Lead acid Battery
Now let’s move on to rechargeable battery! This is a lead-acid battery. It is a wet-cell, secondary battery. In the charging state, it uses pure lead as the negative electrode and PbO2 on the positive side. And for the electrolyte, it uses an aqueous sulphuric acid.
You might see it at places such as your car battery. It is the most economical battery for large power applications where weight is not the priority. Although it has a very low energy to weight and energy to volume ratio, it’s able to have a relatively large power to weight ratio, combined with the low cost makes it a very attractive option for providing the current required by motor vehicles.
This is the schematic of a lead-acid battery:
This is the chemical reaction for a lead-acid battery:
It has a gravimetric energy density of 30~50 Wh/kg (Wh = watt-hour), a cycle life of 200 to 300, a cell voltage of 2V. And the typical battery cost of $25 (7.,2V) (which is $0.10 cost per cycle)
Its application is at places such as hospital equipment, wheelchairs, emergency lighting.
However, there is a risk of explosion when it is excessively charged, which will emit hydrogen and oxygen, and the accumulation of both of the sometimes ignite it and close an internal explosion.