Description of hydrogen and oxygen fuel cells

Fuel cell is a promising new power supply, generally hydrogen, carbon, methanol, borohydride, gas or natural gas as fuel, as a negative electrode, with oxygen in the air as a positive electrode. The main difference between the battery and the general battery is that the active substance of the general battery is pre-placed inside the battery, so the battery capacity depends on the amount of stored active substance; The active substances of the fuel cell (fuel and oxidizer) are continuously input at the same time of reaction, so this kind of battery is actually just an energy conversion device. This type of battery has the advantages of high conversion efficiency, large capacity, high specific energy, wide power range, no charging, but due to high cost, the system is more complex, limited to some special uses, such as spacecraft, submarines, military, TV transfer stations, lighthouses and buoys.

How it works:

Hydrogen and oxygen fuel cells use hydrogen as fuel as reducing agent, oxygen as oxidizing agent, through the combustion reaction of fuel, chemical energy into electric energy battery, the working principle is the same as that of galvanic cell.

When the hydrogen-oxygen fuel cell works, hydrogen is supplied to the hydrogen electrode and oxygen is supplied to the oxygen electrode. Hydrogen and oxygen, under the action of a catalyst on the electrode, form water through the electrolyte. At this time, the hydrogen electrode has an excess electron and is negatively charged, and the oxygen electrode is positively charged due to the lack of electrons. When the circuit is switched on, the reaction process, which is similar to combustion, can proceed continuously.

When working, fuel (hydrogen) is supplied to the negative electrode and oxidizer (oxygen) is supplied to the positive electrode. Hydrogen is decomposed into positive ions H+ and electrons e- under the action of a catalyst on the negative electrode. The hydrogen ions enter the electrolyte, while the electrons move along the external circuit towards the positive electrode. The load is connected to the external circuit. At the positive electrode, oxygen and hydrogen ions in the electrolyte absorb electrons arriving at the positive electrode to form water. This is the reverse process of the electrolytic reaction of water.

Hydrogen and oxygen fuel cells do not require a device that stores all reducing agents and oxidants in the battery.

The reactants of the hydrogen and oxygen fuel cell are all on the outside of the cell and it just provides a container for the reaction

Both hydrogen and oxygen can be supplied outside the battery.

A fuel cell is a chemical battery that uses the energy released during a chemical reaction to convert it directly into electricity. From this point of view, it is similar to other chemical batteries such as zinc-manganese dry batteries and lead-acid batteries. However, when it works, it needs to be continuously supplied with reactive substances - fuel and oxidant, which is not the same as other ordinary chemical batteries. Because it converts the energy released by the fuel through a chemical reaction into electrical energy output, it is called a fuel cell.

Specifically, fuel cells are "generators" that utilize the reverse reaction of electrolysis of water. It consists of a positive electrode, a negative electrode and an electrolyte plate sandwiched between the positive and negative electrodes. Initially, the electrolyte plate was formed by using electrolytes to penetrate porous plates, and in 2013, it is being developed to directly use solid electrolytes.

When working, fuel (hydrogen) is supplied to the negative electrode, and oxidizing agent (air, the active component is oxygen) is supplied to the positive electrode. Hydrogen splits into positive ions H+ and electrons e- at the negative electrode. When hydrogen ions enter the electrolyte, electrons move along the external circuit towards the positive electrode. The load is connected to the external circuit. At the positive electrode, oxygen in the air and hydrogen ions in the electrolyte absorb electrons arriving at the positive electrode to form water. This is the reverse process of the electrolytic reaction of water. The water in this process can be reused, and the power generation principle is similar to that of solar cells that can be used at night.

The electrode materials of fuel cells are generally inert electrodes, which have strong catalytic activity, such as platinum electrodes and activated carbon electrodes.

Using this principle, the fuel cell can continuously transmit electricity to the outside while working, so it can also be called a "generator".

In general, writing the chemical reaction equations of fuel cells requires a high degree of attention to the acidity and alkalinity of the electrolyte. The electrode reaction occurring on the positive and negative electrodes is not isolated, it is often closely related to the electrolyte solution. For example, hydrogen-oxygen fuel cells have two types of acid and basic:

If the electrolyte solution is alkali, salt solution

The negative reaction formula is: