Battery Accumulator

Verified Timeline

Lore & Background

Swedish inventor Waldemar Jungner invented the nickel–cadmium battery in 1899 and experimented with substituting iron for the cadmium, including 100% iron. Jungner discovered that the main advantage over nickel–cadmium was cost, but due to lower charging efficiency and more pronounced hydrogen formation (gassing), the nickel–iron technology was abandoned. He had several patents for the iron version: Swedish patents 8.558/1897, 10.177/1899, 11.132/1899, 11.487/1899 and German Patent 110.210/1899. In 1901 Thomas Edison patented and commercialized NiFe in the United States, offering it as the energy source for electric vehicles such as the Detroit Electric and Baker Electric. Edison claimed the design was "far superior to batteries using lead plates and acid" (lead–acid battery). He held U.S. patents 678,722/1901, 692,507/1902, and German patent 157.290/1901. Edison was disappointed his battery was not adopted for starting internal combustion engines and that electric vehicles went out of production only a few years after his battery was introduced. His batteries had significantly higher energy density than lead–acid batteries and could be charged in half the time, but performed poorly at low temperatures and were more expensive. Edison's batteries were profitably made from about 1903 to 1972 by the Edison Storage Battery Company in West Orange, New Jersey. In 1972 the company was sold to Exide Battery Corporation, which discontinued the product in 1975.

In Their Own Story

A 50 volt nickel–iron battery was the main D.C. power supply in the World War II German V-2 rocket, together with two 16 volt batteries powering the four gyroscopes. A smaller version was used in the V-1 flying bomb. Many railway vehicles use NiFe batteries, including London underground electric locomotives and New York City Subway car – R62A. The technology has regained popularity for off-the-grid applications where daily charging makes it appropriate. In 2023, Battolyser Systems installed the first industrial-scale Battolyser system at the RWE Magnum power gas plant in Delfzijl. Nickel–iron cells were made with capacities from 5 to 1250 Ah. Many original manufacturers no longer make them, but production by new companies has started in several countries.

Reader's Guide

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 further increases gassing and temperature. The voltage required to charge the NiFe battery is equal to or greater than 1.6 volts per cell. The equalization charge voltage is 1.65 volts. The open-circuit voltage is 1.4 volts, dropping to 1.2 volts during discharge. 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 inclusion of lithium hydroxide improves performance. The ability of these batteries to survive frequent cycling is due to the low solubility of the reactants in the electrolyte. The formation of metallic iron during charge is slow because of the low solubility of ferrous hydroxide. While the slow formation of iron crystals preserves the electrodes, it also limits high rate performance: these cells charge slowly and are only able to discharge slowly. The elements must remain covered with electrolyte; if they dry out, the negative plates oxidize and require a very long charge.

Did You Know?

• A 50 volt nickel–iron battery was the main D.C. power supply in the World War II German V-2 rocket.
• Thomas Edison claimed his nickel–iron design was 'far superior to batteries using lead plates and acid'.
• Nickel–iron cells were made with capacities from 5 to 1250 Ah.
• The open-circuit voltage of a nickel–iron cell is 1.4 volts, dropping to 1.2 volts during discharge.
• In 2023, the first industrial-scale Battolyser system was installed at the RWE Magnum power gas plant in Delfzijl.