The energy generated by the batteries is the result of chemical reactions. The basic elements of their manufacture are generally heavy metals(mercury cadmium, lead). The environment authorities try to replace the manufacturing technologies with heavy metals of batteries or to impose a controlled recycling. The mercury concentration in batteries was limited to 0.0005% – with the exception being the coin type batteries which can have a concentration of maximum 2% of its total weight, the nickel-cadmium, from 2009 remain to be used only in military applications, medical and safety lighting, the rest of applications being replaced with nickel metal hydride accumulators; lead remains in use because there is not an economical solution to replace it. Fortunately, the very high recycling rate of lead batteries (approximately 98%) postpones the decision to ban their use. In parallel, alternative metals (Ni-MH, Li-ion) were searched for, which have a lower level of toxicity, but the large quantities used on the market require a high level of recycling (approximately 60%). Unfortunately, their recycling is not as attractive as that of lead batteries because the collection and separation costs are high. The danger generated by throwing batteries in the household waste is that, following the corrosion of the case, heavy metals end up infiltrating into groundwater layers and posioning people and animals. Although Li-ion batteries are less toxic, uncontrolled disposal can cause fires by igniting the lithium in the humid atmosphere.
The collection of used batteries can be done at their points of sale, traders having the obligation to hand them over to be recycled or disposed of.