Practical batteries have come a long way since it was first made. Daniell cell, Porous cell, Gravity cell, Grove cell, Dun cell were all cells which used to be drained when either their acidic electrolyte or the electrodes were consumed. These were called the primary cells. In 1859, Gaston Plante invented the Lead-acid battery which could be recharged by passing a reverse current where the chemical reactions taking place could be reversed. And thus the first rechargeable battery was born. Batteries which can be recharged are called the secondary cells. Lead-acid battery had sulphuric acid as electrolyte and lead in anode and lead dioxide as cathode.
- How Ni-Cd batteries came into existence:
In 1899, a Swedish scientist by the name Waldemar Junger invented the Nickel- Cadmium (Ni-Cd) batteries which were the first ones to have an alkaline electrolyte, instead of an acidic one. Nickel Cadmium battery uses Nickel oxide hydroxide and metallic Cadmium as electrodes and Potassium hydroxide as electrolyte. They have a separator which ensures that both the anode and cathode do not touch and form a short circuit. They had better energy density than the Lead-acid batteries.
- Uses of Ni-Cd batteries:
Ni-Cd batteries were used in portable power tools, biomedical instruments, professional photography instruments, two-way radios especially in the airline industry and flashlights and emergency lightings.
- Advantages of Ni-Cd batteries:
One of the main advantages of Ni-Cd battery is that it delivers practically its full power even at high discharge rates till the end of its discharge cycle.
The sealed Ni-Cd cell can be stored and has a long shelf time in its charged or discharged state.
And with proper care and a little cleaning, more cycles of charging and discharging can be obtained.
It is unaffected by low temperatures or change in temperatures.
They have low internal resistance. Because of this they are able to discharge as well as accept (charge) a lot of power very easily.
Since the internal temperature is less, they can be charged or discharged very fast.
They are able to maintain a steady voltage until they are completely discharged.
It is economically priced and comes in a lot of sizes and lots of variations based on its functionality.
- Why it is used in portable power tools:
Ni-Cd cells maintain steady power till the end of discharge cycle. So the power tools are able to operate at same speed throughout. But with other type of cells, the power tool has high power during the initial stages and almost slows down and dies after the first stage.
Ni-Cd battery was widely used in cassette players, remotes and calculators because of its low self-discharge rate.
Even though the newer Ni-MH batteries and the Li-ion batteries have replaced the Ni-Cd batteries, it is still used in air flights and in places where very high discharge rates are required.