Cells, Batteries and Fuel Cells

Cells

• An electrochemical cell is made up of two electrodes and an electrolyte.
• The two electrodes must be able to conduct electricity, and so are ususally metals.
• Th electrolyte is a liquid that contains ions that react with the electrodes.
• The chemical reactions between the electrodes and the electrolyte set up a charge difference between the electrodes.
• If the electrodes are then connected by a wire, the charge is able to flow and electricity is produced. A voltmeter can also be added to the circuit to measure the voltage of the cell.
• Different metals react differently with a given electrolyte- this is what causes the charge difference, or the voltage, of the cell. So the type of electrodes used will determine the voltage of the cell.
• The bigger the difference in reactivity between the metal electrodes, the bigger the voltage of the cell.
• The electrolyte used in a cell will also affect the size of the voltage since different ions in solution will react differently with the metal electrodes used.
• A battery is formed by connecting 2+ cells together in series. The voltages of the cells in the battery are combined so there is a bigger voltage overall.
• In some cells, the reactions that happen in the electrodes are irreversible.
• Over time the reacting particles- the ions in the electrolyte and the metal ions on the electrode- get used up and turned into products of the reaction.
• Once any one of the reactants get used up, the reaction can't happen so no electricity is produced.
• The products can't be turned back into the reactants, so the cell can't be recharged.
• In rechargeable cells, the reaction can be reversed by…