German innovation in information security
"Handys in die Dose, Deckel drauf," or "Phones in the can, lid on it." According to an article in WirtschaftsWoche, that's part of how German chemical company Evonik Industries deals with industrial espionage.
Evonik is apparently worried that Chinese or Russian intelligence agencies can use people's cell phones as listenting devices, so their corporate security policy requires employees to put their cell phones in a metal can when they're either inside their corporate headquarters or in meetings held elsewhere where sensitive information is discussed.
Because it's apparently possible for intelligence agencies to remotely activate cell phones that are turned off, either removing the phones' batteries or storing them in a container that shields them from any electromagnetic radiation (like a metal can) are the only ways to make sure that your cell phone isn't turned into a bug.
Given these two options, it looks like Evonik made the right choice. Taking the battery out of your cell phone regularly would get very annoying very quickly. And by having people put their phones in a metal can, they're probably reinforcing the message that everyone needs to take security seriously.