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How does passivation affect the operation of a lithium battery?

Passivation is a surface protecting reaction which occurs spontaneously in all lithium batteries based on a liquid cathode, and plays a major role in many of these beneficial characteristics. However, when not well managed, passivation can adversely affect the operation of the application.

Why is passivation important in lithium thionyl chloride battery?

Passivation is a necessary intermediary layer that it inhibits the immediate reaction of the solid lithium anode with the liquid thionyl chloride cathode, thus providing for the stability and very low self-discharge (<3% typical) of the lithium thionyl chloride battery.

What is a lithium passivation layer?

It is a self-assembled, thin, highly resistant layer of lithium chloride crystals on the surface of the lithium metal. This passivation layer partially blocks the chemical reaction between the solid lithium (anode) and the liquid thionyl chloride (cathode), inhibiting the battery chemical reaction from generating the electrons (electrical current).

Why do batteries need a passivation layer?

Put simply, it prevents the battery to be in permanent internal short circuit and discharging of its own accord. That's why it enables liquid cathode-based cells to have a long shelf life. The passivation layer is electronically insulating, which may have some consequences for battery operation.

How does temperature affect the passivation layer of a battery?

Higher temperature causes a thicker passivation layer, thus storing at cooler (room) temperature helps mitigate passivation layer growth. Consequently, using fresher batteries helps assure a less resistive passivation layer has formed in the battery. The passivation layer is diminished by appropriate electrical current flow through the cell.

How does the passivation layer reduce electrical path resistance?

The passivation layer is diminished by appropriate electrical current flow through the cell. This current flow breaks down the passivation layer to reduce the electrical path resistance via a more efficient chemical reaction between the solid lithium anode and liquid thionyl chloride cathode.