Battery Corrosion?

[bklein]

I could research this but perhaps several of you have special takes on this.
What causes battery corrosion at contact points in our detectors?
Why can't it be prevented or designed away?

[Davor]

Perhaps it happens to boost sales of ridiculously expensive batteries... that can also spoil your fun. You know the ones you yank from the little pink bunnies. My approach is to use the least expensive alkaline batteries and hope for the best. I've noticed that when alkalines leak, which is not too common to start with, the metal parts they are in contact with do not corrode, and residue is cleanable by brushing. Capacity-wise they are cheaper than "standard" or "heavy duty" batteries that leak often and corrode all over the place.

[bklein]

I've read that cheaper batteries have thinner cases and these thin over time - the seal then weakens at the cap and leaks.
What I don't get is that the batteries that I have leak/corrode do so all the way to the battery contact. Why can't the battery have some sort of barrier coating? I've also seen that batteries corrode installed in devices but sitting in a parts bin - no.