The battery is the power of the drone, which directly affects the flight time and weight.
Why don't drones use lead battery?
If you've ever seen a lead battery, the weight of lead battery(about the two boxes of paper) is 7.1 kg, while the density is 40 Wh/kg. The density of a lithium battery is 130 to 150 Wh/kg. However Lithium battery are only a quarter of the mass of lead batteries.
In addition, the electrolyte of lead battery is highly corrosive, and lead battery has heavy metal lead and cadmium which are harmful to human body and environment, and it not accords with environmental protection requirements.