Nav: Home

Researchers use X-rays to understand the flaws of battery fast charging

February 11, 2019

A closer look reveals how speedy charging may hamper battery performance.

While gas tanks can be filled in a matter of minutes, charging the battery of an electric car takes much longer. To level the playing field and make electric vehicles more attractive, scientists are working on fast-charging technologies.

Fast charging is very important for electric vehicles," said battery scientist Daniel Abraham of the U.S. Department of Energy's (DOE) Argonne National Laboratory. ?"We'd like to be able to charge an electric vehicle battery in under 15 minutes, and even faster if possible."

"By seeing exactly how the lithium is distributed within the electrode, we're gaining the ability to precisely determine the inhomogeneous way in which a battery ages." -- Daniel Abraham, Argonne battery scientist

The principal problem with fast charging happens during the transport of lithium ions from the positive cathode to the negative anode. If the battery is charged slowly, the lithium ions extracted from the cathode gradually slot themselves between the planes of carbon atoms that make up the graphite anode -- a process known as lithium intercalation.

But when this process is sped up, lithium can end up depositing on the surface of the graphite as metal, which is called lithium plating. ?"When this happens, the performance of the battery suffers dramatically, because the plated lithium cannot be moved from one electrode to the other," Abraham said.

According to Abraham, this lithium metal will chemically reduce the battery's electrolyte, causing the formation of a solid-electrolyte interphase that ties up lithium ions so they cannot be shuttled between the electrodes. As a result, less energy can be stored in the battery over time.

To study the movement of lithium ions within the battery, Abraham partnered with postdoctoral researcher Koffi Pierre Yao and Argonne X-ray physicist John Okasinski at the laboratory's Advanced Photon Source, a DOE Office of Science User Facility. There, Okasinski essentially created a 2Dimage of the battery by using X-rays to image each phase of lithiated graphite in the anode.

By gaining this view, the researchers were able to precisely quantify the amount of lithium in different regions of the anode during charging and discharging of the battery. 

In the study, the scientists established that the lithium accumulates at regions closer to the battery's separator under fast-charging conditions.

"You might expect that just from common sense," Abraham explained. ?"But by seeing exactly how the lithium is distributed within the electrode, we're gaining the ability to precisely determine the inhomogeneous way in which a battery ages."

To selectively see a particular region in the heart of the battery, the researchers used a technique called energy dispersive X-ray diffraction. Instead of varying the angle of the beam to reach particular areas of interest, the researchers varied the wavelength of the incident light.

By using X-rays, Argonne's scientists were able to determine the crystal structures present in the graphite layers. Because graphite is a crystalline material, the insertion of lithium causes the graphite lattice to expand to varying degrees. This swelling of the layers is noticeable as a difference in the diffraction peaks, Okasinski said, and the intensities of these peaks give the lithium content in the graphite.

While this research focuses on small coin-cell batteries, Okasinski said that future studies could examine the lithiation behavior in larger pouch-cell batteries, like those found in smartphones and electric vehicles.
-end-
A paper based on the study, "Quantifying lithium concentration gradients in the graphite electrode of lithium-ion cells using operando energy dispersive X-ray diffraction," appeared in the January 9online issue of Energy and Environmental Science. The research was a team effort with significant contributions from former Argonne postdoctoral researcher Kaushik Kalaga and Argonne scientist Ilya Shkrob.

The research was supported by DOE's Office of Energy Efficiency and Renewable Energy (Office of Vehicle Technologies).

DOE's Office of Energy Efficiency and Renewable Energy supports early-stage research and development of energy efficiency and renewable energy technologies to strengthen U.S. economic growth, energy security, and environmental quality.

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 the Office of Science website.

DOE/Argonne National Laboratory

Related Lithium Articles:

A seaweed derivative could be just what lithium-sulfur batteries need
Lithium-sulfur batteries have great potential as a low-cost, high-energy, energy source for both vehicle and grid applications.
Risk of cardiac malformations from lithium during pregnancy less significant
New research suggests there may be a more modest increased risk of cardiac defects when using lithium during the first trimester of pregnancy.
Graphene-nanotube hybrid boosts lithium metal batteries
Rice University scientists build high-capacity lithium metal batteries with anodes made of a graphene-carbon nanotube hybrid.
Better cathode materials for lithium-sulphur-batteries
A team at the Helmholtz-Zentrum Berlin (HZB) has for the first time fabricated a nanomaterial made from nanoparticles of a titanium oxide compound (Ti4O7) that is characterized by an extremely large surface area, and tested it as a cathode material in lithium-sulphur batteries.
Stabilizing molecule could pave way for lithium-air fuel cell
Lithium-oxygen fuel cells boast energy density levels comparable to fossil fuels and are thus seen as a promising candidate for future transportation-related energy needs.
Freezing lithium batteries may make them safer and bendable
Columbia Engineering Professor Yuan Yang has developed a new method that could lead to lithium batteries that are safer, have longer battery life, and are bendable, providing new possibilities such as flexible smartphones.
Electrochemical performance of lithium-ion capacitors
Pre-lithiated multiwalled carbon nanotubes and activated carbon (AC) materials were used as anode and cathode respectively for Lithium-ion capacitors (LICs).
Lighter, more efficient, safer lithium-ion batteries
Researchers from Universidad Carlos III de Madrid and the Council for Scientific Research (initialed CSIC in Spanish) have patented a method for making new ceramic electrodes for lithium-ion batteries that are more efficient, cheaper, more resistant and safer than conventional batteries.
Clarifying how lithium ions ferry around in rechargeable batteries
IBS scientists observe the real-time ultrafast bonding of lithium ions with the solvents, in the same process that happens during charging and discharging of lithium batteries, and conclude that a new theory is needed.
New gel-like coating beefs up the performance of lithium-sulfur batteries
Yale scientists have developed an ultra-thin coating material that has the potential to extend the life and improve the efficiency of lithium-sulfur batteries, one of the most promising areas of energy research today.

Related Lithium Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#513 Dinosaur Tails
This week: dinosaurs! We're discussing dinosaur tails, bipedalism, paleontology public outreach, dinosaur MOOCs, and other neat dinosaur related things with Dr. Scott Persons from the University of Alberta, who is also the author of the book "Dinosaurs of the Alberta Badlands".