JP-2026075339-A - Electric double-layer capacitor and method for manufacturing the same

Abstract

[Problem] To provide an electric double-layer capacitor with a long lifespan while suppressing deterioration of its aerodynamic characteristics, and a method for manufacturing the same. [Solution] The electric double-layer capacitor comprises a capacitor element in which an electrolyte is impregnated into polarizable electrodes, a case for housing the capacitor element, and a sealing body for sealing the case. The electrolyte contains sulfolane or γ-butyrolactone. The sealing body has a permeability coefficient of N2 gas of 3.42 × 10⁻¹⁰ [cc・cm/( cm² ・s・cmHg)] of 2 to 6 times, and a permeability coefficient of He gas of 2.751 × 10⁻¹⁰ [cc・cm/( cm² ・s・cmHg)] of 1.1 to 2.5 times. The electric double-layer capacitor includes an element formation step of impregnating the polarizable electrodes with this electrolyte to form a capacitor element, a sealing body formation step of forming the sealing body, and a sealing step of housing the capacitor element in the case and sealing the case with the sealing body. [Selection Diagram] None

Inventors

• 義原 千花歩
• 菅野 正輝
• ▲高▼橋 文子
• 高橋 秀明

Assignees

• 日本ケミコン株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (3)

1. A capacitor element in which an electrolyte is impregnated into a polarity electrode, A case for housing the aforementioned capacitor element, A sealing body for sealing the aforementioned case, Equipped with, The electrolyte contains sulfones or lactones, The sealing body has a permeability coefficient for N2 gas of 3.429 × 10⁻¹⁰ [cc・cm/( cm² ・s・cmHg)] that is 2 times or more and 6 times or less, and a permeability coefficient for He gas of 2.751 × 10⁻⁹ [cc・cm/( cm² ・s・cmHg)] that is 1.1 times or more and 2.5 times or less. An electric double-layer capacitor characterized by the following.
2. The sealing body has a moisture absorption capacity of 6.4584 [mg・mm/ cm² ] or less than three times that amount. An electric double layer capacitor according to claim 1, characterized by the above.
3. A device formation step in which a capacitor element is formed by impregnating an electrolyte containing sulfones or lactones into a polarizing electrode, A sealing body forming step in which a sealing body is formed in which the permeability coefficient of N2 gas is 2 times or more and 6 times or less of 3.429 × 10⁻¹⁰ [cc・cm/( cm² ・s・cmHg)] and the permeability coefficient of He gas is 1.1 times or more and 2.5 times or less of 2.751 × 10⁻⁹ [cc・cm/( cm² ・s・cmHg)], A sealing step of housing the capacitor element in a case and sealing the case with the sealing body, Including, A method for manufacturing an electric double layer capacitor characterized by the following.

Description

This invention relates to an electric double-layer capacitor having an electric double-layer effect and a method for manufacturing the same. An electric double-layer capacitor is constructed by impregnating polarizable electrodes with an electrolyte. This electric double-layer capacitor utilizes the energy storage effect of the electric double layer formed at the interface between the polarizable electrodes and the electrolyte. Specifically, when the positive electrode is a polarizable electrode, the anions of the electrolyte align at the interface with the polarizable electrode, forming pairs with vacancies within the polarizable electrode at a very short distance. This creates a potential barrier at the positive electrode. Similarly, when the negative electrode is a polarizable electrode, the cations of the electrolyte align at the interface with the polarizable electrode, forming pairs with electrons within the polarizable electrode at a very short distance, thus creating a potential barrier at the negative electrode. Thus, capacitors utilizing an electric double layer store electric charge physically, without relying on chemical reactions for charging and discharging. Therefore, capacitors using an electric double layer experience less degradation of their constituent materials and have superior charge-discharge cycle life. Consequently, capacitors using an electric double layer are often adopted in applications or installation locations where periodic component replacement is difficult, aiming to reduce replacement frequency and achieve maintenance-free operation. In this electric double-layer capacitor, to suppress the evaporation of the electrolyte solution, which is formed by impregnating polarizable electrodes with the electrolyte, the capacitor element is sealed within a case and a sealing body (see, for example, Patent Document 1). The sealing body is a component that seals the opening of the bottomed cylindrical case that houses the capacitor element. This sealing body is provided with an elastomer material such as butyl rubber. However, the case is equipped with an explosion-proof valve to prevent the electric double-layer capacitor from rupturing. If the internal pressure of the case reaches a specified level due to evaporation of the electrolyte and gas generation inside the electric double-layer capacitor, the explosion-proof valve will open to prevent a serious accident. Japanese Patent Application Publication No. 10-70051 This graph shows the relationship between the permeability coefficient of N2 gas and the case expansion ratio.This graph shows the relationship between the permeability coefficient of He gas and the expansion ratio of the case.This graph shows the relationship between the permeability coefficient of N2 gas and ΔCap.This graph shows the relationship between the permeability coefficient of He gas and ΔCap. The following describes a sealing body and an electric double-layer capacitor according to embodiments of the present invention. However, the present invention is not limited to the embodiments described below. (Overview of electric double-layer capacitors) An electric double-layer capacitor is a passive element that stores and discharges electric charge through capacitance. The capacitor element of an electric double-layer capacitor comprises a positive electrode foil, a negative electrode foil, a separator, and an electrolyte. The positive and negative electrode foils face each other via a separator. The electrolyte fills the voids within the capacitor element. This capacitor element has an electric double layer. Specifically, layers of electrode active material are formed on both the positive and negative electrode foils, and the electric double layer is formed at the interface between the polarizing electrode of at least one of the positive or negative electrode foils and the electrolyte. Besides capacitors with polarizing electrodes on both the positive and negative electrode foils, hybrid capacitors are also called electric double-layer capacitors. A hybrid capacitor has a polarizing electrode on the positive electrode foil and a layer of electrode active material consisting of metal compound particles capable of intercalating and deintercalating lithium ions, or a Faraday reaction electrode made of carbon material, on the negative electrode foil. This capacitor element is formed during the element formation process by overlapping a positive electrode foil and a negative electrode foil with a separator in between, and then impregnating the laminate with an electrolyte. Alternatively, the positive electrode foil, negative electrode foil, and separator may be formed into a cylindrical shape by winding them together in a long, elongated form. The capacitor element is housed in the case of the electric double-layer capacitor during the sealing process and sealed with a sealing body. The case is a bottomed cylindrical structure that houses the capacitor element and is, f