Lithium polymer batteries (Li-polymer), also known as high molecular weight lithium-ion batteries, are a type of chemical battery. Lithium polymer batteries are characterized by their ultra-thin design, allowing them to be manufactured in various shapes and capacities to meet the needs of different products; theoretically, the minimum thickness can reach 0.5mm.
Lithium polymer batteries use a lithium alloy as the positive electrode and a polymer conductive material, polyacetylene, polyaniline or poly(p-phenol) as the negative electrode, with an organic solvent as the electrolyte. The specific energy of lithium polyaniline batteries can reach 350 W·h/kg, but the specific power is only 50-60 W/kg. The operating temperature is -40-70 degrees Celsius, and the lifespan is about 330 cycles.
Compared to lithium-ion batteries, lithium polymer batteries have the following characteristics:
1. It relatively improves the battery leakage problem, but does not completely solve it.
2. Can be made into thin batteries: with a capacity of 3.6V 250mAh, its thickness can be as thin as 0.5mm.
3. Batteries can be designed in various shapes.
4. Can be made into a single high-voltage cell: Liquid electrolyte batteries can only achieve high voltage by connecting several cells in series, while polymer batteries, since they do not contain liquid, can be made into multi-layer combinations within a single cell to achieve high voltage.
5. Discharge capacity is theoretically 10% higher than that of lithium-ion batteries of the same size.
Lithium polymer batteries have many advantages, such as high energy density, miniaturization, ultra-thinness, lightweight and high safety. Based on these advantages, lithium polymer batteries can be made into batteries of any shape and capacity to meet the needs of various products. Furthermore, they use aluminum-plastic packaging, so any internal problems can be immediately reflected through the outer packaging. Even if there are safety hazards, they will not explode, but will only swell.
In polymer batteries, the electrolyte serves a dual function as both a separator and a liquid electrolyte: on the one hand, it acts like a separator to isolate the positive and negative electrode materials, preventing self-discharge and short circuits within the battery; on the other hand, it acts like a liquid electrolyte to conduct lithium ions between the positive and negative electrodes. Polymer electrolytes not only possess excellent conductivity but also exhibit the unique properties of polymer materials, such as light weight, good elasticity, and ease of film formation, aligning with the development trend of lightweight, safe, efficient, and environmentally friendly chemical power sources.
