Dry Cell

Dry Cell is a portable electrochemical cell invented by German scientist Carl Gassner in 1888. Unlike traditional wet cells, a dry cell features a paste or gel-like electrolyte, eliminating the risk of leakage and enhancing portability. It is commonly used in household essentials such as flashlights and remote controls. Dry Cells are reliable and convenient energy storage devices.

In this article, we will read in detail about the dry cell, its components, working, chemical reactions inside it, its advantages, and uses.

What is a Dry Cell?

A dry cell is a type of electrochemical cell, commonly used as a portable source of electric power. It is called a “dry cell” because it does not contain liquid electrolytes, unlike wet cells such as car batteries. Dry cells are commonly used in household items like flashlights, remote controls, and portable electronic devices.

It consists of a cathode (positive electrode) made of a mixture of manganese dioxide and carbon powder, an anode (negative electrode) usually composed of zinc, and a moist paste or gel-like electrolyte. The components are housed in a zinc container, and a separator prevents direct contact between the cathode and anode.

Dry Cell was invented by Carl Gassner, a German scientist, in 1888. Gassner’s design improved upon earlier battery technologies by using a paste electrolyte instead of a liquid one, making the battery more portable and less prone to leakage.

Dry Cell Definition

Dry cell is an electrochemical cell that generates electrical energy through a chemical reaction without using a liquid electrolyte.

Learn, What is an Electric Cell

Structure of Dry Cell Battery

Structure of dry cell is discussed below:

• Dry cell is based on the Leclanche cell, this cell is made of a circular cylinder of Zn (zinc) metal, it acts as an anode.
• There is a graphite rod fixed in the middle of this cell which acts as a cathode.
• A wet paste of mixture of carbon and MnO₂ is filled near the graphite rod and a wet paste of NH₄Cl and ZnCl₂ is filled in the circular vessel of zinc metal.
• To make this cell insulated from all sides, a cover of thick paper is applied.
• When the cell is connected to the electric circuit, Zn gets converted into Zn₂ by giving up electrons, these electrons reach the cathode through the external circuit and are accepted by the cathode, the NH₄ ions present at the cathode transfer the electrons. After being absorbed, they become neutral and here MnO₂ is reduced.

Dry Cell Components

Components of dry cell are listed below:

Zinc Container (Anode)

• Anode (negative electrode) of the dry cell is normally zinc housed in its casing.
• It also acts as support structures and aids in the chemical reactions.

Carbon Rod (Cathode)

• In the center of the cell there is a carbon rod which acts as cathode.
• It is enclosed within a combination of manganese dioxide and other substances.
• During the electrolysis, electrons flow through an external circuit from a zinc container (anode) to a carbon rod (cathode), resulting in an electric current.

Manganese Dioxide (MnO₂)

• Black powdery material that coats the carbon rod is manganese dioxide.
• It serves as a depolarizer, preventing accumulation of hydrogen gas and reacting chemically.

Ammonium Chloride (NH₄Cl) Paste

• Area between the zinc container and carbon rod is packed with a paste of ammonium chloride.
• Presence of ammonium chloride as an electrolyte makes it possible for the ions to diffuse between the cathode and anode.

Working of Dry Cell

Working of dry cell can be understood in following points

• In dry cell batteries, electric current is generated by converting chemical energy into electrical energy, generally zinc and carbon or zinc and manganese dioxide are used in these cells.
• These substances are mixed in the electrolyte of the battery, that is, both of them are made into a paste and used as electrolyte.
• These substances react chemically with each other, that is, carbon or manganese dioxide substance reacts with zinc and through this chemical reaction, the chemical substance generates electrical energy which produces electric current.
• This electric current is obtained through the positive and negative ends of the battery i.e. electrodes.

Chemical Reactions in Dry Cell

In dry cell chemical reactions occur at cathode and anode. Let’s see the reactions separately and then we will learn the combined chemical reaction in dry cell

Chemical Reaction at Anode

First is the oxidation reaction of zinc. In this the zinc cathode is oxidized into positively charged zinc ions, releasing two ions.

Zn(s) → Zn²⁺ (aq) + 2e^–

Chemical Reaction at Cathode

These electrons generated in the above reaction are collected by the cathode. This is followed by the reduction reaction.

2MnO₂(s) + H₂O(l) + 2e^– → Mn₂O₃(s) + 2OH^–

Overall Reaction

The overall reaction inside the dry cell is given below. Electric current is generated from this reaction. This releases oxide ions along with manganese dioxide. This reaction occurs when manganese is mixed with an electrolyte.

Zn(s) + 2MnO₂(s) + 2NH₄Cl(aq) → ZnCl₂(aq) + Mn₂O₃(s) + 2NH₃ (g) + H₂O(l)

Types of Dry Cell

There are mainly two types of electric cells:

• Primary Cell: Dry cell, Daniell cell, Voltaic cell etc.
• Secondary Cell: Lead acid cell, nickel cadmium cell etc.

Primary Cell

Primary cell or battery is one that cannot be easily recharged after one use, and is discarded after being discharged. These cells are not chargeable because the electrode reaction occurs only once and after some period of use the battery becomes dead and cannot be reused.

Example: Dry cell, mercury cell and Daniel cell etc. are examples of primary cells.

Types of Primary Cells

There are following types of primary cells

1. Dry Cell
2. Leclanche Cell
3. Rechargeable Cell
4. Lithium Cell
5. Zinc Chloride Cell
6. Silver Oxide Cell
7. Bunsen Cell
8. Voltaic Cell
9. Nickel Cadmium Cell
10. Alkaline Cell
11. Mercury Cell

Dry Cell: Dry cell consists of a metal container in which a low moisture electrolyte paste covers graphite rods or metal electrodes.

Leclanche Cell: Leclanche cell is a primary cell, which converts the chemical energy stored in it into electrical energy.

Rechargeable Cell: A rechargeable battery is an energy storage device that can be recharged after being discharged by applying DC current to its terminals.

Lithium Cell: A rechargeable battery that uses lithium ions as the primary component of the electrolyte. Note: Lithium-ion batteries are common in portable electronic devices such as cell phones and laptop computers.

Zinc Chloride Cell: Zinc-chloride cells (usually marketed as “heavy duty” batteries) use high concentrations of anolyte (or anode electrolyte) that is primarily zinc chloride, which can produce more consistent voltage output in high drain applications.

Silver Oxide Cell: The excellent properties of silver oxide-zinc alkaline cell are its low weight, high current capacity, constant voltage and high efficiency at low temperatures. It is a primary cell of low shelf life that contains an alkaline KOH electrolyte that is added immediately before use.

Bunsen Cell: Bunsen cell is an elementary zinc-carbon cell composed of a zinc anode in dilute sulfuric acid separated from a carbon cathode in nitric or chromic acid by a porous pot.

Voltaic Cell: A voltaic cell is an electrochemical cell that produces electrical energy using a chemical reaction. Oxidation and reduction reactions are divided into half the cell compartments.

Nickel Cadmium Cell:Nickel-cadmium (NiCd) batteries are direct competitors with lead-acid batteries as these batteries offer similar technical characteristics but with better cycling capability and energy density. In NiCd batteries, nickel oxide hydroxide is used to make the cathode, and the anode is made from the metal cadmium.

Alkaline Cell: Alkaline batteries are disposable batteries with electrodes made of zinc and manganese dioxide. Potassium or sodium hydroxide alkaline electrolyte is used. These batteries have a constant voltage and are more energy dense and leak resistant than carbon zinc batteries.

Mercury Cell: Mercury cell is a type of dry cell which has zinc anode, mercuric oxide cathode and potassium hydroxide as electrolyte.

Secondary Cell or Storage Cell

Secondary Cell can be reused after use by recharging it by passing an electric current in the opposite direction. A good storage cell can go through several cycles of charging and discharging. The different types of secondary cell are discussed below:

Lead Accumulator Cell

Lead accumulator cells are commonly used in vehicles and inverters. In this, the anode is made of lead and the cathode is a grid filled with lead dioxide (PbO₂). 38% H₂SO₄ solution works as an electrolyte.

Nickel Cadmium cell

Nickel Cadmium Cell is a type of accumulator cell, which has a longer life than the lead accumulator cell, but its manufacturing cost is higher. In this cell, nickel 3rd compound of cadmium metal anode acts as cathode.

Lithium-Ion Battery

Lithium-ion is the widest used among all rechargeable battery chemistries. We use Lithium Ion batteries on a daily basis. Our mobile phones and electric cars are powered by lithium-ion batteries.

Nickel-Metal Hydride Battery

Rechargeable nickel-metal hydride batteries (NiMH) are prevalent in many laptop computers, mobile phones and webcams among several other electronic devices.

A NiMH battery negative electrode is typically a hydrogen-absorbing alloy and sometimes several different intermetallic compounds.

Dry Cell vs Wet Cell

Dry cell and wet cell are two different types of cells based on the electrolytes inside them. The difference between them is tabulated below:

Difference between Dry Cell and Wet Cell
Dry Cell	Wet Cell
These cells are small.	These cells are large.
In this electrolyte are moist solids.	In this electrolyte are liquids.
In this there is no leaking of chemicals	In this corrosive chemical tend to leak.
It is easy to handle.	It is difficult to handle.
It is more expensive.	It is less expensive.
It is difficult to manufacture.	It is easy to manufacture.
These cannot withstand overcharging.	It has the ability to withstand overcharging.

Applications of Dry cell

Various uses of dry cell in daily life are as follows:

• Flashlights: Dry cells, especially zinc-carbon and alkaline batteries, are commonly used to power flashlights. Their portable nature and relatively long shelf life make them ideal for emergency lighting.
• Remote Controls: Many remote controls for televisions, audio systems, and other electronic devices are powered by dry cells.
• Toys: Battery-operated toys often rely on dry cells for power.
• Clocks and Watches: Small electronic timekeeping devices, including wall clocks and wristwatches, often use button cells or other small dry cells. The long life and consistent voltage of these batteries make them suitable for these applications.
• Calculators: Small electronic devices like calculators commonly use button cells or other small dry cell batteries due to their compact size and relatively low power consumption.
• Remote Sensors: Wireless sensors, such as those used in home security systems or environmental monitoring devices, often use dry cells for power. The low self-discharge rate and convenience of dry cells make them suitable for such applications.
• Portable Radios: Battery-operated radios, commonly used during outdoor activities or in emergency situations, often use dry cells for their power source.
• Medical Devices: Certain medical devices, especially those designed for portable or intermittent use, may be powered by dry cells. This includes devices like blood glucose monitors and certain types of medical sensors.

Advantages of Dry Cell

The advantages of dry cell are mentioned below:

• Portability: Dry cells are compact and lightweight, making them highly portable.
• No Leakage: Unlike wet cells that use liquid electrolytes, dry cells use a paste or gel-like electrolyte. This design minimizes the risk of leakage, making dry cells more suitable for moving devices.
• Long Shelf Life: Dry cells have a relatively long shelf life, and they can be stored for extended periods without significantly degrading their performance.
• Ease of Use: Dry cells are easy to handle and install in electronic devices. Their simple design and the absence of liquid electrolytes contribute to user-friendly operation.
• Stable Voltage Output: Dry cells generally provide a stable voltage output during their discharge cycle. This characteristic is important for maintaining consistent power delivery to electronic devices.
• Cost-Effective: Many types of dry cells, such as zinc-carbon batteries, are relatively cheaper compared to some other types of batteries.

Disadvantages of Dry Cell

Although, dry cell offers several advantages but it still has some limitations or disadvantages. Some of them are discussed below:

• Limited Rechargeability: Most dry cells are not rechargeable. Once they are depleted, they need to be replaced.
• Voltage Decline: The voltage of a dry cell gradually decreases as it discharges.
• Temperature Sensitivity: Dry cell performance can be affected by temperature extremes. Extremely low temperatures may reduce the efficiency of the chemical reactions, leading to decreased output.
• Environmental Impact: Disposal of used dry cells can contribute to environmental concerns due to the presence of materials such as zinc, manganese, and other potentially harmful substances.
• Limited Energy Density: Dry cells, in general, have lower energy density compared to some other types of batteries, such as lithium-ion batteries.

Dry Cell Frequently Asked Questions

Is Dry Cell AC or DC?

Dry cells give DC (direct current). Internal chemical reactions within the dry cell cause an unidirectional continuous electric current.

Who Invented the Dry Cell?

Carl Gassner invented dry cell in 1886.

What is Reaction in a dry cell

In a zinc-carbon dry cell, the reaction is Zn + 2NH₄Cl + 2MnO₂ → ZnCl₂ + 2MnO (OH) + 2NH₃. This chemical process generates the electrical energy needed to power devices.

What is Wet and Dry Cell?

A wet cell has a liquid electrolyte, which is commonly used in car batteries. On the contrary, a dry cell incorporates an electrolyte paste or gel and is often found in domestic batteries. Dry cells are more portable and less prone to leak than wet cell.

Are all Dry Cells Reachargeable?

No, all dry cells are not rechargeable. Some of them such as NiMH. Li-ion etc. are only rechargeable

How does a Dry Cell Work?

A dry cell typically consists of a zinc anode, a manganese dioxide cathode, and a paste or gel-like electrolyte. The chemical reactions between these components generate electrical energy, which can be used to power electronic devices.

What are Advantages of Dry Cells?

There are several advantages of dry cells. Some of them are portability, less leakage, ease of use etc.