A method for producing an electrolytic capacitor, the electrolytic capacitor including a capacitor element including an anode body and a cathode body each having a foil shape. The anode body includes a dielectric layer on a surface of the anode body. The method includes a step of forming a capacitor element precursor by winding or stacking a separator, the anode body, and the cathode body with the separator interposed between the anode body and the cathode body, a step of impregnating the capacitor element precursor with a treatment liquid containing a polyhydric alcohol, a solvent, and a conductive polymer component, a step of impregnating the capacitor element precursor with a liquid component after the step of impregnating the capacitor element precursor with the treatment liquid, and a step of forming the capacitor element by eluting the polyhydric alcohol into the liquid component.

An electrolytic solution for an electrolytic capacitor contains: an electrolytic solution additive for an electrolytic capacitor (B) containing a polymer (A) that has a (meth)acrylic monomer (a) as an essential component; an organic solvent (C) having a hydroxyl group concentration higher than 10 mmol/g; and an electrolyte (D), the electrolytic solution for an electrolytic capacitor being characterized in that the content of a (meth)acrylic monomer having a hydroxyl group (a1) is 60-100 wt % of the total monomers constituting the polymer (A).

An electrolytic solution for an electrolytic capacitor contains: an electrolytic solution additive for an electrolytic capacitor (B) containing a polymer (A) that has a (meth)acrylic monomer (a) as an essential component; an organic solvent (C) having a hydroxyl group concentration higher than 10 mmol/g; and an electrolyte (D), the electrolytic solution for an electrolytic capacitor being characterized in that the content of a (meth)acrylic monomer having a hydroxyl group (a1) is 60-100 wt % of the total monomers constituting the polymer (A).

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%.

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%.

A capacitive coupler provides high coupling capacitance through the use of an electrolyte and insulator formed as an oxide layer on at least one plate of the coupler. The coupler can be independent or provide a hydrodynamic or hydrostatic bearing as well as capacitive coupling, and the circulated dielectric can provide for cooling of associated machinery.

An electrolytic capacitor includes a capacitor element. The capacitor element includes an electrode group including an anode body, a cathode body, a separator, and an electrolyte layer. The anode body and the cathode body each has a foil shape. The anode body has a dielectric layer on a surface of the anode body. The electrolyte layer is in contact with the anode body, the cathode body, and the separator. The electrolyte layer contains a conductive polymer and a hydroxyl group-containing compound having a melting point of 50° C. or higher. The hydroxyl group-containing compound is at least one compound selected from the group consisting of a sugar and a polyhydric alcohol. The hydroxyl group-containing compound is unevenly distributed more in a peripheral portion of the capacitor element than in a central portion of the capacitor element.

An electrolytic capacitor includes a capacitor element. The capacitor element includes an electrode group including an anode body, a cathode body, a separator, and an electrolyte layer. The anode body and the cathode body each has a foil shape. The anode body has a dielectric layer on a surface of the anode body. The electrolyte layer is in contact with the anode body, the cathode body, and the separator. The electrolyte layer contains a conductive polymer and a hydroxyl group-containing compound having a melting point of 50° C. or higher. The hydroxyl group-containing compound is at least one compound selected from the group consisting of a sugar and a polyhydric alcohol. The hydroxyl group-containing compound is unevenly distributed more in a peripheral portion of the capacitor element than in a central portion of the capacitor element.

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.