Edison cell

H2SO( concentration during use of a lead cell provides the basis for the convenient hydrometer test of the state of discharge of an automobile battery. The hydrometer measures the density of the electrolyte solution, thus indicating how much of the H2SOi has been consumed. Obviously, this method cannot be used to check an Edison cell since the electrolyte concentration is constant. 

Another example of a practical battery, but one less commonly used, is the Edison cell. The active electrode materials consist of iron and nickel dioxide in contact with an electrolyte consisting of aqueous potassium hydroxide solution. Owing to its marked instability, the Ni02 changes spontaneously to Ni203 with liberation of oxygen. The reactions responsible for the flow of current are as follows ... 

The Edison cell uses an iron anode, nickel oxide eathode, and KOH electrolyte. This cell is extremely rugged and is still used in certain industrial apphcations, but it was never able to displace the lead-acid cell as Edison had hoped.. 

The rechargable alkaline nickel-iron Edison cell (1901) is still used as a power source. 

Edison cell — A nickel-iron (Ni-Fe) secondary (rechargeable) cell independently developed by Edison in USA and W. Jiinger in Sweden in 1900. The cell (-> battery) is based on the use of nickel oxyhydroxide (NiOOH) at the positive electrode and metallic iron for the negative electrode, and a potassium hydroxide (KOH) solution containing lithium hydroxide (LiOH) is the electrolyte. The Ni-Fe cell is represented as ( Fe/KOH/NiOOH. The charge-discharge reactions for the Edison (Ni-Fe) cell are as follows ... 

Nickel-cadmium cell Ni-Cd cell Nickel-iron rechargeable cell -> Edison cell Nickel-metal hydride cell - Ni-MFlcell Nicotinamide adenine dinucleotide - NADH Nigraniline - poly aniline... 

The most important example of a secondary cell is the lead storage battery used in automobiles. Other examples of secondary cells are the Edison cell and the nickel-cadmium rechargeable cells used in calculators and flash lamps. 

Nickel iron batteries were developed by Edison, and were commonly known as the Edison cells. Of all batteries, perhaps the Nickel Iron can claim to be the most rugged and reliable as well as being virtually indestructible. In the 1920 s and 30s these batteries were found everywhere, and when the need arose for heavy water during the Manhattan project, the electrolyte from thousands of these batteries were used as an enriched source. The cell reaction is given below ... 

The Edison cells have ceased production In North America, and USSR today has the largest production capability In these batteries. 

In the nickel-cadmium alkaline storage battery, the iron of the Edison cell is replaced by cadmium to give the following equivalent reaction ... 

The average cell voltage of 1.2 V is slightly lower than that of the Edison cell. Cadmium is preferred to iron in the nickel-aUcaline cell because cadmium hydroxide is more conductive than iron hydroxide. The absence of higher oxidation states for cadmium minimizes side reactions, which occur in the Edison cell. The nickel-cadmium cell can also be charged at a lower voltage since there is no overvoltage, as there is at the iron electrode. 

This is the most common of the rechargable batteries and has extensive use in cordless power tools, electric razors, and electronics. It has similarities to the Edison cell, but better performance in its areas of application. 

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