Li-ion batteries are batteries available for many premium cellular phones and computers. It depends on the chemistry of the battery. It is recomended to discharge them once in a while, to help increase the life span of the battery. Batteries that are not used on regular basis, such as camcorder batteries, Should always be fully charged before putting them away. Doing this can double the life of a battery.
Most batteries are now recyclable here is a link to obtain more info.
You can also find a recycling facility near you. It stands for Milli Amp Hours. This is a measurment of storage capacity given to the battery. The higher the number of mAh, the more storage capacity the battery has.