Why does my Xbox controller smell so strange of batteries?

I have an xbox one s, and a normal xbox controller but when I put old batteries in, it suddenly smelled so funny, and now whenever I put in new batteries it smells so strange about batteries, but it goes I can use it. Can I still use the dry smell?!

Maybe a battery has leaked

Of course you can still use it!

It was the same for me, only the stench disappeared after a short time.

No, it can't be, otherwise the controller would probably no longer work

How do batteries smell?

But it doesn't really matter, as long as they are OK you can continue to use the controller with a clear conscience.