Today, upon periodic inspection of a light that doesn’t see regular usage, I discovered the condition below.
The dark deposits are hard, and perhaps crusty.
The lighter deposits that look like grease can be smeared a bit, like a thick grease. However, it isn’t excess lube from the threads or anything of that nature.
The spring cleaned up fine with some contact cleaner, and wasn’t corroded like one would see with alkalines.
Can’t say when the cell was manufactured, but the light it was bundled with was obtained ten months ago in October 2019.
I’ve never experienced a leaking Li cell before, so I’m trying to get a better understanding of the situation. But, my overall experience suggests that unexpected secretions are not good things, for either people or batteries.