You can think of a battery as a small power plant that converts a chemical reaction into electrical energy.
Batteries are a great thing to have in our lives but not a good thing if they are stored incorrectly. Storing batteries in a storage unit is not a good idea, but if you feel there is no other recourse there are guidelines that you should follow to prevent damage or loss to the items stored.
The temperatures in storage units are constantly changing with the environment around them. Batteries if not stored correctly can cause leakage or rupture, resulting in personal injury or property damage.
9 Volt batteries are especially dangerous to store. They should never be stored without the post being covered with masking, duct, or electrical tape. They should never be stored with any kind of metal objects or other batteries. The reason for this is that they can start a fire. Since the posts of the battery are on the end of the battery together, metal objects can cause a short which will over heat the battery and lead to a possible fire. There have been several fires where a 9 volt battery has been the cause. Check out this report on You Tube http://youtu.be/CnVDayI-gwI
Dos and Don’ts for storing batteries:
Do practice proper battery storage by keeping batteries in a cool, dry place at normal temperatures.
Don’t store batteries, or battery powered devices in hot places. Elevated temperatures can lead to leakage or rupture to batteries causing risk of fire.
Never store batteries in a cloth or flammable bag.
You can find more information here http://www.wikihow.com/Store-Batteries