Molecular "Pulley" Binder -- A Breakthrough on the Performance of Lithium-ion Battery

Silicon anodes are of great concern in the battery community. Compared with lithium ion batteries currently using graphite anodes, they can provide 3-5 times more capacity. Greater capacity means that the battery is used longer after each charge. This can significantly extend the mileage of electric vehicles. Although silicon is abundant and cheap, the number of charge and discharge cycles of the Si anode is limited. During each charge and discharge cycle, their volume will greatly expand, and even the attenuation of their capacitance will cause the electrode particles to break or layer the electrode membrane. phenomenon.

A molecular pulley adhesive for Silicon anode lithium-ion batteries was reported on 20 July by the KAIST research team led by Professor JangWook Choi and Professor AliCoskun.

The KAIST team integrated the molecular pulley(called polystane) into the battery electrode adhesive, including adding a polymer to the battery electrode to attach the electrode to the metal substrate. The ring in the polystane is twisted into the polymer skeleton and can be freely moved along the skeleton.

The ring in the polyalkane can move freely with the volume of Silicon particles, and the sliding of the ring can effectively maintain the shape of Si particles so that they will not disintegrate during continuous volume changes. It is worth noting that even crushed Silicon particles can remain cohesive due to the high elasticity of the polystane binder. The function of the new binder is in stark contrast to the existing binder(usually a simple linear polymer). The existing binder has limited elasticity and therefore can not firmly maintain the particle shape. Previous adhesives can scatter crushed particles, which can reduce or even lose the capacity of Silicon electrodes.

The authors say this is an excellent demonstration of the importance of basic research, and Polyrotaxane won a Nobel Prize last year for the concept of "mechanical bonds." "Mechanical binding" 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 in the direction of battery technology at an unexpected rate. The authors also note that they are currently working with a large battery manufacturer to integrate its molecular pulleys into actual battery products.

Northwestern University's 2006 Nobel Laureate Prize in Chemistry Sir FraserStoddart also added: "Mechanical bonds recovered for the first time in an energy storage environment. The KAIST team cleverly used the mechanical binder in the sliding ring polystyrene, in the α-ring. The functional on the polyethylene glycol screw, This marks a breakthrough in the performance of lithium-ion batteries on the market. When pulley polymers with mechanical adhesives replace conventional materials with only single chemical bonds, this physical bond will have a very significant impact on the performance of materials and equipment. "

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