Tag Archives: National Renewable Energy Laboratory

Not ageing gracefully; the lithium-ion battery story

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There’s an alphabet soup’s worth of agencies involved in research on lithium-ion battery ageing which has resulted in two papers as noted in a May 30, 2014 news item Azonano,

Batteries do not age gracefully. The lithium ions that power portable electronics cause lingering structural damage with each cycle of charge and discharge, making devices from smartphones to tablets tick toward zero faster and faster over time. To stop or slow this steady degradation, scientists must track and tweak the imperfect chemistry of lithium-ion batteries with nanoscale precision.

In two recent Nature Communications papers, scientists from several U.S. Department of Energy national laboratories—Lawrence Berkeley, Brookhaven, SLAC, and the National Renewable Energy Laboratory—collaborated to map these crucial billionths-of-a-meter dynamics and lay the foundation for better batteries.

A May 29, 2014 Brookhaven National Laboratory news release by Justin Eure, which originated the news item, describes the research techniques in more detail,

“We discovered surprising and never-before-seen evolution and degradation patterns in two key battery materials,” said Huolin Xin, a materials scientist at Brookhaven Lab’s Center for Functional Nanomaterials (CFN) and coauthor on both studies. “Contrary to large-scale observation, the lithium-ion reactions actually erode the materials non-uniformly, seizing upon intrinsic vulnerabilities in atomic structure in the same way that rust creeps unevenly across stainless steel.”

Xin used world-leading electron microscopy techniques in both studies to directly visualize the nanoscale chemical transformations of battery components during each step of the charge-discharge process. In an elegant and ingenious setup, the collaborations separately explored a nickel-oxide anode and a lithium-nickel-manganese-cobalt-oxide cathode—both notable for high capacity and cyclability—by placing samples inside common coin-cell batteries running under different voltages.

“Armed with a precise map of the materials’ erosion, we can plan new ways to break the patterns and improve performance,” Xin said.

In these experiments, lithium ions traveled through an electrolyte solution, moving into an anode when charging and a cathode when discharging. The processes were regulated by electrons in the electrical circuit, but the ions’ journeys—and the battery structures—subtly changed each time.

The news release first describes the research involving the nickel-oxide anode, one of the two areas of interest,

For the nickel-oxide anode, researchers submerged the batteries in a liquid organic electrolyte and closely controlled the charging rates. They stopped at predetermined intervals to extract and analyze the anode. Xin and his collaborators rotated 20-nanometer-thick sheets of the post-reaction material inside a carefully calibrated transmission electron microscope (TEM) grid at CFN to catch the contours from every angle—a process called electron tomography.

To see the way the lithium-ions reacted with the nickel oxide, the scientists used a suite of custom-written software to digitally reconstruct the three-dimensional nanostructures with single-nanometer resolution. Surprisingly, the reactions sprang up at isolated spatial points rather than sweeping evenly across the surface.

“Consider the way snowflakes only form around tiny particles or bits of dirt in the air,” Xin said. “Without an irregularity to glom onto, the crystals cannot take shape. Our nickel oxide anode only transforms into metallic nickel through nanoscale inhomogeneities or defects in the surface structure, a bit like chinks in the anode’s armor.”

The electron microscopy provided a crucial piece of the larger puzzle assembled in concert with Berkeley Lab materials scientists and soft x-ray spectroscopy experiments conducted at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL). The combined data covered the reactions on the nano-, meso-, and microscales.

Next, there’s this about the second area of interest, a lithium-nickel-manganese-cobalt-oxide (NMC) cathode (from the news release),

In the other study, scientists sought the voltage sweet-spot for the high-performing lithium-nickel-manganese-cobalt-oxide (NMC) cathode: How much power can be stored, at what intensity, and across how many cycles?

The answers hinged on intrinsic material qualities and the structural degradation caused by cycles at 4.7 volts and 4.3 volts, as measured against a lithium metal standard.

As revealed through another series of coin-cell battery tests, 4.7 volts caused rapid decomposition of the electrolytes and poor cycling—the higher power comes at a price. A 4.3-volt battery, however, offered a much longer cycling lifetime at the cost of lower storage and more frequent recharges.

In both cases, the chemical evolution exhibited sprawling surface asymmetries, though not without profound patterns.

“As the lithium ions race through the reaction layers, they cause clumping crystallization—a kind of rock-salt matrix builds up over time and begins limiting performance,” Xin said. “We found that these structures tended to form along the lithium-ion reaction channels, which we directly visualized under the TEM. The effect was even more pronounced at higher voltages, explaining the more rapid deterioration.”

Identifying this crystal-laden reaction pathways hints at a way forward in battery design.

“It may be possible to use atomic deposition to coat the NMC cathodes with elements that resist crystallization, creating nanoscale boundaries within the micron-sized powders needed at the cutting-edge of industry,” Xin said. “In fact, Berkeley Lab battery experts Marca Doeff and Feng Lin are working on that now.”

Shirley Meng, a professor at UC San Diego’s Department of NanoEngineering, added, “This beautiful study combines several complementary tools that probe both the bulk and surface of the NMC layered oxide—one of the most promising cathode materials for high-voltage operation that enables higher energy density in lithium-ion batteries. The meaningful insights provided by this study will significantly impact the optimization strategies for this type of cathode material.”

The TEM measurements revealed the atomic structures while electron energy loss spectroscopy helped pinpoint the chemical evolution—both carried out at the CFN….

The scientists next want to observe these changes in real-time which will necessitate the custom design of some new equipment (“electrochemical contacts and liquid flow holders”).

Here are links to and citations for the papers,

Phase evolution for conversion reaction electrodes in lithium-ion batteries by Feng Lin, Dennis Nordlund, Tsu-Chien Weng, Ye Zhu, Chunmei Ban, Ryan M. Richards, & Huolin L. Xin. Nature Communications 5, Article number: 3358 doi:10.1038/ncomms4358 Published 24 February 2014

Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries by Feng Lin, Isaac M. Markus, Dennis Nordlund, Tsu-Chien Weng, Mark D. Asta, Huolin L. Xin & Marca M. Doeff. Nature Communications 5, Article number: 3529 doi:10.1038/ncomms4529 Published 27 March 2014

Both of these articles are behind a paywall and they both offer previews via ReadCube Access.

Controlling crystal growth for plastic electronics

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A July 4, 2013 news item on Nanowerk highlights research into plastic electronics taking place at Imperial College London (ICL), Note: A link has been removed,

Scientists have discovered a way to better exploit a process that could revolutionise the way that electronic products are made.

The scientists from Imperial College London say improving the industrial process, which is called crystallisation, could revolutionise the way we produce electronic products, leading to advances across a whole range of fields; including reducing the cost and improving the design of plastic solar cells.

The process of making many well-known products from plastics involves controlling the way that microscopic crystals are formed within the material. By controlling the way that these crystals are grown engineers can determine the properties they want such as transparency and toughness. Controlling the growth of these crystals involves engineers adding small amounts of chemical additives to plastic formulations. This approach is used in making food boxes and other transparent plastic containers, but up until now it has not been used in the electronics industry.

The team from Imperial have now demonstrated that these additives can also be used to improve how an advanced type of flexible circuitry called plastic electronics is made.

The team found that when the additives were included in the formulation of plastic electronic circuitry they could be printed more reliably and over larger areas, which would reduce fabrication costs in the industry.

The team reported their findings this month in the journal Nature Materials (“Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents”).

The June 7, 2013 Imperial College London news release by Joshua Howgego, which originated the news item, describes the researchers and the process in more detail,

Dr Natalie Stingelin, the leader of the study from the Department of Materials and Centre of Plastic Electronics at Imperial, says:

“Essentially, we have demonstrated a simple way to gain control over how crystals grow in electrically conducting ‘plastic’ semiconductors. Not only will this help industry fabricate plastic electronic devices like solar cells and sensors more efficiently. I believe it will also help scientists experimenting in other areas, such as protein crystallisation, an important part of the drug development process.”

Dr Stingelin and research associate Neil Treat looked at two additives, sold under the names IrgaclearÒ XT 386 and MilladÒ 3988, which are commonly used in industry. These chemicals are, for example, some of the ingredients used to improve the transparency of plastic drinking bottles. The researchers experimented with adding tiny amounts of these chemicals to the formulas of several different electrically conducting plastics, which are used in technologies such as security key cards, solar cells and displays.

The researchers found the additives gave them precise control over where crystals would form, meaning they could also control which parts of the printed material would conduct electricity. In addition, the crystallisations happened faster than normal. Usually plastic electronics are exposed to high temperatures to speed up the crystallisation process, but this can degrade the materials. This heat treatment treatment is no longer necessary if the additives are used.

Another industrially important advantage of using small amounts of the additives was that the crystallisation process happened more uniformly throughout the plastics, giving a consistent distribution of crystals.  The team say this could enable circuits in plastic electronics to be produced quickly and easily with roll-to-roll printing procedures similar to those used in the newspaper industry. This has been very challenging to achieve previously.

Dr Treat says: “Our work clearly shows that these additives are really good at controlling how materials crystallise. We have shown that printed electronics can be fabricated more reliably using this strategy. But what’s particularly exciting about all this is that the additives showed fantastic performance in many different types of conducting plastics. So I’m excited about the possibilities that this strategy could have in a wide range of materials.”

Dr Stingelin and Dr Treat collaborated with scientists from the University of California Santa Barbara (UCSB), and the National Renewable Energy Laboratory in Golden, US, and the Swiss Federal Institute of Technology on this study. The team are planning to continue working together to see if subtle chemical changes to the additives improve their effects – and design new additives.

There are some big plans for this discovery, from the news release,

They [the multinational team from ICL, UCSB, National Renewable Energy Laboratory, and Swiss Federal Institute of Technology]  will be working with the new Engineering and Physical Sciences Research Council (EPSRC)-funded Centre for Innovative Manufacturing in Large Area Electronics in order to drive the industrial exploitation of their process. The £5.6 million of funding for this centre, to be led by researchers from Cambridge University, was announced earlier this year [2013]. They are also exploring collaborations with printing companies with a view to further developing their circuit printing technique.

For the curious, here’s a link to and a citation for the published paper,

Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents by Neil D. Treat, Jennifer A. Nekuda Malik, Obadiah Reid, Liyang Yu, Christopher G. Shuttle, Garry Rumbles, Craig J. Hawker, Michael L. Chabinyc, Paul Smith, & Natalie Stingelin. Nature Materials 12, 628–633 (2013) doi:10.1038/nmat3655 Published online 02 June 2013

This article is open access (at least for now).

Smart wall or smart window? Ravenbrick brings one to the market in 2013

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Alex Davies posted a July 10, 2012 article on the Treehugger website about a smart window/wall system from RavenBrick. From the article (Note: I have removed links),

The RavenWindow from RavenBrick changes its tint in response to temperature, so it blocks sunlight entering a building after a set temperature has been reached. Combine it with a layer of insulating materials that store heat during the day and release it at night, and you’ve got the RavenSkin Smart Wall System.

Here’s a little more about the RavenWindow from the company’s Project Portfolio page,

RavenBrick has installed their RavenWindow product at the [US] Department of Energy’s National Renewable Energy Lab in Golden Colorado. This LEED platinum building was designed to use the most energy efficient products available. This installation, on the executive floor, is the first of three installations that will be done at NREL.

RavenWindow at NREL in the clear state viewed from the inside (from the RavenBrick website)

 

RavenWindow at NREL in the tinted state viewed from the inside (from the RavenBrick website)

Then, here is the view of the tinted windows from the outside,

RavenWindow at NREL in the tinted state viewed from outside (from the RavenBrick website)

They do give a fairly simple explanation of the technology, from the company’s The Technology page,

RavenBrick’s smart window systems are changing the rules of energy efficent design by doing something that previous generations of building materials simply couldn’t: letting the sun’s heat into the building when you need it, and keeping it out when you don’t.

Our thermochromic filters utilize advances in nanotechnology, pioneered and patented by RavenBrick, to transition from a transparent to a reflective state in response to changes in the outside temperature. This transition allows a building to use the sun as a source of free heat on cold days and block solar heat effectively on hot days.

RavenBrick’s technology diagram (from the RavenBrick website)

Davies’ Treehugger article offers some figures regarding savings (and another illustration),

The RavenSkin Smart Wall System promises to cut energy bills by as much as 30 percent, so it’s sure to offset the costs of installation (not listed on the RavenBrick website). The “infrared power system” doesn’t involve electricity, moving parts or wires, so it’s low maintenance, [sic]

I would have liked a little more detail. How did they derive the savings number, i.e.,  “by as much as 30%”? Also, is there any data from the US Dept. of Energy? At any rate, this product is due to reach the marketplace sometime in 2013.

I last mentioned RavenBrick and their windows in my Aug. 5, 2009 posting. In my Sept. 7, 2011 posting about the US Dept. of Energy, I focussed on smart window research being done at their Lawrence Berkeley National Laboratory (Berkeley Lab).

Window sunglasses; insect microids; open access to science research?; theatre and science

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Having windows that can darken or lighten according to the amount of sunshine would save money and energy. Such windows have been around for over two decades but they haven’t worked very well. Researchers at the US National Renewable Energy Laboratory (NREL) are working on a new, more successful generation of such windows (electrochromic windows). From the article by Joe Verrengia on physorg.com,

Insulated windows are made from multiple layers of glass. Typically the spaces between the panes are filled with a gas. Electrochromic windows are made with a very thin stack of dynamic materials deposited on the outside pane.

The dynamic portion consists of three layers: active and counter electrodes separated by an ion conductor layer. NREL researchers are experimenting with electrode layers made of nickel and tungsten oxides; the ions are lithium.

The window changes from clear to tinted when a small electric field is applied and the lithium ions move into the working electrode layers. The change can be triggered by sensors in an automated building management system, or by a flick of a switch. Electrochromic windows can block as much as 98 percent of the direct sunlight. Reversing the polarity of the applied voltage causes the ions to migrate back to their original layer, and the glass returns to clear.

It sounds exciting to someone like me who doesn’t handle the heat or air conditioning well. I just hope they can get the costs down as it’s about $1000 per square metre at this point.

While it’s not strictly speaking nanotechnology, a researcher (Jason Clark) at Purdue University is working on an insect robot, a microid.  From the news item on Nanowerk,

His [Clark’s] concept, a sort of solid-state muscle for microid legs and mandibles, would allow the robot to nimbly traverse harsh environments such as sand or water. The concept appears to be the first to show such insectlike characteristics at the microscale, he said.
“The microids would be able to walk, run, jump, and pick up and move objects many times their own weight,” Clark said. “A microid can also do what no insect or other microrobot can do, which is continue walking if flipped on its back. Who knows, maybe flight is next.”
He also envisions the possibility of hordes of microids working in unison and communicating with each other to perform a complex task.
“You can’t underestimate the power of having thousands of microids working together, much like ant colonies,” he said.

Those last bits about flying and working in unison bring Michael Crichton’s 2002 nanotechnology novel, Prey, to mind. Crichton conceptualized a swarm that was intelligent, voracious, and almost unstoppable. As I recall, Crichton included aspects of insect behaviour, network theory, neuroscience, and self-assembling nanotechnology to describe his swarm. It caused a bit of a kerfuffle in the nanotech research community as scientists were concerned that it might set off a controversy similar to  ‘frankenfoods’ or GM (genetically modified) foods but nothing came of it at the time.

Techdirt had an interesting bit last week about open access to science research,

Via James Boyle, we’re pointed to an editorial that supposedly is all about improving access to research via open access policies for the public — and just so happens to be locked up behind a paywall itself. Apparently, the publisher doesn’t necessarily agree with the authors’ conclusions.

I did check out the link to find the publisher is the journal Science and they require a free registration or a subscription  for access to the editorial. Either Techdirt made a mistake or the editors at Science changed access to the editorial.

Combining insects with the journal, I found a news item on physorg.com about a theatre review published in Science,

Typically science doesn’t bed down with theatre, much less mate with artistic vigor, but the accord between the two is explored in the recent production Heuschrecken [The Locusts] developed by Stefan Kaegi of Rimini Protokoll. “And why not?” asks Arizona State University’s Manfred Laubichler and Gitta Honegger who review the production in the Jan. 29 issue of the journal Science.

…

The marriage of theatre and science is not new. The Greeks, starting with Aristotle embraced a more integrated relationship of the two. “But a divide came when we associated science with the brain and the arts with emotions,” Honegger says.

The news item goes on to discuss the particulars of the production such as a 60 square metre terrarium of 10,000 locusts, actors, scientists, video cameras, interwoven narratives, and locust music. I am quite inspired by it.

Coincidentally, Rimini Protokoll, the German theatre arts company mentioned in the news item, has a production here in Vancouver (as part of PUSH International Performing Arts Festival 2010 [Jan. 20 to Feb. 6]) which integrates video games and theatre. From the Canwest article by Peter Birnie,

Tim Carlson is a Vancouver playwright who was in Berlin in 2006 for a production of his play Omniscience. Carlson was so impressed by a Rimini Protokoll production of Friedrich Schiller’s Wallenstein trilogy in the German capital that, when he subsequently learned the PuSh International Performing Arts Festival was bringing Rimini Protokoll here, asked to work with them.

“I knew that they shape their shows for particular cities,” Carlson explains, “and they would want to do research here. I had them meet [former city councillor] Jim Green, they visited In-Site and had an architecture tour with [noted critic] Trevor Boddy. One thing that really captured their interest was the video-gaming industry in town, so that kind of turned the light on.”

Electronic artist Brady Marks was hired to find a way that 200 people could game together, and other electronic designers were brought on board to do the 3D modelling. As it does in other productions, Rimini Protokoll then hired local experts — not actors — to perform as themselves.

Marks is the electronic artist directing things, with animator Duff Armour as a game tester, former politician (and Railway Club owner) Bob Williams as a politician and traffic flagger Ellen Schultz as, well, the traffic flagger for the show. Carlson explains that Williams will be something of a political commentator when the audience holds its own presidential election.

You can phone 604.251.1363 to inquire about tickets for the production (Best Before) at the Vancouver East Cultural Centre.