Daniell cell, developed by John Daniell in the 19th century, was one of the earliest electrochemical cells that produced a steady electrical current. The device consisted of two half-cells: one containing copper sulfate with a copper electrode, and the other containing zinc sulfate with a zinc electrode. The flow of electrons from the zinc to the copper electrode through an external circuit produced electrical power.In modern electronics, the fundamental principles behind the Daniell cell—specifically, the conversion of chemical energy into electrical energy—continue to be relevant. Today, batteries and fuel cells operate on similar principles, though with more advanced materials and technologies.