Ernst Waldemar Jungner (June 19, 1869 – August 30, 1924) was a Swedish inventor and engineer.
In 1899 he invented the nickel-iron electric storage battery (NiFe), the nickel-cadmium battery (NiCd) and the rechargeable alkaline silver-cadmium battery (AgCd).
As an inventor he also fabricated a fire alarm based on different dilutions of metals.
He worked on the electrolytic production of sodium carbonate, and patented a rock drilling device.