Cells and Batteries

• Electrochemical cells (or 'cells'), use chemical reactions to produce electricity.
• A cell can be made by connecting two different electrodes with a wire, and placing them in contact with an electrolyte. An electrolyte is just a liquid through which charged ions can flow. There will often also be a voltmeter so that you can measure the voltage of the cell. 

  
• Batteries are very similar, but consist of two or more cells connected together in series to provide a greater voltage.

  
• Factors that affect the voltage of a cell

  1. The metals used for the two electrodes. The greater the difference in reactivity of the two metals, the greater the voltage will be.
  2. The type and concentration of the electrolyte used.
  3. The conditions, such as temperature.
• Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied. These are the batteries used in laptops and mobile phones.
• In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up. These are the batteries usually used in smoke alarms and tv remotes. Alkaline batteries are non-rechargeable.