how do I keep my phone warm in my car while at work

[Vicrooloo]

And here I thought electronics function better in colder environments.

Never knew that the battery life would be affected by colder temperatures.

 

[HEK]

And here I thought electronics function better in colder environments.

Never knew that the battery life would be affected by colder temperatures.

Electrical production from batteries is a chemical process. Lower the perturbed slow down the chemical process. See atoms move more slowly, interact less often the colder it gets. Just another one of those pesky physical laws.
And yes there is such a thing as supercooling, where electrical resistance is reduced to near zero. But that's another physical effect on state of resistance to electron flow. Not a chemical process of interacting atoms and molecules.