Lithium Battery Chemistries

Common types of lithium based batteries are in use currently and they include but not limited to:

1. Lithium Ion (Li-ion)
2. Lithium Polymer (Li-po)
3. Lithium-thionyl chloride (Li-SOCl₂)
4. Lithium-sulfur dioxide (Li-SO₂)
5. Lithium-manganese dioxide (Li-MnO₂)

Lithium Ion (Li-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.
• 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

• The lithium-polymer differentiates itself from the conventional battery 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.

Lithium-manganese dioxide (Li-MnO₂)

• Lithium-manganese dioxide cells have a metallic lithium anode (the lightest of all the metals) and a solid manganese dioxide cathode.
• Lithium-manganese dioxide cells are immersed in a non-corrosive, non-toxic organic electrolyte.
• They deliver a voltage of 2.8 V and are cylindrical in shape, in 1/2 AA to D format, with spiral electrodes.

Lithium-sulfur dioxide (Li-SO₂)

• Lithium-sulphur dioxide cells have a metallic lithium anode (the lightest of all the metals) and a liquid cathode comprising a porous carbon current collector filled with a sulphur dioxide (SO₂) solution.
• They deliver a voltage of 2.8 V and are cylindrical in shape, in ½ AA to double-D format, with spiral electrodes.
• Lithium-sulphur dioxide cells have a high energy density (250 Wh/kg) and a good capability for delivering repeated bursts of high power (up to 400 W/kg), derived from the spiral construction and is utilised in most of the applications addressed by this type of cell.

Lithium-thionyl chloride (Li-SOCl₂)

• Lithium-thionyl chloride cells have a metallic lithium anode (the lightest of all the metals) and a liquid cathode comprising a porous carbon current collector filled with thionyl chloride (SOCl₂).

They deliver a voltage of 3.6 V and are cylindrical in shape, in 1/2AA to D format, with spiral electrodes for power applications and bobbin construction for prolonged discharge.

Lithium-thionyl chloride cells have a high energy density, partly because of their high nominal voltage of 3.6 V. Bobbin versions can reach 1220 Wh/L and 760 Wh/kg, for a capacity of 18.5 Ah at 3.6 V in D format. Because self-discharge is extremely low (less than 1% per year), this kind of cell can support long storage periods and achieve a service life of up to 20 years.

Until next time - Dan Hagopian, BatteryShip.com
Copyright © BatteryEducation.com. All rights reserved.