What is the Difference Between Lithium Ion and Lithium Polymer?

Lithium ion:

  • The lightest of all metals
  • The greatest electrochemical potential
  • The largest energy density for weight.
  • The load characteristics are reasonably good in terms of discharge.
  • The high cell voltage of 3.6 volts allows battery pack designs with only one cell versus three.
  • It is is a low maintenance battery.
  • No memory and no scheduled cycling is required to prolong the battery's life.
  • Lithium-ion cells cause little harm when disposed.
    It is fragile and requires a protection circuit to maintain safe operation.
  • Cell temperature is monitored to prevent temperature extremes.
  • Capacity deterioration is noticeable after one year (whether the battery is in use or not).

Lithium Polymer:

  • Lithium polymer chemistry differentiates itself from Lithium Ion in the type of electrolyte used (a plastic-like film that does not conduct electricity but allows ion exchange – electrically charged atoms or groups of atoms).
  • The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte.
  • The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry.
  • Cell thickness measures as little as one millimeter (0.039 inches).
  • Can be formed and shaped in any way imagined.
  • Commercial lithium polymer batteries are hybrid cells that contain gelled electrolyte to enhane conductivity.
  • Gelled electrolyte added to the lithium ion polymer replaces the porous separator. The gelled electrolyte is simply added to enhance ion conductivity.
  • Capacity is slightly less than that of the standard lithium ion battery.
    Lithium ion polymer finds its market niche in wafer-thin geometries, such as PDA batteries.
  • Improved safety – more resistant to overcharge; less chance for electrolyte leakage.

Until Next Time – Dan Hagopian, BatteryShip.com
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