I have a bunch of unused Panasonic AA Zinc Chloride batteries. Expiry 2027. However I looked at them and they all have this rusty-looking ring around the bottom. Is it leaking/corrosion? Or is it just the colour of the materials of the seal?
I have a few Kodaks too, also exp 2027. They don't have this, but they seem to be constructed differently.

It seems a shame to throw them out, and seems strange that every single one of them would be leaking/corroding before ever being used and 2 years before the expiry date. Especially because for Zinc batteries Panasonic are supposed to be the best, the most leak-proof. What do you think?

Here's a photo of the Panasonics, and 2 Kodaks on the right for comparison.