Lead–acid battery

Lead–acid battery is a type of rechargeable battery that uses lead dioxide (PbO2) on the positive plate, sponge lead (Pb) on the negative plate, and sulfuric acid (H2SO4) solution as the electrolyte. It was invented by French physicist Gaston Planté in 1859 and is the oldest type of rechargeable battery still in widespread use. Lead–acid batteries are widely used in various applications, including automobiles, uninterruptible power supplies (UPS), golf carts, and marine equipment, due to their ability to supply high surge currents and their low cost.

History

The lead–acid battery was invented in 1859 by Gaston Planté and has undergone numerous improvements and modifications over the years. Its ability to provide high surge currents relative to its capacity has made it the battery of choice for motor vehicles that require a large current to start the engine.

Construction and Chemistry

A lead–acid battery consists of a series of lead dioxide (PbO2) plates, which serve as the positive electrodes, and sponge lead (Pb) plates, which serve as the negative electrodes. These plates are immersed in a solution of sulfuric acid (H2SO4), which acts as the electrolyte. The chemical reaction between the lead dioxide, sponge lead, and sulfuric acid generates electrical energy.

When the battery is discharging, the lead dioxide (positive plate) reacts with the sulfuric acid to form lead sulfate (PbSO4) and water (H2O), releasing electrons. Simultaneously, the sponge lead (negative plate) reacts with the sulfuric acid to form lead sulfate and hydrogen ions, absorbing electrons. This process results in a flow of electrons from the negative to the positive terminal, creating an electric current.

During charging, the process is reversed. Electrical energy is applied to the battery, causing the lead sulfate to decompose back into lead dioxide, sponge lead, and sulfuric acid, restoring the battery's charge.

Types

Lead–acid batteries come in several types, each designed for specific applications. The main types include:

• Flooded or Wet Cells: These batteries contain a liquid electrolyte and require regular maintenance, such as topping up with distilled water.
• Valve-Regulated Lead-Acid (VRLA) Batteries: These are sealed batteries that do not require regular maintenance. VRLA batteries are further divided into two types: Absorbent Glass Mat (AGM) and Gel batteries.
• AGM (Absorbent Glass Mat) Batteries: These use a fiberglass mat to absorb the electrolyte, making them spill-proof and more resistant to vibration.
• Gel Batteries: These contain a gelified electrolyte, which reduces the risk of leakage and extends the battery's life.

Applications

Lead–acid batteries are used in a wide range of applications, including:

• Automobiles: For starting, lighting, and ignition (SLI) systems.
• Uninterruptible Power Supplies (UPS): To provide backup power for computers and telecommunications equipment.
• Golf Carts and Electric Vehicles (EVs): As a power source for propulsion.
• Marine Equipment: For starting boat engines and powering electrical systems.
• Solar Power Systems: As storage for solar energy.

Advantages and Disadvantages

The main advantages of lead–acid batteries include their low cost, high surge current capability, and reliability. However, they also have several disadvantages, such as a relatively short lifespan, heavy weight, and the need for regular maintenance (for flooded types).

Environmental Impact

Lead–acid batteries are recyclable, and the lead and sulfuric acid can be recovered and reused. However, improper disposal can lead to environmental contamination. Recycling programs and regulations are in place to ensure that lead–acid batteries are disposed of safely.

See Also

• Battery (electricity)
• Lithium-ion battery
• Nickel-metal hydride battery

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