Fused Molecules Are Constructing Blocks for Safer Lithium-Ion Batteries

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By fusing collectively a pair of contorted molecular constructions, Cornell researchers created a porous crystal that may uptake lithium-ion electrolytes and transport them easily by way of one-dimensional nanochannels — a design that might result in safer solid-state lithium-ion batteries.

The staff’s paper, “Supramolecular Meeting of Fused Macrocycle-Cage Molecules for Quick Lithium-Ion Transport,” was printed Sept. 9 within the Journal of the American Chemical Society. The lead creator is Yuzhe Wang ’24.

The venture was led by Yu Zhong, assistant professor of supplies science and engineering in Cornell Engineering and the paper’s senior creator, whose lab makes a speciality of synthesizing “mushy” and nanoscale supplies that may advance power storage and sustainability applied sciences.

Zhong had simply joined Cornell’s college two years in the past when he was contacted by Wang, an undergraduate switch pupil starting his junior 12 months, who was smitten by taking over a analysis venture.

On the prime of Zhong’s listing of potential subjects was discovering a approach to make a safer lithium-ion battery. In typical lithium-ion batteries, the ions are shuttled alongside by way of liquid electrolytes. However liquid electrolytes can type spiky dendrites between the battery’s anode and cathode, which quick out the battery or, in uncommon instances, explode.

A solid-state battery can be safer, however that comes with its personal challenges. Ions transfer slower via solids, as a result of they face extra resistance. Zhong needed to design a brand new crystal that was porous sufficient that ions might transfer via some type of pathway. That pathway would must be easy, with weak interactions between the lithium ions and the crystal, so the ions wouldn’t stick. And the crystal would wish to carry sufficient ions to make sure a excessive ion focus.

Supported with a grant from the school’s Engineering Studying Initiatives, Wang went to work and devised a technique of fusing collectively two eccentric molecular constructions which have complementary shapes: macrocycles and molecular cages.

Macrocycles are molecules with rings of 12 or extra atoms, and molecular cages are multi-ringed compounds that roughly resemble their identify.

“Each macrocycles and molecular cages have intrinsic pores the place ions can sit and go via,” Wang stated. “By utilizing them because the constructing blocks for porous crystals, the crystal would have massive areas to retailer ions and interconnected channels for ions to move.”

Wang fused the elements collectively, with a molecular cage on the middle and three macrocycles radially connected, like wings or arms. These macrocycle-cage molecules use hydrogen bonds and their interlocking shapes to self-assemble into bigger, extra difficult, three-dimensional crystals which might be nanoporous, with one-dimensional channels — “the perfect pathway for the ion to move,” in keeping with Zhong — that obtain ionic conductivity of as much as 8.3 × 10-4 siemens per centimeter.

“That conductivity is the report excessive for these molecule-based, solid-state lithium-ion-conducting electrolytes,” Zhong stated.

As soon as the researchers had their crystal, they wanted to higher perceive its make-up, so that they collaborated with Judy Cha, Ph.D. ’09, professor of supplies science and engineering, who used scanning transmission electron microscopy to discover its construction, and Jingjie Yeo, assistant professor of mechanical and aerospace engineering, whose simulations clarified the interactions between the molecules and lithium ions.

“So with all of the items collectively, we ultimately established a superb understanding of why this construction is actually good for ion transport, and why we get such a excessive conductivity with this materials,” Zhong stated.

Along with making safer lithium-ion batteries, the fabric may be doubtlessly used to separate ions and molecules in water purification and to make combined ion-electron-conducting constructions for bioelectronic circuits and sensors.

“This macrocycle-cage molecule is certainly one thing new on this group,” Zhong stated. “The molecular cage and macrocycle have been identified for some time, however how one can actually leverage the distinctive geometry of those two molecules to information the self-assembly of recent, extra difficult constructions is type of an unexplored space. Now in our group, we’re engaged on the synthesis of various molecules, how we are able to assemble them and make a molecule with a distinct geometry, so we are able to develop all the chances to make new nanoporous supplies. Perhaps it’s for lithium-ion conductivity or possibly for even many different totally different purposes.”

Co-authors embrace doctoral pupil Kaiyang Wang, M.S. ’19; grasp’s pupil Ashutosh Garudapalli; postdoctoral researchers Stephen Funni and Qiyi Fang; and researchers from Rice College, College of Chicago and Columbia College.

The analysis was supported by Cornell Engineering’s Engineering Studying Initiatives.

The researchers made use of the Cornell Heart for Supplies Analysis and the Columbia College Supplies Analysis Science and Engineering Heart, each of that are funded by the Nationwide Science Basis’s Supplies Analysis Science and Engineering Heart program.

By David Nutt, Cornell Chronicle