|Battery Application & Technology
All lead-acid batteries operate on the
same fundamental reactions. As the battery discharges, the
active materials in the electrodes (lead dioxide in the
positive electrode and sponge lead in the negative
electrode) react with sulfuric acid in the electrolyte to
form lead sulfate and water. On recharge, the lead sulfate
on both electrodes converts back to lead dioxide (positive)
and sponge lead (negative), and the sulfate ions (SO42
) are driven back into the electrolyte solution to form
sulfuric acid. The reactions involved in the cell follow.
At the positive electrode:
At the negative electrode:
Therefore the maximum open-circuit voltage
that can be developed by a single lead-acid cell is 2.041 V.