 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078664187/179001/ch21_chapter.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> |
 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0078664187/179001/ch21_1.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (20.0K)</a>]]> | Electric
Cars
As pollution awareness increases, industrialized nations are looking for ways to curtail emissions. The Department of Energy and the transportation industry, a major contributor to air pollution, are looking at fuel cells to supply the energy for automobiles. These automobiles will contain electric engines powered by fuel cells with a supplemental battery used to supply energy during acceleration and for cold starts. |
| Fuel cells, introduced in 1839 by Sir William Grove, have been used by the Apollo mission and NASA to power spacecraft. Fuel cells are similar to batteries but have fuel tanks. Batteries and fuel cells both generate electricity chemically and depend on electrodes that are connected by an electrolyte. Batteries produce electricity as long as there are solid electrodes but fuel cells produce electricity as long as they have fuel, and never need recharging. Hydrogen fuel needed for a fuel cell can be obtained from hydrogen gas, natural gas or methanol, and the oxygen is obtained from the air. These fuels are electrochemically combined in a fuel cell to produce electricity, heat, and pure water. |
| At
present, there are many prototypes for fuel cell vehicles for
mass production in 2004. All fuel cells produce electricity
the same way in these prototypes, but the source of hydrogen
is the difference. A possible source of hydrogen is a pressurized
tank of hydrogen gas, which is bulky and heavy. The size of
hydrogen tanks needed to store this very light gas would limit
the driving range of the automobile. Another method for supplying
fuel cells with hydrogen uses methanol, which can be produced
from biomass, coal, or natural gas. In this instance, methanol
is stored onboard the vehicle in a tank similar to the gasoline
tank of today's internal combustion automobiles. Methanol is
converted to hydrogen by reformers attached to the fuel cell
engine or by direct conversion. Tanks filled with methanol will
supply enough fuel to allow these vehicles to have a range similar
to today's automobiles. Methanol retail stations have been installed
in Europe, Japan, Canada, and the United States. |
| The supplemental battery aboard a fuel cell-driven automobile may be one of two types of secondary batteries, a lithium-ion battery or a nickel-metal-hydride battery. The nickel-metal hydride battery has an electrode made of a metallic alloy developed for advanced hydrogen energy storage. The hydrogen atoms can then participate in a reversible cell reaction to power this battery. The lithium ion battery uses lithium metallic oxide at the cathode and carbon material at the anode. The lithium ions inside this battery transfer between the positive electrode and the negative electrode during charge and discharge. Both of these batteries are rechargeable, but will need to be replaced just as the lead storage battery in today's automobiles. |
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 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078664187/179001/POWproblem_1.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | Below
is a diagram of a methanol fuel cell.
a. Identify the cathode and anode.
b. Write the reaction that takes place at the cathode
and the reaction that takes place at the anode.
c. Write the overall reaction for the methanol fuel
cell. |
 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0078664187/179001/ch21_2.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (38.0K)</a>]]> |
 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078664187/179001/POWproblem_2.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> |
The anode half-reaction for a nickel-metal-hydride battery is:
MH + OH- → M + H2O + e-
-0.83V
The cathode half-reaction is:
NiOOH + H2O + e- → Ni(OH)2
+ OH- +0.52VDetermine the overall reaction and calculate the cell potential for this battery. |
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 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078664187/179001/POWproblem_3.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | The anode reaction of a lithium ion battery is:
Li+ + e- + Lix-1/graphite
↔ Lix/graphite
-3.0 V
The cathode reaction is:
Li+ + e- + Li1-xCoO2
↔ LixCO2
+0.5 VDetermine the overall reaction and calculate the cell potential of this battery. |
 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078664187/179001/webLinks.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>]]> | Useful Web Sites:
A Basic Overview of Fuel Cell Technology
Additional Materials in Redox and Electrochemistry
Multiple Types of Fuel Cells
Fuel Cell Basics
Transportation Applications of Fuel Cells
Fuel Cells
Automobiles Using Fuel Cells
Direct Methanol Fuel Cell Research
Batteries: History, Present, and Future of Battery Technology
Battery QuickRef - Lithium-Ion
Secondary Lithium Batteries for Spacecraft
Lithium Ion Batteries Ready for Takeoff
Nickel-Metal Hydride
Nickel/Metal Hydride (NiMH) Cells |
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