Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Track 3D Nanoscale Changes in Rechargeable Battery Material During Operation

31.03.2014

First 3D nanoscale observations of microstructural degradation during battery charge-discharge cycles

First 3D nanoscale observations of microstructural degradation during charge-discharge cycles could point to new ways to engineer battery electrode materials for better performance 


Courtesy Brookhaven National Laboratory

These images show how the surface morphology and internal microstructure of an individual tin particle changes from the fresh state through the initial lithiation and delithiation cycle (charge/discharge). Most notable are the expansion in overall particle volume during lithiation, and reduction in volume and pulverization during delithiation. The cross-sectional images reveal that delithiation is incomplete, with the core of the particle retaining lithium surround by a layer of pure tin.

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have made the first 3D observations of how the structure of a lithium-ion battery anode evolves at the nanoscale in a real battery cell as it discharges and recharges. The details of this research, described in a paper published in Angewandte Chemie, could point to new ways to engineer battery materials to increase the capacity and lifetime of rechargeable batteries.

"This work offers a direct way to look inside the electrochemical reaction of batteries at the nanoscale to better understand the mechanism of structural degradation that occurs during a battery's charge/discharge cycles," said Brookhaven physicist Jun Wang, who led the research. "These findings can be used to guide the engineering and processing of advanced electrode materials and improve theoretical simulations with accurate 3D parameters."

Chemical reactions in which lithium ions move from a negatively charged electrode to a positive one are what carry electric current from a lithium-ion battery to power devices such as laptops and cell phones. When an external current is applied-say, by plugging the device into an outlet-the reaction runs in reverse to recharge the battery.

Scientists have long known that repeated charging/discharging (lithiation and delithiation) introduces microstructural changes in the electrode material, particularly in some high-capacity silicon and tin-based anode materials. These microstructural changes reduce the battery's capacity-the energy the battery can store-and its cycle life-how many times the battery can be recharged over its lifetime. Understanding in detail how and when in the process the damage occurs could point to ways to avoid or minimize it.

"It has been very challenging to directly visualize the microstructural evolution and chemical composition distribution changes in 3D within electrodes when a real battery cell is going through charge and discharge," said Wang.

A team led by Vanessa Wood of the university ETH Zurich, working at the Swiss Light Source, recently performed in situ 3D tomography at micrometer scale resolution during battery cell charge and discharge cycles.

Achieving nanoscale resolution has been the ultimate goal.

"For the first time," said Wang, "we have captured the microstructural details of an operating battery anode in 3D with nanoscale resolution, using a new in-situ micro-battery-cell we developed for synchrotron x-ray nano-tomography-an invaluable tool for reaching this goal." This advance provides a powerful new source of insight into microstructural degradation.

Building a micro battery

Developing a working micro battery cell for nanoscale x-ray 3D imaging was very challenging. Common coin-cell batteries aren't small enough, plus they block the x-ray beam when it is rotated.

"The whole micro cell has to be less than one millimeter in size but with all battery components-the electrode being studied, a liquid electrolyte, and the counter electrode-supported by relatively transparent materials to allow transmission of the x-rays, and properly sealed to ensure that the cell can work normally and be stable for repeated cycling," Wang said. The paper explains in detail how Wang's team built a fully functioning battery cell with all three battery components contained within a quartz capillary measuring one millimeter in diameter.

By placing the cell in the path of high-intensity x-ray beams generated at beamline X8C of Brookhaven's National Synchrotron Light Source (NSLS), the scientists produced more than 1400 two-dimensional x-ray images of the anode material with a resolution of approximately 30 nanometers. These 2D images were later reconstructed into 3D images, much like a medical CT scan but with nanometer-scale clarity. Because the x-rays pass through the material without destroying it, the scientists were able to capture and reconstruct how the material changed over time as the cell discharged and recharged, cycle after cycle.

Using this method, the scientists revealed that, "severe microstructural changes occur during the first delithiation and subsequent second lithiation, after which the particles reach structural equilibrium with no further significant morphological changes."

Specifically, the particles making up the tin-based anode developed significant curvatures during the early charge/discharge cycles leading to high stress. "We propose that this high stress led to fracture and pulverization of the anode material during the first delithiation," Wang said. Additional concave features after the first delithiation further induced structural instability in the second lithiation, but no significant changes developed after that point.

"After these initial two cycles, the tin anode shows a stable discharge capacity and reversibility," Wang said.

"Our results suggest that the substantial microstructural changes in the electrodes during the initial electrochemical cycle-called forming in the energy storage industry-are a critical factor affecting how a battery retains much of its current capacity after it is formed," she said. "Typically a battery loses a substantial portion of its capacity during this initial forming process. Our study will improve understanding of how this happens and help us develop better controls of the forming process with the goal of improving the performance of energy storage devices."

Wang pointed out that while the current study looked specifically at a battery with tin as the anode, the electrochemical cell her team developed and the x-ray nanotomography technique can be applied to studies of other anode and cathode materials. The general methodology for monitoring structural changes in three dimensions as materials operate also launches an opportunity to monitor chemical states and phase transformations in catalysts, other types of materials for energy storage, and biological molecules.

The transmission x-ray microscope used for this study will soon move to a full-field x-ray imaging (FXI) beamline at NSLS-II, a world-class synchrotron facility now nearing completion at Brookhaven Lab. This new facility will produce x-ray beams 10,000 times brighter than those at NSLS, enabling dynamic studies of various materials as they perform their particular functions.

Jiajun Wang and Yu-chen Karen Chen-Wiegart are research associates in Wang's research group and performed the work together.

This research was funded as a Laboratory Directed Research and Development project at Brookhaven Lab and by the DOE Office of Science. The transmission x-ray microscope used in this work was built with funding from the American Recovery and Reinvestment Act.

DOE'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, please visit science.energy.gov.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

***

Media Contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov

To view an electronic version of this news release and related graphics go to: http://www.bnl.gov/newsroom/news.php?a=11619

Related Links

Scientific paper:"In Situ Three Dimensional Synchrotron X-ray Nano-tomography of (De)lithiation Process in Sn Anodes"
http://dx.doi.org/10.1002/anie.201310402

Karen McNulty Walsh | newswise
Further information:
http://www.bnl.gov

Further reports about: Laboratory batteries battery capacity cycles electrode materials nanoscale structural

More articles from Power and Electrical Engineering:

nachricht New high energy density automotive battery system from Fraunhofer IISB and international partners
25.08.2015 | Fraunhofer-Gesellschaft

nachricht New research may enhance display & LED lighting technology
10.08.2015 | University of Illinois College of Engineering

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Im Focus: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

Im Focus: Self-healing landscape: landslides after earthquake

In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.

These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...

Im Focus: FIC Proteins Send Bacteria Into Hibernation

Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.

For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...

Im Focus: Fraunhofer IPA develops prototype of intelligent care cart

It comes when called, bringing care utensils with it and recording how they are used: Fraunhofer IPA is developing an intelligent care cart that provides care staff with physical and informational support in their day-to-day work. The scientists at Fraunhofer IPA have now completed a first prototype. In doing so, they are continuing in their efforts to improve working conditions in the care sector and are developing solutions designed to address the challenges of demographic change.

Technical assistance systems can improve the difficult working conditions in residential nursing homes and hospitals by helping the staff in their work and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

Interstellar seeds could create oases of life

28.08.2015 | Physics and Astronomy

An ounce of prevention: Research advances on 'scourge' of transplant wards

28.08.2015 | Health and Medicine

Fish Oil-Diet Benefits May be Mediated by Gut Microbes

28.08.2015 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>