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The lead accumulator is a secondary cell because the electrical energy is not generated inside the cell but rather stored until being supplied by an external source.
It’s a reversible cell since the cell reactions are reversible if the applied external emf is sufficiently larger than the cell’s emf. As a result, total cell reactions are reversed in this cell by exerting external opposition to e.m.f that is bigger than the cell’s e.m.f.
This cell has the ability to store electrical energy from charging or an external source, and it can also supply energy during the discharge process. As a result, the energy is stored in chemical form. As a result, this cell denotes an accumulator, storage cell, or storage battery.
The voltage of the cells is not affected by the size of the electrodes or the size of the cell, but it is affected by the strength of the sulphuric acid solution.
Cell Discharging:
When the cell is turned on, oxidation takes place on the lead plates, followed by reduction using PbO (Lead Oxide). The discharge of the cell is the term for this.
Chemical reaction
The Negative Electrode’s Reaction (Anode)
At the positive electrode, the reaction occurs (cathode)
Now we’ll look at the cell’s overall reaction as it’s being discharged.
Cell charging:
When the emf operating outside is greater than the emf applied to the cell, accurate reverse reactions occur. On positive electrodes, oxidation occurs, while on negative electrodes, reduction occurs. The charging of the cell is the term for this process.
Uses of a Lead Accumulator:
As a result of their widespread use in automobiles and other vehicles, lead accumulators are commonly referred to as “car batteries.” Six cells are usually connected in series to provide a voltage of 12V.
In telegraph and telephone offices, lead accumulators are used.
They have access to radios, electric clocks, and burglar alarms, among other things.
They are used as a continuous DC voltage source in scientific laboratories.
Charging a Lead Acid Battery
The sulphuric acid in the lead discharge battery breaks down and must be refilled. The plates might change their structure on their own at times. The battery will eventually become less efficient and will need to be charged or replaced.
When automotive batteries are left in their drained states for long periods of time, the lead sulphate build-up can be difficult to remove. Lead-acid batteries must be charged as soon as possible for this reason (to prevent building up of lead sulfate). The lead batteries are normally charged by using an external current source.
The chemical reaction proceeds in the reverse direction once a plug is placed and connected to the lead-acid battery. The charging process may become ineffective in circumstances when the sulphuric acid in the battery (or another component of the battery) has decomposed. As a result, it’s a good idea to check the batteries on a regular basis.
What is the difference between a sealed lead acid battery and an open lead acid battery?
A 12-volt motorbike battery with six cells and a plastic casing is known as a sealed lead acid battery. Each cell has a set of positive and negative plates that are submerged in a weak sulphuric acid solution that serves as the electrolyte. When completely charged, each cell has roughly 2.1 volts. The six cells are wired together to create a 12.6-volt battery when fully charged.
So, how is it possible to make electricity by immersing lead plates in sulfuric acid? The battery works by converting chemical energy into electrical energy through an electrochemical reaction. The plates in each cell resemble a little square tennis racket. Lead calcium or lead antimony are used to make them. The plates are adhered to with a paste known as active material. The negative plates are made of sponge lead, whereas the positive plates are made of lead dioxide. When an electrical load is applied to the battery’s terminals, the chemical reaction with sulphuric acid occurs in the active material.
Recharging Chemical Reaction
The chemical reaction that occurs during the recharging of a lead-acid battery is shown below.
Negative:
Pb(s) + HSO4– + H2O(l) –> 2e– + PbSO4(s) + H3O+(aq) –> Pb(s) + HSO4– + H2O(l) (reduction)
Positive:
PbO2(s) + HSO4–(aq) + 3H3O+(aq) → 2e– + PbSO4(s) + 5H2O(l) –> PbO2(s) + HSO4–(aq) + 3H3O+(aq) + 2e– (oxidation)
The automotive battery behaves like an electrolytic cell during recharging. The energy required to power the recharge is provided by an external source, such as a car’s motor. It’s also worth noting that overcharging the battery can lead to the creation of by-products like hydrogen and oxygen gas. These gasses have a tendency to escape from the battery, resulting in reactant loss.
Conclusion
The oldest type of rechargeable battery is a lead acid battery, often known as a lead storage battery. As an energy storage device, the battery is widely used. Even though lead-acid batteries are extremely reliable, their lifespan is limited. Lead-acid batteries can take or supply energy very instantly, depending on the power conversion technology. Temperature has an effect on lead-acid batteries, which is why they require maintenance to extend their life.
