Q-Batteries电池内部 – 铅酸电池是如何工作的？

Alongside the development of technology, batteries become one of the most crucial components in powering modern devices. One of the battery technologies types that is known as the oldest technology that is still being used massively up until now is lead acid. Lead acid batteries have been known to provide reliable performance since long ago, so even now battery technology has developed rapidly, and lead acid is still one of the most popular technologies.

However, while many of us are aware of the various advantages that lead acid batteries offer, do you know how does lead acid battery work in generating energy? In this article, we will discuss thoroughly how does lead acid battery work up to the applications that are known to still use this type of battery as a source of energy.

What is Lead Acid Battery?

Before understanding further how a lead-acid battery works, it is better to first understand what battery acid is. So, battery acid is a term referring to the sulfuric acid solution (H2SO4) used as an electrolyte in a battery, especially in lead-acid batteries.

Lead-acid batteries themselves are known as rechargeable batteries and are one of the oldest battery technologies that still attract interest today because they are able to provide large capacities at more affordable prices. This type of battery is widely used for conventional vehicles with fossil fuels and various energy storage systems.

Chemical Composition of Battery Lead Acid

The chemical composition contained in a battery typically affects how the battery works. Therefore, to understand more about how does lead acid battery work, we’ll discuss the chemical composition of lead acid batteries first. The chemical and physical properties contained in a battery allow redox (reduction-oxidation) reactions to occur to produce electric current. The following is a detailed explanation of the chemical composition of lead acid batteries to understand further how does lead acid battery work.

Chemical Composition

Lead acid batteries generally consist of a mixture of two main components as follows.

• Sulfuric Acid (H₂SO₄): A colorless but slightly yellowish strong mineral acid.
• Water (H₂O): Used to dilute sulfuric acid to a concentration point suitable for a battery (around 30-50%).

When the two solutions are mixed, an exothermic reaction will occur that produces H⁺ and SO₄^2- ions that will act as electrical charge carriers in the solution.

Physical Properties of Lead Acid Batteries

A combination of two chemical compositions, makes battery acid have its own physical and chemical properties. The following are the physical properties possessed by lead acid batteries.

• Color: Usually lead acid battery solution has no color and only clear, but it can turn cloudy if contaminated.
• Specific gravity: Lead acid batteries have a specific gravity of about 1,265 g/cm3 when the battery is full.
• Solubility: Highly soluble in water, but mixing of the two solutions should be done very carefully.
• Boiling Point: Has a boiling point of about 300°C for pure H₂SO₄, but because the lead acid battery solution has been diluted, the boiling point can be lower.
• Melting Point: H₂SO₄ is known to have a melting point of about 10°C, but the solution form of the melting point will vary more.

Chemical Properties of Lead Acid Batteries

In addition to physical properties, battery acid is also known to have chemical properties as follows.

• Corrosive: The sulfuric acid contained in lead acid batteries can cause serious burns against the skin or even damage metals and organic materials.
• Reactive: Easily reacts with metals, so when they contact it will produce flammable hydrogen gas.

Read how dangerous is battery acid to understand more about the risks posed by lead acid batteries.

Properties Change During Use

When the battery is in use, the sulfuric acid concentration will decrease as it reacts to form lead sulfate (PbSO₄) and water. This also causes the specific gravity of the solution to decrease and the ability to produce electric current drops. This is what makes specific gravity used as an indicator of how to check battery health in lead-acid batteries.

Basic Components of Lead Acid Battery

To understand further how does lead acid battery work, it’s also important to understand the main components that compose lead acid batteries. Each constituent component of lead-acid batteries has its own specific role in generating and storing electrical energy. The lead acid battery’s internal structure is designed so that chemical reactions can proceed efficiently during the charging and discharging process. The following is an explanation of the main components of lead-acid batteries.

• Cathode (Positive Plate): The raw material commonly used is made of lead dioxide (PbO₂) which is commonly colored dark or almost black. This component functions as an oxidizer when the battery releases energy and the place where the chemical reaction produces lead sulfate (PbSO₄) when used.
• Anode (Negative Plate): The raw material of this component consists of sponge lead (Pb) which is soft and easily oxidized. This component will function as a reductor during the discharge process.
• Electrolyte: A sulfuric acid solution (H₂SO₄) that has been mixed with water and serves to transfer ions from the cathode to the anode and vice versa. The electrolyte concentration in lead acid batteries itself can change depending on the state of charge.
• Separator: A thin membrane that separates the anode and cathode, usually made of acid-resistant materials such as fiberglass or polyethylene.
• Battery Case: The main material usually used for lead acid battery cases is made of acid-resistant plastic materials such as polypropylene. The battery case is used to protect the internal components of the battery from physical and chemical damage.

How Does Lead Acid Battery Work?

After understanding well the main components and chemical composition of lead acid batteries, we’ll discuss specifically how does lead acid battery work in this session. Lead acid batteries work based on the principle of converting chemical energy into electrical energy during discharging and work the other way when recharged. Understanding how does lead acid battery work is crucial to know how the battery supplies power and why its maintenance affects its lifespan and performance.

Discharging Process

In the discharge process, lead acid batteries will work as follows.

• When the battery is connected to a load (such as a motor or lamp), a reaction will occur between the plates and the electronics. The chemical reaction will occur as follows.
  PbO₂ + Pb + 2H₂SO₄ → 2PbSO₄ + 2H₂O

• Electrons flow from the negative plate (Pb) to the positive plate (PbO2) through the external circuit, producing an electric current for the connected device.
• Inside the battery itself, H⁺ and SO₄^2- ions will move through the electrolyte to maintain charge balance.
• Both plates will become lead sulfate (PbSO₄), and the electrolyte will become more diluted as water (H₂O) is formed.
• As a result, the sulfuric acid concentrations will decrease and cause the battery voltage to decrease.

Charging Process

In charging process, the battery will work in reverse. Here is how does lead acid battery work when the charging process is in progress.

• When electric current is applied from an external source (such as an alternator or charger), the flow direction will immediately reverse and the reaction will change. Chemical reactions during the charging process will occur as follows.
  2PbSO₄ + 2H₂O → PbO₂ + Pb + 2H₂SO₄

• Electrical energy will force the chemical reaction to move backward, where the electric current will break down PbSO₄ back into PbO₂ and Pb.
• Water will be converted back into sulfuric acid, thus increasing the electrolyte concentration.
• This will cause the battery voltage to rise back to its full state.

Charging and Discharging Cycle of Lead Acid Battery

The charge and discharge cycle is essentially an iterative process that determines a lead acid battery’s lifespan and performance. Each time a battery is used and recharged, it is referred to as one cycle. Understanding this process will guide us know more about how to maintain the battery efficiently.

• Discharge Cycle: As the battery is used, the voltage will slowly decrease as the active substance is depleted. The battery is considered discharged when its voltage drops to the minimum point.
• Charging Cycle: When the battery is in charging mode, the battery voltage will slowly increase and return to normal, this makes the electrolyte density increase again and the battery can be used for the next use.
• Depth of Discharge (DoD): DoD usually calculates how much battery capacity is used in one cycle. The deeper the state of discharge, the shorter the battery life.
• Lifespan and Degradation: Lead acid batteries typically have a battery life cycle of around 200-500 cycles before slowly experiencing a capacity degradation. This nominal cycle can vary based on how the battery is maintained and used.

Applications of Lead Acid Battery

Lead acid batteries have been used for more than a decade for various applications because of their relatively low cost. Instead of that, these types of batteries also provide plenty of advantages such as reliability and high current, ideal for various applications that need high power. Although it is known that there are modern technologies that are more reliable and popular, lead acid batteries are known to still be one of the mainstays in various application sectors. Here are some applications that are known to use lead acid batteries as an energy source.

• Conventional Vehicles: Conventional vehicles such as gasoline/diesel motorcycles and cars are known to still use lead acid batteries to start the engine and various electrical systems such as lights and others. Lead acid batteries are very suitable for this type of application as they can provide a large current to be able to start the vehicle engine.
• Electrical Backup System (UPS): Lead acid batteries also can be used as a temporary backup power source when the electricity goes out. This system is also widely used in crucial sectors such as hospitals, offices, data centers, telecommunications, and other important facilities to ensure that crucial devices continue to work optimally.
• Renewable Energy (Solar & Wind Systems): In renewable energy systems, lead acid batteries act as energy storage from solar panels or wind turbines for nighttime use or when the main power supply is unavailable.
• Emergency Power Systems: Lead-acid batteries are also widely used in emergency power systems such as emergency lights, fire alarms, and evacuation systems when the primary source fails.

Conclusion

So, how does lead acid battery work? Lead acid batteries generally work based on the principle of converting chemical energy into electrical energy through the reaction between lead plates and sulfuric acid solution. All of the main components of a lead acid battery– the two electrodes, the electrolyte, the separator, and the casing– work together in a repeatable cycle of charging and discharging.

Although it is known that this technology has been around for a long time, lead acid batteries are still one of the reliable choices in the market today. By understanding how does lead acid battery work, we can use these batteries more efficiently and can maintain them properly so that they have a longer lifespan.