Modern Engineering Thermodynamics

15.15 Fuel Cells 637
Anode
Electrolyte
Cathode
Hydrogen
Oxygen
− +
H 2
Catalyst
Electric
power
H 2 O
FIGURE 15.13
Fuel cell and fuel battery technology.
WHY IS AN ELECTROCHEMICAL CELL CALLED A BATTERY?
The term battery was introduced by the American scientist and diplomat Benjamin Franklin (1706–1790) for describing a
group of interconnected capacitors. Though it technically means two or more items (like a cannon in an artillery battery),
today, single electrochemical cells are often referred to as batteries (e.g., the cells in a flashlight should be called flashlight
cells not flashlight batteries).
WHAT IS A FUEL CELL?
A fuel cell is an electrochemical open energy conversion system that converts the chemical energy of its fuel directly into
electrical work energy output by a chemical oxidation reaction.
WHO INVENTED THE FUEL CELL?
Though fuel cells offer an exciting high-efficiency alternative to traditional heat engine energy conversion technology, they
are not a new concept. The credit for developing the first fuel cell is given to the British physicist and lawyer Sir William
Robert Grove (1811–1896). In 1839, he constructed a fuel battery that consisted of a test tube containing a platinum electrode
inverted in a sulfuric acid solution (Figure 15.14). When an electric current was passed through the cell to charge it,
the water in the electrolyte decomposed into hydrogen and oxygen inside the inverted test tube. When an electrical load
was applied to the electrodes, the hydrogen and oxygen recombined again to form water and produced an electrical current.
It is easy to see how this can become a true open system fuel cell if the hydrogen and oxygen are continuously supplied
from outside the system.
(Continued)