite electrode foil roll for manufacturing an electrolytic capacitor, including: bands of electrode foils; strips of an isolating material positioned along a width of the composite electrode foil roll at a plurality of locations. The plurality of locations are at equal distances and correspond to a length of an inner cavity of a case of the electrolytic capacitor. The bands of electrode foils and strips of an isolating material are alternating. A method of manufacturing the composite electrode foil roll including alternating bands of electrode foils and strips of an isolating material. The strips are positioned along a width of the composite electrode foil roll at repeated locations. The repeated locations are at equal distances corresponding to a length of an inner cavity of a case of the electrolytic capacitor.

A composite electrode foil roll for manufacturing an electrolytic capacitor, including: bands of electrode foils; strips of an isolating material positioned along a width of the composite electrode foil roll at a plurality of locations. The plurality of locations are at equal distances and correspond to a length of an inner cavity of a case of the electrolytic capacitor. The bands of electrode foils and strips of an isolating material are alternating. A method of manufacturing the composite electrode foil roll including alternating bands of electrode foils and strips of an isolating material. The strips are positioned along a width of the composite electrode foil roll at repeated locations. The repeated locations are at equal distances corresponding to a length of an inner cavity of a case of the electrolytic capacitor.

Provided is a solid electrolytic capacitor having large capacitance, low ESR, and superior high-frequency characteristics and high-temperature endurance. The solid electrolytic capacitor is provided with: a cathode 10 having a cathode substrate 11 made of a valve metal and having an etching pit 11a; an oxide layer 12 made of an oxide of the valve metal provided on a surface of the cathode substrate 11, and a carbon coating layer 13 provided on a surface of the oxide layer 12, the carbon coating layer 13 including carbon particles and having an entry area 13a that enters the etching pit 11a and a penetration area 13b that penetrates through the oxide layer 12 and conducts with the cathode substrate 11; an anode having an anode substrate made of a valve metal, and a dielectric layer provided on a surface of the anode substrate and made of an oxide of the valve metal that composes the anode substrate; and a solid electrolyte layer including a conductive polymer provided between the carbon coating layer of the cathode and the dielectric layer of the anode.