Fuel cell type acid-base production method

Abstract

Fuel cells using salts as electrolytes can obtain acids and bases. An electric field is applied to the fuel cell solution, so that active substances around the fuel electrode and the air electrode are increased. Therefore, the reaction efficiency of the fuel cell can be improved, and the adverse effect of polarization is eliminated. And the reaction speeds of the fuel electrode and the air electrode can be calculated according to the Nernst equation.

Description

Technical Field

[0001] The present invention relates to the field of electrochemistry, in particular to the field of fuel cells. Background Art

[0002] A fuel cell is a power generation device that converts the chemical energy of a fuel directly into electrical energy.

[0003] The history of fuel cells can be traced back to the work of Sir William Robert Grove, a 19th-century British judge and scientist. In 1839, Grove's experiments with electrolysis—using electricity to split water into hydrogen and oxygen—became the first device that would later be called a fuel cell. Grove hypothesized that if oxygen and hydrogen reacted, the electrolysis process could be reversed to produce electricity. To test this theory, he placed two platinum ribbons in two sealed bottles, one containing hydrogen and the other oxygen. When these containers were immersed in a dilute sulfuric acid solution, an electric current began to flow between the electrodes, producing water in the bottle containing the gas. To increase the generated voltage, Grove connected several of these devices in series, ultimately creating what he called a "gas cell." The term "fuel cell" was coined in 1889 by chemists Ludwig Mond and Charles Langer, who were attempting to create the first practical device using air and industrial gas. It soon became apparent that commercializing this technology would require overcoming numerous scientific and technological hurdles. As a result, the early interest in Grove's invention began to wane. By the end of the last century, the advent of the internal combustion engine and the widespread use of fossil fuels meant that fuel cells were considered little more than a scientific curiosity. A major chapter in the history of fuel cells was then written by Dr. Francis Thomas Bacon, an engineer at the University of Cambridge. In 1932, Bacon, inspired by the device invented by Mond and Langer, modified the original design several times, including replacing the platinum electrodes with cheaper nickel mesh and replacing the alkaline potassium hydroxide with sulfuric acid, a less corrosive electrolyte. Bacon called this device the Bacon cell, and it was effectively the first alkaline fuel cell.

[0004] A fuel cell is an electrochemical device with the same components as a conventional battery. Each cell consists of two electrodes (positive and negative)—a negative electrode (fuel electrode) and a positive electrode (oxidant electrode)—and an electrolyte. Unlike conventional batteries, the active material is stored internally, limiting its capacity. In contrast, the positive and negative electrodes in a fuel cell do not contain active materials themselves; they serve only as catalytic converters. Therefore, a fuel cell is truly an energy conversion machine, converting chemical energy into electrical energy. During operation, fuel and oxidant are supplied externally and react. In principle, as long as the reactants are continuously supplied and the reaction products are continuously removed, the fuel cell can generate electricity continuously. This example uses a hydrogen-oxygen fuel cell to illustrate the principle of the hydrogen-oxygen fuel cell reaction, which is the reverse process of water electrolysis.

[0005] The electrodes should be: Negative electrode: H2+2OH - →2H2O +2e - Positive electrode: 1 / 2O2+H2O 2e - →2OH - Battery reaction: H2+1 / 2O2=H2O In addition, the fuel cell itself alone cannot work; it must have a set of corresponding auxiliary systems, including reactant supply system, heat removal system, drainage system, electrical performance control system and safety devices.

[0006] A fuel cell typically consists of an electrolyte plate that forms an ion conductor, with a fuel electrode (anode) and an air electrode (cathode) arranged on either side of the electrolyte plate, and gas flow paths on both sides. The function of the gas flow paths is to allow the fuel gas and air (oxidant gas) to pass through the flow paths.

[0007] Battery polarization: When a current flows through a battery, causing the potential to deviate from the equilibrium potential, this phenomenon is called electrode polarization. The overpotential is the difference between the actual potential and the equilibrium potential and is used to measure the degree of polarization.

[0008] According to the cause of polarization, polarization can be divided into three types: electrochemical polarization, concentration polarization and ohmic polarization.

[0009] 1. Electrochemical polarization, also known as activation polarization, is caused by the electrochemical reaction rate of the positive and negative active materials being less than the electron movement rate, and the response time is in the microsecond range. 2. Concentration polarization occurs when the electrode surface is not replenished in time due to the consumption of reactants (or a certain product accumulates on the electrode surface and cannot be evacuated in time). For example, the accumulation of hydrogen at the positive electrode of the battery causes the electrode potential to deviate from the average value calculated based on the overall concentration before power is applied. The response time is in the order of seconds. 3. Ohmic polarization is polarization caused by the electrolyte, electrode material, diaphragm resistance and contact resistance between various components, and occurs instantaneously.

[0010] The above three polarizations are the resistance to electrochemical reactions. The internal resistance of a battery is the sum of the ohmic internal resistance, electrochemical polarization internal resistance, and concentration polarization internal resistance.

[0011] The Nernst equation is an expression that quantitatively describes the diffusion potential of a specific ion between two systems, A and B. In electrochemistry, the Nernst equation is used to calculate the equilibrium voltage of a given redox couple at an electrode relative to the standard potential. The Nernst equation is only meaningful when both species in the redox couple are present. This equation, which links chemical energy to the electrode potential of a galvanic cell, made a significant contribution to electrochemistry and is named after its discoverer, the German chemist Nernst, who was awarded the 1920 Nobel Prize in Chemistry for this work.

[0012] Ion membrane principle: A technology based on the principle of ion selective permeability, using membranes with specific pore sizes and spatial structures to separate positive and negative ions in a solution. Ion membranes exhibit ion-selective permeability, allowing specific ions to pass while blocking the transmission of other ions. Ion membranes are fabricated by attaching ion exchange groups to the membrane. Typically, the exchange groups in ion exchange membranes incorporate charged groups, imparting ion selectivity. The specific selectivity of ion membranes is determined by a combination of factors such as the spacing between the groups, pore size, and charge state. Within an ion membrane, positive and negative ions migrate through electrostatic interactions with the exchange groups and differences in ion concentration in the solution. Positive ions migrate from areas of high concentration to areas of low concentration, while negative ions migrate in the opposite direction. Due to the ion selectivity of ion membranes, only specific ions are permitted to pass, while other ions are blocked. By controlling the membrane's pore size and the properties of the exchange groups, ion membranes can selectively transmit specific ions. For example, an anion exchange membrane allows only anions to pass while blocking cations. Utilizing this principle, ion membranes are widely used in electrolytic processes, such as ion selective permeability, ion exchange, and electrolyte separation. In general, the ion membrane principle is a technology that separates positive and negative ions in a solution by using ion exchange groups and electrostatic interactions based on the ion selective permeability of the membrane. Summary of the Invention

[0013] Applying an electric field to the fuel cell solution increases the active substances around the fuel and air electrodes. This can increase the reaction efficiency of the fuel cell and eliminate the adverse effects of polarization. The reaction rates of the fuel and air electrodes can be calculated based on the Nernst equation. Acids and bases are obtained by using salt as an electrolyte. The present invention uses relatively cheap materials, such as changing the proton membrane to a cationic membrane. The cost and durability of the cationic membrane are better than those of the proton membrane. The output is not only electricity, but also products such as acid and base. This is better than a simple fuel cell with only power generation function.

[0014] Specific implementation like Figure 1 shown Positive electrode 1; negative electrode 2, fuel electrode 3, air electrode 4, hydrochloric acid solution 5, salt water solution 6, anion membrane 7, using hydrogen as fuel and air as oxidant.

[0015] Positive electrode 1 and negative electrode 2 generate an electric field, causing chloride ions in saline solution 6 to pass through anionic membrane 7 and reach hydrochloric acid solution 5. This causes hydrochloric acid solution 5 to become negatively charged, while saline solution 6 becomes positively charged. The voltage at the positive and negative electrodes is less than or equal to the voltage at which gas is generated, preventing gas formation.

[0016] The reaction that occurs is: Fuel electrode: H2=2H + +2e - ; The hydrochloric acid solution 5 is negatively charged, and the hydrogen decomposes into hydrogen ions while releasing electrons, and the hydrogen ions and chloride ions generate hydrochloric acid.

[0017] Air electrode: O2 +2H2O=4OH - -4e - ; The salt water solution 6 is positively charged, and the oxygen gains electrons to form oxygen ions; the oxygen ions combine with water to form hydroxide ions, and the hydroxide ions and sodium ions form sodium hydroxide.

[0018] The hydrogen ions produced by the fuel electrode and the chloride ions brought by the electric field will increase the hydrochloric acid concentration of the hydrochloric acid solution 5.

[0019] The air electrode produces hydroxide ions, the electric field takes away the chloride ions, and the salt water solution 6 will become a sodium hydroxide solution.

[0020] Second implementation method like Figure 2 shown Positive electrode 11; negative electrode 12, fuel electrode 13, air electrode 14, salt water solution 15, sodium hydroxide solution 16, cationic membrane 17, using hydrogen as fuel and air as oxidant.

[0021] Positive electrode 11 and negative electrode 12 generate an electric field, causing sodium ions in saline solution 15 to pass through the cationic membrane and reach sodium hydroxide solution 16. This results in saline solution 15 becoming negatively charged and sodium hydroxide solution 16 becoming positively charged. The voltage at the positive and negative electrodes is less than or equal to the voltage at which gas is generated, preventing gas formation.

[0022] The reaction that occurs is: Fuel electrode: H2=2H + +2e - ;The salt water solution 15 is negatively charged, and the hydrogen gas decomposes into hydrogen ions while releasing electrons. The hydrogen ions and chloride ions generate hydrochloric acid.

[0023] Air electrode: O2 +2H2O=4OH - -4e - ; The sodium hydroxide solution 6 is positively charged, and the oxygen gains electrons to form oxygen ions; the oxygen ions combine with water to form hydroxide ions, and the hydroxide ions and sodium ions generate sodium hydroxide.

[0024] Third implementation method like Figure 3 shown Positive electrode 21; negative electrode 22, fuel electrode 23, air electrode 24, hydrochloric acid 25, sodium chloride solution 26, sodium hydroxide solution 27, anion membrane 28, cation membrane 29, using hydrogen as fuel and air as oxidant.

[0025] Positive electrode 21 and negative electrode 22 generate an electric field, causing sodium ions in sodium chloride solution 26 to pass through cationic membrane 29 to reach sodium hydroxide solution 27, while chloride ions in sodium chloride solution 26 pass through anionic membrane to reach hydrochloric acid solution 25. Sodium hydroxide solution 26 is positively charged, while hydrochloric acid solution 25 is negatively charged. The voltage at the positive and negative electrodes is less than or equal to the voltage at which gas is generated, preventing gas generation.

[0026] The reaction that occurs is: Fuel electrode: H2=2H + +2e - ;Hydrochloric acid 25 is negatively charged, and hydrogen decomposes into hydrogen ions while releasing electrons. Hydrogen ions and chloride ions form hydrochloric acid.

[0027] Air electrode: O2 +2H2O=4OH - -4e - ; The sodium hydroxide solution 27 is positively charged, and the oxygen gains electrons to form oxygen ions; the oxygen ions combine with water to form hydroxide ions, and the hydroxide ions and sodium ions generate sodium hydroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the principle of the first implementation method Figure 2This is a schematic diagram of the principle of the second implementation method Figure 3 This is a third embodiment showing the principle of the present invention.

Claims

1. A fuel cell capable of producing acid and alkali, characterized in that : The fuel electrode 3 is located on one side of the anion membrane 7: The air electrode 4 is located on the other side of the anion membrane 7.

2. According to claim 1, it is characterized in that : The positive electrode 1 and the fuel electrode 3 are located on one side of the ion membrane 7; the negative electrode 2 and the air electrode 4 are located on the other side of the anion membrane 7.

3. A fuel cell capable of producing acid and alkali, characterized in that : The fuel electrode 13 is located on one side of the cation membrane 17 : The air electrode 14 is located on the other side of the cation membrane 17 .

4. According to claim 3, it is characterized in that : The positive electrode 11 and the fuel electrode 13 are located on one side of the cation membrane 17; the negative electrode 12 and the air electrode 14 are located on the other side of the cation membrane 17.

5. A fuel cell capable of producing acid and alkali, characterized in that : The fuel electrode 23, the acid solution 25, and the anion membrane 28 are located on one side of the salt solution 26: the air electrode 24, the alkaline solution 27, and the cation membrane 29 are located on the other side of the salt solution 26: the salt solution 26 is between the anion membrane 28 and the cation membrane 29.

6. According to claim 5, it is characterized in that : The acid solution 25 is a hydrochloric acid solution, the alkali solution 27 is a sodium hydroxide solution, and the salt solution 26 is a sodium chloride solution.

7. According to claim 5, it is characterized in that : The fuel electrode 23, the acid solution 25, the positive electrode 21, and the anion membrane 28 are located on one side of the salt solution 26: the air electrode 24, the alkaline solution 27, the negative electrode 22, and the cationic membrane 29 are located on the other side of the salt solution 26: the salt solution 26 is between the anion membrane 28 and the cationic membrane 29.

8. A method for improving the polarization effect of a fuel cell, characterized in that : Applying an external electric field in the solution of the fuel cell increases the active substances around the fuel electrode and the air electrode.

9. According to claim 8, it is characterized in that :The maximum intensity of the external electric field is when the positive or negative electrode just produces matter.

10. According to claim 8, it is characterized in that :The maximum intensity of the external electric field is when the positive or negative electrode just produces gas.

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