Hello loyal readers,
As I’m absolutly sure you read all my articles, particularly the ones talking about the physical explanation about fuel cell, you are perfectly aware that fuel cell uses hydrogen and oxygen to form electricity and water. And now, I must admit that I kind of simplified the truth, and yes, it’s more complicated that than. In fact, several types of fuel cell exist, and for principal part of them, the element crossing the electrolyte permits to different them.
So the most “easy” one (to understand, not to produce) is the SOFC (Solid Oxide Fuel Cell): the electrolyte permits to anions O2- to cross it, and water formation happen at the anode :
This kind of cell works at high temperature, approximately 900°C, and must be made of ceramics (ZrO2 + Y2O3, Ce02 + Gd2O3…) and has one of the highest electrical efficiency of fuel cells 55 or 60%.
Another kind of fuel cell is the PCFC (Protonic, Conducting Fuel Cell) using also ceramics materials because it works between 400 and 700°C, and have a little bit lower electrical efficiency than SOFC. As you can see on the schematic representation below, the electrolyte (central part) only let protons H+ crossing it :
The PEMFC (Proton Exchange Membrane Fuel Cell) like PCFC uses an H+ proton exchange electrolyte to separate the anode and the cathode. The difference resides on the materials used. Where a PCFC uses ceramics, the PEMFC uses polymer membranes which permit to work at only 60 or 100°C. The electrical efficiency of the system is lower than the SOFC and PCFC ones, only 30 until 50%.