Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Seeing how a lithium-ion battery works: An exotic state of matter -- a 'random solid solution' -- affects how ions move through battery material

Diagram illustrates the process of charging or discharging the lithium iron phosphate (LFP) electrode. As lithium ions are removed during the charging process, it forms a lithium-depleted iron phosphate (FP) zone, but in between there is a solid solution zone (SSZ, shown in dark blue-green) containing some randomly distributed lithium atoms, unlike the orderly array of lithium atoms in the original crystalline material (light blue). This work provides the first direct observations of this SSZ phenomenon.

Illustration courtesy of the authors
Diagram illustrates the process of charging or discharging the lithium iron phosphate (LFP) electrode. As lithium ions are removed during the charging process, it forms a lithium-depleted iron phosphate (FP) zone, but in between there is a solid solution zone (SSZ, shown in dark blue-green) containing some randomly distributed lithium atoms, unlike the orderly array of lithium atoms in the original crystalline material (light blue). This work provides the first direct observations of this SSZ phenomenon.

Illustration courtesy of the authors

Abstract:
New observations by researchers at MIT have revealed the inner workings of a type of electrode widely used in lithium-ion batteries. The new findings explain the unexpectedly high power and long cycle life of such batteries, the researchers say.

Seeing how a lithium-ion battery works: An exotic state of matter -- a 'random solid solution' -- affects how ions move through battery material

Cambridge, MA | Posted on June 9th, 2014

The findings appear in a paper in the journal Nano Letters co-authored by MIT postdoc Jun Jie Niu, research scientist Akihiro Kushima, professors Yet-Ming Chiang and Ju Li, and three others.

The electrode material studied, lithium iron phosphate (LiFePO4), is considered an especially promising material for lithium-based rechargeable batteries; it has already been demonstrated in applications ranging from power tools to electric vehicles to large-scale grid storage. The MIT researchers found that inside this electrode, during charging, a solid-solution zone (SSZ) forms at the boundary between lithium-rich and lithium-depleted areas — the region where charging activity is concentrated, as lithium ions are pulled out of the electrode.

Li says that this SSZ "has been theoretically predicted to exist, but we see it directly for the first time," in transmission electron microscope (TEM) videos taken during charging.

The observations help to resolve a longstanding puzzle about LiFePO4: In bulk crystal form, both lithium iron phosphate and iron phosphate (FePO4, which is left behind as lithium ions migrate out of the material during charging) have very poor ionic and electrical conductivities. Yet when treated — with doping and carbon coating — and used as nanoparticles in a battery, the material exhibits an impressively high charging rate. "It was quite surprising when this [rapid charging and discharging rate] was first demonstrated," Li says.

"We directly observed a metastable random solid solution that may resolve this fundamental problem that has intrigued [materials scientists] for many years," says Li, the Battelle Energy Alliance Professor of Nuclear Science and Engineering and a professor of materials science and engineering.

The SSZ is a "metastable" state, persisting for at least several minutes at room temperature. Replacing a sharp interface between LiFePO4 and FePO4 that has been shown to contain many additional line defects called "dislocations," the SSZ serves as a buffer, reducing the number of dislocations that would otherwise move with the electrochemical reaction front. "We don't see any dislocations," Li says. This could be important because the generation and storage of dislocations can cause fatigue and limit the cycle life of an electrode.

Unlike conventional TEM imaging, the technique used in this work, developed in 2010 by Kushima and Li, makes it possible to observe battery components as they charge and discharge, which can reveal dynamic processes. "In the last four years, there has been a big explosion of using such in situ TEM techniques to study battery operations," Li says.

A better understanding of these dynamic processes could improve the performance of an electrode material by allowing better tuning of its properties, Li says.

Despite an incomplete understanding to date, lithium iron phosphate nanoparticles are already used at an industrial scale for lithium-ion batteries, Li explains. "The science is lagging behind the application," he says. "It's already scaled up and quite successful on the market. It's one of the success stories of nanotechnology."

"Compared to traditional lithium-ion, [lithium iron phosphate] is environmentally friendly, and very stable," Niu says. "But it's important for this material to be well understood."

While the discovery of the SSZ was made in LiFePO4, Li says, "The same principle may apply to other electrode materials. People are looking for high-power electrode materials, and such metastable states could exist in other electrode materials that are inert in bulk form. … The phenomenon discovered could be very general, and not specific to this material."

###

The research was supported by the National Science Foundation.

Written by David Chandler, MIT News Office

####

For more information, please click here

Contacts:
Andrew Carleen

617-253-1682

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Patent for the Novel Cancer Therapies – Ceramide Nanoliposomes March 4th, 2015

Magnetic vortices in nanodisks reveal information: Researchers from Dresden and Jülich use microwaves to read out information from smallest storage devices March 4th, 2015

CiQUS researchers obtain high-quality perovskites over large areas by a chemical method March 4th, 2015

Arrowhead to Present at 2015 Barclays Global Healthcare Conference March 4th, 2015

Imaging

Forbidden quantum leaps possible with high-res spectroscopy March 2nd, 2015

International research partnership tricks the light fantastic March 2nd, 2015

Important step towards quantum computing: Metals at atomic scale March 2nd, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Govt.-Legislation/Regulation/Funding/Policy

The taming of magnetic vortices: Unified theory for skyrmion-materials March 3rd, 2015

Black phosphorus is new 'wonder material' for improving optical communication March 3rd, 2015

New nanodevice defeats drug resistance: Tiny particles embedded in gel can turn off drug-resistance genes, then release cancer drugs March 2nd, 2015

Forbidden quantum leaps possible with high-res spectroscopy March 2nd, 2015

Discoveries

Experiment and theory unite at last in debate over microbial nanowires: New model and experiments settle debate over metallic-like conductivity of microbial nanowires in bacterium March 4th, 2015

Magnetic vortices in nanodisks reveal information: Researchers from Dresden and Jülich use microwaves to read out information from smallest storage devices March 4th, 2015

CiQUS researchers obtain high-quality perovskites over large areas by a chemical method March 4th, 2015

Nanosorbents Increase Extraction, Recycling of Silver from Aqueous Solutions March 4th, 2015

Announcements

Experiment and theory unite at last in debate over microbial nanowires: New model and experiments settle debate over metallic-like conductivity of microbial nanowires in bacterium March 4th, 2015

Magnetic vortices in nanodisks reveal information: Researchers from Dresden and Jülich use microwaves to read out information from smallest storage devices March 4th, 2015

CiQUS researchers obtain high-quality perovskites over large areas by a chemical method March 4th, 2015

Arrowhead to Present at 2015 Barclays Global Healthcare Conference March 4th, 2015

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Experiment and theory unite at last in debate over microbial nanowires: New model and experiments settle debate over metallic-like conductivity of microbial nanowires in bacterium March 4th, 2015

Magnetic vortices in nanodisks reveal information: Researchers from Dresden and Jülich use microwaves to read out information from smallest storage devices March 4th, 2015

Nanosorbents Increase Extraction, Recycling of Silver from Aqueous Solutions March 4th, 2015

The taming of magnetic vortices: Unified theory for skyrmion-materials March 3rd, 2015

Tools

Keysight Technologies Shifts to Direct Sales of High-Performance Products in North America March 3rd, 2015

Forbidden quantum leaps possible with high-res spectroscopy March 2nd, 2015

International research partnership tricks the light fantastic March 2nd, 2015

Important step towards quantum computing: Metals at atomic scale March 2nd, 2015

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Glass coating improves battery performance: To improve lithium-sulfur batteries, researchers added glass cage-like coating and graphene oxide March 2nd, 2015

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

In quest for better lithium-air batteries, chemists boost carbon's stability: Nanoparticle coatings improve stability, cyclability of '3DOm' carbon February 25th, 2015

Dendrite eraser: New electrolyte rids batteries of short-circuiting fibers: Solution enables a battery with both high efficiency & current density February 24th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE