The lead-acid storage battery, commonly known as the lead storage battery, is a type of rechargeable battery used in various applications such as automobiles, uninterruptible power supplies (UPS), and solar energy storage. It consists of several lead plates immersed in a sulfuric acid electrolyte solution.

Here’s a simplified explanation of the working of a lead storage battery:

1. Electrodes: The lead storage battery has two types of electrodes: a negative electrode (cathode) and a positive electrode (anode). The negative electrode is made of lead (Pb), and the positive electrode is made of lead dioxide (PbO2). Both electrodes are immersed in a sulfuric acid (H2SO4) electrolyte solution.
2. Discharge:
   • During discharge (when the battery is being used), the chemical reactions occur as follows:
   • At the negative electrode (cathode): Pb(s) + HSO4-(aq) → PbSO4(s) + H+(aq) + 2e-
   • At the positive electrode (anode): PbO2(s) + 3H+(aq) + HSO4-(aq) + 2e- → PbSO4(s) + 2H2O(l)
   • Overall cell reaction: Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)
   In this process, lead (Pb) at the negative electrode combines with sulfate ions (SO4²-) from the electrolyte to form lead sulfate (PbSO4) on both electrodes. The release of protons (H+) and the flow of electrons create an electric current that can be utilized for powering devices.
3. Charging:
   • During the charging process (when the battery is being recharged), an external electrical source is connected to the battery terminals. This causes the direction of the chemical reactions to reverse, effectively regenerating the reactants.
   • The lead sulfate (PbSO4) formed during discharge at both electrodes is converted back to lead (Pb) at the negative electrode and lead dioxide (PbO2) at the positive electrode.
   • The overall reaction during charging is the reverse of the discharge reaction.
4. Reversibility:
   • The lead storage battery can be charged and discharged multiple times due to the reversible nature of the chemical reactions.
   • However, repeated charging and discharging can lead to the gradual accumulation of lead sulfate (PbSO4) on the electrodes, which can reduce the battery’s performance over time. This is known as sulfation and can be mitigated by proper charging and maintenance.

The lead storage battery relies on the reversible reactions between lead and lead dioxide and their conversion to lead sulfate during charge and discharge cycles. The repeated conversion between these states allows the battery to store and release electrical energy efficiently.