Batteries or accumulators are any source of electrical energy generated by direct conversion of chemical energy and consisting of one or more primary battery cells (non-rechargeable) or consisting of one or more secondary battery cells (rechargeable).
Most types of batteries contain toxic heavy metals, including nickel, cadmium and mercury. All of these metals can be recovered and re-used. Recycling batteries is good for the environment as it keeps them out of landfill, where heavy metals may leak into the ground, causing soil and water pollution and endangering animal and plant life. If batteries are incinerated with household waste, the heavy metals inside them cause air pollution.