Today, the market share of Li-polymer battery is rapidly growing. It is widely used in many digital devices such as smartphone and portable charger. It is like a car’s fuel tank and transmission, is responsible for the entire endless mobile power and directly determines good or bad. Here we will explore its mysterious world comprehensively.
The lithium-polymer differentiates itself from conventional battery systems in the type of electrolyte used. The original polymer design, dating back to the 1970s, uses a solid (dry) polymer electrolyte that resembles a plastic-like film. This insulator allows the exchange of ions (electrically charged atoms) and replaces the traditional porous separator that is soaked with electrolyte.
But the solid polymer has a poor conductivity at room temperature and the battery must be heated to 50–60°C to enable current flow. So it is unsuitable for portable applications, and the much anticipated “true plastic battery” promised in the early 2000s did not materialize.
To compromise, gelled electrolyte is added. All Li-ion polymer cells today incorporate a separator prepared from the same traditional porous polyethylene or polypropylene separator filled with a polymer, which gels upon filling with the liquid electrolyte. Thus the commercial “lithium-ion polymer” (Li-polymer for short) cells are very similar in chemistry and materials to their liquid electrolyte counter parts.
Even so, the Li‑polymer is unique. It offers higher specific energy and reduces the weight by over 20 percents than conventional Li-ion, while the manufacturing cost increases by 10–30 percent, but its market share is still growing. Furthermore, the Li-polymer battery can be made into any shape, fitting neatly into stylish smartphones, portable chargers and laptops to make them smaller, thinner and lighter.
Very low profile: batteries resembling the profile of a credit card are feasible.
Flexible form factor: manufacturers are not bound by standard cell formats. With high volume, any reasonable size can be produced economically.
Lightweight: gelled electrolytes enable simplified packaging by eliminating the metal shell.
Improved safety: more resistant to overcharge; less chance for electrolyte leakage.
Expensive to manufacture.
No standard sizes. Most cells are produced for high volume consumer markets.
Higher cost-to-energy ratio than lithium-ion