[stonemetal]

tangentially related to how much electric power it makes when doing its designed chemical reaction.

Yeah but how much electric power it makes when doing it designed chemical reaction is only tangentially related to how much energy(note no mention of electrical energy during normal operation just energy) it contains. Rather akin to saying "a gallon of gasoline doesn't contain that much energy because we are using it to turn a water wheel and a gallon of liquid falling a few feet doesn't contain that much energy."

[noonespecial]

I think we're pretty much talking about setting it all on fire in this context. But dropping them out of 3rd story windows could be fun too.

[stonemetal]

For the energy in the battery you quote how much electricity it can store as if setting it on fire was just going to drain the battery. In battery fires most of the energy comes from burning chemicals in the battery not the electrical charge it was holding.