Batteries are like humans. But there are competing interests. Storage as cold as possible above probably 35 or so for longevity. That is not the temperature that allows regen. Ideally store at 40 and then warm up to 70 for driving. Then pull into a refrigerator and get back down to 40 as quickly as possible. This neglects of course any damage that might happen from temperature swings. If storing for a long time, the temperature swing is less of an issue.
The battery will hold more energy as it gets hotter so then you want it closer to 100.
Competing interests. Storage at about 60 is a good compromise. Garage at 80 or 90 will hurt the life of any battery. The original Volt is interesting in that it will actually cool to 70 if plugged in an 80 degree garage. Tesla uses about 100 as the temp that will tell it to cool down. That is clearly a compromise to limit electricity use. The problem with the volt is that if the garage is 100, it will run all night intermittently to keep the battery cool. Doing that actually warms up the garage a decent amount. So there are people who have a Volt and a Leaf and report the "Volt cooked my Leaf's battery" - which it essentially does since the Leaf just lives at ambient temperature.
The early Leaf was a great experiment and we all learned a lot. But a big part of it's issue was the design of the battery and not the lack of cooling. But there are truths that apply still to all batteries just to a lesser degree. Storage temperature is a big factor for degradation.
Chemical reactions degrade things. Reach back to HS Chemistry and remember what temperature does to nearly all chemical reactions.