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What is Nickel-Iron cell or Edison cell? Nickel-iron cell or Edison cell what hot hai?

Hello friends in this article we will know that nickel-iron Cell What are Nickel-iron cells? What is this type of structure like? And learn about their working method and learn about many facts related to it.

Nickel-Iron Cell | Nickel-iron cell

Nickel-iron cell was discovered in 1909 by American scientist Thomas A. but was developed by Edison. It has less weight and longer life than lead-acid cells. As a result, these cells are very suitable for portable work. The emf of this cell is about 1.36 V.


Structure of the Nickel-Iron Cell | Construction of Nickel-iron cell

When the nickel-iron cell is in a charged state, the active substance Ni(OH) on the positive plates4 and iron (Fe) on the negative plates. The positive and negative plates are placed in a nickel-plated steel container; The plates are being separated from each other by strips of hard rubber. The container contains a 21 percent solution of KOH (electrolyte) to which a small amount of lithium hydrate (LiOH) is added to increase the cell’s capacity.

  • Positive plates Ni(OH)4 Perforated nickel-plated steel tubes filled with and metal are in the form of flakes of nickel; Adding nickel flakes reduces the internal resistance of the cell.
  • Negative plates are also in the form of perforated nickel-plated steel tubes filled with powdered iron oxide and a little mercuric oxide. The purpose of mercuric oxide is to reduce the internal resistance of the cell.

chemical change Chemical changes

Electrolyte (KOH) Molecule K, and OH, dissociates into ions.

KOH K, + OH,

During discharge, K, The ions move to the positive plate (anode) and Ni(OH)4 By reducing Ni(OH)2 Let’s do it. OH, The ions move to the negative plate (cathode) and oxidize iron. The chemical changes during discharge can be represented by the following equations:

Positive plate: Ni(OH)4 + 2K → Ni(OH)2 + 2KOH


Negative plate: Fe + 2OH → Fe(OH)2

During recharging, K, The ions move towards the negative plate (cathode) and OH, The ions move to the positive plate (anode), causing the following chemical changes:

Positive plate: Ni(OH)2 + 2OH Ni(OH)4

Negative plate: Fe(OH)2 + 2K Fe + 2KOH


Discharging and recharging during chemical reactions can be expressed in a single reversible equation as follows:

Ni(OH)4 + KOH + Fe Ni(OH)2 + KOH + Fe(OH)2


It can be seen from the above equation that no water is formed in the reaction, as a result, the specific gravity of the electrolyte (KOH) remains unchanged during charging or discharging. For this reason, a nickel iron cell is not damaged if stolen in a fully discharged condition for a considerable period of time.

pay attention : Since the electrolyte (KOH) does not change in specific gravity during charge or discharge, the state of charge of this cell cannot be determined by the specific gravity of the electrolyte. Instead, a voltmeter is applied to detect whether the cell is charged up to its rated voltage.


Battery Charging Circuit. battery charging circuit

Figure 10.6 shows the battery charging circuit. a D.C. A source of suitable magnitude is connected in series with a rheostat R, ammeter and the battery to be charged. Make sure the polarity is correct Le, the positive terminal of dc. The source should be connected to the positive terminal of the battery.




Nickel-iron cell

The charging current is adjusted to the required value with the help of rheostat. As the charging process progresses, the terminal voltage of the battery increases but the charging current is kept constant by adjusting the value of rheostat R. The terminal voltage of the battery and the specific gravity of the electrolyte are checked at regular intervals of time.

When the terminal voltage stops rising, the specific gravity of the electrolyte reaches a value of 1.28 and sufficient gasping occurs in the plates, the battery is fully charged. It is then taken out of the charging circuit. The entire charging process may take several hours.



How do you calculate charging?

When the battery is being charged, its E.M.F. Acts in opposition to the applied voltage. The applied voltage V sends a charging current (I) against the back emf. Eb battery. Input power is VI but the power supplied to the battery is EbI is. The electrical energy is converted into chemical energy which is stored in the battery;

Charging current, I = (V – Eb)/(R + r)


where, R = resistance of the rheostat in the circuit

r = internal resistance of the battery

The charging current is kept constant throughout (by adjusting R) except when the charge is gone.



Precautions during charging

The following points can be kept in mind during charging:-


  • When the battery is being charged, the vents must be open so that the gases (H, and 0,) can escape, otherwise the case may be cracked.
  • A mixture of hydrogen and oxygen is explosive. Therefore, care should be taken not to place an open flame or a lit cigarette near the battery being charged.
  • The charging current must be such that the temperature of the battery does not exceed 40 °C and does not cause violent gassing. Instead of a constant charging current, the common practice is to charge the battery at a tapered rate, that is, at first at a higher rate but gradually at a lower rate as the battery becomes fully charged.
  • After charging, water should be added to compensate for the loss of water by gas and evaporation. The electrolyte level should be 1 cm above the top of the plates. If water is not added, excessive concentrations of H, SO can burn the separators, causing permanent damage to the battery.

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