eiXtra: published by NEMA Hot Topics
On the Hill/Around the Nation
International News
NEMAVoice
Monday, August 23, 2010
feature story
Wax, Soap Clean Up Obstacles to Better Batteries

Paraffin, and surfactant oleic acid improve synthesis of lithium manganese phosphate electrodes

Made with a one-step method, these flakes of lithium manganese phosphate can serve as electrodes for batteries.
Made with a one-step method, these flakes of lithium manganese phosphate can serve as electrodes for batteries.
A little wax and soap can help build electrodes for cheaper lithium-ion batteries, according to a study in the August issue of Nano Letters. The one-step method will allow battery developers to explore lower-priced alternatives to the lithium-ion metal oxide batteries currently on the market.

"Paraffin provides a medium in which to grow good electrode materials," said materials scientist Daiwon Choi of the Department of Energy's Pacific Northwest National Laboratory (PNNL). "This method will help researchers investigate cathode materials based on cheaper transition metals such as manganese or iron."

Consumers use long-lasting rechargeable lithium-ion batteries in everything from cell phones to the latest portable gadgets. Some carmakers want to use them in vehicles. Most lithium-ion batteries available today are designed with an oxide of metal such as cobalt, nickel, or manganese. Mr. Choi and colleagues at PNNL and State University of New York at Binghamton wanted to explore both cheaper metals and the more stable phosphate in place of oxide.

The Recharge Tale

These rechargeable batteries work because lithium is selfish and wants its own electron. Positively charged lithium ions normally hang out in metal oxide, the stable, positive electrode in batteries. Metal oxide generously shares its electrons with the lithium ions.

Charging with electricity pumps electrons into the negative electrode, and when the lithium ions see the free-floating negative charges across the battery, they become attracted to life away from the metal oxide cage. So off the lithium ions go, abandoning the metal oxide and its shared electrons to spend time enjoying their own private ones.

But the affair doesn't last—using the battery in an electronic device creates a conduit through which the slippery electrons can flow. Losing their electrons, the lithium ions slink back to the ever-waiting metal oxide. Recharging starts the whole sordid process over.

Cheaper, Stabler

While cobalt oxide performs well in lithium batteries, cobalt and nickel are more expensive than manganese or iron. In addition, substituting phosphate for oxide provides a more stable structure for lithium.

Lithium iron phosphate batteries are commercially available in some power tools and solar products, but synthesis of the electrode material is complicated. Mr. Choi and colleagues wanted to develop a simple method to turn lithium metal phosphate into a good electrode.

Lithium manganese phosphate (LMP) can theoretically store some of the highest amounts of energy of the rechargeable batteries, weighing in at 171 milliamp hours per gram of material. High storage capacity allows the batteries to be light. But other investigators working with LMP have not even been able to eke out 120 milliamp hours per gram so far from the material they've synthesized.

Mr. Choi reasoned the 30 percent loss in capacity could be due to lithium and electrons having to battle their way through the metal oxide, a property called resistance. The less distance lithium and electrons have to travel out of the cathode, he thought, the less resistance and the more electricity could be stored. A smaller particle would decrease that distance.

But growing smaller particles requires lower temperatures. Unfortunately, lower temperatures means the metal oxide molecules fail to line up well in the crystals. Randomness is unsuitable for cathode materials, so the researchers needed a framework in which the ingredients—lithium, manganese, and phosphate—could arrange themselves into neat crystals.

Wax On, Wax Off

Paraffin wax is made up of long straight molecules that don't react with much, and the long molecules might help line things up. Soap—a surfactant called oleic acid—might help the growing crystals disperse evenly.

Mr. Choi and colleagues mixed the electrode ingredients with melted paraffin and oleic acid and let the crystals grow as they slowly raised the temperature. By 400 Celsius (four times the temperature of boiling water), crystals had formed and the wax and soap had boiled off. Materials scientists generally strengthen metals by subjecting them to high heat, so the team raised the temperature even more to meld the crystals into a plate.

"This method is a lot simpler than other ways of making lithium manganese phosphate cathodes; other groups have a complicated, multi-step process. We mix all the components and heat it up," Mr. Choi said.

To measure the size of the miniscule plates, the team used a transmission electron microscope in EMSL, DOE's Environmental Molecular Sciences Laboratory on the PNNL campus. Up close, tiny, thin rectangles poked every which way. The nanoplates measured about 50 nanometers thick—about a thousand times thinner than a human hair—and up to 2,000 nanometers on a side. Other analyses showed the crystal growth was suitable for electrodes.

To test LMP, the team shook the nanoplates free from one another and added a conductive carbon backing, which serves as the positive electrode. The team tested how much electricity the material could store after charging and discharging fast or slowly.

When the researchers charged the nanoplates slowly over a day and then discharged them just as slowly, the LMP mini battery held a little more than 150 milliamp hours per gram of material, higher than other researchers had been able to attain. But when the battery was discharged fast—say, within an hour, that dropped to about 117, comparable to other material.

Its best performance knocked at the theoretical maximum at 168 milliamp hours per gram, when it was slowly charged and discharged over two days. Charging and discharging in an hour—a reasonable goal for use in consumer electronics—allowed it to store a measly 54 milliamp hours per gram.

Although this version of an LMP battery charges slower than other cathode materials, Mr. Choi said the real advantage to this work is that the easy, one-step method will let them explore a wide variety of cheap materials that have traditionally been difficult to work with in developing lithium ion rechargeable batteries.

In the future, the team will change how they incorporate the carbon coating on the LMP nanoplates, which might improve their charge and discharge rates.



We thank you for your cooperation in improving the quality of our materials.
Please contact Bill Green
at Communications@nema.org if you have any questions or suggestions related to eiXtra.


Hot Topics

08.17.10
Fight Against Counterfeit Electrical Products
The counterfeiting of well-known brands and products has been a growing problem
worldwide for more than a decade, and has increased by 10,000 percent over the
past 20 years.

08.16.10
AWEA Applauds FERC’s Rejection of Proposed Discriminatory Tariff on Wind
The American Wind Energy Association (AWEA) issued a statement from Denise Bode, AWEA CEO, on the decision by the Federal Energy Regulatory Commission (FERC) to reject a wind tariff proposal from investor-owned utility Puget Sound Energy.

08.15.10
LCD Enclosures—A New Approach to Outdoor Digital Signage
Attracting customers and raising awareness about your products and services is the primary reason businesses advertise. And the growing number of mediums that businesses can use to market their companies makes it difficult for companies to asses the worth of particular advertising campaigns.

[ top ]
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

On the Hill/Around the Nation

08.18.10
Stimulus Programs Hobbled by Regulations
The Recovery and Reinvestment Act—also known as the stimulus—was supposed to be timely, targeted, and temporary. A year and a half since its passing, much of the money devoted to tax cuts and aid to states and social benefits has been paid out. But some of the act's more ambitious programs have failed on the first score.

08.16.10
White House Under Fire for Unspent Infrastructure Cash
The Obama administration has paid out less than a third of the nearly $230 billion allocated to big infrastructure projects in the economic stimulus program. Now Republicans are zeroing in on the unspent stimulus money in fresh attacks on the administration's economic policy.

[ top ]
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

International News

08.23.10
Executive-Led Green ICT and Energy Efficiency Trade Mission
Dates: September 27–29, 2010
Location: Mexico City, Mexico
This is the first ever Green ICT & Energy Efficiency Trade Mission to Mexico City.

08.17.10
Zambia Hydropower Project to Begin in 2011
Construction on the $1.5-billion Kafue Gorge Lower hydropower project, in Zambia, will start in June 2011.

[ top ]
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • •


NEMAcastNEMA podcast for the electroindustry.

NEMAcast focuses on news, information, and opportunities in the electroindustry. Listen online at podcast.nema.org. NEMAcast has several channels, each with a special focus on different parts of the electroindustry. Listen to this week's podcast on "Manufacturers Unveil Radiation Therapy Readiness Check Initiative."


NEMAVoice

Industry News

Contracts

Personnel

[ Industry News Archives ]

NEMA/BIS

[ top ]
Market Comments by Tom Robinson
Copy to come. read more...


Upcoming Events:

Eicareers.org: The Electroindustry Career Portal - powered by NEMA
Job Title Company Name
Director of Facilities New Jersey City University
Process Validation Engineer Boehringer Ingelheim
Click here to view ALL job Listings

Sponsored by
Sponsored by UL University a Certified PV System Installer

PV is Growing–Want to Get a Piece of the Action?
With module prices dropping by 40 percent and tax credits covering up to 30 percent of the cost, demand for PV is building, with projected annual growth close to 40 percent. PV, including modules, system components and installation, will grow from a $36.1 billion industry in 2009 to $116.5 billion by 2019.

UL University’s training and certification program delivers an opportunity to set yourself apart with a credential focused on the critical knowledge and skills of PV installation.

Register today and save 40% off the price to the PV Installation training when you use discount code NEMA40.

Contact UL University at 1.888.503.5536, email ULUniversity@us.ul.com or visit www.uluniversity.us/certification for training and certification exam dates, locations, pricing and to register.

To view this email on the web, go to http://www.nema.org/media/eiextra/briefs/20100823eiXtra.htm

Event Calendar
August 2010
S M T W T F S
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31
.
Email
 

NEMA's 84th Annual Meeting: Illuminations Weekend, The Breakers, Palm Beach, FL - Nov 5-6, 2010

NEMA's ESPG 2009-2010

CSA Advertisement

IHS Advertisement

Subscribe to NEMAcast

NEMACurrents Blog

NEMA on YouTube.

NEMAupdates

2010 National Electrical Manufacturers Association. eiXtra is a biweekly e-newsletter for electroindustry professionals summarizing key manufacturer, standardization, and regulatory news. NEMA does not sell or release subscriber's personal information and will never willfully disclose individually identifiable information to any third party without first receiving your permission. Privacy policy.
Follow NEMA: Blog BlogPodcasts PodcastsTwitter TwitterYouTube YouTubeLinkedIn LinkedIn
Printer-friendly version | Unsubscribe