The Nickel-iron accumulator (NiFe accumulator, Jungner accumulator, Edison cell) was invented by the Swedish inventor Jungner in 1899 and was refined by Edison in 1901. It was the first alkaline accumulator and is often thought off as a predecessor of the Nickel-cadmium battery. The positive electrode consists of nickel (nickel hydroxide in Edison's version) and the negative of iron. The NiFe accumulator commonly uses potassium hydroxide as the electrolyte. It has a voltage of 1.2v/cell and has a discharge energy of about 100kJ/kg.
This type of accumulator is mostly replaced by the NiCd accumulator. Building a NiFe cell is sometimes used as a school experiment, since it consists of relatively common materials and doesn't contain highly toxic elements like the NiCd cell.