Types Of Battery - Primary cell & Secondary cell

Italian scientist Alessandro Volta in 1800 formed the battery and that's called the Voltas invention and also known by the name of voltaic Pile. The invention of the battery was a great discovery at that time. Before the battery, there were no electricity experiments because it was unsafe to experiment directly from the electricity.

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This Story also Contains

1. Types Of Batteries
2. Secondary cell
3. Some Solved Examples
4. Summary

Types Of Batteries

Batteries can be categorized based on their chemistry, usage, and whether they are rechargeable or non-rechargeable.

Non-rechargeable batteries are called primary cell

Rechargeable batteries are called secondary cell

Primary Cells

In such cells, redox reaction occurs only once so cells can not be recharged again. The cell becomes dead after some time as electrode reactions cannot be reversed. For example, dry cells and mercury cells.

• Dry Cell
  • It is a compact form of the Lechlanche cell.
  • It has an anode of Zn-container and a cathode of graphite rod surrounded by MnO₂ + carbon.
  • Here a paste of NH₄Cl and ZnCl₂ is filled in between the electrodes.
    
    Cell Reactions
    At anode:
    Zn(s)→Zn+2(aq)+2e−
    At cathode:2MnO2( s)+2NH44(aq)+2e→Mn2O3( s)+2NH3( g)+H2O
  • Zn⁺² combines with NH₃ to form diammine Zn(II) cation.
  • A dry cell has a short life as NH₄Cl (acidic) corrodes the Zn-container even if the cell is not in use.
  • The cell potential is 1.25 to 1.5 volt
• Mercury Cell
  • In commonly used mercury cells the reducing agent is zinc and the oxidizing agent is mercury(II) oxide.
    
    Cell Reactions
    At anode:
    Zn(Hg)+2OH→ZnO(s)+H2U+2em
    
    At cathode:
    HgO+H2O+2e−→Hg(l)+2OH
  • 
    
    The overall reaction is:Zn(Hg)+HgO(s)→ZnO(s)+Hg(l)
  • The cell potential is approximately 1.35 V and remains constant throughout its life as the overall reaction does not involve any ion, whose concentration can change during its lifetime. It is used in hearing aids, watches, etc.

Secondary cell

A secondary cell, also known as a rechargeable battery, is a type of battery that can be recharged and used multiple times. Unlike primary cells, which are designed for single-use and must be disposed of once depleted, secondary cells can be restored to their full charge by applying an external electrical current.

Rechargeability
- Secondary cells can be recharged and used again after the initial discharge. This is achieved through a process where electrical energy is converted into chemical energy during charging.

Chemistry
- Various chemistries are used in secondary cells, including:
- Lead-Acid: Uses lead and lead dioxide electrodes with a sulfuric acid electrolyte.
- Nickel-Cadmium (NiCd): Uses nickel and cadmium electrodes with a potassium hydroxide electrolyte.

Applications
- Secondary cells are widely used in various applications, including:
- Consumer Electronics: Smartphones, laptops, tablets, and cameras.
- Electric Vehicles: Batteries for electric cars, bicycles, and scooters.
-*Power Tools: Rechargeable drills, saws, and other tools.
- Energy Storage Systems: Home energy storage and backup power solutions.

Advantages
- Cost-Efficient: Over time, secondary cells can be more economical than primary cells because they can be reused multiple times.
- Environmental Impact: Rechargeable batteries reduce waste since they do not need to be disposed of after a single use.
- Performance: Modern secondary cells often provide higher energy density and better performance compared to primary cells.

Disadvantages
-Initial Cost: Rechargeable batteries can be more expensive upfront compared to disposable ones.
- Maintenance: They may require specific charging protocols and can degrade over time, reducing their effective lifespan.

Recommended topic video on (Batteries)

Some Solved Examples

Example.1

1. Choose the correct option :

a) Mercury batteries using a mercury oxide cathode have a flat discharge curve

b) Mercury batteries are used in voltage reference in electric instruments and in photographic light meters

c) Silver oxide batteries are used as an alternative to mercury batteries

1)a,b

2)b

3) (correct)a,b,c

4)a,c

Solution

Mercury batteries using mercury oxide cathode have a flat discharge curve and provide a constant voltage of 1.35 v for 95% of their lifetime. The rest is also correct.

Hence, the answer is the option (3).

Example.2

2 . Select the correct option in the context of dry cell

a) it is also called Lechlance cell

b) It can also be called Daniel cell

c) Electrolyte used is a moist paste of PbSO4 and PbSO4

1)a,c

2) (correct)c

3)a,b

4)b,c

Solution

As we have learned,

Batteries - Primary Cells
In such cells, redox reaction occurs only once so cells can not be recharged again. The cell dies after some time as electrode reactions cannot be reversed—for example, dry cells and mercury cells.

• Dry Cell
  • It is a compact form of the Leclanche cell.
  • It has an anode of Zn-container and a cathode of graphite rod surrounded by MnO₂ + carbon.
  • Here a paste of NH₄Cl and ZnCl₂ is filled in between the electrodes.
    Cell Reactions
    At anode:
    Zn(s)→Zn+2(aq)+2e−
  • 
    At cathode:2MnO2( s)+2NH4+(aq)+2e−→Mn2O3( s)+2NH3( g)+H2O
  • Zn⁺² combines with NH₃ to form diammine Zn(II) cation.
  • A dry cell has a short life as NH₄Cl (acidic) corrodes the Zn-container even if the cell is not in use.
  • The cell potential is 1.25 to 1.5 volt
• Lechlance and Daniel cells are different from dry cell

Hence, the answer is the option (2).

Example.3

3. A depolarizer used in dry cells is:

1)Ammonium chloride

2) (correct)Manganese dioxide

3)Potassium oxide

4)Sodium phosphate

Solution

As we have learned,

• Dry Cell
  • It is a compact form of the Leclanche cell.
  • It has an anode of Zn-container and a cathode of graphite rod surrounded by MnO₂ + carbon.
  • Here a paste of NH₄Cl and ZnCl₂ is filled in between the electrodes.
    Cell Reactions
    At anode:
    Zn(s)→Zn+2(aq)+2e−
  • 
    At cathode:2MnO2( s)+2NH4+(aq)+2e−→Mn2O3( s)+2NH3( g)+H2O
  • 
    
  • Zn⁺² combines with NH₃ to form diammine Zn(II) cation.
  • A dry cell has a short life as NH₄Cl (acidic) corrodes the Zn-container even if the cell is not in use.
  • The cell potential is 1.25 to 1.5 volts

MnO₂ acts as the depolarizer and presents the buildup of hydrogen gas molecules.

Hence, the answer is the option (2).

Example.4

4. Choose the incorrect option in the context of mercury cell :

a) AqO+KOH is used as an electrolyte

b) Zn is used as an electrolyte.

c) ZnO+KOH is used as an electrolyte

1)a,b.c

2) (correct)a,b

3)b,c

4)b

Solution

Electrolyte moist paste of KOH.

Cathode reaction IgO(s)+H2O(l)+2e−→Hg(1)+2OH−

Anode reaction Zn(Hg)+2OH−→ZnO(s)+H2O+2e−

ZnO+KOH◻ in the moist form is used as an electrolyte and zinc is used as an anode.

Hence, the answer is the option (2).

Example.5

5. Compound A used as a strong oxidizing agent is amphoteric. It is part of lead storage batteries. Compound A is:

1)PbO

2)Pb₃O₂

3) (correct)PbO₂

4)PbSO4

Solution

PbO₂ is an amphoteric and strong oxidizing agent and also a component of lead storage batteries in the cathode

Hence, the answer is the option (3).

Summary

Batteries are important as they provide a source of energy this feature makes them very important as they are used in mobiles and many more things. Dry cells are very small and easy to carry with them and due to their small size, they are very portable so they can be used in small devices. Mercury cells provide a consistent voltage output over a wide range of temperatures and has long shell life.