Zinc Carbon Battery |Types of Zinc Carbon Battery | Advantages and Disadvantages

Zinc Carbon Battery

The Zinc carbon battery has been widely used for over 100 years. There are two main types: Leclanché batteries and Zinc chloride batteries. Both are primary batteries. Georges Leclanché invented this battery in 1866, introducing a less corrosive electrolyte, ammonium chloride. Before this, only strong mineral acids were used in batteries.
In the original Leclanché battery, a glass jar served as the main container, filled with ammonium chloride solution as the electrolyte. An amalgamated zinc rod was used as the negative electrode (anode). The positive electrode (cathode) was a porous pot filled with an equal mixture of manganese dioxide and carbon powder, with a carbon rod inserted into the mixture.

In 1876, Leclanché improved his zinc carbon battery design by mixing a resin gum binder with manganese dioxide and carbon powder to form a solid block. This eliminated the need for a porous pot. In 1888, Dr. Carl Gassner further developed the battery by using a paste of plaster of Paris and ammonium chloride as the electrolyte instead of liquid ammonium chloride. He made the container out of zinc, which also served as the anode, and minimized local chemical action by wrapping zinc chloride–ammonium chloride-saturated cloths around the cathode mix.

Later, he replaced plaster of Paris with wheat flour in the electrolyte mixture, creating the first commercial dry zinc carbon battery. The Leclanché battery continued to evolve in the 20th century. Acetylene black carbon, which is more conductive than graphite, was used as the cathode current collector. Improvements were also made in separator design and venting seal systems.

After 1960, more effort was directed in development of zinc chloride battery cell. This is also a popular version of zinc carbon battery. Here, zinc chloride is used as electrolyte instead of ammonium chloride. This was developed to provide better performance in the heavy drain application. In other words, zinc chloride battery is improved substitute of Leclanche’ battery in heavy drain applications.

Chemical Reaction in Zinc Carbon Battery

In Leclanche battery cell, zinc is used as anode, manganese dioxide is used as cathode and ammonium chloride is used as main electrolyte but there is some percentage of zinc chloride in the electrolyte. In zinc chloride battery cell, zinc is used as anode, manganese dioxide is used as cathode and zinc chloride is used as electrolyte.
In both of the zinc carbon battery, during discharge, zinc anode involves in oxidation reaction and each zinc atom involved in this reaction releases two electrons.

These electrons come to the cathode through external load circuit.
In Leclanche battery cell ammonium chloride (NH₄Cl) exists in electrolyte mixture as NH₄⁺ and Cl ^–. In cathode MnO² will be reduced to Mn₂O₃ in reaction with ammonium ion (NH₄⁺). In addition to Mn₂O₃ this reaction also produces ammonia (NH₃) and water (H₂0).

But during this chemical process some of ammonium ions (NH₄⁺ ) are directly reduced by electrons and form gaseous ammonia (NH₃) and hydrogen(H₂).

In zinc carbon battery this ammonia gas further reacts with zinc chloride (ZnCl₂) to form solid zinc ammonium chloride and gaseous hydrogen reacts with manganese dioxide to form solid di-manganese trioxide and water. These two reactions prevent formation of gas pressure during discharging of battery.

Overall reaction is,

A zinc chloride battery is an improved version of zinc carbon battery. These batteries are generally labeled as heavy duty battery. A zinc chloride cell contains only zinc chloride (ZnCl₂) paste as electrolyte. This battery provides more current, more voltage and more life than a general purpose zinc carbon battery. The cathode reaction is,

Overall reaction is,

Voltage Rating of Zinc Carbon Battery

Standard voltage rating of a zinc carbon battery is determined by the type of anode and cathode materials used in the battery cell. In zinc carbon battery cell, zinc is the anode material and manganese dioxide is the cathode material. Electrode potential of zinc is – 0.7 volt whereas electrode potential of manganese dioxide is 1.28.
Therefore, theoretical voltage of each cell should be – (- 0.76) + 1.23 = 1.99 V but considering many practical conditions, the actual voltage output of a standard zinc carbon battery is not more than 1.5 V.

Energy Density of Zinc Carbon Battery Cell

The molar weight of cathode material, manganese dioxide is 87 g/mol. Here in the reaction of the battery it is found that two electrons reduce two manganese dioxide molecules. Hence, as per Faraday’s constant 28.6 Ah can be delivered by complete reduction of one mole or 87 g of manganese dioxide. Therefore, 87/26.8 = 3.24 g manganese dioxide is required to deliver 1 Ah electricity.
The molar weight of anode, material zinc is 65 g/mol. Here in the reaction of battery it is found that two electrons oxidize one zinc atom. Hence, as per Faraday’s constant 28.6 Ah can be delivered by complete oxidation of one mole or 65/2 g or 32.5 g of zinc. Therefore, 32.5/26.8 = 1.21 g of zinc is required to deliver 1 Ah electricity.
Total energy density of zinc carbon battery is 3.24 g/Ah + 1.21 g/Ah = 4.45 g/Ah =1 / 4.45 Ah/g = 0.224 Ah/g or 224 Ah/Kg. This is absolutely theoretical calculation, but in practice many other materials like, electrolyte, carbon black, water to be included in the battery, weight of which cannot be omitted. In addition to these many other practical conditions are to be considered in a battery. Considering everything in account, a practical low discharge Leclanche’ battery cell have energy density of 75 Ah/Kg and the same for heavy duty and intermittent discharge battery, is about 35 Ah/Kg.

Types of Zinc Carbon Battery

As we said earlier, there are two types of zinc carbon battery .

1. Leclanche’ battery
2. Zinc chloride battery.

Again Leclanche’ battery are of main two types, general purpose cells and heavy duty cells.
In general purpose low cost Leclanche’ battery, pure zinc is used as anode, ammonium chloride is used as main electrolyte along with a percentage of zinc chloride. Here natural manganese dioxide ore is used as cathode material. These batteries are generally used where cost is more a vital factor than their performance.
Application of heavy duty Leclanche’ battery is dominated by zinc chloride battery but still some of the manufacturers continue to produce heavy duty Leclanche’ battery by adding electrolytic or chemical manganese dioxide along with manganese dioxide ore as the cathode.
In general purpose zinc chloride battery, pure zinc is used as anode; zinc chloride is used as electrolyte. Sometimes a small quantity of ammonium chloride is added to the electrolyte. Here also natural manganese dioxide ore is used as cathode material.
For Industrial heavy duty applications, electrolytic manganese dioxide is added to natural ore manganese dioxide in cathode. These batteries are in cost competition with heavy duty Leclanche’ battery. This battery has low leakage, compared to Leclanche’ cell.
In extra or super heavy duty zinc chloride cell, very small quantity of ammonium chloride is added to zinc chloride electrolyte. The quantity of zinc chloride must be less than 1% of its cathode weight. The ore manganese oxide is replaced by electrolyte manganese oxide in cathode materials. These cells use paper separator coated with cross linked or modified starches, which enhance their stability in the electrolyte. Extra or super heavy duty zinc chloride battery is used where high performance is required even at the cost of high expenditure. It performs well in low temperature, which is not possible in case of Leclanche’ cell.

Types of Zinc Carbon Batteries according to Size

Size	Weight	Diameter	Height	Reference Figure
N	6.2 gram	12 mm	30.2 mm
AAA	8.5 gram	10.5 mm	44.5 mm
AA	15 gram	14.5 mm	50.5 mm
C	41 gram	26.2 mm	50 mm
D	90 gram	34.2 mm	61.5 mm
F	160 gram	34 mm	92 mm
No – 6	900 gram	67 mm	170 mm

Advantages and Disadvantages of Zinc Carbon Battery

The advantages of Zinc carbon battery can be listed as below.

Advantages of Leclanche’ Battery

1. The cost of this battery cell is quite low.
2. Various shapes, sizes and capacities of these cells are easily available.
3. Long traditional reliability.

Disadvantages of Leclanche’ Battery

1. Its energy density is quite low.
2. It gives poor service in low temperature.
3. It has poor leakage resistance.
4. Cannot perform efficiently at high current drain application.
5. Self life is not very good.
6. Its voltage falls steadily with discharge.

Advantages of Zinc Chloride Battery

1. Higher energy density is available in zinc chloride battery.
2. Zinc chloride battery has high efficiency under heavy discharge condition.
3. It has better low temperature performance.
4. Smaller leakage resistance.

Disadvantages of Zinc Carbon Battery

1. Gassing rate of this battery is higher.
2. This is more oxygen sensitive.