Can you fill a lithium battery with epoxy?

Question

Batteries

I am working on an electronic device that will need to be poured into an epoxy "brick" in its entirety, including the power source. Will a lithium-ion battery (18650 bank) survive such mockery? Does it emit gases during operation that can break the fill? What to look for when choosing a resin?

Answer 1

Lithium-ion batteries should not actually emit gases under normal operation. However, over time (years of use) due to gradual degradation, batteries can increase in thickness (losing capacity but still remaining functional). If the battery is packaged in hard resin, there is a chance that increasing compression will cause the battery to degrade more quickly, and possibly internally short out the battery. Therefore, if I planned to make such a device, I would not use epoxy resin, but a polyurethane or neutral silicone compound, which have a certain degree of elasticity. Another point - rarely when devices really need to be completely poured "into the brick" - often it is enough just to apply a uniform thick layer of sealing polyurethane varnish over the entire surface, or by sealing the device with a resin plug in a sealed plastic or metal case. Even aviation flight recorders are not packed in epoxy "brick".

Answer 2

If lithium batteries start to emit gases, they can be thrown away.
So - you can pour, the main thing is not to overheat.

Answer 3

Before pouring, place it in a case made of 5 mm foam rubber; during operation, it is important to observe the temperature standards of the environment, the input load and charge modes (if necessary);)