From Wikipedia:
"Lithium batteries and methamphetamine labs
Unused lithium batteries provide a convenient source of lithium metal for use as a reducing agent in illegal methamphetamine labs. Some jurisdictions restrict or limit the sale of lithum batteries in an attempt to help curb the creation of illegal meth labs. However, the heavy demand for lithium batteries for use in modern, current-hungry devices such as digital cameras conflicts with such restrictions, and they remain controversial. For example, in Wal-Mart stores the limit of sale is four packages of lithium batteries (three in Missouri). [8] Rechargeable Ni-MH batteries are overtaking the disposable lithium batteries since they are more economical."