Lead-acid batteries work by harnessing the chemical reactions between lead plates and sulfuric acid to store and release electrical energy. The reaction is reversible, so the battery can be recharged.
The formation of this lead sulfate uses sulfate from the sulfuric acid electrolyte surrounding the battery. As a result, the electrolyte becomes less concentrated. Full discharge would result in both electrodes being covered with lead sulfate and water rather than sulfuric acid surrounding the electrodes.
What is a lead acid battery?
It consists of a spongy metallic lead anode, lead dioxide (PbO 2) cathode, and an electrolyte of a diluted mixture of aqueous sulfuric acid (H 2 SO 4) with a voltage range of 1.8–2.2 V. Lead–acid batteries are shock-resistant, reliable, durable, cheap, and capable of withstanding extreme temperatures .
Voltage of lead acid battery upon charging. The charging reaction converts the lead sulfate at the negative electrode to lead. At the positive terminal the reaction converts the lead to lead oxide. As a by-product of this reaction, hydrogen is evolved.
The chemistry of lead-acid batteries involves oxidation and reduction reactions. During discharge, lead dioxide and sponge lead react with sulfuric acid to produce lead sulfate (PbSO4) and water. When recharged, the process is reversed, regenerating lead dioxide, sponge lead, and sulfuric acid.
What happens if a battery reacts with a sulfuric acid?
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.
Efficiency: Lead acid batteries typically operate at about 70-80% efficiency. This means that a portion of the energy is lost as heat during the conversion processes. Applications: Lead acid batteries are widely used in automobiles, uninterruptible power supplies, and renewable energy storage systems.