![\"A](\"https:\/\/www.controleng.com\/wp-content\/uploads\/2024\/11\/RU2204_WEB_IMG_Rice-University-Lithium.jpg\")
Their paper in the American Chemical Society journal\u00a0ACS Energy Letters\u00a0supports theories Tang and his colleagues formed several years ago that\u00a0foresaw how lithium travels\u00a0in the dynamic environment inside a typical commercial\u00a0cathode.<\/p>\n
Being able to watch sealed cathodes charge and discharge at Brookhaven offered absolute proof.<\/p>\n
\u201cBatteries have a lot of particle aggregates that soak up and give up lithium, and we wanted to know what happens on their surfaces, how uniform the reaction is,\u201d said Tang, an associate professor of materials science and nanoengineering. \u201cIn general, we always want a more uniform reaction so we can charge the battery faster.\u201d<\/p>\n
In images taken at Brookhaven\u2019s powerful X-ray\u00a0synchrotron, the researchers saw some regions inside the cathode were better at absorption than others. The ability to look at single or aggregated particles in 3D showed that rather than reacting over their entire surfaces, lithium favored particular regions over others.<\/p>\n
\u201cThis is very different from conventional wisdom,\u201d Tang said. \u201cThe most interesting observation is that these reaction regions are shaped like one-dimensional filaments lying across the surface of these aggregated particles. It was kind of weird, but it matched what we saw in our models.\u201d<\/p>\n
He said stress between misaligned crystallites in the particle agglomerates prevents lithium from being uniformly inserted into or extracted from the aggregate surface because that will generate too large an energy penalty. Instead, lithium is forced to flow into or out of the aggregates at \u201chot spots\u201d that develop the filament shape.<\/p>\n Tang said the lithium filaments looked something like thick nanotubes and were several hundred nanometers wide and several microns long.<\/p>\n What does this mean for battery performance?<\/p>\n \u201cThis is a bad thing,\u201d Tang said. \u201cBecause the lithium can\u2019t go into the cathode uniformly, it slows down the intercalation mechanics.<\/p>\n \u201cWhat our study offers is some potential ways to help make lithium insertion or extraction more uniform on these aggregates or individual particles,\u201d he said. \u201cIntroducing some porosity in the particle agglomerates might sacrifice some energy density, but at the same time would allow lithium to go in more uniformly. That could allow you to get more energy at a given charge\/discharge rate.<\/p>\n \u201cAnother thought is if we can somehow align the orientation of these small particles so their maximum expansion is perpendicular to each other, they\u2019ll better accommodate lithium intercalation,\u201d he said.<\/p>\n That would be a challenge for battery manufacturers, he admitted.<\/p>\n \u201cWe don\u2019t have enough experience in synthesis to know how to make that happen,\u201d Tang said. \u201cWhat we\u2019re providing is bait. Let\u2019s see if somebody bites.\u201d<\/p>\n![\"A](\"https:\/\/www.controleng.com\/wp-content\/uploads\/2024\/11\/RU2204_WEB_IMG_Rice-University-Lithium-Fig2.jpg\")