Polymer batteries are also called Li-polymer batteries, or polymer lithium batteries. It is also a kind of lithium-ion batteries, but compared with liquid lithium batteries (Li-ion), it has many obvious advantages, such as high energy density, smaller size, ultra-thin, lightweight, and high security. It is a new type of battery. In shape, lithium polymer batteries are ultra-thin and can be made into batteries of any shape and capacity to meet the needs of various products. The minimum thickness of this kind of battery can be up to 0.5mm. Like Li-ion, its nominal voltage is 3.7V, without memory effect.