Tag Archives: li-ion batteries

Friendlier (halogen-free) lithium-ion batteries

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An Oct. 24, 2014 news item on ScienceDaily mentions a greener type of lithium-ion battery from a theoretical (keep reading till you reach the first paragraph of the university news release) perspective,

Physics researchers at Virginia Commonwealth University have discovered that most of the electrolytes used in lithium-ion batteries — commonly found in consumer electronic devices — are superhalogens, and that the vast majority of these electrolytes contain toxic halogens.

At the same time, the researchers also found that the electrolytes in lithium-ion batteries (also known as Li-ion batteries) could be replaced with halogen-free electrolytes that are both nontoxic and environmentally friendly.

“The significance [of our findings] is that one can have a safer battery without compromising its performance,” said lead author Puru Jena, Ph.D., distinguished professor in the Department of Physics of the College of Humanities and Sciences. “The implication of our research is that similar strategies can also be used to design cathode materials in Li-ion batteries.”

An Oct. 24, 2014 Virginia Commonwealth University news release by Brian McNeill (also on EurekAlert), which originated the news item, describes the researchers’ hopes and the inspiration for this work,

“We hope that our theoretical prediction will stimulate experimentalists to synthesize halogen-free salts which will then lead manufacturers to use such salts in commercial applications,” he said.

The researchers also found that the procedure outlined for Li-ion batteries is equally valid for other metal-ion batteries, such as sodium-ion or magnesium-ion batteries.

Jena became interested in the topic several months ago when he saw a flyer on Li-ion batteries that mentioned the need for halogen-free electrolytes.

“I had not done any work on Li-ion batteries at the time, but I was curious to see what the current electrolytes are,” he said. “I found that the negative ions that make up the electrolytes are large and complex in nature and they contain one less electron than what is needed for electronic shell closure.”

Jena had already been working for more than five years on superhalogens, a class of molecules that mimic the chemistry of halogens but have electron affinities that are much larger than that of the halogen atoms.

“I knew of many superhalogen molecules that do not contain a single halogen atom,” he said. “My immediate thought was first to see if the anionic components of the current electrolytes are indeed superhalogens. And, if so, do the halogen-free superhalogens that we knew serve the purpose as halogen-free electrolytes? Our research proved that to be the case.”

Here’s a link to and a citation for the paper,

Superhalogens as Building Blocks of Halogen-Free Electrolytes in Lithium-Ion Batteries by Dr. Santanab Giri, Swayamprabha Behera and Prof. Puru Jena. Angewandte Chemie, DOI: 10.1002/ange.201408648 Article first published online: 14 OCT 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Sand and nanotechnology

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There’s some good news coming out of the University of California, Riverside regarding sand and lithium-ion (li-ion) batteries, which I will temper with some additional information later in this posting.

First, the good news is that researchers have a new non-toxic, low cost way to produce a component in lithium-ion (li-ion) batteries according to a July 8, 2014 news item on ScienceDaily,

Researchers at the University of California, Riverside’s Bourns College of Engineering have created a lithium ion battery that outperforms the current industry standard by three times. The key material: sand. Yes, sand.

“This is the holy grail — a low cost, non-toxic, environmentally friendly way to produce high performance lithium ion battery anodes,” said Zachary Favors, a graduate student working with Cengiz and Mihri Ozkan, both engineering professors at UC Riverside.

The idea came to Favors six months ago. He was relaxing on the beach after surfing in San Clemente, Calif. when he picked up some sand, took a close look at it and saw it was made up primarily of quartz, or silicon dioxide.

His research is centered on building better lithium ion batteries, primarily for personal electronics and electric vehicles. He is focused on the anode, or negative side of the battery. Graphite is the current standard material for the anode, but as electronics have become more powerful graphite’s ability to be improved has been virtually tapped out.

A July 8, 2014 University of California at Riverside news release by Sean Nealon, which originated the news item, describes some of the problems with silicon as a replacement for graphite and how the researchers approached those problems,

Researchers are now focused on using silicon at the nanoscale, or billionths of a meter, level as a replacement for graphite. The problem with nanoscale silicon is that it degrades quickly and is hard to produce in large quantities.

Favors set out to solve both these problems. He researched sand to find a spot in the United States where it is found with a high percentage of quartz. That took him to the Cedar Creek Reservoir, east of Dallas, where he grew up.

Sand in hand, he came back to the lab at UC Riverside and milled it down to the nanometer scale, followed by a series of purification steps changing its color from brown to bright white, similar in color and texture to powdered sugar.

After that, he ground salt and magnesium, both very common elements found dissolved in sea water into the purified quartz. The resulting powder was then heated. With the salt acting as a heat absorber, the magnesium worked to remove the oxygen from the quartz, resulting in pure silicon.

The Ozkan team was pleased with how the process went. And they also encountered an added positive surprise. The pure nano-silicon formed in a very porous 3-D silicon sponge like consistency. That porosity has proved to be the key to improving the performance of the batteries built with the nano-silicon.

…

Now, the Ozkan team is trying to produce larger quantities of the nano-silicon beach sand and is planning to move from coin-size batteries to pouch-size batteries that are used in cell phones.

The research is supported by Temiz Energy Technologies. The UCR Office of Technology Commercialization has filed patents for inventions reported in the research paper.

Here’s a link to and a citation for the research paper,

Scalable Synthesis of Nano-Silicon from Beach Sand for Long Cycle Life Li-ion Batteries by Zachary Favors, Wei Wang, Hamed Hosseini Bay, Zafer Mutlu, Kazi Ahmed, Chueh Liu, Mihrimah Ozkan, & Cengiz S. Ozkan. Scientific Reports 4, Article number: 5623 doi:10.1038/srep05623 Published 08 July 2014

While this is good news, it does pose a conundrum of sorts. It seems that supplies of sand are currently under siege. A documentary, Sand Wars (2013) lays out the issues (from the Sand Wars website’s Synopsis page),

Most of us think of it as a complimentary ingredient of any beach vacation. Yet those seemingly insignificant grains of silica surround our daily lives. Every house, skyscraper and glass building, every bridge, airport and sidewalk in our modern society depends on sand. We use it to manufacture optical fiber, cell phone components and computer chips. We find it in our toothpaste, powdered foods and even in our glass of wine (both the glass and the wine, as a fining agent)!

Is sand an infinite resource? Can the existing supply satisfy a gigantic demand fueled by construction booms?  What are the consequences of intensive beach sand mining for the environment and the neighboring populations?

Based on encounters with sand smugglers, barefoot millionaires, corrupt politicians, unscrupulous real estate developers and environmentalists, this investigation takes us around the globe to unveil a new gold rush and a disturbing fact: the “SAND WARS” have begun.

Dr. Muditha D Senarath Yapa of John Keells Research at John Keells Holdings comments on the situation in Sri Lanka in his June 22, 2014 article (Nanotechnology – Depleting the most precious minerals for a few dollars) for The Nation,

Many have written for many years about the mineral sands of Pulmoddai. It is a national tragedy that for more than 50 years, we have been depleting the most precious minerals of our land for a few dollars. There are articles that appeared in various newspapers on how the mineral sands industry has boomed over the years. I hope the readers understand that it only means that we are depleting our resources faster than ever. According to the Lanka Mineral Sands Limited website, 90,000 tonnes of ilmenite, 9,000 tonnes of rutile, 5,500 tonnes of zircon, 100 tonnes of monazite and 4,000 tonnes of high titanium ilmenite are produced annually and shipped away to other countries.

…

… It is time for Sri Lanka to look at our own resources with this new light and capture the future nano materials market to create value added materials.

It’s interesting that he starts with the depletion of the sands as a national tragedy and ends with a plea to shift from a resource-based economy to a manufacturing-based economy. (This plea resonates strongly here in Canada where we too are a resource-based economy.)

Sidebar: John Keells Holdings is a most unusual company, from the About Us page,

In terms of market capitalisation, John Keells Holdings PLC is one of the largest listed conglomerate on the Colombo Stock Exchange. Other measures tell a similar tale; our group companies manage the largest number of hotel rooms in Sri Lanka, own the country’s largest privately-owned transportation business and hold leading positions in Sri Lanka’s key industries: tea, food and beverage manufacture and distribution, logistics, real estate, banking and information technology. Our investment in Sri Lanka is so deep and widely diversified that our stock price is sometimes used by international financial analysts as a benchmark of the country’s economy.

Yapa heads the companies research effort, which recently celebrated a synthetic biology agreement (from a May 2014 John Keells news release by Nuwan),

John Keells Research Signs an Historic Agreement with the Human Genetics Unit, Faculty of Medicine, University of Colombo to establish Sri Lanka’s first Synthetic Biology Research Programme.

Getting back to sand, these three pieces, ‘sand is good for li-ion batteries’, ‘sand is a diminishing resource’, and ‘let’s stop being a source of sand for other countries’ lay bare some difficult questions about our collective future on this planet.

Charging portable electronics in 10 minutes (hopefully) with a 3D (silicon-decorated) carbon nanotube cluster

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I sometimes think there’s a worldwide obsession with lithium-ion batteries as hardly a day passes without at least one story about them. To honour that obsession, here’s a June 11, 2014 news item on Azonano describing a new technique which could lead to a faster charging time for mobile electronics,

Researchers at the University of California, Riverside [UCR] Bourns College of Engineering have developed a three-dimensional, silicon-decorated, cone-shaped carbon-nanotube cluster architecture for lithium ion battery anodes that could enable charging of portable electronics in 10 minutes, instead of hours.

A June 10, 2014 UCR news release by Sean Nealon, which originated the news item, notes the ubiquity of lithium-ion batteries in modern electronics and explains why silicon was used in this research,

Lithium ion batteries are the rechargeable battery of choice for portable electronic devices and electric vehicles. But, they present problems. Batteries in electric vehicles are responsible for a significant portion of the vehicle mass. And the size of batteries in portable electronics limits the trend of down-sizing.

Silicon is a type of anode material that is receiving a lot of attention because its total charge capacity is 10 times higher than commercial graphite based lithium ion battery anodes. Consider a packaged battery full-cell. Replacing the commonly used graphite anode with silicon anodes will potentially result in a 63 percent increase of total cell capacity and a battery that is 40 percent lighter and smaller.

The news release then provides a very brief description of the technology,

…, UC Riverside researchers developed a novel structure of three-dimensional silicon decorated cone-shaped carbon nanotube clusters architecture via chemical vapor deposition and inductively coupled plasma treatment.

Lithium ion batteries based on this novel architecture demonstrate a high reversible capacity and excellent cycling stability. The architecture demonstrates excellent electrochemical stability and irreversibility even at high charge and discharge rates, nearly 16 times faster than conventionally used graphite based anodes.

The researchers believe the ultrafast rate of charge and discharge can be attributed to two reasons, said Wei Wang, lead author of the paper.

One, the seamless connection between graphene covered copper foil and carbon nanotubes enhances the active material-current collector contact integrity which facilitates charge and thermal transfer in the electrode system.

Two, the cone-shaped architecture offers small interpenetrating channels for faster electrolyte access into the electrode which may enhance the rate performance.

Here’s a link to and a citation for the paper,

Silicon Decorated Cone Shaped Carbon Nanotube Clusters for Lithium Ion Battery Anodes by Wei Wang, Isaac Ruiz, Kazi Ahmed, Hamed Hosseini Bay, Aaron S. George, Johnny Wang, John Butler, Mihrimah Ozkan, and Cengiz S. Ozkan. Small DOI: 10.1002/smll.201400088 Article first published online: 19 APR 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

A new artform: folded lithium-ion batteries made of paper coated with carbon nanotubes

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The above image illustrates the architecture of a foldable lithium-ion battery ASU engineers have constructed using paper coated with carbon nanotubes. They began with a porous, lint-free paper towel, coated it with polyvinylidene difluoride to improve adhesion of carbon nanotubes and then immersed the paper into a solution of carbon nanotubes. Powders of lithium titanate oxide and lithium cobalt oxide — standard lithium battery electrodes — are sandwiched between two sheets of the paper. Thin foils of copper and aluminum are placed above and below the sheets of paper to complete the battery.. Courtesy: Arizona State University

The above image illustrates the architecture of a foldable lithium-ion battery ASU engineers have constructed using paper coated with carbon nanotubes. They began with a porous, lint-free paper towel, coated it with polyvinylidene difluoride to improve adhesion of carbon nanotubes and then immersed the paper into a solution of carbon nanotubes. Powders of lithium titanate oxide and lithium cobalt oxide — standard lithium battery electrodes — are sandwiched between two sheets of the paper. Thin foils of copper and aluminum are placed above and below the sheets of paper to complete the battery.. Courtesy: Arizona State University

Despite the fact that I’m wondering about what happened to A (in the illustration), here’s the Oct. 22, 2013 Arizona State University news release by Joe Kullman (h/t Azonano) which describes the ‘origami’ breakthrough,

Arizona State University engineers have constructed a lithium-ion battery using paper coated with carbon nanotubes that provide electrical conductivity.

Using an origami-folding pattern similar to how maps are folded, they folded the paper into a stack of 25 layers, producing a compact, flexible battery that provides significant energy density —  or the amount of energy stored in a given system or space per unit of volume of mass.

Their research paper in the journal Nano Letters has drawn attention from websites that focus on news of technological breakthroughs.

The researchers have also developed a new process to incorporate a polymer binder onto the carbon nanotube-coated paper. The polymer binder improves adhesion of the structure’s active materials.

The achievements open up possibilities of using the origami technique to create new forms of paper-based energy storage devices, including batteries, light-emitting diodes, circuits and transistors, says Candace Chan, who led the research team.

Here’s a link to and a citation for article in Nano Letters,

Folding Paper-Based Lithium-Ion Batteries for Higher Areal Energy Densities by Qian Cheng, Zeming Song, Teng Ma, Bethany B. Smith, Rui Tang, Hongyu Yu, Hanqing Jiang, and Candace K. Chan. Nano Lett., 2013, 13 (10), pp 4969–4974 DOI: 10.1021/nl4030374 Publication Date (Web): September 23, 2013
Copyright © 2013 American Chemical Society

This article is behind a paywall.

Keeping it together—new glue for lithium-ion batteries

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Glue isn’t the first component that comes to my mind when discussing ways to make lithium-ion (Li-ion) batteries more efficient but researchers at SLAC National Accelerator Laboratory at Stanford University have proved that the glue used to bind a Li-ion battery together can make a difference to its efficiency (from the Aug. 20, 2013 news item on phys.org),

When it comes to improving the performance of lithium-ion batteries, no part should be overlooked – not even the glue that binds materials together in the cathode, researchers at SLAC and Stanford have found.

Tweaking that material, which binds lithium sulfide and carbon particles together, created a cathode that lasted five times longer than earlier designs, according to a report published last month in Chemical Science. The research results are some of the earliest supported by the Department of Energy’s Joint Center for Energy Storage Research.

“We were very impressed with how important this binder was in improving the lifetime of our experimental battery,” said Yi Cui, an associate professor at SLAC and Stanford who led the research.

The Aug. 19, 2013 SLAC news release by Mike Ross, which originated the news item, provides context for this accidental finding about glue and Li-ion batteries,

Researchers worldwide have been racing to improve lithium-ion batteries, which are one of the most promising technologies for powering increasingly popular devices such as mobile electronics and electric vehicles. In theory, using silicon and sulfur as the active elements in the batteries’ terminals, called the anode and cathode, could allow lithium-ion batteries to store up to five times more energy than today’s best versions. But finding specific forms and formulations of silicon and sulfur that will last for several thousand charge-discharge cycles during real-life use has been difficult.

Cui’s group was exploring how to create a better cathode by using lithium sulfide rather than sulfur. The lithium atoms it contains can provide the ions that shuttle between anode and cathode during the battery’s charge/discharge cycle; this in turn means the battery’s other electrode can be made from a non-lithium material, such as silicon. Unfortunately, lithium sulfide is also electrically insulating, which greatly reduces any battery’s performance. To overcome this, electrically conducting carbon particles can be mixed with the sulfide; a glue-like material – the binder – holds it all together.

Scientists in Cui’s [Yi Cui, an associate professor at SLAC and Stanford who led the research] group devised a new binder that is particularly well-suited for use with a lithium sulfide cathode ­– and that also binds strongly with intermediate polysulfide molecules that dissolve out of the cathode and diminish the battery’s storage capacity and useful lifetime.

The experimental battery using the new binder, known by the initials PVP, retained 94 percent of its original energy-storage capacity after 100 charge/discharge cycles, compared with 72 percent for cells using a conventionally-used binder, known as PVDF. After 500 cycles, the PVP battery still had 69 percent of its initial capacity.

Cui said the improvement was due to PVP’s much stronger affinity for lithium sulfide; together they formed a fine-grained lithium sulfide/carbon composite that made it easier for lithium ions to penetrate and reach all of the active material within the cathode. In contrast, the previous binder, PVDF, caused the composite to grow into large clumps, which hindered the lithium ions’ penetration and ruined the battery within 100 cycles

Even the best batteries lose some energy-storage capacity with each charge/discharge cycle. Researchers aim to reduce such losses as much as possible. Further enhancements to the PVP/lithium sulfide cathode combination will be needed to extend its lifetime to more than 1,000 cycles, but Cui said he finds it encouraging that improving the usually overlooked binder material produced such dramatic benefits.

Here’s a link to and a citation for the published paper,

Stable cycling of lithium sulfide cathodes through strong affinity with a bifunctional binder by Zhi Wei Seh, Qianfan Zhang, Weiyang Li, Guangyuan Zheng, Hongbin Yaoa, and Yi Cui. Chem. Sci., 2013,4, 3673-3677 DOI: 10.1039/C3SC51476E First published online 11 Jul 2013

There’s a note on the website stating the article is free but the instructions for accessing the article are confusing seeming to suggest you need a subscription of some sort or you need to register for the site.

I have written about Yi Cui’s work with lithium-ion batteries before including this Jan. 9, 2013 posting, How is an eggshell like a lithium-ion battery?, which also features a news release by Mike Ross.

Life-cycle assessment for electric vehicle lithium-ion batteries and nanotechnology is a risk analysis

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A May 29, 2013 news item on Azonano features a new study for the US Environmental Protection Agency (EPA) on nanoscale technology and lithium-ion (li-ion) batteries for electric vehicles,

Lithium (Li-ion) batteries used to power plug-in hybrid and electric vehicles show overall promise to “fuel” these vehicles and reduce greenhouse gas emissions, but there are areas for improvement to reduce possible environmental and public health impacts, according to a “cradle to grave” study of advanced Li-ion batteries recently completed by Abt Associates for the U.S. Environmental Protection Agency (EPA).

“While Li-ion batteries for electric vehicles are definitely a step in the right direction from traditional gasoline-fueled vehicles and nickel metal-hydride automotive batteries, some of the materials and methods used to manufacture them could be improved,” said Jay Smith, an Abt senior analyst and co-lead of the life-cycle assessment.

Smith said, for example, the study showed that the batteries that use cathodes with nickel and cobalt, as well as solvent-based electrode processing, show the highest potential for certain environmental and human health impacts. The environmental impacts, Smith explained, include resource depletion, global warming, and ecological toxicity—primarily resulting from the production, processing and use of cobalt and nickel metal compounds, which can cause adverse respiratory, pulmonary and neurological effects in those exposed.

There are viable ways to reduce these impacts, he said, including cathode material substitution, solvent-less electrode processing and recycling of metals from the batteries.

The May 28, 2013 Abt Associates news release, which originated the news item, describes some of the findings,

Among other findings, Shanika Amarakoon, an Abt associate who co-led the life-cycle assessment with Smith, said global warming and other environmental and health impacts were shown to be influenced by the electricity grids used to charge the batteries when driving the vehicles.
“These impacts are sensitive to local and regional grid mixes,” Amarakoon said.  “If the batteries in use are drawing power from the grids in the Midwest or South, much of the electricity will be coming from coal-fired plants.  If it’s in New England or California, the grids rely more on renewables and natural gas, which emit less greenhouse gases and other toxic pollutants.” However,” she added, “impacts from the processing and manufacture of these batteries should not be overlooked.”
In terms of battery performance, Smith said that “the nanotechnology applications that Abt assessed were single-walled carbon nanotubes (SWCNTs), which are currently being researched for use as anodes as they show promise for improving the energy density and ultimate performance of the Li-ion batteries in vehicles.  What we found, however, is that the energy needed to produce the SWCNT anodes in these early stages of development is prohibitive. Over time, if researchers focus on reducing the energy intensity of the manufacturing process before commercialization, the environmental profile of the technology has the potential to improve dramatically.”

Abt’s Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles can be found here, all 126 pp.

This assessment was performed under the auspices of an interesting assortment of agencies (from the news release),

The research for the life-cycle assessment was undertaken through the Lithium-ion Batteries and Nanotechnology for Electric Vehicles Partnership, which was led by EPA’s Design for the Environment Program in the Office of Chemical Safety and Pollution Prevention and Toxics, and EPA’s National Risk Management Research Laboratory in the Office of Research and Development.  [emphasis mine] The Partnership also included industry partners (i.e., battery manufacturers, recyclers, and suppliers, and other industry groups), the Department of Energy’s Argonne National Lab, Arizona State University, and the Rochester Institute of Technology

I highlighted the National Risk Management Research Laboratory as it reminded me of the lithium-ion battery fires in airplanes reported in January 2013. I realize that cars and planes are not the same thing but lithium-ion batteries have some well defined problems especially since the summer of 2006 when there was a series of li-ion battery laptop fires. From Tracy V. Wilson’s What causes laptop batteries to overheat? article for How stuff works.com (Note: A link has been removed),

In conjunction with the United States Consumer Product Safety Commission (CPSC), Dell and Apple Computer announced large recalls of laptop batteries in the summer of 2006, followed by Toshiba and Lenovo. Sony manufactured all of the recalled batteries, and in October 2006, the company announced its own large-scale recall. Under the right circumstances, these batteries could overheat, potentially causing burns, an explosion or a fire.

Larry Greenemeier in a Jan. 17, 2013 article for Scientific American offers some details about the lithium-ion battery fires in airplanes and elsewhere,

Boeing’s Dreamliner has likely become a nightmare for the company, its airline customers and regulators worldwide. An inflight lithium-ion battery fire broke out Wednesday [Jan. 16, 2013] on an All Nippon Airways 787 over Japan, forcing an emergency landing. And another battery fire occurred last week aboard a Japan Airlines 787 at Boston’s Logan International Airport. Both battery failures resulted in release of flammable electrolytes, heat damage and smoke on the aircraft, according to the U.S. Federal Aviation Administration (FAA).

…

Lithium-ion batteries—used to power mobile phones, laptops and electric vehicles—have summoned plenty of controversy during their relatively brief existence. Introduced commercially in 1991, by the mid 2000s they had become infamous for causing fires in laptop computers.

More recently, the plug-in hybrid electric Chevy Volt’s lithium-ion battery packs burst into flames following several National Highway Traffic Safety Administration (NHTSA) tests to measure the vehicle’s ability to protect occupants from injury in a side collision. The NHTSA investigated and concluded in January 2012 that Chevy Volts and other electric vehicles do not pose a greater risk of fire than gasoline-powered vehicles.

Philip E. Ross in his Jan. 18, 2013 article about the airplane fires for IEEE’s (Institute of Electrical and Electronics Engineers) Spectrum provides some insight into the fires,

It seems that the batteries heated up in a self-accelerating pattern called thermal runaway. Heat from the production of electricity speeds up the production of electricity, and… you’re off. This sort of things happens in a variety of reactions, not just in batteries, let alone the Li-ion kind. But thermal runaway is particularly grave in Li-ion batteries because they pack a lot more power than the tried-and-true metal-hydride ones, not to speak of Ye Olde lead-acid.

It’s because of this very quality that Li-ion batteries found their first application in small mobile devices, where power is critical and fires won’t cost anyone his life. It’s also why it took so long for the new tech to find its way into electric and hybrid-electric cars.

…

Perhaps it would have been wiser of Boeing to go for the safest possible Li-ion design, even if it didn’t have quite as much oomph as possible. That’s what today’s main-line electric-drive cars do, as our colleague, John Voelcker, points out.

“The cells in the 787 [Dreamliner], from Japanese company GS Yuasa, use a cobalt oxide (CoO2) chemistry, just as mobile-phone and laptop batteries do,” he writes in greencarreports.com. “That chemistry has the highest energy content, but it is also the most susceptible to overheating that can produce “thermal events” (which is to say, fires). Only one electric car has been built in volume using CoO2 cells, and that’s the Tesla Roadster. Only 2,500 of those cars will ever exist.” Most of today’s electric cars, Voelcker adds, use chemistries that trade some energy density for safety.

The Dreamliner (Boeing 787) is designed to be the lightest of airplanes and using a more energy dense but safer lithium-ion battery seems not to have been an acceptable trade-off.  Interestingly, Boeing according to Ross still had a backlog of orders after the fires.

I find that some of the discussion about risk and nanotechnology-enabled products oddly disconnected. There are the concerns about what happens at the nanoscale (environmental implications, etc.) but that discussion is divorced from some macroscale issues such as battery fires. Taken to absurd lengths, technology at the nanoscale could be considered safe while macroscale issues are completely ignored. It’s as if our institutions are not yet capable of managing multiple scales at once.

For more about an emphasis on scale and other minutiae (pun intended), there’s my May 28, 2013 posting about Steffen Foss Hansen’s plea to revise current European Union legislation to create more categories for nanotechnology regulation, amongst other things.

For more about airplanes and their efforts to get more energy efficient, there’s my May 27, 2013 posting about a biofuel study in Australia.

Bend it, twist it, any way you want to—a foldable lithium-ion battery

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A Feb. 26, 2013 news item on ScienceDaily features an extraordinary lithium-ion battery,

Northwestern University’s Yonggang Huang and the University of Illinois’ John A. Rogers are the first to demonstrate a stretchable lithium-ion battery — a flexible device capable of powering their innovative stretchable electronics.

No longer needing to be connected by a cord to an electrical outlet, the stretchable electronic devices now could be used anywhere, including inside the human body. The implantable electronics could monitor anything from brain waves to heart activity, succeeding where flat, rigid batteries would fail.

Huang and Rogers have demonstrated a battery that continues to work — powering a commercial light-emitting diode (LED) — even when stretched, folded, twisted and mounted on a human elbow. The battery can work for eight to nine hours before it needs recharging, which can be done wirelessly.

The researchers at Northwestern have produced a video where they demonstrate the battery’s ‘stretchability’,

The Northwestern University Feb. 26, 2013 news release by Megan Fellman, which originated the news item, offers this detail,

“We start with a lot of battery components side by side in a very small space, and we connect them with tightly packed, long wavy lines,” said Huang, a corresponding author of the paper. “These wires provide the flexibility. When we stretch the battery, the wavy interconnecting lines unfurl, much like yarn unspooling. And we can stretch the device a great deal and still have a working battery.”

…

The power and voltage of the stretchable battery are similar to a conventional lithium-ion battery of the same size, but the flexible battery can stretch up to 300 percent of its original size and still function.

…

Huang and Rogers have been working together for the last six years on stretchable electronics, and designing a cordless power supply has been a major challenge. Now they have solved the problem with their clever “space filling technique,” which delivers a small, high-powered battery.

For their stretchable electronic circuits, the two developed “pop-up” technology that allows circuits to bend, stretch and twist. They created an array of tiny circuit elements connected by metal wire “pop-up bridges.” When the array is stretched, the wires — not the rigid circuits — pop up.

This approach works for circuits but not for a stretchable battery. A lot of space is needed in between components for the “pop-up” interconnect to work. Circuits can be spaced out enough in an array, but battery components must be packed tightly to produce a powerful but small battery. There is not enough space between battery components for the “pop-up” technology to work.

Huang’s design solution is to use metal wire interconnects that are long, wavy lines, filling the small space between battery components. (The power travels through the interconnects.)

The unique mechanism is a “spring within a spring”: The line connecting the components is a large “S” shape and within that “S” are many smaller “S’s.” When the battery is stretched, the large “S” first stretches out and disappears, leaving a line of small squiggles. The stretching continues, with the small squiggles disappearing as the interconnect between electrodes becomes taut.

“We call this ordered unraveling,” Huang said. “And this is how we can produce a battery that stretches up to 300 percent of its original size.”

The stretching process is reversible, and the battery can be recharged wirelessly. The battery’s design allows for the integration of stretchable, inductive coils to enable charging through an external source but without the need for a physical connection.

Huang, Rogers and their teams found the battery capable of 20 cycles of recharging with little loss in capacity. The system they report in the paper consists of a square array of 100 electrode disks, electrically connected in parallel.

I’d like to see this battery actually powering a device even though the stretching is quite alluring in its way. For those who are interested here’s a citation and a link to the research paper,

Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems by Sheng Xu, Yihui Zhang, Jiung Cho, Juhwan Lee, Xian Huang, Lin Jia, Jonathan A. Fan, Yewang Su, Jessica Su, Huigang Zhang, Huanyu Cheng, Bingwei Lu,           Cunjiang Yu, Chi Chuang, Tae-il Kim, Taeseup Song, Kazuyo Shigeta, Sen Kang, Canan Dagdeviren, Ivan Petrov  et al.   Nature Communications 4, Article number: 1543 doi: 10.1038/ncomms2553  Published 26 February 2013

The article is behind a paywall.

A ‘wandering meatloaf’ with teeth inspires nanomaterials for solar cells and Li-ion batteries

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The ‘wandering meatloaf’ is a species of marine snail (or chiton) that has extraordinary teeth according to the Jan. 16, 2013 news item on ScienceDaily,

An assistant professor [David Kisailus] at the University of California, Riverside’s Bourns College of Engineering is using the teeth of a marine snail found off the coast of California to create less costly and more efficient nanoscale materials to improve solar cells and lithium-ion batteries.

…

The paper is focused on the gumboot chiton, the largest type of chiton, which can be up to a foot-long. They are found along the shores of the Pacific Ocean from central California to Alaska. They have a leathery upper skin, which is usually reddish-brown and occasionally orange, leading some to give it the nickname “wandering meatloaf.”

Over time, chitons have evolved to eat algae growing on and within rocks using a specialized rasping organ called a radula, a conveyer belt-like structure in the mouth that contains 70 to 80 parallel rows of teeth. During the feeding process, the first few rows of the teeth are used to grind rock to get to the algae. They become worn, but new teeth are continuously produced and enter the “wear zone” at the same rate as teeth are shed.

The University of California Riverside Jan. 15, 2013 news release by Sean Nealon, which originated the news item, describes the chiton’s teeth and the specifics of Kisailus’ inspiration (Note: A link has been removed),

Over time, chitons have evolved to eat algae growing on and within rocks using a specialized rasping organ called a radula, a conveyer belt-like structure in the mouth that contains 70 to 80 parallel rows of teeth. During the feeding process, the first few rows of the teeth are used to grind rock to get to the algae. They become worn, but new teeth are continuously produced and enter the “wear zone” at the same rate as teeth are shed.

Kisailus, who uses nature as inspiration to design next generation engineering products and materials, started studying chitons five years ago because he was interested in abrasion and impact-resistant materials. He has previously determined that the chiton teeth contain the hardest biomineral known on Earth, magnetite, which is the key mineral that not only makes the tooth hard, but also magnetic.

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Kisailus is using the lessons learned from this biomineralization pathway as inspiration in his lab to guide the growth of minerals used in solar cells and lithium-ion [li-ion] batteries. By controlling the crystal size, shape and orientation of engineering nanomaterials, he believes he can build materials that will allow the solar cells and lithium-ion batteries to operate more efficiently. In other words, the solar cells will be able to capture a greater percentage of sunlight and convert it to electricity more efficiently and the lithium-ion batteries could need significantly less time to recharge.

Using the chiton teeth model has another advantage: engineering nanocrystals can be grown at significantly lower temperatures, which means significantly lower production costs.

While Kisailus is focused on solar cells and lithium-ion batteries, the same techniques could be used to develop everything from materials for car and airplane frames to abrasion resistant clothing. In addition, understanding the formation and properties of the chiton teeth could help to create better design parameters for better oil drills and dental drill bits.

Here’s a representation of the teeth from the University of California Riverside,

A series of images that show the teeth of the gumboot chiton (aka, snail, aka, wandering meatloaf)

A series of images that show the teeth of the gumboot chiton (aka, snail, aka, wandering meatloaf)

You can find other images and media materials in the ScienceDaily news item or the University of California Riverside news release. This citation and link for the research paper is from the ScienceDaily news item,

Qianqian Wang, Michiko Nemoto, Dongsheng Li, James C. Weaver, Brian Weden, John Stegemeier, Krassimir N. Bozhilov, Leslie R. Wood, Garrett W. Milliron, Christopher S. Kim, Elaine DiMasi, David Kisailus. Phase Transformations and Structural Developments in the Radular Teeth ofCryptochiton Stelleri. Advanced Functional Materials, 2013; DOI: 10.1002/adfm.201202894

This article is behind a paywall.

How is an eggshell like a lithium-ion battery?

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How is an eggshell like a lithium-ion battery? It’s all about the yolk. Some days I can’t resist the urge for some wordplay, even if it isn’t the best fit, and the Jan. 9, 2013 news item by Mike Ross on phys.org proved irresistible,

SLAC [Stanford National Accelerator Laboratory] and Stanford [University] scientists have set a world record for energy storage, using a clever “yolk-shell” design to store five times more energy in the sulfur cathode of a rechargeable lithium-ion battery than is possible with today’s commercial technology. The cathode also maintained a high level of performance after 1,000 charge/discharge cycles, paving the way for new generations of lighter, longer-lasting batteries for use in portable electronics and electric vehicles.

The study has been published in Nature Communications where this explanatory image amongst others can be viewed,

[downloaded from Nature Communications: http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2327.html]

[downloaded from Nature Communications: http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2327.html]

You can find out more about the research here,

Sulphur–TiO2 yolk–shell nanoarchitecture with internal void space for long-cycle lithium–sulphur batteries by Zhi Wei Seh, Weiyang Li, Judy J. Cha,    Guangyuan Zheng, Yuan Yang, Matthew T. McDowell, Po-Chun Hsu & Yi Cui in Nature Communications 4, Article number: 1331 doi:10.1038/ncomms2327

The Jan. 8, 2013 SLAC news release, which originated the news item, provides more details about the lithium-ion batteries in general and this attempt to improve their energy storage capacity,

Lithium-ion batteries work by moving lithium ions back and forth between two electrodes, the cathode and anode. Charging the battery forces the ions and electrons into the anode, creating an electrical potential that can power a wide range of devices. Discharging the battery – using it to do work – moves the ions and electrons to the cathode.

Today’s lithium-ion batteries typically retain about 80 percent of their initial capacity after 500 charge/discharge cycles.

For some 20 years, researchers have known that sulfur could theoretically store more lithium ions, and thus much more energy, than today’s cathode materials…

Cui’s innovation is a cathode made of nanoparticles, each a tiny sulfur nugget surrounded by a hard shell of porous titanium-oxide, like an egg yolk in an eggshell. Between the yolk and shell, where the egg white would be, is an empty space into which the sulfur can expand. During discharging, lithium ions pass through the shell and bind to the sulfur, which expands to fill the void but not so much as to break the shell. The shell, meanwhile, protects the sulfur-lithium intermediate compound from electrolyte solvent that would dissolve it.

Each cathode particle is only 800 nanometers (billionths of a meter) in diameter, about one-hundredth the diameter of a human hair.

…

“After 1,000 charge/discharge cycles, our yolk-shell sulfur cathode had retained about 70 percent of its energy-storage capacity. This is the highest performing sulfur cathode in the world, as far as we know,” he [Cui] said. “Even without optimizing the design, this cathode cycle life is already on par with commercial performance. This is a very important achievement for the future of rechargeable batteries.”

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Over the past seven years, Cui’s group has demonstrated a succession of increasingly capable anodes that use silicon rather than carbon because it can store up to 10 times more charge per weight. Their most recent anode also has a yolk-shell design that retains its energy-storage capacity over 1,000 charge/discharge cycles.

The group’s next step is to combine the yolk-shell sulfur cathode with a yolk-shell silicon anode to see if together they produce a high-energy, long-lasting battery.

I have posted a number of recent pieces about lithium-ion (li-ion) batteries including a Dec. 12, 2012 piece about using the Madder plant to develop a greener li-ion battery, a Dec. 10, 2012 piece about the break-up of 123 Systems, a manufacturer of li-ion batteries, and a Nov. 27, 2012 piece about a project in Québec to combine lithium iron phospate with graphene for improved li-ion batteries.

Mad about Madder in lithium-ion batteries

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It hasn’t happened yet but it looks like the future might hold greener lithium-ion (Li-ion) batteries. According to the Dec. 11, 2012 news release on EurekAlert,

Scientists at Rice University and the City College of New York have discovered that the madder plant, aka Rubia tinctorum, is a good source of purpurin, an organic dye that can be turned into a highly effective, natural cathode for lithium-ion batteries. The plant has been used since ancient times to create dye for fabrics.

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The goal, according to lead author Arava Leela Mohana Reddy, a research scientist in the Rice lab of materials scientist Pulickel Ajayan, is to create environmentally friendly batteries that solve many of the problems with lithium-ion batteries in use today.

Purpurin, left, extracted from madder root, center, is chemically lithiated, right, for use as an organic cathode in batteries. The material was developed as a less expensive, easier-to-recycle alternative to cobalt oxide cathodes now used in lithium-ion batteries. Credit: Ajayan Lab/Rice University

The Dec. 11, 2012 Rice University news release by Mike Williams, the origin for the one on EurekAlert, describes why the researchers are so interested in a more environmentally-friendly cathode,

While lithium-ion batteries have become standard in conventional electronics since their commercial introduction in 1991, the rechargeable units remain costly to manufacture, Reddy said. “They’re not environmentally friendly. They use cathodes of lithium cobalt oxide, which are very expensive. You have to mine the cobalt metal and manufacture the cathodes in a high-temperature environment. There are a lot of costs.

“And then, recycling is a big issue,” he said. “In 2010, almost 10 billion lithium-ion batteries had to be recycled, which uses a lot of energy. Extracting cobalt from the batteries is an expensive process.”

Reddy and his colleagues came across purpurin while testing a number of organic molecules for their ability to electrochemically interact with lithium and found purpurin most amenable to binding lithium ions. With the addition of 20 percent carbon to add conductivity, the team built a half-battery cell with a capacity of 90 milliamp hours per gram after 50 charge/discharge cycles. The cathodes can be made at room temperature, he said.

“It’s a new mechanism we are proposing with this paper, and the chemistry is really simple,” Reddy said. He suggested agricultural waste may be a source of purpurin, as may other suitable molecules, which makes the process even more economical.

Innovation in the battery space is needed to satisfy future demands and counter environmental issues like waste management, “and hence we are quite fascinated by the ability to develop alternative electrode technologies to replace conventional inorganic materials in lithium-ion batteries,” said Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry.

“We’re interested in developing value-added chemicals, products and materials from renewable feedstocks as a sustainable technology platform,” said co-lead author George John, a professor of chemistry at the City College of New York-CUNY and an expert on bio-based materials and green chemistry. “The point has been to understand the chemistry between lithium ions and the organic molecules. Now that we have that proper understanding, we can tap other molecules and improve capacity.”

For anyone who’s interested, you can read the researchers’ article (open access),

Lithium storage mechanisms in purpurin based organic lithium ion battery electrodes by Arava Leela Mohana Reddy,  Subbiah Nagarajan, Porramate Chumyim, Sanketh R. Gowda, Padmanava Pradhan, Swapnil R. Jadhav, Madan Dubey,  George John & Pulickel M. Ajayan in Scientific Reports 2 Article number: 960 doi:10.1038/srep00960

You might also want to check out Dexter Johnson’s Nov. 26, 2012 posting (on Nanoclast, an IEEE [Institute of Electrical and Electronics Engineers] blog)where he mentions a technical deficiency (recharging becomes increasingly difficult) with the current Li-ion batteries in the context of his description of a new imaging technique.