Review of Batteries

1
Review of Batteries

• Define the following terms
• Primary Cell
• Secondary Cell
• Power Density
• Memory Effect

2
Nickel-Cadmium

• Advantages
• Can be recharged 1000 times or more
• Low cost/cycle
• Tough, stands up to abuse
• Disadvantages
• Low energy density
• Memory effect
• Contains toxic metals
• Popular Uses
• Two-way radios, power tools, medical equipment

3
Lithium-Ion

• Advantages
• High energy density
• No memory effect
• Disadvantages
• More expensive than Ni-Cd
• Not fully mature, technology is still evolving
• Popular Uses
• Cell-phones, iPods, laptop computers

4
Lead-Acid

• Advantages
• Mature technology, well understood
• Cheap and easy to manufacture
• No memory effect
• Disadvantages
• Very low energy density most applications
  require huge batteries
• Limited number of full discharge cycles
• Environmental concerns
• Popular Uses
• Electric cars, golf carts, scooters

5
Reusable Alkaline

• Advantages
• Cheap to manufacture
• More economical than primary alkaline cells
• Disadvantages
• Limited current, cannot be made on large scale
• Limited cycle life (about 10 cycles) fully
  discharging shortens life
• Popular Uses
• Personal CD players, radios, flashlights

6
Fuel Cells

• Behind the hype

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The Limit of Batteries

• A battery is a fancy type of galvanic cell. It
  changes chemicals into electricity.
• Eventually, all the chemical are reacted and the
  battery goes dead.
• If the battery is a secondary cell, you can
  recharge it, but this takes time and energy.
  Also, there is a limited number of times you can
  do this.
• Wouldnt it be nice to be able to just open up a
  battery, and pour in some more chemicals, like
  refueling a car?

8
Fuel Cells The Ultimate Battery

• A fuel cell is a type of galvanic cell that
  allows you to add fresh chemicals continuously.
  It will continue to run as long as you keep
  adding fuel.

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Fuel Cell Comparisons
Battery Fuel Cell Engine
Energy Conversion Chemicalgt Electrical Chemicalgt Electrical Chemicalgt Mechanicalgt Electrical
Fuel Zinc or other metal H2, Methane, Propane, Methanol, etc. Propane, Methane, Gasoline
Powered By Electrochemical Reaction Electrochemical reaction Combustion Reaction
Power Output Low Variable High
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Advantages of Fuel Cells

• Extremely versatile can power everything from
  cell phones to buses
• Can run on a variety of fuels
• More environmentally friendly than combustion

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Disadvantages of Fuel Cells

• Technology is still somewhat unreliable
• Some types still produce greenhouse gas emissions
• EXPENSIVE

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The Promise of Hydrogen

• Many Fuel Cells are emission-free because they
  run on hydrogen

O2(g)
H2(g)
2 H
2 e-
Anode
Cathode
Electrolyte
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The Promise of Hydrogen

• Many Fuel Cells are emission-free because they
  run on hydrogen

H2(g)
H2O(l)
Anode
Cathode
Electrolyte
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Overall Reaction H2 O2 ? H2O Question Where
does hydrogen come from?
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Types of Fuel Cells

• Proton Exchange Membrane (PEM)
• Solid Oxide Fuel Cells (SOFC)
• Alkaline Fuel Cells (AFC)
• Direct Methanol Fuel Cells (DMFC)
• There are many more, but we wont get into them
  here

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Your Task

• You will work in groups of about 5
• Half of each group will argue for a particular
  type of fuel cell the other half will argue
  against
• Each half-group will prepare an extremely short
  (60 s) presentation to convince the audience of
  their stance
• The class will vote on who was most convincing