Featured Research

from universities, journals, and other organizations

Success in observation of swelling of single-particle of silicon electrode for lithium ion batteries during charging reaction

Date:
April 28, 2013
Source:
National Institute for Materials Science
Summary:
Scientists 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.

Expansion of a silicon particle accompanying charging. Under an electric current of 3nA, a silicon particle expansion process was observed. As a copper plating was applied to the tip of the probe, the tip displays a copper-brown color. The black silicon particle (with partial metallic gloss), which is in contact with the probe, undergoes swelling accompanying charging (in red circle).
Credit: Image courtesy of National Institute for Materials Science

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.

Researchers 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 (10-20μm) 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.


Story Source:

The above story is based on materials provided by National Institute for Materials Science. Note: Materials may be edited for content and length.


Cite This Page:

National Institute for Materials Science. "Success in observation of swelling of single-particle of silicon electrode for lithium ion batteries during charging reaction." ScienceDaily. ScienceDaily, 28 April 2013. <www.sciencedaily.com/releases/2013/04/130428144958.htm>.
National Institute for Materials Science. (2013, April 28). Success in observation of swelling of single-particle of silicon electrode for lithium ion batteries during charging reaction. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2013/04/130428144958.htm
National Institute for Materials Science. "Success in observation of swelling of single-particle of silicon electrode for lithium ion batteries during charging reaction." ScienceDaily. www.sciencedaily.com/releases/2013/04/130428144958.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com
Stranded Whale Watching Boat Returns to Boston

Stranded Whale Watching Boat Returns to Boston

Reuters - US Online Video (July 29, 2014) Passengers stuck overnight on a whale watching boat return safely to Boston. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins