LiPo battery
A LiPo, short for lithium polymer, is a type of rechargeable lithium-ion battery built in flat, flexible pouches instead of hard metal cans. It stores a lot of energy for its weight and can deliver very high currents, which makes it common in drones and radio-controlled models. Each cell is about 3.7 V nominal, and packs are labeled by cell count, such as 6S for six cells in series.
Example: The flat, shrink-wrapped battery pack that slides into a radio-controlled car is usually a LiPo.