Every battery, including with zinc, needs special precautions so that its anode corrodes only when current is drawn. Even after over a century of zinc battery development, self-discharge still exists.
Previous methods included alloying zinc with a bit of
mercury, yuk, and forbidden in the EU. Presently (since zinc batteries haven't fully disappeared yet) mercury is excluded, and the same result is obtained from
zinc purity as far as I know - and possibly from other additives.
This looks very similar to corrosion control. It's sensitive to minor impurities and to the metallurgical state of the alloy.
What are the chemistries of acid zinc batteries? I thought they were saline, and had imagined that self-discharge is uncontrollable with acid electrolytes. I mean, when an acid-metal reaction is shown in a classroom, it's typically with zinc.
O yes, zinc-cerium batteries use an acid
http://en.wikipedia.org/wiki/Zinc%E2%80%93cerium_battery