The Daniell cell is a type of electrochemical cell invented in 1836 by John Frederic Daniell, a British chemist and meteorologist, and consists of a copper pot filled with a copper (II) sulfate solution, in which is immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode. He was searching for a way to eliminate the hydrogen bubble problem found in the voltaic pile, and his solution was to use a second electrolyte to consume the hydrogen produced by the first. Zinc sulfate may be substituted for the sulfuric acid. The Daniell cell was a great improvement over the existing technology used in the early days of battery development. A later variant of the Daniell cell called the gravity cell or crowfoot cell was invented in the 1860s by a Frenchman named Callaud and became a popular choice for electrical telegraphy.
Daniell cells, 1836.
Daniell cell demonstration made of zinc and copper electrodes in half cells
Diagram of early Daniell cell published by Daniell in 1839. In this design the original perforated disc has become a cylinder inside the upper part of the cell to hold copper sulfate crystals
Porous pot cell
An electrochemical cell is a device that generates electrical energy from chemical reactions. Electrical energy can also be applied to these cells to cause chemical reactions to occur. Electrochemical cells that generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells.
A modern electrolytic cell consisting of two half reactions, two electrodes, a salt bridge, voltmeter, and a battery.
Circuit diagram of a primary cell showing difference in cell potential, and flow of electrons through a resistor.
Lead acid car battery (secondary cell)