image: Images produced by transmission electron microscopy verified the transformation of the electrode material from a disordered arrangement of atoms (left) to an ordered, crystalline structure (right). view more
Credit: (Image by Argonne National Laboratory.)
Charging and discharging a battery cell transforms its electrode material into a “super” material.
Over the last decade, advances in research and development have led to more efficient lithium-ion batteries. Yet, significant shortcomings remain. One challenge is the need for faster charging, which can help speed the adoption of electric vehicles.
A research team led by Boise State University and the University of California San Diego has taken an unconventional approach to this problem. Using the resources of the U.S. Department of Energy’s (DOE) Argonne National Laboratory, they created a high performance material for battery electrodes. The compound, niobium pentoxide, has a novel crystalline structure. It shows promise for speeding up charging while providing excellent storage capacity.
During charging, lithium ions move from the positive electrode (cathode) to the negative electrode (anode), commonly made of graphite. At higher charging speeds, lithium metal tends to accumulate on the graphite’s surface. This effect, known as plating, tends to degrade performance and can cause batteries to short circuit, overheat and catch on fire.
“The facilities and staff at Argonne are world-class. This work to discover the unique transformation in niobium pentoxide benefited tremendously from the collaboration with Argonne scientists.” — Claire Xiong, Boise State
Niobium pentoxide is much less susceptible to plating, potentially making it safer and more durable than graphite. In addition, its atoms can arrange in many different stable configurations that don’t require much energy to reconfigure. This presents opportunities for researchers to discover new structures that could enhance battery performance.
For this study, the researchers built a coin cell with niobium pentoxide as the electrode material. (A coin cell, also known as a button cell, is a small, circular-shaped battery device.) The niobium pentoxide had an amorphous structure — in other words, a disordered arrangement of atoms. When the cell was charged and discharged numerous times, the disordered structure transformed into an ordered, crystalline one. This particular structure had never been previously reported in the scientific literature.
Compared to the disordered arrangement, the crystalline structure enabled easier, faster transport of lithium ions into the anode during charging. This finding points to the material’s promise for fast charging, and other measurements suggest that it can store a large amount of charge.
Argonne provides several complementary tools
Because of the complex changes during the charge-discharge cycle, several complementary diagnostic tools were needed for a comprehensive understanding. That’s where Argonne — and a pair of DOE Office of Science user facilities at the laboratory — came in.
Yuzi Liu, a scientist in Argonne’s Center for Nanoscale Materials (CNM), used a technique called transmission electron microscopy to verify the structural transformation from amorphous to crystalline. This technique sends high-energy electron beams through a material sample. It creates digital images based on the interaction of the electrons with the sample. The images show how atoms are arranged.
“Since the electron beam is focused on a small area of the sample, the technique provides detailed information about that particular area,” said Liu.
Hua Zhou, a physicist in Argonne’s Advanced Photon Source (APS), confirmed the structural change with another technique known as synchrotron X-ray diffraction. This involves hitting the sample with high-energy X-ray beams, which are scattered by the electrons of the atoms in the material. A detector measures this scattering to characterize the material’s structure.
X-ray diffraction is effective for providing information about overall structural changes across an entire material sample. This can be helpful in studying battery electrode materials because their structures tend to vary from one area to another.
“By hitting the anode material with X-ray beams at different angles, I confirmed that it was uniformly crystalline along the surface and in the interior,” said Zhou.
The research also drew upon other Argonne capabilities for characterizing materials. Justin Connell, a materials scientist in Argonne’s Electrochemical Discovery Laboratory, used a tool called X-ray photoelectron spectroscopy to evaluate the anode material. Connell shot X-ray beams into the anode, ejecting electrons from it with a certain energy.
“The technique revealed that niobium atoms gain multiple electrons as the cell is charged,” said Connell. “This suggests that the anode has a high storage capacity.”
Argonne physicist Sungsik Lee also evaluated niobium’s gain and loss of electrons. He used another technique called X-ray absorption spectroscopy. This involved hitting the anode material with intense synchrotron X-ray beams and measuring the transmission and absorption of the X-rays in the material.
“The technique provided an overall picture of the state of the electrons across the entire anode,” said Lee. “This confirmed that niobium gains multiple electrons.”
Argonne is unusual in that it has all these research capabilities on its campus. Claire Xiong, the study’s lead investigator, did her postdoctoral research at Argonne’s CNM before joining the Boise State faculty as a materials scientist. She was quite familiar with Argonne’s extensive capabilities and had previously collaborated with the Argonne scientists who contributed to the study.
“The facilities and staff at Argonne are world-class,” said Xiong. “This work to discover the unique transformation in niobium pentoxide benefited tremendously from the collaboration with Argonne scientists. It also benefited from the access to the APS, Electrochemical Discovery Laboratory and CNM.”
New synthesis method could support innovation in many areas
It is very difficult to make the high performance, crystalline niobium pentoxide with traditional synthesis methods, such as those that subject materials to heat and pressure. The unconventional synthesis approach used successfully in this study — charging and discharging a battery cell — could be applied to make other innovative battery materials. It could potentially even support fabrication of novel materials in other fields, such as semiconductors and catalysts.
The study was published in Nature Materials in May 2022. Besides the aforementioned Argonne scientists and Boise State’s Xiong, the other authors were:
- Pete Barnes, Kiev Dixon, Dewen Hou, Changjian Deng, Kassiopeia Smith, Eric Gabriel, Olivia O. Maryon, Paul H. Davis, Hoayu Zhu, Paul J. Simmonds, Ariel E. Briggs, Darin Schwartz, Hui Xiong (Boise State)
- Yunxing Zuo, Ji Qi, Zhuoying Zhu, Chi Chen, Shyue Ping Ong (University of California San Diego)
- Zhiyuan Ma (Argonne)
- Yingge Du, Zihua Zhu, Yadong Zhou (Pacific Northwest National Laboratory)
About Argonne’s Center for Nanoscale Materials
The Center for Nanoscale Materials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit https://science.osti.gov/User-Facilities/User-Facilities-at-a-Glance.
The Joint Center for Energy Storage Research (JCESR), a DOE Energy Innovation Hub, is a major partnership that integrates researchers from many disciplines to overcome critical scientific and technical barriers and create new breakthrough energy storage technology. Led by the U.S. Department of Energy’s Argonne National Laboratory, partners include national leaders in science and engineering from academia, the private sector, and national laboratories. Their combined expertise spans the full range of the technology-development pipeline from basic research to prototype development to product engineering to market delivery.
About the Advanced Photon Source
The U. S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS.
This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
Journal
Nature Materials
Article Title
Electrochemically induced amorphous-to-rock-salt phase transformation in niobium oxide electrode for Li-ion batteries.
Article Publication Date
2-May-2022