Battalai na Tetsu da Kasa ko da Iya da kuma Muhimman Abubuwa

Wani batari ya zama mafi yawan gaskiya kadan bayan yawan gaskiyar da ke da kyau don in taimaka wajen zama batari da masu energy density ta fiye don electric vehicle? Amsa ta zai zama Nickel Iron Battery ko Edison Battery. A cikin kalma, Ni-Fe battery shi ne batari mai tsarki sosai. Wannan batari na da tasirin da take da ita domin in yi overcharging, over discharging, short-circuiting, bata da suka. Batari na iya taimakawa daidai hatta idan ba ake charge daga lokacin daɗi. Saboda rarrabe ta, an yi amfani da batari na a wurare da ake amfani da shi idan ba za a iya jin daidai, misali, a solar energy system, a wind energy system, bata da suka, a matsayin backup. Durability da lifespan ta cell ta nickel-iron suna da tsawon da ya fiye da lead acid battery, amma haka, batari ta nickel-iron ta ci gaskiya saboda costin da ke da kyau na ingantaccen.

Za a iya duba wasu siffofin da suka da batari ta nickel-iron (Ni-Fe) ko Edison battery.

Batari na iya haɗa 30 zuwa 50 kW energy delivery capacity per kg of its weight. Charging efficiency ta batari na shine kusan 65%. Yana nufin cewa 65% of input electrical energy takes stored in this battery as chemical energy during its charging process. Discharging efficiency ta shine kusan 85%. Yana nufin cewa batari na iya haɗa 85% of stored energy to the load as electrical energy and the rest gets discharged due to self-discharging of the battery. Idan batari na ba a yi amfani da shi daga lokacin daɗi, zai faruwa 10% zuwa 15 % of its stored energy due to self-discharging. Nickel Iron battery has a significantly longer lifespan, and it is about 30 to 100 years. This period is much longer than the normal lifespan of a lead acid battery which is about ten years. Nominal voltage rating per nickel iron cell is 1.4 V.

Nickel Iron Battery

The basic components used in Nickel iron battery are nickel(III) hydroxide as the cathode, iron as anode and potassium hydroxide as the electrolyte. We add Nickel sulfate and Ferrous sulfide to the active material.

Construction of Edison Batteries

The capacity of Ne-Fe cell depends upon size and number of positive and negative plates. The appearance of both positive and negative plates in this type of battery cells is same. Both of the plates consist of the rectangular grid made of nickel-plated iron. Each of the grid holes is filled with shallow and finely perforated nickel-plated steel box.

Although both of the plates are appeared to be same, they contain different active materials. Perforated nickel-plated steel boxes of positive plates contain a mixture of an oxide of nickel and pulverized carbon, and some of the negative plates contain fine grains of the oxide of iron with the fine dust of carbon. In both the plates, the fine dust of carbon, mixed with active materials, helps to increase electrical conductivity. We use 20% diluted caustic potash as an electrolyte.

Nickel plated iron gets used to make the vessel containing electrolyte and electrodes. Ebonite sticks are placed between the plates of different polarities to prevent them from coming into direct contact and causing a short circuit. There is another specialty in the construction of Edison battery or nickel iron battery, which the number of negative plates is one more than that of the number of positive plates, and we electrically connect the last negative plate to the container. Plates of same polarities are welded to a common strap, and they make a cell, and combining several cells, the battery gets constructed.

Operation of Nickel Iron Batteries

We already know that the main operation of the nickel-iron battery is the chemical reaction within the battery which is known as electrolysis. Electrolysis is nothing but the chemical reaction taking place when there is current flow, it can be both cause and result of the chemical reaction. The chemistry of nickel-iron cell is very much complicated because the exact formula for the positive active material is not well established yet. But if we can assume that the material to be Ni(OH)3, then we can explain it to some extent. During charging, nickel compound at the positive plates gets oxidized to nickel peroxide. Charging process changes iron compound to spongy iron in negative plates.

In the fully charged condition, the active material of the positive plates is nickel hydroxide [Ni(OH)3], while that in pockets of the negative plate is iron, Fe. When the cell delivers current to load, the active material of the positive plate changes from Ni(OH)3 to Ni(OH)2 and that of the negative plate changes from iron to Ferrous hydroxide (Fe(OH)2). The electrochemical process in the Edison battery can be expressed by the equation

The equation expresses both the phenomenon of charging and discharging. The right side flow of the equation is the reaction of the discharging phenomenon, and the left side flow of the equation expresses the charging phenomenon. The reaction occurs by transfer of electrons through the external circuit to the positive plate during discharge. There is a provision for giving off the corrosive fume which is generated during the electrolysis inside the battery so that no special care is needed in mounting the cell.

Characteristics of Nickel Iron Batteries

The emf of a fully charged Edison battery is 1.4 V. The average discharge voltage is about 1.2 V and the average charging voltage is about 1.7 V per cell. The characteristics of this type of battery are shown below in the figure.

The voltage characteristics of the Nickel Iron battery are similar to that of the lead-acid cell. As the fully charged emf 1.4 V and it slowly decreases to 1.3 V and then very slowly to 1.1 or 1.0 V during discharge. From the graph, we can see that there is no lower limit for discharging emf beyond which the output of the battery will be zero. That’s why after a certain period the battery stop to any output. The emf of a battery is directly proportional to the temperature, which means the emf of the battery increases with increase in temperature.
The average time of charging of a battery is 7 hours and discharging time is 5 hours. Another characteristic of Edison battery is that continuous operation at higher temperature decreases the life of the battery, the same thing happens if the battery is charged for more than the average time of charging.
The ampere-hour and watt-hour efficiency of this nickel-iron battery is 85 % and 60 % respectively. At 4oC temperature, the capacity of Edison battery falls to zero, that’s why the battery should be heated up before operation though during operation the I