Storage and fuel cells

• Primary cells

  -non-rechargable and single use

  -electrical energy is produced by the oxidation and reduction of electrodes

  -most are alkaline based Zn/MnO2
• Secondary cells

  -rechargeable and cell reaction can be reversed during re-charging

  e.g NiCd
• what are the Lithium ion and lithium ion polymer cell limitations?

  -unstable at high temperatures so fires can occur to devices which is a safety hazard

  -very reactive metal so care must be taking int recycling

  -demand exceeds supply so might become unsustainable

  -can be wasted if not recycled properly
• What are the advantages Lithium ion and lithium ion polymer cells?

  -lithium has a low density an a relatively high electrode potential

  -solid polymer is flexible so it can be easily formed into various shapes and sizes

  • ideal for fitting around other components in tightly packed spaces

  -lightweight
• lithium ion and lithium ion polymer cells

  -electrons move through connecting wires to power the appliance

  -lithium ions move between electrodes

  • positive electrode: metal oxides CoO2
  • negative electrode : graphite coated in lithium metal
• fuel cells

  uses energy from the reaction of a fuel cell with oxygen

  • fuel and oxygen flow into the cell and products flow out
  • can constanly operate if fuel and oxygen is supplied
  • don’t have to be recharged
• hydrogen fuel cells advantages

  -water is the only reaction product

  -occurs at room temperature

  -all bond energy is converted to light energy
• risks and disadvantages to hydrogen fuel cells

  -hydrogen is highly flammable so the storage and production is a safety hazard

  -very thick walled cylinders and pipes are expensive

  -production of hydrogen is a by product of the crude-oil industry so it relies on the non-renewable finite resources
• Hydrogen fuel cells can be alkaline or acidic