WORKING PRINCIPLE OF FUEL CELL

Fuel cell is a device electrochemical energy conversion that will convert hydrogen and oxygen into water, simultaneously generating electrical energy and heat in the process. Fuel cell is a form of simple technologies such as rechargeable batteries fuel to get his energy back, in this case the fuel is oxygen and hydrogen.

Just like a battery, any kind of fuel cell has positive and negative electrodes also called cathode and anode. The chemical reaction that produces electricity occurs on the electrode. In addition to electrodes, one unit there electrolyte fuel cell that will carry electrical charges from one electrode to the other electrode, and a catalyst that will accelerate the reaction at the electrode. Generally distinguish the types of material electrolyte fuel cell is used. Electric current and heat is generated every type of fuel cell is a by-product of chemical reactions that occur in the cathode and anode.

 Figure 1.

Diagram of Fuel Cells

Because the energy produced by the fuel cell is a chemical reaction forming water, an electrochemical energy conversion device will not produce side effects that are harmful to the environment as conventional energy conversion devices (eg combustion processes in the engine). In terms of energy efficiency, the application of fuel cells inportable batteries such as mobile phones or laptops will hold ten times longer than lithium batteries. And to replenish the energy will be faster because the energy is used instead of electricity, but the fuel is liquid or gas.

The working principle of the fuel cell is the reverse process of electrolysis, where hydrogen reacted with oxygen and produce electricity.

2H₂ + O₂ à 2H₂O

In the aforementioned reaction liberated heat energy can then be generated electrical energy. The resulting electrical current is very small. This is due to several things:

(a)    The low contact area between gas, electrode and electrolyte;

(b)   The long distance between the electrodes and the electrolyte causing the electrical current prisoners. So as to improve the performance of electrodes made ​​into a plate with a thin layer of electrolyte (as shown in Figure 2). Electrode structure made ​​from porous materials that cause electrolyte on one side and the other side can penetrate. 

Figure 2.

The Basic Structure Of The Fuel Cell

At the anode, the acid from the electrolyte, the hydrogen will produce ionized electrons and hydrogen ions (protons). This reaction will liberate energy.

2H₂ à 4H⁺ + 4e^-

While at the cathode, oxygen reacts with the electrons extracted from the electrodes and protons (hydrogen ions) to form water.

O₂ + 4e^- + 4H⁺ à 2H₂O

The above reaction takes place continuously, the electrons produced at the anode should be able to pass through the electric circuit to the cathode. Likewise, hydrogen ions (protons) must be able to pass through the electrolyte.