Search

EP-4742287-A1 - SOLID ELECTROLYTIC CAPACITOR AND PRODUCTION METHOD

EP4742287A1EP 4742287 A1EP4742287 A1EP 4742287A1EP-4742287-A1

Abstract

A solid electrolytic capacitor with high withstand voltage while maintaining low equivalent series resistance characteristic, and the manufacturing method thereof are provided. A separator is intervened between the anode body and the cathode body. The separator holds conductive polymer particles and intervenes a layer of the conductive polymer particles between the anode body and the cathode body. The separator contains manila fiber, esparto fiber, or rayon fiber and has the air resistance of 0.35 [s/100mL] or more. This solid electrolytic capacitor is manufactured by an element formation process of forming an element having an anode body having a dielectric film, a cathode body, and a separator by making the anode body and the cathode body to face each other via the separator; and a solid electrolyte layer formation process of impregnating the capacitor element with a conductive polymer dispersion in which conductive polymer particles are dispersed.

Inventors

  • SATO, KENTA
  • SHIN, RYUTARO

Assignees

  • Nippon Chemi-Con Corporation

Dates

Publication Date
20260513
Application Date
20240805

Claims (8)

  1. A solid electrolytic capacitor comprising: an anode body having a dielectric film; a cathode body facing the anode body; a layer of conductive polymer particles intervening between the anode body and the cathode body; and a separator intervening between the anode body and the cathode body and holding the conductive polymer particles, wherein the separator contains a manila fiber, an esparto fiber, or a rayon fiber and has an air resistance of 0.35 [s/100mL] or more.
  2. The solid electrolytic capacitor according to claim 1, wherein the dielectric film of the anode body is a chemical conversion film with a withstand voltage of 300 V or more.
  3. The solid electrolytic capacitor according to claim 1, wherein the dielectric film of the anode body has a thickness of 330 nm or more.
  4. The solid electrolytic capacitor according to claim 1, wherein the separator has the air resistance of 3.3 [s/100mL] or more.
  5. The solid electrolytic capacitor according to any one of claims 1 to 4, containing water of 1 wt% to 15 wt% relative to a total liquid content.
  6. The solid electrolytic capacitor according to any one of claims 1 to 4, further comprising an electrolytic solution, wherein the electrolytic solution contains a withstand voltage improving agent of 15 wt% or more relative to the total amount of the electrolytic solution.
  7. The solid electrolytic capacitor according to any one of claims 1 to 4, wherein a particle size D50 of the conductive polymer particles is 5 to 500 nm.
  8. A manufacturing method of a solid electrolytic capacitor, comprising: an element formation process of forming an element having an anode body having a dielectric film, a cathode body, and a separator by making the anode body and the cathode body to face each other via the separator; and a solid electrolyte layer formation process of forming a solid electrolyte layer between the anode body and the cathode body using a conductive polymer dispersion in which conductive polymer particles are dispersed, wherein the separator contains a manila fiber, an esparto fiber, or a rayon fiber and has an air resistance of 0.35 [s/100mL] or more.

Description

FIELD OF INVENTION The present disclosure relates to a solid electrolytic capacitor and a manufacturing method thereof. BACKGROUND Capacitors are used in various application. For example, in the field of power electronics, power supply circuits, which convert AC power into DC power by converter circuits and convert said DC power into desired AC power by inverter circuits, are provided with smoothing capacitors to suppress pulsation of DC output from the converter circuits, smooth the suppressed DC, and then input the DC to the inverter circuits. Furthermore, for stable operation and noise removal of semi-conductor switching elements such as gallium nitride, decoupling capacitors are provided near said semi-conductor switching elements. Along with a recent trend for higher power consumption, there is a strong demand for capacitors with large capacity. The electrolytic capacitors can easily meet this higher capacity, because it can increase the capacity easier than film capacitors. The electrolytic capacitors include valve metal, such as tantalum or aluminum, as an anode foil and a cathode foil. A surface of the anode foil is enlarged by making the valve metal into a sintered body or a shape such as an etching foil, and the anode foil has a dielectric film by performing treatment such as anode oxidation on the enlarged surface of the anode foil. Electrolytes intervene between the anode foil and the cathode foil. The specific surface area of the electrolytic capacitors can be enlarged by enlarging the surface of the anode foil, which can meet the demand for higher capacitance and large capacity. Among the solid electrolytic capacitors, solid electrolytic capacitors using solid electrolytes are getting attention. The solid electrolytic capacitors have a small size, large capacity, and have lower equivalent series resistance due to high conductivity of the solid electrolytes. Manganese dioxide and 7,7,8,8-tetracyanoquinodimethane (TCNQ) complexes are known as a solid electrolyte. In recent years, conductive polymers derived from monomers having π-conjugated double bonds, such as poly(3,4-ethylenedioxythiophene) (PEDOT) with slow reaction speed and excellent adhesion to the dielectric film, are rapidly becoming popular as a solid electrolyte. In the conductive polymer, acid compounds such as polyanions are used as a dopant, and the conductive polymer has a partial structure acting as a dopant in monomer molecules, exhibiting high conductivity. PRIOR ART DOCUMENT PATENT DOCUMENT Patent Document 1: JP2017-38010A SUMMARY OF INVENTION PROBLEMS TO BE SOLVED BY INVENTION Meanwhile, in the field of power electronics, capacitors with high withstand voltage are expected. For example, smoothing capacitors with the withstand voltage of 250 V are used in inverters for driving motors installed in electric cars. For hybrid-type solid electrolytic capacitors used in such a field of high withstand voltage, the dielectric film with the chemical conversion voltage of 300 V or more must be formed on the anode foil. The present disclosure has been proposed to address the above problems, and an objective is to provide a solid electrolytic capacitor with high withstand voltage while maintaining low equivalent series resistance characteristics, and the manufacturing method thereof. MEANS TO SOLVE THE PROBLEM To address the above problems, a solid electrolytic capacitor of the present embodiment includes: an anode body having a dielectric film; a cathode body facing the anode body; a layer of conductive polymer particles intervening between the anode body and the cathode body; and a separator intervening between the anode body and the cathode body and holding the conductive polymer particles, in which the separator contains a manila fiber, an esparto fiber, or a rayon fiber and has an air resistance of 0.35 [s/100mL] or more. The dielectric film of the anode body may be a chemical conversion film with a withstand voltage of 300 V or more. The dielectric film of the anode body may have a thickness of 330 nm or more. The separator may have the air resistance of 3.3 [s/100mL] or more. The solid electrolytic capacitor may contain water of 1 wt% to 15 wt% relative to a total liquid content. The solid electrolytic capacitor may further include an electrolytic solution, and the electrolytic solution may contain a withstand voltage improving agent of 15 wt% or more relative to the total amount of the electrolytic solution. The solid electrolytic capacitor may further include the electrolytic solution with a solute concentration of 0.08 mol/kg to 0.24 mol/kg. A particle size D50 of the conductive polymer particles may be 5 to 500 nm. To address the above problems, a manufacturing method of a solid electrolytic capacitor of the present embodiment includes: an element formation process of forming an element having an anode body having a dielectric film, a cathode body, and a separator by making the anode body and the cathode body to face each othe