Views: 201 Author: Hedy Publish Time: 2023-06-12 Origin: Site
which have piqued the interest of the battery industry. They can deliver 3-5 times the capacity of lithium-ion batteries with graphite anodes. Because the battery has a bigger capacity, it will last longer after each charge, which can greatly increase the driving range of electric vehicles. Despite the fact that silicon is abundant and inexpensive, the charge-discharge cycles of Si anodes are restricted. Their volume will be substantially increased with each charge-discharge cycle, and even their capacitance will decrease, resulting in the fracture of the electrode particles or the delamination of the electrode film.The KAIST researchers, lead by Professor Jang Wook Choi and Professor Ali Coskun, published a molecular pulley adhesive for large capacity lithium ion batteries with silicon anodes on July 20.
The KAIST researchers combined molecular pulleys (called polyrotaxanes) into battery electrode binders, including adding polymers to the battery electrodes to connect the electrodes to metal substrates. Polyrotane rings are fastened into the polymer skeleton and can freely move along it.Polyrotane rings may move freely when the volume of silicon particles changes. The slip of rings may efficiently preserve the form of silicon particles, preventing them from disintegrating during the continual volume change process.
Because of the great elasticity of polyrotane adhesives, even crushed silicon particles can stay coalescent. The function of the new adhesives differs significantly from that of the previous adhesives (which are typically simple linear polymers). Because conventional adhesives have low flexibility, they cannot securely hold the particle form. Previous adhesives can disperse crushed particles and limit or even eliminate silicon electrode capacity.
The author believes that this is an excellent demonstration of the importance of basic research. Polyrotaxane won the Nobel Prize last year for the concept of "mechanical bonds". "Mechanical bonding" is a newly defined concept that can be added to classical chemical bonds, such as covalent bonds, ionic bonds, coordination bonds and metal bonds. Long-term basic research is gradually addressing the long-standing challenges of battery technology at an unexpected rate. The authors also mentioned that they are currently working with a large battery manufacturer to integrate their molecular pulleys into actual battery products.
"Mechanical bonds have recovered for the first time in an energy storage environment," said Sir Fraser Stoddart, 2006 Noble Laureate Chemistry Award recipient at Northwestern University. When pulley-shaped aggregates with mechanical binders were combined with slip-ring polyrotaxanes and functionalized alpha-cyclodextrin spiral polyethylene glycol, the KAIST team achieved a breakthrough in the performance of lithium-ion batteries on the market. Compounds replace traditional materials with a single chemical bond, which has a substantial influence on material and equipment qualities.