Silver–cadmium battery facts for kids
A silver–cadmium battery is a special type of rechargeable battery. It uses cadmium metal for its negative side and silver oxide for its positive side. Inside, it has a liquid called an electrolyte which is made of water and a chemical called potassium hydroxide.
This battery produces about 1.1 volts of power. It can store about 40 watt-hours of energy for every kilogram it weighs. Silver-cadmium batteries can hold more energy than nickel-cadmium batteries of the same weight. They also last longer than silver-zinc batteries. However, they give out less voltage and store a bit less energy than silver-zinc ones.
The main reasons these batteries are not used everywhere are the high cost of silver and the fact that cadmium can be harmful if not handled safely.
A Look Back: History of Silver-Cadmium Batteries
The first silver–cadmium batteries were created around 1900. A scientist named Waldemar Jungner developed them. He even used them in an electric car to show how they worked! His company then started making these batteries for sale.
However, these early batteries didn't last very long. It wasn't until 1941 that a better material was invented. This new material helped stop the silver oxide from moving around inside the battery. This made the batteries last much longer.
In the 1950s, people started working on these batteries again. They wanted to use them because they lasted longer than silver-zinc batteries.
How Silver-Cadmium Batteries Work
Like other batteries that use silver oxide, silver–cadmium batteries keep a steady voltage as they are used up. This means the power stays pretty much the same until the battery is almost empty.
The positive part of the battery is made from silver powder pressed onto a silver grid. The silver oxide can be made separately or formed when the battery is first charged. The negative part is made from cadmium.
The liquid inside, the electrolyte, is a mix of potassium hydroxide and water. These batteries often have special caps. These caps stop the liquid inside from reacting with air.
When you charge a silver-cadmium battery, the voltage needed is higher than the voltage it gives out when it's being used. This means about 70% of the energy put in during charging is used. The battery is usually charged slowly, over 10 or 20 hours. Charging stops when the battery reaches about 1.6 volts per cell.
These batteries are made in many sizes. They can range from small ones (2 ampere-hours) to very large ones (2500 ampere-hours). They are often made specially for different uses.
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