EP-4741533-A1 - ELECTROLYSIS CELL AND MANUFACTURING METHOD THEREFOR

EP4741533A1EP 4741533 A1EP4741533 A1EP 4741533A1EP-4741533-A1

Abstract

The present invention relates to an electrolysis cell including: a gas diffusion layer, a cathode, an anode, an electrolyte, and a separation membrane positioned between the cathode and the anode, wherein the separation membrane includes a porous substrate and a coating layer disposed on at least one surface of the porous substrate, wherein the coating layer includes an anion exchange ionomer, and the anion exchange ionomer is not included inside the pores of the porous substrate, so as to have low interfacial resistance and obtain high electric conversion efficiency.

Inventors

KIM, SUNG YEON
NOH, TAE GEUN

Assignees

LG Chem, Ltd.

Dates

Publication Date: 20260513
Application Date: 20240828

Claims (14)

An electrolysis cell including: a gas diffusion layer, a cathode, an anode, an electrolyte, and a separation membrane positioned between the cathode and the anode, wherein the separation membrane includes a porous substrate and a coating layer disposed on at least one surface of the porous substrate, wherein the coating layer includes an anion exchange ionomer, and the anion exchange ionomer is not included inside the pores of the porous substrate.
The electrolysis cell according to claim 1, wherein the coating layer is disposed on a surface facing the cathode among both surfaces of the porous substrate.
The electrolysis cell according to claim 1, wherein the porous substrate comprises at least one selected from the group consisting of polyethersulfone, polyvinylidene difluoride, cellulose acetate, polytetrafluoroethylene, and polyimide.
The electrolysis cell according to claim 1, wherein the anion exchange ionomer is a hydrocarbon-based ionomer or a perfluorinated ionomer.
The electrolysis cell according to claim 1, wherein the electrolysis cell is a zero-gap membrane electrode assembly cell in which the gas diffusion layer, the cathode, the separation membrane, and the anode having an anolyte path formed therein are sequentially stacked without gaps.
The electrolysis cell according to claim 1, wherein the ratio of the thickness of the coating layer to the thickness of the porous substrate is 1:10 to 200.
The electrolysis cell according to claim 1, wherein the thickness of the coating layer is 1.0 µm or more and 10.0 µm or less.
The electrolysis cell according to claim 1, wherein the thickness of the porous substrate is 5.0 µm or more and 250.0 µm or less.
The electrolysis cell according to claim 1, wherein the average pore size of the pores of the porous substrate is 10.0 nm or more and 450.0 nm or less.
The electrolysis cell according to claim 1, wherein the electrolysis cell electrolyzes carbon dioxide.
The electrolysis cell according to claim 1, wherein the electrolysis cell generates at least one product selected from the group consisting of carbon monoxide, ethylene, methane, formic acid, hydrocarbon, aldehyde, and alcohol.
A method for manufacturing an electrolysis cell, the method including the steps of: manufacturing a separation membrane having a coating layer disposed on one surface (S10); installing a cathode on one surface of the separation membrane having the coating layer disposed and installing an anode on the other surface of both surfaces of the separation membrane (S20); and installing a bipolar plate on the outside of each of the cathode and the anode (S30), wherein the step (S10) of manufacturing the separation membrane includes the steps of: preparing a coating composition comprising an anion exchange ionomer and an organic solvent, and a porous substrate (S1); applying the coating composition on one surface of the porous substrate to form a coating layer (S2); and drying the coating layer to manufacture the separation membrane (S3).
The method for manufacturing an electrolysis cell according to claim 12, wherein the coating composition includes 1 wt% or more and 10 wt% or less of the anion exchange ionomer.
The method for manufacturing an electrolysis cell according to claim 12, wherein in the step (S30), the coating layer is formed to have a thickness of 1.0 µm or more and 10.0 µm or less.

Description

[Technical Field] CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of priority to Korean Patent Application No. 10-2023-0112690 filed on August 28, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field The present invention relates to an electrolysis cell for electrolyzing carbon dioxide and a manufacturing method thereof. [Background Art] Carbon dioxide is a greenhouse gas that causes global warming and must be reduced. Methods such as capture, chemical conversion, or electrochemical conversion are known as methods for reducing carbon dioxide. Among them, the electrochemical conversion method can precisely control the components so that other synthetic gases can be produced, resulting in economic benefits rather than simply removing carbon dioxide. In addition, carbon dioxide can be electrolyzed with water to obtain organic substances such as carbon monoxide, ethylene, methane, formic acid, formate, various hydrocarbons, and aldehyde or alcohol. The process of electrochemically decomposing carbon dioxide is similar to the water electrolysis technology, but since the activity of the electrochemical reaction is improved in a strongly alkaline atmosphere, an aqueous solution of KOH having a certain concentration is generally used as the electrolyte. When an electric current is applied while supplying water to the anode, the water is decomposed into hydrogen ions and electrons along with the generation of oxygen gas. The electrons move to the cathode through an external conductor, and the hydrogen ions move to the cathode through an ion-selective separation membrane. The moved electrons react with carbon dioxide and water supplied to the cathode to decompose them into carbon monoxide and hydroxide ions (OH-), and the generated hydroxide ions react with the hydrogen ions (H+) of the anode to generate water, thereby becoming electrically neutral. The electrochemical decomposition reaction of carbon dioxide is completed through the above process. In this case, the water supplied together with the carbon dioxide reacts with the moved electrons separately from the generation reaction of the carbon monoxide to be electrolyzed, thereby generating hydrogen gas and simultaneously generating hydroxide ions. This reaction between water and electrons can be said to be a reaction in a competitive relationship with the above carbon monoxide generation reaction. Since the above reactions are electrochemical reactions, the amount of carbon monoxide produced and the hydrogen/carbon dioxide ratio can be easily controlled by adjusting the voltage. Meanwhile, the electrolysis cell includes a cathode, an anode, an electrolyte, and a separation membrane. Conventionally, a commercially available anion exchange membrane is generally used as the separation membrane, and in particular, Sustainion from Dioxide Materals is the most widely used anion exchange separation membrane. However, this is expensive and may have economical cost problem for use, cannot be supplied in large quantities, and may crack and crumble in a dry state due to low mechanical strength, so the work processability was very low when the Sustainion anion exchange separation membrane was fastened to the electrolysis cell. Accordingly, research on a porous substrate that can replace the Sustainion anion exchange separation membrane is underway, but such a porous substrate still has poor mechanical strength due to its porosity, and has a problem in that cations cross over from the electrolyte at the anode side to the cathode side due to the porosity, thereby lowering the electrolysis efficiency. Therefore, research is required on a separation membrane that is capable of mass production at low cost, has high durability and mechanical strength, and has an equivalent or higher carbon dioxide conversion efficiency, and thus can replace the Sustainion anion exchange separation membrane or improve the porous substrate. (Patent Document 1) KR 2019-0125822 A [Disclosure] [Technical Problem] An object to be achieved by the present invention is to provide a separation membrane that improves electrolysis efficiency by maintaining pore characteristics of a porous substrate and also having ion selectivity of an ionic polymer separation membrane, and an electrolysis cell including the same. In addition, another object to be achieved by the present invention is to provide a separation membrane that can be used on a large area instead of a commercial anion exchange separation membrane fastened to an existing electrolysis cell and has high chemical and mechanical strength, and a method for manufacturing an electrolysis cell including the same. [Technical Solution] The present invention provides an electrolysis cell and a method of manufacturing the same. (1) The present invention provides an electrolysis cell including: a gas diffusion layer, a cathode, an anode, an electrolyte, and a separation membrane positioned