It can cause exterior short circuit if the two exterior ends of battery connect any conductor.
Battery types are different, short circuit maybe cause different serious results. As the battery can't be used again, leak liquid, explosion and more. So, don't have the exterior of battery short circuit.
Don't place battery in wet circumstance. and don't mix the battery with conductor, as the key in pocket together, which maybe all cause the short circuit.
Quotation from article at http://www.my-battery.co.uk/laptop-batteries/dell-inspiron-1100-series.htm (Care Dell Inspiron 1100 battery life)
See more information about laptop battery, laptop battery charger, laptop battery pack, power supply adapter at http://www.my-battery.co.uk