General RULE is to store batts in a waterproof container that does NOT allow terminals of the batts to touch each other. Generally speaking, the lower the temp of the stored batt, the slower the deterioration of initial charge. Storage of batts in original container in bottom of properly adjusted fridge is fine, as long as the batt containers are encapsulated in air-tight/water-tight baggies.
For field use, strongly suggest decent and durable waterproof containers that prevent inadvertant batt terminal connection, no matter if some batts have been removed.
It may be tempting to buy an inexpensive and "decent" batt holder/container and use a baggie over it for field use. Likely fine for fridge storage, but suggest that baggies are fragile and unreliable in the field.