fgrieu:
Any good sources on the exact chemistry in the battery, and how it degenerates in case of thermal runaway ?
Lithium Battery Failures gives a good overview.
http://www-scf.usc.edu/~rzhao/LFP_study.pdf gives a deeper look at the normal chemistry of Lithium ion batteries.
Types of Lithium-ion Batteries compares different variations on the Lithium ion chemistry.
http://www.kta-ev.com/v/vspfiles/ass...chnologies.pdf gives another overview of alternative Lithium chemistries, including some safety information and includes the useful point:
From a thermal/safety perspective, cobalt is generally considered the least stable cathode chemistry, but among the highest in terms of energy density.
I found a very good scholarly analysis of the exact anode, cathode, and electrode reactions involved in thermal runaway, but I don't have the URL handy at the moment. Possibly later.