Why can't a lead storage battery be recharged indefinitely?
A direct current must pass through the cells.
The electrodes lose lead sulfate.***
It is difficult to reverse the direction of current flow.
The electrolyte is too expensive.
the electrodes lose lead sulfate
The correct answer is: The electrodes lose lead sulfate.
A lead storage battery, also known as a lead-acid battery, is commonly used to store electrical energy and provide power to vehicles, UPS systems, and other applications. The battery consists of two lead electrodes immersed in a sulfuric acid electrolyte.
During the discharging process, the lead sulfate (PbSO4) formed on the electrodes breaks down into lead (Pb) and sulfuric acid (H2SO4), while releasing energy. However, when the battery is recharged, the reverse reaction occurs. The lead and sulfuric acid combine to form lead sulfate. This is a reversible chemical reaction.
Although the recharging process is generally efficient, it is not 100% perfect. Some of the lead sulfate formed during discharging may not fully convert back into lead and sulfuric acid during recharging. This results in a gradual accumulation of lead sulfate on the electrodes over multiple charge and discharge cycles.
This buildup of lead sulfate on the electrodes, known as sulfation, gradually reduces the battery's capacity and overall performance. The lead sulfate crystals can become physically and chemically hard, making it difficult for them to dissolve during the recharging process. This leads to decreased efficiency and capacity of the battery over time.
Therefore, a lead storage battery cannot be recharged indefinitely because of the gradual loss of active material on the electrodes due to sulfation. Eventually, the battery's capacity diminishes to the point where it can no longer effectively store and deliver electrical energy, requiring it to be replaced.