Technical Information
Lithium Battery Information [Back to Top]
Lithium batteries are the cell of choice for numerous applications due to their high energy density and compact size. Lithium batteries are very reliable and have high capacity. Lithium batteries are extremely attractive for applications in the oilfield due to their ability to perform in extreme environments. |
Lithium Battery Advantages [Back to Top]
· High voltage (3.0 – 3.9 volts per cell)
· High capacity
· Long shelf life due to extremely low self discharge rate
· Capable of withstanding high amounts of shock and vibration
· Performance at extreme temperatures from - 40o C up to 200o C |
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The two most common lithium cell chemistries used in down hole applications are lithium thioynl chloride and lithium sulfuryl chloride. Lithium/Thionyl Chloride (Li/SOCL2) which is probably the most commonly used type, has one the highest energy densities of available battery systems. All of our suppliers manufacture this type. Lithium/Sulfuryl Chloride (Li/SO2CL2) is another commonly used lithium chemistry. Although similar, this type is different from Lithium/Thionyl Chloride cells in the increased current capability due to higher conductivity of electrodes. The most noticeable difference to users of lithium batteries however is the difference in open circuit voltage. Lithium/Thionyl Chloride cells have an open circuit voltage (OCV) of approximately 3.6 volts, while Lithium /Sulfuryl Chloride cells have an OCV of 3.9 volts. However both of these chemistries perform very similar under closed circuit conditions. |
Cell Construction [Back to Top]
Three different type of construction are used to manufacture lithium cells.
These construction techniques determine the performance and capabilities of the cells. The cell chemistry and construction has an effect on which applications they are best suited for. For more information on which cell is best suited for which application please contact Innovative Battery Solutions. Explained below are the three techniques that our cell suppliers utilize in the construction of lithium cells. |
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Moderate Rate (Dual Anode) Cell Construction
Double or Dual Anode cells have a greater electrode surface area than bobbin cells due to an extra layer of anode material, and can therefore deliver higher current and better performance in moderate current drain applications. These cells are also ideally suited for use in high shock and vibration environments.
Bobbin Cell Construction
Bobbin cells have a smaller electrode surface area, and therefore are generally used in applications which require very low current drain, such as battery backup and other low temperature applications. This type of cell typically consists of one cylinder of cathode surrounded by one cylinder of anode. The relatively simple assembly of these cells leads to a lower cost per cell.
Spiral Cell Construction
Spiral wound cells offer higher energy density, higher current capability and more consistent performance for high rate applications. In addition, a number of spiral wound cells offer superior restart performance for pulsed or intermittent applications. In most cases theses cells operate with the least noticeable effects of passivation. However, the advanced construction techniques used in the manufacture of this cell type causes these cells to be more costly. |
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Passivation [Back to Top]
Passivation is a thin layer formed in a cell between the lithium anode and the carbon based cathode of a lithium cell. It is formed as a result of a reaction between the electrolyte and the lithium anode. Without this layer, this particular type of lithium battery could not exist because the lithium would discharge and degrade quite rapidly. |
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An advantage of the passivation layer is it allows the battery to have a very low self discharge rate and extremely long shelf life. In most cases a thin passivation layer will not degrade the performance of your cell or battery pack. However, if this layer becomes to thick it will have some effects on the performance of your battery. The most noticeable effect of passivation to lithium battery users is voltage delay. This is when a load is applied to a battery and the voltage drops down before returning to the normal load voltage of an unpassivated battery. |
Coping with Passivation [Back to Top]
- In order to depassivate a battery, apply a load equal to the maximum continuous discharge current of the battery, just prior to use
- Avoid storing batteries at high temperatures (above room temperature)
- Remember high current loads and prior use increase the effects of passivation
- Use at low temperatures also increases passivation
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For more information on Passivation, Please contact Innovative Battery Solutions.
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