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Inside GBS cells

6373 Views 13 Replies 7 Participants Last post by  Elithion

Note that the bottom cell is bloated, and the separators have a burned color.
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LiPo is NOT a battery chemistry, but a type. LiFePO4 can be LiPo).
Bless you for saying that!

  • LiPo not necessarily pouch (prismatic cells can be LiPo)
  • Pouch not necessarily LiPo (pouch can use a standard separator)
  • LiPo not necessarily LiCoO2 (LiPo can be LiFePO4)
  • LiCoO2 not necessarily LiPo (LiCoO2 can be any format)
  • LiPo not necessarily 3.6 V (LiFePO4 LiPo is 3.2 V)
  • 3.6 V not necessarily LiPo (Laptop cells are 3.6 V)
LiPo is an arcane technology inside some cells, and whether or not that technology happens to be used in a given cell has no effect to us users.

So, why use the term LiPo at all? Beats me.
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Can you determine how they are constructed?
Same as all other prismatic cells: many sets of cells in a bag, many bags in a case. The positive tabs from each cell are pressed together, and clamped to the case positive terminal. Same for the negative terminal.

While the guts of a prismatic cell are somewhat similar to a pouch cell, they are different in at least one major point: each bag is not sealed (pouch cells are sealed), so they share the gaseous portion of the electrolyte. The electrolyte is poured into the case through the plug at the top, at the end of construction.
Re: hard to pour peanut butter...

electrolyte... has the viscosity of grease and is spread on the foils like peanut butter.
Actually, I am not so sure. I do know of solid electrolytes for pouch cells. I do believe that many (all?) cylindrical cells use liquid electrolyte. But you're making me doubt what I understood about prismatic cells.


Could someone with more direct know-how chime in?
The Rickard thundersky dissection video shows essentially no free liquid and the anodes/cathodes barely wet with electrolyte.
Correct: as my reference (above) says, the electrolyte is very precisely metered.
Only the exact amount of electrolyte is poured in that will be completely absorbed by the cell, leaving no unabsorbed electrolyte. If indeed it is poured in a prismatic cell (as I remember being told). If is "spread like peanut butter", then no. We're looking for someone who actually knows the answer. I am not an expert in Li-ion chemistry and manufacture.

And, indeed, no liquid poured from any of the 4 GBS cells we just opened.
see if the electrode foils and electrolyte are actually visible,,,
They are visible: you can see them clearly in the picture. The white sheets are the separators.

... or if these might be separately sealed pouches?
They are not separate pouches. That is, they are not a bunch of individually sealed bags.
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