Re: I wonder
Lower pressure and or pressure changes won't cause any problems for a li-ion battery.
Batteries don't "burst open" as such. Battery cells release a small amount of hydrogen when being charged or discharged (which is why they tell you not to leave batteries charging whilst unsupervised). When charged or discharged at a higher rate then much more hydrogen is released.
The trend to ever thinner, lighter and more sealed/waterproof devices (exclusively achieved by cutting safety margins) means that your stripping out protections against cells in a multi cell battery touching and shorting. A short is effectively just a very high rate discharge as far as the battery is concerned
When batteries catch fire ("venting with flame" is the technical term) you've hit a last ditch design measure to prevent an explosion. Hydrogen is being released fast enough to burn under the pressure it's venting under as it can't escape fast enough, and the explosion happens if the battery and housing is flimsy and the vents for the hydrogen is either non existent (because it's waterproof and the vents are sealed) or too small to allow the hydrogen to vent fast enough.
The underlying technology has not advanced significantly in past years, the increase in performance is largely made from cutting safety margins from "exceedingly generous" to "razor thin". Razor thin safety margins mean that you get cut occasionally.
Check out the MSDS for a lithium battery for more information, especially the dangers of hydrofluoric acid which is released from the battery in both smoke and residue when a cell vents with flame if your working in IT and may be required to deal with the aftermath of a battery going up. The stuff scares anybody who knows anything about it.