Iron electrode secondary batteries

The first patent on an alkaline secondary battery was taken out by Walde-mar Jungner of Sweden, who in 1899 proposed a system based on nickel hydroxide as the positive electroactive material, a mixture of cadmium and iron as the negative electrode, and an aqueous solution of potassium... 

The nickel-based systems have traditionally included the following systems -nickel-iron (Ni/Fe), nickel-cadmium (NiCd), nickel metal hydrides (NiMH), nickel hydrogen (Ni/H2), and nickel-zinc (Ni/Zn). Of these, the metal hydride chemistry has been the most successful in the secondary battery market. AU nickel systems are based on the use of a nickel oxide active material (undergoing one valence change from charge to discharge or vice-versa). The electrodes can be pocket type, sintered type, fibrous type, foam type, pasted type, or plastic roll-bonded type. All systems use an alkaline electrolyte, KOH. 

Most recently, iron electrodes have been considered and tested as cathodes too. Based upon high valence state iron, Fe(VI), these cathodes have shown promise in experimental cells when coupled with zinc or metal hydride anodes for portable primary and secondary batteries. The results are discussed in Sec. 25.7. 

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 ... 

---