Always store batteries separately
Used batteries are classified as hazardous waste and should never be thrown in household trash.
They must be stored separately and taken to your resouce center or a designated collection point to ensure proper and safe recycling.

Cover 9V and button cell batteries with tape
To prevent short circuits between used batteries, always cover the terminals of 9-volt and button cell batteries with adhesive tape.
Store them high up, out of reach of children, in a dry place at room temperature
Heat, humidity or easy access can increase the risk of spark or damage.
Some batteries, like button cells, are dangerous if swallowed so it's important to store them in a closed container safely away from children's reach.
Handle damaged, swollen or leaking batteries with care
If a battery is damaged, swollen, or leaking, isolate it by placing it in a sealed plastic bag or a non-metal container. Wear gloves if possible, as the chemicals may be corrosive or irritating.
Never puncture or press on the battery, and take it to your local resource center as soon as possible.
Do not leave batteries in unused devices
Even when turned off devices can draw residual power, which may lead to leaks or swelling if batteries are left in too long.