Rice, Lawrence Livermore scientists calculate materials’ potential for use as electrodes
Lithium-ion batteries could benefit from a theoretical model created at Rice University and Lawrence Livermore National Laboratory that predicts how carbon components will perform as electrodes.
New work by scientists at Lawrence Livermore National Laboratory and Rice University details the binding properties of lithium ions to various types of carbon that may be used for lithium-ion batteries. The “universal descriptor” they found has the potential to speed the development of materials for commercialization. (Credit: Yuanyue Liu/Rice University)
The model is based on intrinsic electronic characteristics of materials used as battery anodes. These include the material’s quantum capacitance (the ability of the material to absorb charge) and the material’s absolute Fermi level, which determines how many lithium ions may bond to the electrodes.
Subtle changes in the structure, chemistry and shape of an electrode can significantly alter how strongly lithium ions bond to it and affect a battery’s capacity, voltage and energy density. The researchers found a universal correlation between these properties and a simple quantity they called the “states-filling work” that should allow scientists to fine-tune electrodes.
The research appears in the journal Physical Review Letters. Lawrence Livermore scientist Brandon Wood and Rice theoretical physicist Boris Yakobson led the study.
Fine-tuning becomes critically important as materials scientists test more 2-D materials like graphene and nanotubes for use as electrodes. The materials offer vast surface area for ions to bind to in a compact package, Yakobson said.
“This work emphasizes the role of quantum capacitance,” he said. “Capacitance in a battery is usually defined by the configuration of your electrodes; people think about this as the distance between the plates.
“But if the plates become very close and the electrodes and electrolyte are tight, then quantum capacitance becomes the limiting parameter.”
“The Fermi level of the electrode material is also important,” said Rice graduate student Yuanyue Liu, the paper’s lead author. “The lower it is, the stronger lithium will bind.”
Liu and Lawrence Livermore staff scientist Brandon Wood were looking for a “descriptor,” a characteristic that would capture the essential physics of interactions between lithium and a variety of carbon materials, including pristine, defective and strained graphene, planar carbon clusters, nanotubes, carbon edges and multilayer stacks.
“That descriptor turned out to be the ‘states-filling work’ – the work required to fill previously unoccupied electronic states within the electrode,” Liu said.
“Generally speaking, a descriptor is an intermediate property or parameter that doesn’t give you what you really want to know, but correlates well with the material’s final performance,” Yakobson said.
“The descriptor connects to properties that may be quite complex,” he said. “For instance, you can judge people’s physical strength by how tall they are or by weight. That’s easy to measure. It doesn’t exactly tell you how strong the person will be, but it gives you some idea.”
Based on the descriptor, the researchers were able to evaluate various carbon materials. Specifically, they found materials like defective or curved graphene were good candidates for anodes, as their energy profiles allowed more lithium ions to bind. Ultimately, their work suggested a set of binding guidelines for carbon anodes.
“These allow us to quickly evaluate material performance without doing electrochemical tests or expensive computations,” Liu said.
“The fact that our descriptor predicts the performance of such a wide variety of materials is surprising,” Wood said. “It means the underlying physics is really very similar, even if the structure, morphology, or chemistry differs from one candidate to the next. It’s really a very simple and elegant finding that could accelerate design and discovery.”
Yakobson noted the work is in line with the Materials Genome Initiative (MGI), which aims to double the speed and reduce the cost of developing advanced materials by providing these kinds of tools. Earlier this year, Rice’s George R. Brown School of Engineering hosted a workshop on the MGI initiative, one of four held around the country.
Yakobson is Rice’s Karl F. Hasselmann Professor of Materials Science and NanoEngineering, a professor of chemistry and a member of the Richard E. Smalley Institute for Nanoscale Science and Technology.
Lawrence Livermore National Laboratory and the Department of Energy supported the research.
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,920 undergraduates and 2,567 graduate students, Rice’s undergraduate student-to-faculty ratio is just over 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 2 for “best value” among private universities by Kiplinger’s Personal Finance.
David Ruth | Eurek Alert!
Saving energy by taking a close look inside transistors
10.01.2019 | Friedrich-Alexander-Universität Erlangen-Nürnberg
Tandem Solar Cells – Record Efficiency for Silicon-based Multi-junction Solar Cell
08.01.2019 | Fraunhofer-Institut für Solare Energiesysteme ISE
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.
Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...
Research opens doors in photonic quantum information processing, optical signal processing and microwave photonics
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new integrated photonics platform that can...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
17.01.2019 | Life Sciences
16.01.2019 | Life Sciences
16.01.2019 | Physics and Astronomy