Transcript Ni-Cd Batteries

Ni-Cd Batteries
Alan Kim / Mitchell Stasko / Bryan Zhang
History
1899 / Created by a Swede, Waldemar Jungner.
1902 / Patented in the U.S. by Edison.
1946 / Production began in the U.S.
1947 / Technological advances lead to creation of the
modern sealed battery.
1990s / Sales plummeted due to increasing popularity of
NiMH and Li-ion batteries.
Components
Four parts:
NiOOH cathode.
Cd anode.
Separator.
KOH electrolyte.
Uses
Can be used in electronics and toys.
Good for power tools!
NiCads operate at full capacity for an entire charge.
Also used with remote-controlled toys.
Electrochemistry
Half-reaction at the anode oxidizes cadmium.
Cd + 2OH- → Cd(OH)2 + 2eHalf-reaction at the cathode reduces nickel oxide-hydroxide.
NiO(OH) + H2O + e- → Ni(OH)2 + OHThe net redox reaction:
2NiO(OH) + Cd + 2H2O → 2Ni(OH)2 + Cd(OH)2
Secondary Cell
NiCad batteries are secondary cells.
The redox reaction is reversible but goes forward
spontaneously.
An electrical current can force the reaction to go
backwards by changing the flow of electrons.
Advantages
Low internal resistance.
Works safely from -400C to 700C and thus is more reliable than Li-ion
batteries.
Can be used for 500 recharge cycles.
Endothermic charging allows for short recharge times.
The electrolyte, KOH, is easy to obtain.
Can be made in many different sizes and capacities.
Disadvantages
Easily damaged by overcharging.
Cadmium is a toxic heavy metal that pollutes landfills
and must be carefully disposed of.
It’s also really expensive!
NiMH and Li-ion batteries have replaced NiCad batteries
in the last two decades because of their relative
affordability.
The Memory Effect
Another disadvantage of NiCd batteries
Occurs from repeatedly recharging a battery that isn’t
fully discharged.
Can also be caused by long periods of inactivity and exposure to high
temperatures.
These lead to a buildup of cadmium crystals.
Battery voltage drops significantly even though the
battery isn’t near complete discharge.
Can be prevented with full recharge cycles.
Manufacturing
1. Nickel powder sintered on a wire mesh.
2. NiOOH and Cd deposited on the plate.
3. Nickel tab welded onto the plate corners.
4. Multiple plates put together by aligning tabs.
5. Porous plastic separator placed between.
6. Aqueous KOH added.
Disposal
It’s dangerous to throw away or incinerate NiCads.
Most countries try to recycle these batteries.
Short-term exposure to cadmium can cause pneumonitis.
Long-term exposure can cause lung cancer and kidney
damage.
The EU has banned all NiCad sales except for medical
use, alarms, emergency lighting, and power tools.
Wet Cell
Wet Cell NiCd batteries use liquid cadmium and solid Nickel
Maintains a solid 1.2 V discharge up until it is depleted
Advantages: Maintains its voltage as opposed to slowly losing it, durable.
Disadvantages: Hard to determine charge, extremely heavy, spillage hazards
Used mostly for heavy industrial purposes now due to cost and safety dangers.
Ventilated
Used for large capacities and high discharge rates.
Releases excess hydrogen or oxygen gas created by redox reactions.
Safer, weighs less, and cheaper than other cells.
It is not damaged by overcharge, discharge, or negative charge.
Lasts 20 years longer than other NiCads.
Used in aviation, rail and mass transit, and telecoms backup power.
Electrolyte must be replaced regularly.
Dry Cell
Uses a paste electrolyte.
Cathode rod with anode wrapped around.
Only uses the moisture necessary for current to flow.
Good for portable things because it can operate in any
position!
Citations
"Toxic Heavy Metal." Wikipedia. Wikimedia Foundation, 10 May 2015. Web. 10
May 2015.
"Commercial Galvanic Cells." - Chemwiki. 2015. Web. 10 May 2015.
"Memory Effect - What It Is and What You Can Do about It." Memory Effect What It Is and What You Can Do about It. Zbattery.com. Web. 10 May 2015.
"The Truth About NiCd Batteries - Hardware Secrets." The Truth About NiCd
Batteries. Hardware Secrets, 6 Mar. 2006. Web. 10 May 2015.
"Battery and Energy Technologies." Nickel Cadmium NiCad Batteries.
Electropedia. Web. 10 May 2015.
"What Is a Nickel Cadmium Battery? - How a Battery Works." About.com
Inventors. About.com. Web. 10 May 2015.
"Wet Cell Batteries." Wet Cell Battery Recycling. Battery Solutions, n.d. Web. 10 May 2015.
Torres, Gabriel.
"Nickel-cadmium battery." Wikipedia. Wikimedia Foundation, 10 May 2015. Web. 10
May 2015.
Dingrando, Laurel. Chemistry: Matter and Change. New York, N.Y.: Glencoe/McGraw-Hill, 2002.
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