Whether you use a cell phone or wear a hearing instrument, you want to get the most life out of the batteries that make them work.  With this in mind, take care to store them in a cool, dry place.  While overheating can lead to loss of energy, leaking and rupture, there is no advantage to storing batteries in the refrigerator; doing so can cause condensation inside the battery package, which can damage batteries and shorten lifespans.  Most zinc-air button batteries last for up to three years when kept at room temperature in a dry environment.  Most hearing instrument batteries are powered by oxidizing zinc with oxygen in the air.

P.S.  Wait at least one minute after removing the plastic tab from a zinc-air button battery before inserting it into a hearing instrument.  Doing so allows the battery to fully power up and maximizes its effectiveness.