LiFePO4 bloat and gassing

[Refinished]

In cells that are getting mild bellies, what gas is being produced? Are the vents usually designed to do an as-needed release to keep the pressure under some spec pressure or are they one-time plugs that blow out? Are there generally obvious signs that the valves have released something? No need for Replace Or Die responses - I'm interested in the above answers from a chemistry and engineering PoV. Thanks!

 

[400bird]

I've got no idea on what gasses are released.

On the prismatic cells the pressure release is a scored/thinner part on the top of the case that will tear open when excess pressure builds up on the cell. It is non reversible.

I'm pretty sure the smaller cylindrical cells (18650) are also designed to be non reversible, but there are videos of people clicking them closed again on lipo batteries, so I'd expect something similar on LifePO4 cylindrical cells.

 

[marionw]

Explosion Hazards from Lithium-Ion Battery Vent Gas

Explosion hazards from lithium-ion battery vent gas (Journal Article) | OSTI.GOV

The U.S. Department of Energy's Office of Scientific and Technical Information

www.osti.gov

 

[wpns]

Explosion Hazards from Lithium-Ion Battery Vent Gas

Explosion hazards from lithium-ion battery vent gas (Journal Article) | OSTI.GOV

The U.S. Department of Energy's Office of Scientific and Technical Information

www.osti.gov

The subject is LFP, the above appears to be ‘regular’ lithium