[broadgage]

For storing batteries, I keep them in the original packs in a picnic "cooler" which of course does not actually cool at all. Such boxes are however good thermal insulators and maintain an even internal temperature.
Minimising thermal cycling and extremes of temperature should reduce the risk of leakage or other deteriotation.

As others post, it is sensible to ckeck and preferably replace all batteries in seldom used equipment on a memorable date once a year.

My favoured date is the last week in November for the reason that part used or questionable cells may be used up in toys etc over the Christmas and new year holidays before being discarded.

When a long leak free life is more important than least first cost I would recomend the Energiser disposable lithium cells in AA and AAA sizes. So far as I am aware, Energiser have a wateright patent on this style of cell and generic equivalents are not available.

Small 9 volt disposable lithium batteries are available from several makers and I would recomend any reputable make for expensive or safety critical equipment.