Electrochemical Cells
Electrochemical Cells is how two different metals in a liquid create electricity, like a homemade battery built from zinc and copper.
Two different metals sitting in a liquid work like a lemon battery on your kitchen counter. You push a copper coin and a zinc nail into a lemon, and electrons flow from the zinc to the copper through a wire. The lemon juice acts like the liquid in a real battery — it lets charged particles move between the metals. That flow of electrons is electricity.
Explaining electrochemical cells by grade level
Picture two different metal strips sitting in a cup of salty water. One metal strip wants to give away tiny bits of itself, and the other metal strip wants to take those bits. That pushing and pulling makes electricity flow through a wire between them, enough to light a small bulb.