I looked up the incident (it was July 06), and apparently the Li batts were under no load, and were not charging.
One suspects that the altitude change might have caused a leakage which led to an exotherm chem rxn, and thermal runaway.
And, if this is the case, then the Li batts on the (gorgeous) 787 might malfunction as a result of altitude, whether-or-not the charging would contribute to the issue.
I would hope that they look into NiCd as soon as possible, and consider the Li batt fires to be (relatively) cheap lessons.
.
How many laptops are there on the average jumbo flight? 50? 60? and how many of them have caught fire? Probably none is my guess.
There is something different happening than just the presence of the battery.
Those pilots deserved a medal for bringing that bird in.
On the older aircraft the battery is used for emergency power to run some systems in the event of total AC failure. You could still fly as long as you had hydraulics and engines. Battery power is used for navigation and opening valves etc.
On newer aircraft the battery is more critical because they use fly by wire which is run off electrical power. The newer batteries have to run longer and provide more power than the older (usually lead acid) batteries.
The C5 had two NiCads the size of a loaf of bread.