The person who gives a theory of ions is Michael Faraday. It’s around 1830. He describe the portions of molecules that move from anode to cathode or vice versa.
However, there were no fully explanation until 1884 where the scientist name Svante August Arrhenius describe it in his doctoral thesis.
Michael Faraday did his experimenting with electromagnetism in 1821 by demonstrating the conversion of electrical energy into motive force.
Using his special “induction ring” He discovered “electromagnetic induction” or generation of electricity. This is the first electricity transformer.
In 1837, he showed that electrostatic force consists of a field of curved line of force, and conceived a specific inductive capacity. Then he started to develop the theory of light and gravity.
History of Ions