Separators for Lithium-ion Batteries
Innovative Separator LIELSORT
With the growing popularization of tablet PCs and electric vehicles, lithium-ion batteries (LIBs) are expected to achieve even larger capacity and higher energy density. This has created demand for high-performance separators that electrically isolate the cathode from the anode and inhibit thermal runaway caused by short circuits to provide greater safety and high voltage stability.
In responding to increasingly evolving and diversified market needs, Teijin developed LIELSORT, innovative separators using microporous polyethylene substrate, one coated with TEIJINCONEX meta-aramid, and the other coated with the world's first fluorine-based compound, for superior heat-resistance and adhesion to polymer electrolyte.
Longer Battery Life as well as 20% Higher Output
The separator coated with TEIJINCONEX meta-aramid maintains its shape even at 250℃. In spot heating tests, Teijin has verified that the separator does not break down even at 400℃(see the video shown below). This superior heat-resistance persistently inhibits thermal runaway, enabling production of LIBs with greater safety.
The other type of separator, which is coated with fluorine-based compound, is designed for use in pouch-type LIBs. Such LIBs are used in tablet PCs and smartphones. This separator readily adheres to electrodes, thereby preventing leakage of electrolyte, resulting in LIBs with higher reliability and longer lifespans.
Furthermore, these two types of the innovative LIELSORT separators have superior resistance to oxidation and high affinity or wettability with electrolyte. LIELSORT, in addition to improving output by about 20% compared to conventional LIBs, also can be combined with a high-potential cathode to extend the battery's lifespan by several times longer than batteries with existing separators.
|Meta-aramid coating||Fluorine-based resin coating|
|Heat resistance||A compound coating combining inorganic filler with highly heat-resistant meta-aramid resin dramatically improves heat resistance while maintaining the shutdown function. This superior heat resistance greatly enhances battery safety.||–|
|Wettability||Electrolyte wettability was markedly improved by using coatings made of materials that exhibit high affinity with liquid electrolytes, such as meta-aramid resin and fluorine-based resin. This better wettability contributes to longer battery life.|
|Oxidation resistance||Oxidation resistance has been improved by the use of meta-aramid resin, fluorine-based resin, and fillers. This superior oxidation resistance allows higher voltages and higher energy densities.|
|Electrode adhesion||–||LIELSORT is coated with a Fluorine-based resin that strengthens adhesion of the separator and electrodes. Greater adhesive strength makes laminated batteries more reliable.|
Spot heating tests at 400℃ and nail penetration tests
Production and Sales System Enabling High Productivity and Cutting-edge Functionality
With LIELSORT, Teijin has used its expertise in polymeric chemistry acquired over a long period of time to develop the world´s first technology for simultaneously coating both sides of the separator. It also developed a high-speed coating technology that is five times faster than conventional coating. Both technologies enable more efficient production. Teijin has established separator manufacturing and sales companies in South Korea to build a manufacturing and sales network in close contact with customers and secure a foothold for penetrating the Chinese market. Teijin will continue expanding the market for the innovative LIELSORT separators, which dramatically enhance battery performance, and work to establish them as the de facto standard for next-generation LIB specifications.