JP-2026075784-A - Method and apparatus for predicting current-voltage characteristics

JP2026075784AJP 2026075784 AJP2026075784 AJP 2026075784AJP-2026075784-A

Abstract

[Problem] To provide a method for predicting current-voltage characteristics of a fuel cell equipped with a catalyst made of any material, which can be easily predicted with high accuracy. [Solution] The present invention provides a method for predicting current-voltage characteristics, comprising: a first step of performing RRDE measurement to obtain the measured value of the electrode current; a second step of solving equation (1) below, which relates to the concentration distribution of oxygen molecules and hydrogen peroxide molecules on the electrode surface of the fuel cell, to obtain the theoretical value of the electrode current; a third step of mathematically optimizing the theoretical value so that the difference between the measured value and the theoretical value is small; and a fourth step of substituting the mathematically optimized theoretical value into the Butler-Volmer equation to obtain the activation voltage under conditions where the electrode reaction is in equilibrium, and thereby determining the current-voltage characteristics, wherein the theoretical value obtained in the second step is the sum of the electrode currents for each active site. (C is the concentration distribution, D is the diffusion coefficient, and K is the reaction rate constant.) [Selection Diagram] Figure 1

Inventors

真家卓也
野呂聖弥
窪田裕次

Assignees

日清紡ホールディングス株式会社

Dates

Publication Date: 20260511
Application Date: 20241023

Claims (9)

A method for predicting the current-voltage characteristics of a fuel cell, The first step involves performing RRDE measurements simulating the aforementioned fuel cell to determine the measured values of the electrode current density of the disk electrode and the electrode current of the ring electrode generated by the electrode reaction. The second step involves solving the following equation (1) relating to the concentration distribution of oxygen molecules and hydrogen peroxide molecules on the electrode surface of the RRDE measurement, and determining the theoretical values of the electrode current density and the electrode current from the obtained concentration distribution. A third step involves mathematically optimizing the theoretical value so that the difference between the measured value and the theoretical value is less than or equal to a predetermined magnitude. The fourth step involves substituting the theoretical value after mathematical optimization into the Butler-Volmer equation to determine the activation voltage under the conditions in which the electrode reaction is in equilibrium, and then determining the current-voltage characteristics. A method for predicting current-voltage characteristics, characterized in that the theoretical value obtained in the second step is the sum of the electrode current density and the electrode current, which correspond to the energy change for each active site. (C is the concentration distribution of oxygen molecules and hydrogen peroxide molecules in the catalyst layer, D is the diffusion coefficient of oxygen molecules and hydrogen peroxide molecules, and K is the reaction rate constant of the catalyst layer formed on the electrode surface.)
The method for predicting current-voltage characteristics according to claim 1, characterized in that the concentration distribution C, the diffusion coefficient D, and the reaction rate constant K are each expressed by the following equations (2) to (4). ( CO2 and CH2O2 represent the concentration distributions of oxygen molecules and hydrogen peroxide molecules in the catalyst layer, respectively. DO2 and DH2O2 represent the diffusion coefficients of oxygen molecules and hydrogen peroxide molecules, respectively. K2 , K3 , and K4 represent the reaction rate constants of the catalyst layer in the hydrogen peroxide molecule synthesis reaction, water molecule synthesis reaction, and hydrogen peroxide molecule decomposition reaction, respectively.)
The method for predicting current-voltage characteristics according to claim 1 or 2, characterized in that the energy change for each active site is the energy change for two or more active sites with different activity levels within the catalyst layer.
A method for predicting current-voltage characteristics according to claim 1 or 2, characterized in that the Butler-Volmer equation in the fourth step is multiplied by the ratio of the amount of catalyst to the catalyst density.
The method for predicting current-voltage characteristics according to either claim 1 or 2, characterized in that the mathematical optimization in the third step is performed such that the error index ΔS, represented by the following equation (5), is -1.1 or less at the disk electrode and within the range of -0.9 or less at the ring electrode. ( IM and IC are the measured and theoretical values of the electrode current density of the disk electrode and the electrode current of the ring electrode in the RRDE measurement, respectively. The sum is calculated for the potential condition Emet within the measured potential range.)
The method for predicting current-voltage characteristics according to either claim 1 or 2, characterized in that, in the fourth step, the reduction due to concentration overvoltage and resistance overvoltage is subtracted from the activation voltage of the fuel cell.
The method for predicting current-voltage characteristics according to claim 6, characterized by creating a first database regarding the relationship between catalyst amount and concentration overpotential, and predicting the concentration overpotential by referring to the first database.
The method for predicting current-voltage characteristics according to claim 6, characterized by creating a second database regarding the relationship between the ratio of ionomer amount to catalyst amount in the catalyst layer and the resistance overpotential, and predicting the resistance overpotential by referring to the second database.
A current-voltage characteristic prediction device used in the current-voltage characteristic prediction method according to claim 1 or 2, An input device that inputs the measured values of the electrode current density and electrode current of the disk electrode generated by the electrode reaction using the RRDE measurement described above, A first computing device that solves equation (1) above and determines the theoretical values of the electrode current density and the electrode current from the obtained concentration distribution, A second computing device performs mathematical optimization of the theoretical value so that the difference between the measured value and the theoretical value is less than or equal to a predetermined magnitude. A current-voltage characteristic prediction device comprising: a third calculation device that substitutes the theoretical value after mathematical optimization into the Butler-Volmer equation to derive the relationship between current-voltage characteristics under conditions where the electrode reaction is in equilibrium; and

Description

Application for application of Article 30, Paragraph 2 of the Patent Law 1. Publication date: October 30, 2023, Fuel Cell Vol. 23 No. 2 P. 98-102, Fuel Cell Development Information Center 2. Publication date: March 29, 2024, Japan Radio Technical Report No. 75 P. 18-24, Japan Radio Co., Ltd. This invention relates to a method and apparatus for predicting current-voltage characteristics. Fuel cells are attracting attention as power generation devices that have a low environmental impact and high power generation efficiency. Fuel cells have the function of chemically reacting hydrogen and oxygen to directly convert them into electrical energy. A fuel cell is mainly composed of an electrolyte membrane, a catalyst layer, and a gas diffusion layer, and the performance of the catalyst contained in the catalyst layer, in particular, greatly affects the current-voltage characteristics of the fuel cell. Conventional fuel cells use platinum-supported catalysts (Pt/C) (Patent Document 1, etc.), but from the viewpoint of cost and resources, there is a demand for lower-platinum or non-platinum catalyst layers. There are two main methods for evaluating the characteristics of fuel cells. One is the IV measurement, which involves assembling a membrane-electrode assembly (MEA) and supplying hydrogen and oxygen. While this measurement closely resembles a real fuel cell, the procedure is complex and requires a large sample volume. The other method is the RRDE measurement, which uses a rotating ring-disk electrode in an oxygen-saturated solution. This method is simpler and requires fewer samples, but achieving high accuracy is difficult. Japanese Patent Publication No. 2017-045549 This is a process flow diagram of a method for predicting current-voltage characteristics according to one embodiment of the present invention.(a) A perspective view of the rotating ring-disk electrode of the same embodiment. (b) A diagram illustrating measurement using the rotating ring-disk electrode of the same embodiment.This figure illustrates the reaction-diffusion model used in the same embodiment.(a) and (b) are graphs showing the current-potential curves (LSV) of the disk electrode and ring electrode obtained when the multi-active-point model is applied as Example 1.(a) and (b) are graphs showing the LSV of the disk electrode and ring electrode obtained when the single-active-point model is applied as Comparative Example 1.(a) and (b) are graphs showing the LSV of the disk electrode and ring electrode obtained when the multi-active-point model is applied as Example 2.(a) and (b) are graphs showing the LSV of the disk electrode and ring electrode obtained when the single-active-point model is applied, as Comparative Example 2.(a) This graph shows the predicted and measured values obtained when applying Example 1 to the current-voltage characteristics of a fuel cell using a carbon alloy catalyst. (b) This graph shows the predicted and measured values obtained when applying Example 2 to the current-voltage characteristics of a fuel cell using a platinum catalyst.(a) to (c) are graphs showing the current-voltage characteristics of fuel cells equipped with the catalyst layers of Examples 3 to 5, respectively.(a) to (c) are graphs showing the current-voltage characteristics of fuel cells equipped with catalyst layers according to Examples 6, 3, and 7, respectively. The following describes in detail, with reference to the drawings, a method and apparatus for predicting current-voltage characteristics according to an embodiment of the present invention. Note that, for ease of understanding, the drawings used in the following description may show enlarged versions of key features, and the dimensions, proportions, etc., of each component may not be the same as those in reality. Furthermore, the materials, dimensions, etc., exemplified in the following description are merely examples, and the present invention is not limited to these; it can be implemented with appropriate modifications without altering its essence. <Method for predicting current-voltage characteristics> Figure 1 shows a flowchart of the steps involved in a method for predicting the current-voltage characteristics of a fuel cell according to one embodiment of the present invention. The method for predicting current-voltage characteristics mainly comprises a first, second, and third step of determining the reaction rate constant by mathematical optimization, and a fourth step of calculating the activation voltage using the determined reaction rate constant and determining the current-voltage characteristics. (First step) RRDE measurements are performed to simulate a fuel cell, and the measured values of the electrode currents (disk current I DM , ring current I RM ) generated by the electrode reaction are determined. The measured values obtained by RRDE measurements can be taken at, for example, room temperature, and measurements can be taken at only one temperature, but multiple measur