Electric Vehicles Slow Charging Speeds in Winter... Is It Possible to Fix It?

An organic cathode material that can increase capacity and price competitiveness, which were limitations of fast-charging battery materials, has been developed.



Professor Kang Seok-ju's team from the Department of Energy and Chemical Engineering at Ulsan National Institute of Science and Technology (UNIST) and Dr. Ahn Seok-hoon's team from the Korea Institute of Science and Technology (KIST) announced on the 19th that they have developed a highly



crystalline organic cathode material for lithium-ion batteries. In winter, the charging speed of electric vehicle batteries slows down. This is because the diffusion speed of lithium ions in the battery cathode slows down. For this reason, batteries containing LTO material instead of graphite are used as cathode materials in electric buses where fast charging is important. LTO has the problem of having a capacity that is half that of graphite and being expensive.



The advantages of the highly crystalline organic cathode material synthesized using antisolvent crystallization technology and the developed cathode. [Photo = UNIST]



The research team developed a highly crystalline organic cathode material 'Cl-cHBC' with a maximum capacity 1.5 times greater than that of LTO material. Organic materials have the advantages of being inexpensive and lightweight. Since crystallinity is low, crystallinity must be increased through high-temperature post-processing.



The research team synthesized an organic cathode material that exhibits high crystallinity even at low temperatures through an anti-solvent crystallization process. Anti-solvent crystallization is a process method that crystallizes a solute by adding a solvent with low solubility.



The developed high-crystallinity cathode material has a fast lithium ion diffusion rate and high electrical conductivity. This is because the higher the crystallinity, which is the regularity of the microstructure, the more the path of ions and electrons moves becomes straighter. Thanks to this, fast charging is possible and the output is also improved. The higher the crystallinity, the longer the lifespan.



Stable performance was also secured when producing a battery by pairing it with various cathode materials. When combined with LFP cathode material, it showed a high discharge voltage (3.0 V). This is about 67% higher performance than when using LTO cathode material. LFP cathode material batteries, which are mainly used in imported electric vehicles, are highly price competitive, but have the disadvantage of low discharge voltage, or output.



An official from the joint research team explained, "Since the developed material can be synthesized at low temperatures without a high-temperature post-treatment process, it will be able to secure additional price competitiveness when commercialized," adding, "Because it is lightweight and has high output, it is expected to be applied not only in electric vehicles but also in drones."



The research result (paper title: Highly Crystalline Controlled Coronene Homologous Molecule as Superior Organic Anode Material for Full-Cell Li-ion Batteries), in which UNIST Department of Energy and Chemical Engineering researcher Ha-Ho Ji participated as the first author, was published in the international academic journal in the field of energy materials 'ACS Nano' on the 21st of last month.





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