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 Argon is not the 'dope' for metallic hydrogen
24.03.2017 | Carnegie Institution for Science

nachricht Researchers make flexible glass for tiny medical devices
24.03.2017 | Brigham Young 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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>