Lead-acid batteries are prone to a phenomenon called sulfation, which occurs when the lead plates in the battery react with the sulfuric acid electrolyte to form lead sulfate (PbSO4). Over time, these lead sulfate crystals can build up on the plates, reducing the battery’s capacity and eventually rendering it unusable.
Their sulfuric-acid electrolyte transfers a quantity of sulfate to the plates, and recovers it respectively during these alternating phases. Lead battery sulfation impedes the flow of electrical charges when discharging, until the battery is technically ‘flat’. However, sulfation need not be permanent.
Lead battery sulfation impedes the flow of electrical charges when discharging, until the battery is technically ‘flat’. However, sulfation need not be permanent. A lead battery goes through the sulfation / de-sulfation routine numerous times during its active life. This is because the sulfate is still ‘soft’, and almost all of it removes easily.
Normally, as the lead–acid batteries discharge, lead sulfate crystals are formed on the plates. Then during charging, a reversed electrochemical reaction takes place to decompose lead sulfate back to lead on the negative electrode and lead oxide on the positive electrode.
But if you do this continuously, or even just store the battery with a partial charge, it can cause sulfating. (Spoiler alert: sulfation is not good.) Sulfation is the formation of lead sulfate on the battery plates, which diminishes the performance of the battery. Sulfation can also lead to early battery failure. Pro tips:
A lead acid battery consists of a negative electrode made of spongy or porous lead. The lead is porous to facilitate the formation and dissolution of lead. The positive electrode consists of lead oxide. Both electrodes are immersed in a electrolytic solution of sulfuric acid and water.