Abbreviated as LiPo, LIP or Li-Poly, lithium polymer batteries (more correctly known as lithium-ion polymer batteries) are typically made up from four main components – as listed below:
- Positive Electrode
- Negative Electrode
The positive electrode is essentially comprised of three separate parts; a lithium-transition-metal-oxide, such as lithium cobalt oxide (LiCoO2) or lithium manganese oxide (LiMn2O4), a conductive additive and a polymer binder of poly(vinylidene fluoride) (PVDF). The negative electrode is constructed from the same three parts, with carbon replacing the lithium-metal-oxide.
Separator material typically used in the construction of lithium-ion polymer batteries is either Polyethylene (PE) or Polypropylene (PP), which essentially means that even if the cell has a liquid electrolyte then the battery will still contain a “polymer” component.
Unlike lithium ion batteries, lithium-ion polymer batteries adapt a solid electrolyte within their cell construction, and typically use one of three forms. Dry solid (which was essentially phased out within the prototype years), porous chemical compound or a gel-like compound. The gel-like compound is the most common of the three and more popular among laptop and tablet batteries.
Advantages of lithium-ion polymer:
- Robust + Flexible: Flexible size/shape allow pack manufacturers to create a more bespoke design for customers, with the pack configuration sometimes forming part of the protective housing due to the various sizes available.
- Low profile: Batteries as thin as 1mm (0.039”) are achievable.
- Lower chance of leaking electrolyte: Due to increased safety and higher resistance to overcharge.
Limitations of lithium-ion polymer:
- Lower energy density/shorter lifespan: Decreased cycle life, as opposed to lithium-ion.
- Costly to manufacture: Mass production of cells has a chance to decrease component cost.
Lithium-ion polymer batteries are designated under the UN classification code for lithium-ion batteries as UN3480 (lithium-ion batteries) or UN3481 (lithium-ion batteries contained in equipment/packed with equipment. They must be shipped in accordance with the appropriate regulations as Class 9 dangerous goods.