Difference Between Primary Cell And Secondary Cell

The battery is a cell that can generate electricity. A battery can have one or more electrochemical cells and is composed of terminals that can be connected to a device. The difference Between Primary Cell And Secondary Cell is that Primary cells can not be recharged if charged once. it is light in weight and has a short life. for recharging whole D.C material is to be replaced while a Secondary cell can be recharged after discharging. it is a heavyweight and has a long life.

Primary Cell vs Secondary Cell
Primary Cell vs Secondary Cell

Primary cells are capable of producing electrical current at the time of genesis. They are also called disposable batteries, as they are designed for single use only. These are the most commonly used cells in portable devices that do not require high voltage.

In principle, primary batteries cannot be reliably repeatedly filled because chemical reactions are not reversible and the materials used are unlikely to return to their primary state.

Secondary cells must be charged before use. Also called rechargeable batteries, they are recharged with electrical current, which reverses the course of the chemical reaction that occurs during the use of the battery.

In this post, you are going to learn about the Primary Cell vs Secondary Cell step by step with Diagrams.

This post also includes:

  • Main Difference – Primary vs Secondary Cell
  • What is the primary cell?
  • What is a secondary cell?
  • Difference between primary and secondary cells

So if you want to get benefits from this post you’ll love this post.

Let’s Dive right in..

Main Difference – Primary vs Secondary Cell

Batteries are cells that can generate electricity. A battery can have one or more electrochemical cells and is made up of terminals that can be connected to external devices that are powered by a power source. Primary cells and secondary cells are two types of batteries. 

The main difference between primary and secondary cells is that Primary cells can be used only once. while Secondary cells can be used more than once.

Difference Between Primary Cell and Secondary Cell in Tabular Form

Primary Cell

Secondary Cell

Primary Cells are easily useable and Have high energy density with slow in discharge. 

comparatively, Secondary Cells have smaller energy density.

they are charged once hence can’t be charged again. 

they have the ability to recharge on providing supply.

they are called dry cells because fluids are not present in it.

they are called wet cells because they made up of liquid or flooded along with molted salt.

it has a shorter life.

it has a long life.

internal resistance is high.

internal resistance is low.

used for intermittent works with the usage of the low current rate.

used often for condition ratings usually with the presence of heavyweight currents. 

the chemical reaction is irreversible.

the chemical reaction is reversible.

they provide and produce immediate current so often used for portable devices. 

they to be charged before the time of use and often used in large automobiles and vehicles. 

made for smaller and lighter designs.

made for more complex and heavier designs.

used only once.

can be used for several times. 

present with a cheap initial cost.    

present with a high initial cost. 

it has low life.

it has high life. 

Danial cells, dry cells, and leclanche cells are common examples.

nickel-iron and lead-acid cells are common examples.

Key Points We Covered

1. What are the primary cells?
      Definition, structure, chemical reactions
2. What are secondary cells?
      Definition, structure, chemical reactions
3. What is the difference between primary and secondary cells?
      Comparison of key differences

What is the primary cell?

Primary cells can be used once and discarded. They cannot be recharged and reused. The label on a primary cell always indicates that it should not be recharged because it is harmful to attempt recharging and it may explode if you do. The dry cell and the mercury cell are examples of primary cells. 

The primary cell is essentially a chemical cell and produces electrical current by an irreversible chemical reaction. Once the reaction is done, it cannot be reset. 

For instant, a dry cell consists of a carbon cathode surrounded by NH4Cl in a Zink container. A paste of NH4Cl and ZnCl2 serves as the electrolyte while the zinc container acts as the anode.

 A small amount of MnO2 also mixes with the electrolyte. The chemical process of a dry cell can be summarized as follows;

Zn ——> Zn2 ++ 2 electron (anodic reaction) NH4 + + MnO2 + electron ——> MnO (OH) + NH3 (cathodic reaction)

Primary cells are commonly found and used in most electrical toys, watches, wristwatches, and household remote controls.

Primary cells or primary batteries are also called non-rechargeable batteries. This is mainly because these batteries cannot be recharged when they are depleted and stop working. Although not reusable, primary cells are very useful for storing energy for long-term use because their self-discharge rate is relatively low. 

Therefore, its use can be observed in service pacemakers in cardiac patients, smart meters, and military campaigns where charging is impractical and impossible.

Primary cells are not rechargeable due to the chemical reactions that occur within the battery, which are irreversible. Chemical reactions use all the chemicals present in the cell and when all the chemical species are used, power generation is terminated.

A primary battery or primary cell is made up of an anode (positively charged end) and a cathode (negatively charged end). Graphite is generally used as the cathode and zinc is used as the anode. 

Oxidation reactions occur at the anode where electrons are donated to the circuit and reduction reactions occur at the cathode where electrons are accepted from the outside. There is also an electrolyte that is useful for making a passage for electrical current. 

The electrolyte is made up of electrically charged ions that can carry their charge between the cathode and the anode.

A common example of a primary cell is the Leclancha cell. It is composed of a zinc anode and a porous graphite cathode. The electrolyte present inside the battery is a wet mixture of NH 4 Cl (ammonium chloride), zinc chloride (ZnCl) 2 ) and manganese dioxide (MnO 2 ). Chemical reactions that occur within the cell can occur next.

A primary battery with a zinc anode and a copper cathodeWhat is a secondary cell?

The secondary cell is also a chemical cell but can be recharged for use again. The chemical reaction that produces electricity is reversible, and the cell can be used as new after the recharging process. The cell can be reused but the service life is shortened. Lead-acid and LiFe cells are some examples of secondary cells.

In a lead-acid cell, lead acts as the anode, and a lead grid packed with lead dioxide acts as the cathode. Sulfuric acid is filled to serve as the electrolyte.

The chemical reactions within a lead-acid cell are given below. They are reversible processes.

Pb + So42- ——-> PbSO4 + 2 electrons (anodic reaction) PbO2 + 4H + + SO42- + 2 electrons –—> PbSO4 + 2H2O (cathodic reaction)

Modern hybrid vehicles run on both oil and electric power. The battery is charged when the car is in motion, and then the stored electrical energy can be used to run. All the battery packs inside those cars are made from secondary cells.

Another common use for secondary batteries is vehicle starting, lighting, and ignition. In addition, they are used in uninterruptible power supplies (UPS), telecommunications, and portable tools.

Secondary cells are also known as secondary batteries or rechargeable batteries. These batteries can be used multiple times as they can be charged when they stop working. 

The chemical reactions that occur in these batteries are reversible. This means that those reactions can be reversed by applying an electrical charge. But unlike primary batteries, secondary batteries must be charged before use. The chargers are used for the recharging process.

Different secondary batteries provide different functions. Therefore, the user must know what type of battery should be used for a particular need.

These batteries also have a cathode and an anode just like primary batteries. Reduction reactions occur at the cathode while oxidation reactions occur at the anode. 

A good example of secondary cells is lead / acid battery storage. The reactions that occur within that cell are shown below.

Schematic diagram of the lead battery

Difference between primary and secondary cells

Definition

Primary cells are batteries that cannot be recharged or reused.

Secondary cells are batteries that can be recharged and reused.

Chemical reactions

In primary cells, irreversible reactions occur.

 In secondary cells, reversible reactions occur.

Use

 Primary cells can only be used once.

Secondary cells can be used more than once.

  • Using primary and secondary cells
    Primary cells are used in small but constant current devices: watches, toys, safety equipment, and more. Secondary cells are used in portable devices: laptops, mobile phones, mp3 players, tablets, etc.

Cost-effectiveness

Using primary cells is cost-effective compared to secondary cells, initially.

But using secondary cells would be a long term investment as the primary cells have to be replaced by another set after a while.

Real-Life Examples of Primary Cells

Alkaline batteries, dry cells.

Real-Life Examples of Secondary Cells

Lithium-ion battery, nickel-cadmium.

Importance of Primary and Secondary Cells

Primary cells can produce current immediately; Therefore, they are used in portable devices.

Secondary cells must be loaded prior to use. So that they can be used in cars.

Self-discharge rate

Primary cells have lower self-discharge rates and can be used for long-term energy storage.

Secondary cells have a higher rate of self-discharge compared to primary cells.

Primary cells have a lower self-discharge rate, therefore they are suitable for standby devices that need small currents continuously for a long time. It is an important fact on behalf of security equipment such as smoke/fire detectors, burglar alarms, and clocks.

Secondary cells have a higher self-discharge.

  • Design of primary and secondary cells.
    Primary cells are often “dry cells“, on the technology of their creation. Due to the absence of fluids in the battery, the cells fill with suction, which allows the ions to move but prevents them from falling out. Secondary cells use two other types of cells: wet cells (liquid, flooded cells) and dissolved salt (liquid cells with slightly different contents).
  • Properties of primary and secondary cells.
    Primary cells have high internal resistance, irreversible chemical reactions, high potency, generally smaller and lighter, and generally cheaper. Secondary cells have low internal resistance, need recharging, have chemical reactions, and are much more complex and expensive.

Conclusion (Difference Between Primary Cell And Secondary Cell)

Batteries are very important in technological applications. All batteries are made of electrochemical cells. Primary and secondary cells are two types of batteries that are useful in everyday life. The main difference between primary and secondary cells is that primary cells can only be used once, while secondary cells can be used more than once.

Primary cells are capable of generating electricity during genesis. They are also known as disposable batteries because they are designed for single-use and disposal. These are the most commonly used cells in portable devices that do not require high voltage.

 In fact, basic batteries cannot be reliably recharged over and over again because chemical reactions are irreversible and the materials used are difficult to return to their original state. 

Secondary cells must be recharged before use. Also known as rechargeable batteries, they can be recharged by attracting an electrical current, which changes the chemical reaction that occurs when the battery is used.

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