Alkaline Battery

The alkaline battery is the most commonly used type of battery. Batteries are popular as they can be recharged if their energy production is reduced. The basic principle behind any battery is harnessing the movement of electrons generated due to chemical reactions to produce electricity. 

History of Alkaline Batteries

French scientist George Leclanche invented the first type of battery. Lechlanche’s cell was created using an electrolytic solution, a depolariser, and two electrodes. However, this cell was neither portable nor discrete. To counter the disadvantages of Lechlance’s cell, the alkaline battery was created.

Lew Urry, a Canadian chemical engineer at Eveready Battery, created the first alkaline cell. An alkaline battery is usually cylindrical and contains chemicals that undergo a chemical reaction. The alkaline cell was developed to create a portable battery with a good shelf life.

Construction of an Alkaline Battery

A hollow steel drum forms the body of an alkaline cell. It serves as a container for the chemicals inside and the cathode for the reactions. A cap with a slight projection is placed on the top as the battery’s positive terminal. Manganese dioxide is powdered into a fine grain form for the battery’s cathode mixture and mixed with coal dust. The mixture is then attached to the inner side of the cylindrical container by moulting it to its walls.

A paper separator is inserted between the powdered manganese dioxide and anode on the inner side. The remaining space is where the paper separator is filled with powdered zinc, which acts as the anode. The separator paper is pre-soaked in potassium hydroxide and serves as the electrolyte between the manganese dioxide and zinc anode.

A pin is inserted at the battery’s central axis position to gather a negative charge. This pin is connected to a plate at the bottom on the outer side of the battery. A plastic cover separates the plate and positive drum of the battery. The inserted pin is called the negative collector pin and is usually made of metal like brass.

Working Principle of an Alkaline Battery

An alkaline battery produces electricity via chemical energy. Two different reactions occur inside a battery, the anodic reaction at the anode and the cathodic reaction at the cathode. The electrolyte that acts as the common medium where these reactions occur is the potassium hydroxide soaked into the paper separator between the two electrodes.

At the anode, oxidation takes place and involves the release of electrons. The zinc electrode is oxidised to form zinc oxide. The anodic reaction can be written as

Zns + 2HO–aq → ZnOs + H2O + 2e–

The energy of this reaction is Eanode = –1.28 V

At the cathode, reduction occurs and involves the gain of electrons. Manganese is reduced from its +4 oxidation state to its +2 oxidation state. The cathodic reaction can be given as

2MnO2(s) + H2Oaq + 2e– → Mn2O3(s) + 2OH–aq

The energy of this reaction is given as Ecathode= +0.15 V

When taken in total, the reaction that keeps occurring in the alkaline cell is given by 

Zns + 2MnO2 Mn2O3 + ZnO

The overall energy or voltage that is generated by the reaction is given as

Ecell = Ecathode – Eanode

Ecell = 0.15 – (-1.28) V

Ecell = 1.43 V

Usually, alkaline batteries are rated at 1.5 V, and a fresh alkaline cell with no discharge can have a potential of 1.5 to 1.65 volts. In both reactions, electrons are produced by the anodic reaction and are used by the cathodic reaction. As the anode and cathode are separated, the only way for the electrons to move from anode to cathode is via an external circuit. This movement of electrons results in electricity from the battery.

Advantages and Disadvantages

• High energy density is observed in alkaline cells
• Alkaline cells can be used continuously or in breaks with applications
• Alkaline cells maintain a constant output at both high and low rates of discharge
• They also have a constant output at ambient temperature as well as low temperature
• Alkaline cells show little internal resistance along with a longer shelf life
• Less leakage 

The only disadvantage of an alkaline cell is the comparatively high cost of production, given its massive demand around the world.

Types of Alkaline Batteries

Alkaline batteries get their name from the alkali used to act as an electrolyte between electrodes. As in this example, potassium hydroxide is used as an electrolyte which is an alkali. Based on the active materials used in the plates of the cells, alkali cells come in four types:

• Nickel iron
• Nickel cadmium
• Silver zinc
• Alkum battery

Conclusion

The alkaline battery is the most popular battery currently used. Batteries are popular as they can be recharged if their energy production is reduced. The basic principle behind any battery is harnessing the movement of electrons that is generated due to chemical reactions to produce electricity. 

A Canadian chemical engineer working created the first alkaline cell. An alkaline battery is usually cylindrical and contains chemicals that undergo a chemical reaction inside. The alkaline cell was developed to create a battery that was portable and had a good shelf life.