What kind of material is the electrode of the fuel cell?

Jul 12, 2019   Pageview:72

A fuel cell is a power generation device that directly converts chemical energy present in a fuel and an oxidant into electrical energy. Fuel and air are fed into the fuel cell separately, and the electricity is wonderfully produced. It looks like a positive and negative electrode and electrolyte, like a battery, but in fact it can't "storage electricity" but a "power plant."

 

The electrode of the fuel cell is an electrochemical reaction site where the oxidation reaction between the fuel and the oxidant is reduced. The performance of the fuel cell is the performance of the catalyst, the material of the electrode and the process of the electrode.

 

Commonly used fuel cell electrodes are:

 

1.       Oxyhydrogen fuel cell:

 

The oxyhydrogen fuel cell is generally made of inert metal platinum (Pt) or graphite as an electrode material, the negative electrode is passed into H2, and the positive electrode is introduced into O2.

 

The total response is: 2H2+O2===2H2O

 

2 methanol fuel cell:

 

A methanol fuel cell uses platinum as a bipolar electrode and an alkali or acid as an electrolyte:

 

1. Alkaline electrolyte (for example, KOH solution)

 

Total reaction formula: 2CH4O+3O2+4KOH===2K2CO3+6H2O

 

2. Acid electrolyte (H2SO4 solution as an example)

 

Total reaction: 2CH4O+3O2===2CO2+4H2O

 

3 methane fuel cell:

 

The methane fuel cell has two poles of porous nickel plate, the electrolyte solution is KOH, and the generated CO2 also reacts with KOH to form K2CO3, so the total reaction is: CH4

 

+2KOH+2O2===K2CO3+

 

3H2O.

 

4 aluminum – air – seawater battery:

 

China's first new type of seawater signage lamp using aluminum-air-seawater batteries as an energy source uses seawater as an electrolyte, and the oxygen in the air causes the aluminum to be continuously oxidized to generate electricity. Just put the light into the sea for a few minutes, it will make a dazzling white light. The negative electrode material of the power supply is: aluminum; the positive electrode material of the power supply is: an electrically conductive inert material such as graphite or platinum mesh.

 

The total reaction formula is: 4Al+3O2+6H2O===4Al(OH)3

 

The electrode requirements of the fuel cell cannot be consumed in the work and are consumed. It has to be quite active, that is, to have a catalytic effect, to reduce the reaction conditions, to increase the reaction speed, and to smoothly carry out the reaction. Of course, the graphite electrode is the cheapest. However, it may be a reaction that makes graphite difficult to carry out, but it can be carried out smoothly with other electrodes (such as platinum), which is one of the reasons why many theoretically feasible fuel cells are actually not easy to implement.

 

A fuel cell is a chemical device that directly converts the chemical energy of a fuel into electrical energy, also known as an electrochemical generator. It is the fourth generation technology after hydroelectric, thermal and atomic power generation. Since the fuel cell converts the Gibbs free energy part of the chemical energy of the fuel into electrical energy by electrochemical reaction, it is not limited by the Carnot cycle effect, so the efficiency is high; in addition, the fuel cell uses fuel and oxygen as no mechanical at the same time. Transmission parts, so there is no noise material, and there are very few harmful gases emitted; sound pollution. It can be seen that fuel cells are the most promising power generation technology from the perspective of energy conservation and ecological protection.

 

A power generation device that directly converts chemical energy of a fuel and an oxidant into electrical energy by an electrochemical reaction, fuel cells can theoretically operate at nearly 100% thermal efficiency and are highly economical. At present, various fuel cells in actual operation, due to various technical factors, consider the energy consumption of the entire device system, and the total conversion efficiency is in the range of 45% to 60%, for example, the heat utilization can be more than 80%. In addition, the fuel cell device contains no or few moving parts, is reliable, requires less maintenance, and is quieter than conventional generator sets. In addition, the electrochemical reaction is clean, complete, and rarely produces harmful substances. All of this makes fuel cells a highly promising energy powerplant. [2]

 

The fuel cell is an electrochemical power generation device. The isothermal electrochemical method directly converts chemical energy into electrical energy without passing through the heat engine process, and is not restricted by the Carnot cycle. Therefore, the energy conversion efficiency is high, and there is no noise and no pollution is becoming an ideal way to use energy. At the same time, with the continuous maturity of fuel cell technology and the provision of sufficient natural gas sources in the West-East Gas Pipeline Project, the commercial application of fuel cells has broad prospects for development. [3]

 

The fuel cell is an energy conversion device. It is based on the electrochemical principle, that is, the working principle of the primary battery. The chemical energy stored in the fuel and the oxidant is isothermally converted into electrical energy, and the actual process is a redox reaction. The fuel cell is mainly composed of four parts, namely an anode, a cathode, an electrolyte, and an external circuit. The fuel gas and the oxidizing gas are respectively introduced from the anode and the cathode of the fuel cell. The fuel gas emits electrons on the anode, and the electrons are conducted to the cathode through an external circuit and combined with the oxidizing gas to generate ions. Under the action of an electric field, the ions migrate to the anode through the electrolyte, react with the fuel gas, form a loop, and generate an electric current. At the same time, the fuel cell generates a certain amount of heat due to its own electrochemical reaction and the internal resistance of the battery. The cathodes of the battery, in addition to conducting electrons, also act as a catalyst for the redox reaction. When the fuel is a hydrocarbon, the anode is required to have a higher catalytic activity. The anodes and cathodes are usually porous in order to facilitate the passage of reaction gases and product discharge. The electrolyte functions to transfer ions and separate the fuel gas and the oxidizing gas. In order to block the mixing of the two gases, the internal short circuit of the battery is caused, and the electrolyte is usually a dense structure.

 

The principle of a fuel cell is an electrochemical device having the same composition as a general battery. The unit cell is composed of two positive and negative electrodes (the negative electrode, that is, the fuel electrode and the positive electrode that is, the oxidant electrode) and the electrolyte. The difference is that the active material of the general battery is stored inside the battery, thus limiting the battery capacity. The positive and negative electrodes of the fuel cell do not contain the active material, but only a catalytic converter element. Therefore, fuel cells are truly energy conversion machines that convert chemical energy into electrical energy. When the battery is in operation, the fuel and oxidant are supplied from the outside to react. In principle, as long as the reactants are continuously input and the reaction products are continuously eliminated, the fuel cell can continuously generate electricity. Here, a hydrogen-oxygen fuel cell is taken as an example to illustrate a fuel cell.

 

Hydrogen-oxygen fuel cell reaction principle this reaction is the reverse process of electrolyzing water. The electrode should be: negative: H2+2OH-2H2O+2e-

 

Positive electrode: 1/2O2+H2O+2e-2OH-

 

Battery reaction: H2+1/2O2==H2O

 

In addition, only the fuel cell body is still not working,

 

The fuel cell

 

The fuel cell

 

There must be a corresponding set of auxiliary systems, including reagent supply systems, heat removal systems, drainage systems, electrical performance control systems, and safety devices.

 

The fuel cell is generally composed of an electrolyte plate forming an ion conductor and a fuel electrode (anode) and an air electrode (cathode) disposed on both sides thereof, and a gas flow path on both sides, and the gas flow path functions to make the fuel gas and the air (oxidant) Gas) can pass through the flow path.

 

The page contains the contents of the machine translation.

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