A team of Cornell University researchers has published a paper that reports on their work to fuse together a pair of contorted molecular structures, creating a porous crystal that can uptake lithium-ion electrolytes and transport them smoothly via one-dimensional nanochannels—a design that could lead to safer solid-state lithium-ion batteries.
The paper, “Supramolecular Assembly of Fused Macrocycle-Cage Molecules for Fast Lithium-Ion Transport,” was published in September in the Journal of the American Chemical Society.
The project, which was led by Yu Zhong, Assistant Professor of Materials Science and Engineering in Cornell Engineering, focused on overcoming the problem of dendrite formation in lithium-ion batteries using liquid electrolytes, which can shorten battery life and may lead to explosions. Developing safer solid-state batteries would require designing a new crystal porous enough that ions could move through a smooth pathway without sticking.
Yuzhe Wang, the lead author, devised a method of fusing together two eccentric molecular structures that have complementary shapes: macrocycles and molecular cages. “By using them as the building blocks for porous crystals,” said Wang, “the crystal would have large spaces to store ions and interconnected channels for ions to transport.”
The resulting crystal provided, according to Zhong, “the ideal pathway for the ion to transport. That conductivity is the record high for these molecule-based, solid-state lithium-ion-conducting electrolytes. So with all the pieces together, we eventually established a good understanding of why this structure is really good for ion transport, and why we get such a high conductivity with this material.”
In addition to making lithium-ion batteries safer, the material has potential uses in separating ions and molecules in water purification and in making mixed ion-electron-conducting structures for bioelectronic circuits and sensors.
Source: Cornell University