Nickel-Cadmium Cell
Definition and meaning of Nickel-Cadmium Cell in chemistry.
A nickel-cadmium cell is a common type of rechargeable battery. It uses chemical reactions between cadmium and nickel compounds to store energy. People often call this specific power source a NiCad battery.
In more detail
Inside the cell, the anode is made of solid cadmium metal. The cathode consists of nickel oxide hydroxide material. Both sides sit in a liquid called potassium hydroxide.
This liquid acts as the electrolyte to carry charged ions. A chemical change happens when you use the battery to power a device. The cadmium metal loses electrons and oxidizes into cadmium hydroxide.
The nickel oxide hydroxide gains electrons and reduces to nickel hydroxide. These moving electrons flow through your electronic device to power it. The exact opposite happens when you plug the battery in to recharge.
The strong electric current forces the chemicals back to their original forms. A single cell usually gives out about 1.2 volts of power. These heavy batteries are very tough and can take a lot of abuse.
They handle overcharging and deep freezing better than most other common batteries. They can also provide short bursts of very high electrical power. A major downside to this battery chemistry is the memory effect.
They lose maximum capacity if you recharge them before they are fully empty. The battery acts like it remembers this shorter life span. Furthermore, cadmium is known as a very toxic heavy metal.
This makes the batteries bad for the environment when thrown in the trash. Because of this, modern devices mostly use lithium-ion batteries instead. Students often confuse the flow of chemical ions with the flow of electrons.
The electrons only travel through the metal wires outside the battery. The potassium hydroxide electrolyte only moves charged ions inside the battery cell. The liquid does not allow electrons to pass straight through it.
Key facts
| Cell Reaction | Cd + 2NiO(OH) + 2H2O yields Cd(OH)2 + 2Ni(OH)2 |
|---|---|
| Nominal Voltage | 1.2 V per cell |
| Cycle Life | 500 to 1000 cycles |
| Anode material | Metallic cadmium |
| Electrolyte | Potassium hydroxide (alkaline) |
| Field | Inorganic Chemistry |
For many years, cordless drills relied heavily on NiCad batteries. The batteries could quickly push out the large amount of current needed. A builder could run the drill motor hard without breaking the battery. A typical drill battery could last for a thousand charge cycles.
Frequently asked questions
What is the memory effect in NiCad batteries?
If you recharge the battery before it is completely dead, it loses some maximum capacity. It acts like it remembers this smaller size. You must fully drain it to fix this issue.
Why do we not use NiCad batteries much anymore?
Cadmium is very toxic and harms the environment when thrown in landfills. Newer lithium batteries hold more energy and do not use toxic cadmium.
What does the potassium hydroxide do inside the battery?
It acts as the electrolyte to complete the electrical circuit. It lets charged hydroxide ions move between the two metal sides. It does not get used up in the main reaction.