In 1901 Thomas Edison patented and commercialized NiFe in the United States and offered it as the energy source for electric vehicles, such as the Detroit Electric and Baker Electric. The equalization charge voltage is 1.65 volts. The inclusion of lithium hydroxide improves the performance of the cell. ![]() The voltage required to charge the NiFe battery is equal to or greater than 1.6 volts per cell. The electrolyte mixture of potassium hydroxide and lithium hydroxide is not consumed in charging or discharging, so unlike a lead-acid battery the electrolyte specific gravity does not indicate state of charge. The open-circuit voltage is 1.4 volts, dropping to 1.2 volts during discharge. (Discharging is read left to right, charging is from right to left.) The half-cell reaction at the positive plate from black Nickel(III) oxide-hydroxide NiO(OH) to green Nickel(II) hydroxide Ni(OH) 2 :Ģ NiO(OH) + 2 H 2O + 2 e − ↔ 2 Ni(OH) 2 + 2 OH − Nickel–iron cells should not be charged from a constant voltage supply since they can be damaged by thermal runaway the cell internal voltage drops as gassing begins, raising temperature, which increases current drawn and so further increases gassing and temperature. While the slow formation of iron crystals preserves the electrodes, it also limits the high rate performance: these cells charge slowly, and are only able to discharge slowly. The formation of metallic iron during charge is slow because of the low solubility of the ferrous hydroxide. The ability of these batteries to survive frequent cycling is due to the low solubility of the reactants in the electrolyte. Those "battolysers" could be charged and discharged like conventional batteries, and would produce hydrogen when fully charged. Nickel–iron batteries are being investigated for use as combined batteries and electrolysis for hydrogen production for fuel cell cars and storage. The technology has regained popularity for off-the-grid applications where daily charging makes it an appropriate technology. Some examples are London underground electric locomotives and New York City Subway car – R62A. Many railway vehicles use NiFe batteries. ![]() ![]() Due to its low specific energy, poor charge retention, and high cost of manufacture, other types of rechargeable batteries have displaced the nickel–iron battery in most applications. It is often used in backup situations where it can be continuously charged and can last for more than 20 years. It is a very robust battery which is tolerant of abuse, (overcharge, overdischarge, and short-circuiting) and can have very long life even if so treated. The active materials are held in nickel-plated steel tubes or perforated pockets. The nickel–iron battery (NiFe battery) is a rechargeable battery having nickel(III) oxide-hydroxide positive plates and iron negative plates, with an electrolyte of potassium hydroxide. Thomas Edison in 1910 with his nickel-iron cell from his own production line
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