So I mentioned batteries the other day and thought I should follow up with a bit more electrochemistry. Electroplating is simply the act of using an electrical current to deposit a layer of one thing (usually a metal) on top of another thing. This is fairly common procedure for many things including making car parts and taps shiny by depositing a layer of chromium. In electroplating the object to be covered is located at the cathode (the negative end) and must be electrically conductive. Another electrode is also needed and in some cases is made of the material to be deposited. Both these electrodes are then placed in a solution containing dissolved metal salts (such as copper sulfate). The ions in this solution allow the flow of an electrical current along with providing the metal necessary to coat the cathode. When this system is switched on the dissolved metal ions move towards the cathode and begin to adhere to the surface. This is because the positive charge on the metal ion is removed by the addition of electrons from the power source. This turns the water soluble ionic metal into the non soluble solid metal we all know, coating the cathode in the process. This continues until all the metal ions in the solution are used up or the current can no longer flow. In cases where the anode is made of metal it may also begin to dissolve as it attempts to make up for the ion imbalance in the solution, thus it reduces in mass and itself can transfer to the cathode.
Electroplating can also lead to fractals as seen in the SEM image.
Images: 1, 2