"Inside the insulated cask of the battery, the electromotive apparatus cracks the energy out of lava and converts it to electrical charge."
While these cells are capable of holding a larger amount of energy when compared to standard energy cells, Lava is an somewhat dangerous liquid that is nearly impossible to carry in large amounts and can be fatal if an inappropriate container is used to carry it. Later on, it can be semi-safely generated in huge amounts, but by that time you will most likely have the Biodynamic Cell, which does not carry the risk of killing self by misclicking. Additionally, when full, it has the same amount of charge as simply carrying 4 of the considerably Chem Cells, while only weighing 1 lb less.
A Thermoelectric Cell is one of the various types of Energy Cells available in Caves of Qud.
As an unknown Artifact, it may appear as "small trinket" or "small cube", occasionally containing a few drams of lava.
As a liquid fueled energy cell, it produces power from Lava. Each dram of lava can produce 5000 units of charge, and it can hold a maximum of 8 drams. A fully fueled cell can provide 40000 units of charge.