Introduction to Lead Acid Battery: Construction, Working Principle and Types

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In the year 1801, a French physicist named Nicolas Gautherot discovered that even though the main battery is disconnected, there is a small volume of current in electrolysis research. In 1859, a physicist named Gatson invented the lead acid battery, which was the first to be recharged by the passage of reverse current. This was the first prototype of this kind of battery, to which Faure added more improvements until Henri Tudor invented the practical type of lead acid battery in 1886. Let us delve deeper into this kind of battery, its operation, types, structure, and advantages.

The rechargeable and secondary batteries category includes lead acid batteries. Despite the battery's low energy-to-volume and energy-to-weight ratios, it can deliver higher surge currents. This refers to the fact that lead acid cells have a high power-to-weight ratio.

These are the batteries that transform chemical energy into electrical energy by using lead peroxide and sponge lead. Because of the elevated cell voltage levels and low cost, these are commonly used in substations and power systems.

I. Construction of Lead Acid Battery

The plates and containers are critical elements in the design of a lead acid battery. Each part used in the construction is described in detail in the section below. The schematic of a lead acid battery is seen below:

Container of Lead Acid Battery

This jar component is made of ebonite, lead-coated wood, glass, bituminous hard rubber, ceramic materials, or forged plastic, both of which are mounted on the surface to prevent any electrolyte discharge. In the bottom portion of the container, there are four ribs, two of which are mounted on the positive plate and the others on the negative plate.

The prism serves as a foundation for both plates while also protecting them from short-circuiting. The materials used in the container's construction should not contain sulphuric acid, should not bend or permeate, and should not carry any impurities that could cause electrolyte harm.

Plates of Lead Acid Battery

The plates in a lead acid battery are built in a variety of ways, but they are all made up of the same types of grid, which is made up of active components and lead. The grid is essential for establishing current conductivity and distributing equal quantities of current to the active components. There would be loosening of the active variable if the distribution is unequal. There are two types of plates in this battery. Plante/formed plates and Faure/pasted plates are the two types.

The shaped plates are mostly used in static batteries, and they are both heavy and costly. However, even in continual charging and discharging cycles, they have a long lifespan and are unlikely to lose their active components. This has a low capacity-to-weight ratio.

Although the pasted procedure is more commonly used to create negative plates than positive plates, it is often used to create positive plates. The negative active aspect is more complex, and the charging and discharging mechanisms are slightly altered.

Active Component of Lead Acid Battery

An active component is one that actively participates in the chemical reaction processes that occur in the battery, mostly during charging and discharging. The following are the active ingredients:

• Peroxide of lead – It is a beneficial active ingredient.

• Sponge lead is the negative active portion of the system.

• Sulphuric acid, diluted – This is mostly used as an electrolyte.

Separators of Lead Acid Battery

Porous rubber, treated leadwood, and glass fiber are used to make these thin boards. The separators are used to provide active insulation between the plates. In one rim, they have a grooved form, while the other sides are flat.

Battery Edges of Lead Acid Battery

It has 17.5 mm and 16 mm diameter positive and negative tips, respectively.

II. Working Principle of Lead Acid Battery

Since sulphuric acid is used as an electrolyte in the battery when it dissolves, the molecules are scattered as SO4– (negative ions) and 2H+ (positive ions), which are free to travel. As these electrodes are dipped in the solutions and a DC supply is given, the positive ions begin to travel in the direction of the battery's negative side. Negative ions can also pass in the same direction as the positive ions, moving towards the positive edge of the battery.

Each hydrogen and sulfate ion collects one and two electrons, as well as negative ions, from the cathode and anode, and reacts with water. As a result, hydrogen and sulphuric acid are produced. The products of the above reactions combine with lead oxide to produce lead peroxide. This means that during the charging phase, the lead cathode part remains as lead, while the lead anode is formed as dark brown lead peroxide.

If there is no DC supply and a voltmeter is attached between the electrodes, the potential discrepancy between the electrodes is shown. The flow of current from the negative to the positive plate by an external circuit occurs when wires are connected between the electrodes, indicating that the cell has the potential to produce an electric source of energy.

III. Types of Lead Acid Battery

Sealed Type – This type of lead-acid battery is merely a variation on the flooded type. About the fact that no one has access to each cell in the battery, the internal architecture is nearly identical to that of a flooded form. The biggest difference with this form is that there is a sufficient volume of acid to allow for a smooth flow of chemical reactions during the battery's existence.

VRLA Form – Also known as a sealed type of battery, these are known as Valve Controlled Lead Acid batteries. At the point of charging, the value controlling process allows for the stable evolution of O2 and H2 gases.

AGM Type – This is an Absorbed Glass Matte battery, which allows the electrolyte to be stopped at the plate material. This type of battery improves the discharge and charging processes' performance. These are mostly used in motorsports and engine start-up applications.

Gel Type – This is a wet type of lead-acid battery in which the electrolyte in the cell is silica-based, causing the material to stiffen. As compared to other forms, the recharge voltage values of the cell are small, and it also has more sensitivity.

IV. Features of Lead Acid Battery

1. Lead Acid Battery Chemical Reaction

The chemical reaction in the battery occurs primarily during the discharging and recharging processes, and it is described as follows:

When the battery is fully charged, the anode and cathode are PbO2 and Pb, respectively. As these are associated with resistance, the battery is discharged, and the electrons are charged in the opposite direction. The H2 ions pass into the anode and fuse together to form an atom. It reacts with PbO2 to produce PbSO4, which is white in color.

Similar to the sulfate ion, the sulfate ion moves into the cathode, where it is converted into SO4. It becomes lead sulfate as it reacts with the lead cathode.

PbSO4 + 2H = PbO + H2O

PbO + H2SO4 = PbSO4 + 2H2O

PbO2 + H2SO4 + 2H = PbSO4 + 2H2O

The cathode and anodes are connected to the negative and positive edges of the DC supply during the recharging process. The positive H2 ions pass into the cathode, gaining two electrons and becoming an H2 atom. It forms lead and sulphuric acid after a chemical reaction with lead sulfate.

2. Lead Acid Battery Life

The optimum operating temperature for a lead acid battery is 250 degrees Celsius, or 770 degrees Fahrenheit. Longevity is shortened as the temperature spectrum widens. According to the law, any 80°C rise in temperature decreases the battery's half-life. A performance-operated battery with a 250C operating temperature has a lead acid battery life of ten years. And it only has a 5-year life span when maintained at 330 degrees Celsius.

3. Applications

• Used in electric motors

• Submarines

• Nuclear submarines