Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New test procedure for developing quick-charging lithium-ion batteries

07.12.2017

When lithium-ion batteries are charged too quickly, metallic lithium gets deposited on the anodes. This reduces battery capacity and lifespan and can even destroy the batteries. Scientists at the Forschungszentrum Jülich and the Technical University of Munich (TUM) have now presented a process that, for the first time ever, allows this so-called lithium plating process to be investigated directly. This puts new strategies for quick-charging strategies close at hand.

Lithium plating, the depositing of metallic lithium at the anodes of lithium-ion batteries, is one of the primary factors that limits charging current. The performance of batteries suffers significantly from these metallic deposits. In extreme cases this can result in short circuits and even batteries going up in flames.


Test cell for lithium ion batteries

Forschungszentrum Jülich / T. Schlößer


Analysis of a test cell with EPR spektroskopy

Forschungszentrum Jülich / T. Schlößer

When charging batteries, the positively charged lithium ions move through the liquid electrolytes and are deposited in the porous graphite anodes. However, the larger the current and the lower the temperature, the greater the probability that the lithium ions will not be deposited within the electrodes, as desired, but rather as a solid metallic layer on the outer surface.

Indirect evidence does not serve the goal

Even though this phenomenon is basically well-known, many aspects remain shrouded in mystery. Until now, it was not possible to directly observe how and under which circumstances lithium plating takes place. “Using traditional methods of microscopy, we can only observe a battery after the fact, because it needs to be cut open,” explains Dr. Josef Granwehr at the Jülich Institute of Energy and Climate Research (IEK-9). “In the process, further reactions that distort the results become inevitable.”

Even highly developed processes like neutron scattering allow for only indirect analyses. Compounding the problem is the fact that available slots for measurements at research reactors and large particle accelerators are scarce. This makes these tools more suitable for fundamental investigations than for tedious, practical test series.

Electrons show the way

The electron paramagnetic resonance (EPR) spectroscopy process presented in the renowned scientific journal Materials Today, on the other hand, can be readily integrated into laboratory procedures – with only moderate investment. The method is akin to the better-known nuclear magnetic resonance (NMR) spectroscopy, albeit focusses on electron spins rather than atomic nuclei.

“Electrons are placed in an externally applied, static magnetic field,” explains Granwehr. Unpaired electrons in the sample are “sounded out” using microwaves. In the magnetic field, these stimulate the electrons to flip, which can be measured via the associated drop in microwave radiation intensity. EPR can differentiate between metallic lithium plating and lithium embedded in the graphite anodes.

The test cell is the key

“The key to detecting lithium plating using EPR was the construction of a test cell compatible with the requirements of EPR spectroscopy while at the same time exhibiting good electrochemical properties,” explains lead author Dr. Johannes Wandt. “The geometry is also important. Precise measurement results are contingent on the sample being exposed to the magnetic field but not the inevitably present electric field.”
To ensure this, Wandt developed a rod-shaped cell while he was a doctoral candidate in the group of Prof. Hubert A. Gasteiger (Chair of Technical Electrochemistry) at TUM that allows the formation of metallic lithium to be detected directly and with quantitative precision.

The right strategy for quick charging

“Using this process, it is now for the first time possible to investigate lithium plating and the associated processes in a differentiated manner that is relevant to a whole array of applications,” explains Rüdiger-A. Eichel, a director at the Jülich Institute of Energy and Climate Research (IEK-9). “One example is the development of safe and at the same time fast charging protocols. Our process make determining the maximum charging current before lithium plating sets in possible, as well as ascertaining other boundary conditions like temperature and the influence of electrode geometry.”

Beyond this, the methodology is well suited as a test procedure for a variety of battery materials, for example the development of new admixtures that suppress lithium plating.

The research was funded by the German Federal Ministry of Education and Research (BMBF) in the context of the ExZellTUM II project and the Bavarian State Ministry of Economic Affairs and Media, Energy and Technology in the context of the EEBatt project. The EEBatt project is part of the “TUM.Energy” priority program coordinated by the Munich School of Engineering (MSE).

Original publication:
Johannes Wandt, Peter Jakes, Josef Granwehr, Rüdiger-A. Eichel, Hubert A. Gasteiger
Quantitative and Time Resolved Detection of Lithium Plating on Graphite Anodes in Lithium Ion Batteries

Contact:

Prof. Dr. Josef Granwehr
Institute of Energy- und Climate Research, Fundamental Electrochemistry (IEK-9)
Tel.: +49-2461 61-96400
E-Mail: j.granwehr@fz-juelich.de

Prof. Dr. Rüdiger-A. Eichel
Director Institute of Energy- und Climate Research, Fundamental Electrochemistry (IEK-9)
Tel.: +49 2461 61-5124
E-Mail: Sekretariat-Eichel@fz-juelich.de

Dr. Johannes Wandt
E-Mail: johannes.wandt@tum.de

Press contact:

Dr. Regine Panknin
Forschungszentrum Jülich, Corporate communications
Tel. 02461 61-9054
E-Mail: r.panknin@fz-juelich.de

Tobias Schlößer
Forschungszentrum Jülich, Corporate communications
Tel. 02461 61-4771
E-Mail: t.schloesser@fz-juelich.de

Weitere Informationen:

http://www.fz-juelich.de/SharedDocs/Pressemitteilungen/UK/EN/2017/2017-12-06-lit... - Pressemitteilung

Dipl.-Biologin Annette Stettien | Forschungszentrum Jülich

More articles from Power and Electrical Engineering:

nachricht The role of Sodium for the Enhancement of Solar Cells
17.07.2018 | Max-Planck-Institut für Eisenforschung GmbH

nachricht Behavior-influencing policies are critical for mass market success of low carbon vehicles
17.07.2018 | International Institute for Applied Systems Analysis (IIASA)

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>