Cells, Batteries and Fuel Cells

• Cells contain chemicals which react to produce electricity.
• The voltage of a cell is dependent on factors such as type of electrode and electrolyte
• A simple cell can be made by connecting two different metals in contact with an electrolyte
• A battery is two or more cells connected together in series to provide a greater voltage
• Non rechargeable cells and batteries:

  • Chemical reactions stop when one of the reactants have been used up
  • Alkaline batteries are non rechargeable
• Rechargeable cells and batteries:

  • can be recharged because the chemical reactions are reversed when an external electrical current is appiled
• Hydrogen fuel cells can be used constantly, provided fuel keeps being put in
• Hydrogen is a gas so needs to be stored at high pressure, so is harder to transport
• Hydrogen fuel cells only produce water when burnt
• Rechargeable cells and batteries are hard to dispose of and non biodegradable
• Rechargeable cells and batteries will eventually stop working
• Fuel cells are supplied by an external source of fuel and oxygen or air. The fuel is oxidised electrochemically within the fuel cell to produce a potential difference
• The overall reaction of a hydrogen fuel cell involves the oxidation of hydrogen to produce water
• Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries
• At the anode (positive)

  H2+ -> 2e- + 2H+
• At the cathode (negative)

  4H+ + O2 + 4e- -> 2H20
• Potassium hydroxide can be used as the electrolyte