Yep, li-ion and li-po cells are hermetically sealed for a very specific reason. There was a photo circulating the flashlight forums recently showing a crew compartment inside the International Space Station that had an old style D-cell Maglite hanging from a rack of astronaut gear. The photo was taken around 2018-2021 and there were people asking why the ISS and various space agencies did not seem to have taken advantage of the smaller and far, far more powerful 18650 and 21700 fueled tactical flashlights that are more suited for an environment like a spacecraft. The answer might be that NASA, ESA, JAXA, etc. are concerned about what an accidental puncture or abrasion involving a li-ion cell might do aboard the ISS where simply evacuation is not really an option and stuck to the older ni-cad battery powered tech. But then again, there ARE laptops, tablets, and small auxiliary power supply units aboard the station that are powered by li-ion cells...