Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Success in Observation of Swelling of Single-Particle of Silicon Electrode for Lithium Ion Batteries during Charging Reaction

29.04.2013
The NIMS Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN) and Tokyo Metropolitan University have measured the volumetric expansion of single particles of silicon accompanying the charging reaction. This finding demonstrated the importance of electrode design from the viewpoint of volumetric energy density.
The NIMS Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN) and a research group at Tokyo Metropolitan University succeeded in measuring the volumetric expansion of single particles of silicon, which is a negative electrode material for lithium ion batteries, accompanying the charging reaction, and demonstrated the importance of electrode design from the viewpoint of volumetric energy density based on this finding.

A research group headed by Dr. Kiyoshi Kanamura (NIMS Special Researcher) and Dr. Kei Nishikawa (Postdoctoral Researcher) at the Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN) of the National Institute for Materials Science (President: Sukekatsu Ushioda), in joint research with Tokyo Metropolitan University (President: Fumio Harashima), succeeded in measuring the volumetric expansion of single particles of silicon, which is a negative electrode material for lithium (Li) ion batteries, accompanying the charging reaction, and demonstrated the importance of electrode design from the viewpoint of volumetric energy density.

Li-ion batteries are a type of secondary cell in which a Li-containing transition metal oxide is used as the positive electrode and graphite is used as the negative electrode. Because Li-ion batteries have high energy density in comparison with other secondary cells, such as nickel-metal hydride (NIMH) batteries, etc., they are widely used as a power source for mobile electronics, and are also considered promising for electric vehicle (EV) and stationary power storage applications. At present, graphite is used as the negative electrode material, but in order to achieve higher energy density, materials which utilize the alloying reaction with lithium, represented by silicon, have attracted attention as next-generation negative electrode materials. The most important issues for practical application are elucidation of the mechanism of the large volume change which occur in the charging and discharging reactions, and control of those changes.

A research group at Tokyo Metropolitan University established the technology of a single-particle measurement system to investigate the intrinsic electrochemical properties of single particles of electrode materials for Li-ion batteries. In the present research, this system was introduced in the ultra-dry room at the NIMS Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), and was used to perform electrochemical measurements of single particles (10-20ìm) of silicon, which is seen as a next-generation negative electrode material. To date, the expansion ratio, etc. of single particles of silicon had been estimated from the theoretical crystal size, and volumetric changes accompanying the charging and discharging reactions had not been evaluated quantitatively. This research result was the world’s first example of successful measurement of volumetric expansion of a single particle of silicon accompanying the charging reaction.

The results of this experiment clarified the fact that the volumetric expansion of silicon in the charging reaction is larger than the value estimated theoretically. Although this is thought to be due to the formation of an amorphous phase, etc. as the alloying reaction between the lithium and silicon proceeds, further study will be necessary in order to elucidate the detailed mechanism. Standards have now been established for Li-ion batteries for electric vehicle (EV) and cellphone applications. Conventionally, evaluations of material performance had centered on energy density per unit of mass. However, volumetric energy density is increasingly considered more important than mass energy density. As the present research showed, silicon displays larger volumetric expansion than the predicted value, which results in a decrease in real energy density. Thus, this research demonstrated the importance of actual measurement of volumetric expansion in the search for candidates for next-generation battery materials.

As described above, this research showed the importance of measuring the actual volumetric energy density when adopting a material that displays volumetric changes during charging/discharging in the electrodes of Li-ion batteries. Based on this result, electrode design guidelines which also consider volumetric changes are necessary in research and development in the search for next-generation materials for Li-ion batteries.

These research results was presented at the 80th Spring Meeting of the Electrochemical Society of Japan, which was held at Tohoku University on March 29.

Mikiko Tanifuji | Research asia research news
Further information:
http://www.nims.go.jp/eng/news/press/2013/03/p201303270.html
http://www.researchsea.com

More articles from Materials Sciences:

nachricht In borophene, boundaries are no barrier
17.07.2018 | Rice University

nachricht Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University

All articles from Materials Sciences >>>

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 >>>