Nikola Plans $1 Billion Buckeye, Arizona Fuel Cell Truck Factory


nikola-two

Hydrogen-electric semi-truck startup Nikola Motor Co. plans to build a $1 billion factory in a Phoenix suburb.

The company detailed its plans Tuesday in a joint announcement with Arizona Governor Doug Ducey.

The fuel cell truck developer said it will build a 500-acre, 1 million square foot facility west of Phoenix in Buckeye.

Trevor Milton, Nikola’s chief executive, and Ducey said the plant will create 2,000 jobs and bring more than $1 billion in capital investment to the region by 2024.

Arizona will provide up to $46.5 million in various job training and tax abatement incentives. But the package is performance-based and Nikola benefits only if it makes investments in plant and employees, said Susan E. Marie, senior vice president of the Arizona Commerce Authority.

“Arizona has the workforce to support our growth and a governor that was an entrepreneur himself. They understood what 2,000 jobs would mean to their cities and state,” Milton said.

Nikola will relocate its headquarters and research and development team from Salt Lake City to Arizona by October.

Nikola says it has 8,000 pre-orders for its fuel cell truck.

Ryder System Inc. will serve as Nikola’s exclusive provider for distribution and maintenance nationwide and in parts of Mexico. Caterpillar dealer and early Nikola investor Thompson Machinery will supplement Ryder’s sales and services in Tennessee and Mississippi.

Nikola said its Nikola One sleeper and Nikola Two day cab trucks will be able to run up to 1,200 miles between refueling stops.  The company plans to lease the trucks to users. It will supply fuel as part of the lease cost through a nationwide network of 376 hydrogen fueling stations. It still has to build the network.

The powertrain is rated by the company at 1,000 horsepower and 2,000 pound-feet of torque, which analysts said fits the need for long haul trucking.

“This incredible new technology will revolutionize transportation, and we’re very proud it will be engineered right here in Arizona,” Ducey said. Nikola’s “selection of Arizona demonstrates that we are leading the charge when it comes to attracting innovative, industry-disrupting companies.”

While the factory is under construction truck components company Fitzgerald Gliders will build the first 5,000 production models.

Nikola Motor CEO Trevor Milton and his dog Taffy.

Nikola did not provide any details on how it would fund building the factory.  But in December, truck components company Wabco Holdings acquired a 1 percent stake in Nikola for  $10 million. That deal valued the startup at $1 billion.

The company also raised $110 million in a funding round last year.

“A key challenge for Nikola is to demonstrate that they can raise the significant capital necessary to be a true competitor in this space,” said John Boesel, chief executive of Pasadena-based clean transportation incubator Calstart.

However, Boesel said there is room for Nikola.

“Zero emission truck technology is rapidly evolving,” he said. “There is the opportunity for disruptive companies like Nikola to come into this space.”

Nikola has partnered with well-regarded truck components manufacturers, a smart move that builds confidence in potential customers, said Antti Lindstrom, an analyst with IHS Markit.

It has tapped parts supplier Bosch for joint development of powertrain systems for the Nikola One and the Nikola Two. Bosch also has worked with Nikola to develop the truck’s “eAxle,” which houses the electric motor, transmission and power electronics.

Swedish fuel cell developer PowerCell AB will provide the fuel cell stacks that produce electricity from hydrogen, and Nikola will build the completed fuel cell system.

Nikola plans field tests of truck prototypes this fall using the Nikola Two truck and Nikola test divers. Real-world testing with potential fleet customers will come after that. Testing of the Nikola One sleeper truck will begin later.

“I believe the fuel cell solution is better than battery electric trucks for long haul deliveries,” Lindstrom said. “You don’t have the same weight issue that you have with heavy batteries.”

That allows trucks to have a longer range between fueling and enables heavier freight loads, he said.

“This is a technology that is here and now,” Lindstrom said. “It doesn’t require advancement in technology that battery electric long-haul trucks will require.”

Nikola, however, faces potential competition from well capitalized and mature rivals.

Other players include Toyota, which is testing a Class 8 fuel cell electric drayage truck in Southern California. Kenworth, the Paccar brand, is developing a Class 8 hydrogen fuel cell electric truck prototype.

A host of companies including Tesla, Daimler Trucks, Volvo Trucks, Navistar and Cummins are working on electric trucks that could compete with fuel cell commercial vehicles.

Milton said Nikola settled on Buckeye following a 12-month site selection process that considered nine states and 30 different locations. He said he liked the city’s economic environment, engineering schools, educated workforce and geographic location that provides direct access to major markets.

“The Greater Phoenix region is elevating its brand as a hub for innovation, and companies such as Nikola have taken notice,” said Chris Camacho, chief executive of the Greater Phoenix Economic Council.

Read Next: The Economic Case For The Tesla Semi-Truck

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Another step closer to wearable technology with this flexible supercapacitor from NTU Singapore: YouTube Video


 

NTU Wearable download
 Scientists have created a fabric-like supercapacitor which can be cut, folded or stretched without losing its ability to store and discharge electricity. Able to retain 98% of its power capacity even after 10,000 stretch-and-release cycles, the invention brings us a step closer to powering future wearable technology. #NTUsg

Scientists at Nanyang Technological University, Singapore (NTU Singapore) have created a customizable, fabric-like power source that can be cut, folded or stretched without losing its function.

Led by Professor Chen Xiaodong, Associate Chair (Faculty) at the School of Materials Science & Engineering, the team reported in the journal Advanced Materials (print edition 8 January) how they have created the wearable power source, a supercapacitor, which works like a fast-charging battery and can be recharged many times.

 

 

Crucially, they have made their supercapacitor customizable or “editable”, meaning its structure and shape can be changed after it is manufactured, while retaining its function as a power source. Existing stretchable supercapacitors are made into predetermined designs and structures, but the new invention can be stretched multi-directionally, and is less likely to be mismatched when it is joined up to other electrical components.

The new supercapacitor, when edited into a honeycomb-like structure, has the ability to store an electrical charge four times higher than most existing stretchable supercapacitors. In addition, when stretched to four times its original length, it maintains nearly 98 per cent of the initial ability to store electrical energy, even after 10,000 stretch-and-release cycles.

Experiments done by Prof Chen and his team also showed that when the editable supercapacitor was paired with a sensor and placed on the human elbow, it performed better than existing stretchable supercapacitors. The editable supercapacitor was able to provide a stable stream of signals even when the arm was swinging, which are then transmitted wirelessly to external devices, such as one that captures a patient’s heart rate.

The authors believe that the editable supercapacitor could be easily mass-produced as it would rely on existing manufacturing technologies. Production cost will thus be low, estimated at about SGD$0.13 (USD$0.10) to produce 1 cm2 of the material.

The team has filed a patent for the technology.

Professor Chen said, “A reliable and editable supercapacitor is important for development of the wearable electronics industry. It also opens up all sorts of possibilities in the realm of the ‘Internet-of-Things’ when wearable electronics can reliably power themselves and connect and communicate with appliances in the home and other environments.

“My own dream is to one day combine our flexible supercapacitors with wearable sensors for health and sports performance diagnostics. With the ability for wearable electronics to power themselves, you could imagine the day when we create a device that could be used to monitor a marathon runner during a race with great sensitivity, detecting signals from both under and over-exertion.”

The editable supercapacitor is made of strengthened manganese dioxide nanowire composite material. While manganese dioxide is a common material for supercapacitors, the ultralong nanowire structure, strengthened with a network of carbon nanotubes and nanocellulose fibres, allows the electrodes to withstand the associated strains during the customisation process.

The NTU team also collaborated with Dr. Loh Xian Jun, Senior Scientist and Head of the Soft Materials Department at the Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR).

Dr. Loh said, “Customisable and versatile, these interconnected, fabric-like power sources are able to offer a plug-and-play functionality while maintaining good performance. Being highly stretchable, these flexible power sources are promising next-generation ‘fabric’ energy storage devices that could be integrated into wearable electronics.”

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Watch the various customizable supercapacitors in action:

https://drive.google.com/drive/folders/16qgJpz7CKkGgVKVQeFUQxVscfZhpSAJ5

MIT: Optimizing carbon nanotube electrodes for energy storage and water desalination applications


Opt CNTs for Water Wang-Mutha-nanotubes_0Evelyn Wang (left) and Heena Mutha have developed a nondestructive method of quantifying the detailed characteristics of carbon nanotube (CNT) samples — a valuable tool for optimizing these materials for use as electrodes in a variety of practical devices. Photo: Stuart Darsch

New model measures characteristics of carbon nanotube structures for energy storage and water desalination applications.

Using electrodes made of carbon nanotubes (CNTs) can significantly improve the performance of devices ranging from capacitors and batteries to water desalination systems. But figuring out the physical characteristics of vertically aligned CNT arrays that yield the most benefit has been difficult.

Now an MIT team has developed a method that can help. By combining simple benchtop experiments with a model describing porous materials, the researchers have found they can quantify the morphology of a CNT sample, without destroying it in the process.

In a series of tests, the researchers confirmed that their adapted model can reproduce key measurements taken on CNT samples under varying conditions. They’re now using their approach to determine detailed parameters of their samples — including the spacing between the nanotubes — and to optimize the design of CNT electrodes for a device that rapidly desalinates brackish water.

A common challenge in developing energy storage devices and desalination systems is finding a way to transfer electrically charged particles onto a surface and store them there temporarily. In a capacitor, for example, ions in an electrolyte must be deposited as the device is being charged and later released when electricity is being delivered. During desalination, dissolved salt must be captured and held until the cleaned water has been withdrawn.

One way to achieve those goals is by immersing electrodes into the electrolyte or the saltwater and then imposing a voltage on the system. The electric field that’s created causes the charged particles to cling to the electrode surfaces. When the voltage is cut, the particles immediately let go.

“Whether salt or other charged particles, it’s all about adsorption and desorption,” says Heena Mutha PhD ’17, a senior member of technical staff at the Charles Stark Draper Laboratory. “So the electrodes in your device should have lots of surface area as well as open pathways that allow the electrolyte or saltwater carrying the particles to travel in and out easily.”

One way to increase the surface area is by using CNTs. In a conventional porous material, such as activated charcoal, interior pores provide extensive surface area, but they’re irregular in size and shape, so accessing them can be difficult. In contrast, a CNT “forest” is made up of aligned pillars that provide the needed surfaces and straight pathways, so the electrolyte or saltwater can easily reach them.

However, optimizing the design of CNT electrodes for use in devices has proven tricky. Experimental evidence suggests that the morphology of the material — in particular, how the CNTs are spaced out — has a direct impact on device performance. Increasing the carbon concentration when fabricating CNT electrodes produces a more tightly packed forest and more abundant surface area. But at a certain density, performance starts to decline, perhaps because the pillars are too close together for the electrolyte or saltwater to pass through easily.

Designing for device performance

OPT CNTs III graphic-1

“Much work has been devoted to determining how CNT morphology affects electrode performance in various applications,” says Evelyn Wang, the Gail E. Kendall Professor of Mechanical Engineering. “But an underlying question is, ‘How can we characterize these promising electrode materials in a quantitative way, so as to investigate the role played by such details as the nanometer-scale interspacing?'”

Inspecting a cut edge of a sample can be done using a scanning electron microscope (SEM). But quantifying features, such as spacing, is difficult, time-consuming, and not very precise. Analyzing data from gas adsorption experiments works well for some porous materials, but not for CNT forests. Moreover, such methods destroy the material being tested, so samples whose morphologies have been characterized can’t be used in tests of overall device performance.

For the past two years, Wang and Mutha have been working on a better option. “We wanted to develop a nondestructive method that combines simple electrochemical experiments with a mathematical model that would let us ‘back calculate’ the interspacing in a CNT forest,” Mutha says. “Then we could estimate the porosity of the CNT forest — without destroying it.”

Adapting the conventional model

One widely used method for studying porous electrodes is electrochemical impedance spectroscopy (EIS). It involves pulsing voltage across electrodes in an electrochemical cell at a set time interval (frequency) while monitoring “impedance,” a measure that depends on the available storage space and resistance to flow. Impedance measurements at different frequencies is called the “frequency response.”Opt CNTs II 1-newmodelmeas

The classic model describing porous media uses that frequency response to calculate how much open space there is in a porous material. “So we should be able to use [the model] to calculate the space between the carbon nanotubes in a CNT electrode,” Mutha says.

But there’s a problem: This model assumes that all pores are uniform, cylindrical voids. But that description doesn’t fit electrodes made of CNTs. Mutha modified the model to more accurately define the pores in CNT materials as the void spaces surrounding solid pillars. While others have similarly altered the classic model, Mutha took her alterations a step further. The nanotubes in a CNT material are unlikely to be packed uniformly, so she added to her equations the ability to account for variations in the spacing between the nanotubes. With this modified model, Mutha could analyze EIS data from real samples to calculate CNT spacings.

Using the model

To demonstrate her approach, Mutha first fabricated a series of laboratory samples and then measured their frequency response. In collaboration with Yuan “Jenny” Lu ’15, a materials science and engineering graduate, she deposited thin layers of aligned CNTs onto silicon wafers inside a furnace and then used water vapor to separate the CNTs from the silicon, producing free-standing forests of nanotubes. To vary the CNT spacing, she used a technique developed by MIT collaborators in the Department of Aeronautics and Astronautics, Professor Brian Wardle and postdoc associate Itai Stein PhD ’16. Using a custom plastic device, she mechanically squeezed her samples from four sides, thereby packing the nanotubes together more tightly and increasing the volume fraction — that is, the fraction of the total volume occupied by the solid CNTs.

To test the frequency response of the samples, she used a glass beaker containing three electrodes immersed in an electrolyte. One electrode is the CNT-coated sample, while the other two are used to monitor the voltage and to absorb and measure the current. Using that setup, she first measured the capacitance of each sample, meaning how much charge it could store in each square centimeter of surface area at a given constant voltage. She then ran EIS tests on the samples and analyzed results using her modified porous media model.

Results for the three volume fractions tested show the same trends. As the voltage pulses become less frequent, the curves initially rise at about a 45 degree slope. But at some point, each one shifts toward vertical, with resistance becoming constant and impedance continuing to rise.

As Mutha explains, those trends are typical of EIS analyses. “At high frequencies, the voltage changes so quickly that — because of resistance in the CNT forest — it doesn’t penetrate the depth of the entire electrode material, so the response comes only from the surface or partway in,” she says. “But eventually the frequency is low enough that there’s time between pulses for the voltage to penetrate and for the whole sample to respond.”

Resistance is no longer a noticeable factor, so the line becomes vertical, with the capacitance component causing impedance to rise as more charged particles attach to the CNTs. That switch to vertical occurs earlier with the lower-volume-fraction samples. In sparser forests, the spaces are larger, so the resistance is lower.

The most striking feature of Mutha’s results is the gradual transition from the high-frequency to the low-frequency regime. Calculations from a model based on uniform spacing — the usual assumption — show a sharp transition from partial to complete electrode response. Because Mutha’s model incorporates subtle variations in spacing, the transition is gradual rather than abrupt. Her experimental measurements and model results both exhibit that behavior, suggesting that the modified model is more accurate.

By combining their impedance spectroscopy results with their model, the MIT researchers inferred the CNT interspacing in their samples. Since the forest packing geometry is unknown, they performed the analyses based on three- and six-pillar configurations to establish upper and lower bounds. Their calculations showed that spacing can range from 100 nanometers in sparse forests to below 10 nanometers in densely packed forests.

Comparing approaches

Work in collaboration with Wardle and Stein has validated the two groups’ differing approaches to determining CNT morphology. In their studies, Wardle and Stein use an approach similar to Monte Carlo modeling, which is a statistical technique that involves simulating the behavior of an uncertain system thousands of times under varying assumptions to produce a range of plausible outcomes, some more likely than others. For this application, they assumed a random distribution of “seeds” for carbon nanotubes, simulated their growth, and then calculated characteristics, such as inter-CNT spacing with an associated variability. Along with other factors, they assigned some degree of waviness to the individual CNTs to test the impact on the calculated spacing.

To compare their approaches, the two MIT teams performed parallel analyses that determined average spacing at increasing volume fractions. The trends they exhibited matched well, with spacing decreasing as volume fraction increases. However, at a volume fraction of about 26 percent, the EIS spacing estimates suddenly go up — an outcome that Mutha believes may reflect packing irregularities caused by buckling of the CNTs as she was densifying them.

To investigate the role played by waviness, Mutha compared the variabilities in her results with those in Stein’s results from simulations assuming different degrees of waviness. At high volume fractions, the EIS variabilities were closest to those from the simulations assuming little or no waviness. But at low volume fractions, the closest match came from simulations assuming high waviness.

Based on those findings, Mutha concludes that waviness should be considered when performing EIS analyses — at least in some cases. “To accurately predict the performance of devices with sparse CNT electrodes, we may need to model the electrode as having a broad distribution of interspacings due to the waviness of the CNTs,” she says. “At higher volume fractions, waviness effects may be negligible, and the system can be modeled as simple pillars.”

The researchers’ nondestructive yet quantitative technique provides device designers with a valuable new tool for optimizing the morphology of porous electrodes for a wide range of applications. Already, Mutha and Wang have been using it to predict the performance of supercapacitors and desalination systems. Recent work has focused on designing a high-performance, portable device for the rapid desalination of brackish water. Results to date show that using their approach to optimize the design of CNT electrodes and the overall device simultaneously can as much as double the salt adsorption capacity of the system, while speeding up the rate at which clean water is produced.

This research was supported in part by the MIT Energy Initiative Seed Fund Program and by the King Fahd University of Petroleum and Minerals (KFUPM) in Dhahran, Saudi Arabia, through the Center for Clean Water and Clean Energy at MIT and KFUPM. Mutha’s work was supported by a National Science Foundation Graduate Research Fellowship and Stein’s work by the Department of Defense through the National Defense Science and Engineering Graduate Fellowship Program.

MIT: A new approach to rechargeable batteries – metal-mesh membrane could solve longstanding problems – lead to inexpensive power storage


MIT-Battery-Membranes_0A type of battery first invented nearly five decades ago could catapult to the forefront of energy storage technologies, thanks to a new finding by researchers at MIT. Illustration modified from an original image by Felice Frankel

New metal-mesh membrane could solve longstanding problems and lead to inexpensive power storage.

A type of battery first invented nearly five decades ago could catapult to the forefront of energy storage technologies, thanks to a new finding by researchers at MIT. The battery, based on electrodes made of sodium and nickel chloride and using a new type of metal mesh membrane, could be used for grid-scale installations to make intermittent power sources such as wind and solar capable of delivering reliable baseload electricity.

The findings are being reported today in the journal Nature Energy, by a team led by MIT professor Donald Sadoway, postdocs Huayi Yin and Brice Chung, and four others.

Although the basic battery chemistry the team used, based on a liquid sodium electrode material, was first described in 1968, the concept never caught on as a practical approach because of one significant drawback: It required the use of a thin membrane to separate its molten components, and the only known material with the needed properties for that membrane was a brittle and fragile ceramic. These paper-thin membranes made the batteries too easily damaged in real-world operating conditions, so apart from a few specialized industrial applications, the system has never been widely implemented.

But Sadoway and his team took a different approach, realizing that the functions of that membrane could instead be performed by a specially coated metal mesh, a much stronger and more flexible material that could stand up to the rigors of use in industrial-scale storage systems.

“I consider this a breakthrough,” Sadoway says, because for the first time in five decades, this type of battery — whose advantages include cheap, abundant raw materials, very safe operational characteristics, and an ability to go through many charge-discharge cycles without degradation — could finally become practical.

While some companies have continued to make liquid-sodium batteries for specialized uses, “the cost was kept high because of the fragility of the ceramic membranes,” says Sadoway, the John F. Elliott Professor of Materials Chemistry. “Nobody’s really been able to make that process work,” including GE, which spent nearly 10 years working on the technology before abandoning the project.

As Sadoway and his team explored various options for the different components in a molten-metal-based battery, they were surprised by the results of one of their tests using lead compounds. “We opened the cell and found droplets” inside the test chamber, which “would have to have been droplets of molten lead,” he says. But instead of acting as a membrane, as expected, the compound material “was acting as an electrode,” actively taking part in the battery’s electrochemical reaction.

“That really opened our eyes to a completely different technology,” he says. The membrane had performed its role — selectively allowing certain molecules to pass through while blocking others — in an entirely different way, using its electrical properties rather than the typical mechanical sorting based on the sizes of pores in the material.

In the end, after experimenting with various compounds, the team found that an ordinary steel mesh coated with a solution of titanium nitride could perform all the functions of the previously used ceramic membranes, but without the brittleness and fragility. The results could make possible a whole family of inexpensive and durable materials practical for large-scale rechargeable batteries.

The use of the new type of membrane can be applied to a wide variety of molten-electrode battery chemistries, he says, and opens up new avenues for battery design. “The fact that you can build a sodium-sulfur type of battery, or a sodium/nickel-chloride type of battery, without resorting to the use of fragile, brittle ceramic — that changes everything,” he says.

The work could lead to inexpensive batteries large enough to make intermittent, renewable power sources practical for grid-scale storage, and the same underlying technology could have other applications as well, such as for some kinds of metal production, Sadoway says.

Sadoway cautions that such batteries would not be suitable for some major uses, such as cars or phones. Their strong point is in large, fixed installations where cost is paramount, but size and weight are not, such as utility-scale load leveling. In those applications, inexpensive battery technology could potentially enable a much greater percentage of intermittent renewable energy sources to take the place of baseload, always-available power sources, which are now dominated by fossil fuels.

The research team included Fei Chen, a visiting scientist from Wuhan University of Technology; Nobuyuki Tanaka, a visiting scientist from the Japan Atomic Energy Agency; MIT research scientist Takanari Ouchi; and postdocs Huayi Yin, Brice Chung, and Ji Zhao. The work was supported by the French oil company Total S.A. through the MIT Energy Initiative.

Scientists Create Customizable, Fabric-Like Power Source for Wearable Electronics


supercap for wearables

Scientists at Nanyang Technological University, Singapore (NTU Singapore) have created a customizable, fabric-like power source that can be cut, folded or stretched without losing its function.

Led by Professor Chen Xiaodong, Associate Chair (Faculty) at the School of Materials Science & Engineering, the team reported in the journal Advanced Materials (print edition 8 January) how they have created the wearable power source, a supercapacitor, which works like a fast-charging battery and can be recharged many times.

Crucially, they have made their supercapacitor customizable or “editable”, meaning its structure and shape can be changed after it is manufactured, while retaining its function as a power source. Existing stretchable supercapacitors are made into predetermined designs and structures, but the new invention can be stretched multi-directionally, and is less likely to be mismatched when it is joined up to other electrical components.wearable-textiles-100616-0414_powdes_ti_f1

The new supercapacitor, when edited into a honeycomb-like structure, has the ability to store an electrical charge four times higher than most existing stretchable supercapacitors. In addition, when stretched to four times its original length, it maintains nearly 98 per cent of the initial ability to store electrical energy, even after 10,000 stretch-and-release cycles.

Experiments done by Prof Chen and his team also showed that when the editable supercapacitor was paired with a sensor and placed on the human elbow, it performed better than existing stretchable supercapacitors. The editable supercapacitor was able to provide a stable stream of signals even when the arm was swinging, which are then transmitted wirelessly to external devices, such as one that captures a patient’s heart rate.

The authors believe that the editable supercapacitor could be easily mass-produced as it would rely on existing manufacturing technologies. Production cost will thus be low, estimated at about SGD$0.13 (USD$0.10) to produce 1 cm2 of the material.

The team has filed a patent for the technology.

Professor Chen said, “A reliable and editable supercapacitor is important for development of the wearable electronics industry. It also opens up all sorts of possibilities in the realm of the ‘Internet-of-Things’ when wearable electronics can reliably power themselves and connect and communicate with appliances in the home and other environments.

“My own dream is to one day combine our flexible supercapacitors with wearable sensors for health and sports performance diagnostics. With the ability for wearable electronics to power themselves, you could imagine the day when we create a device that could be used to monitor a marathon runner during a race with great sensitivity, detecting signals from both under and over-exertion.”

The editable supercapacitor is made of strengthened manganese dioxide nanowire composite material. While manganese dioxide is a common material for supercapacitors, the ultralong nanowire structure, strengthened with a network of carbon nanotubes and nanocellulose fibres, allows the electrodes to withstand the associated strains during the customisation process.

The NTU team also collaborated with Dr. Loh Xian Jun, Senior Scientist and Head of the Soft Materials Department at the Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR).

Dr. Loh said, “Customisable and versatile, these interconnected, fabric-like power sources are able to offer a plug-and-play functionality while maintaining good performance. Being highly stretchable, these flexible power sources are promising next-generation ‘fabric’ energy storage devices that could be integrated into wearable electronics.”

Stanford University: Lithium/graphene “foil” makes for a great battery electrode – 2X current Energy Density


Graphene handles the issues that come with an electrode’s lithium moving elsewhere.

Lithium ion batteries, as the name implies, work by shuffling lithium atoms between a battery’s two electrodes. So, increasing a battery’s capacity is largely about finding ways to put more lithium into those electrodes. These efforts, however, have run into significant problems.

If lithium is a large fraction of your electrode material, then moving it out can cause the electrode to shrink. Moving it back in can lead to lithium deposits in the wrong places, shorting out the battery.

Now, a research team from Stanford has figured out how to wrap lots of lithium in graphene. The resulting structure holds a place open for lithium when it leaves, allowing it to flow back to where it started.

Tests of the resulting material, which they call a lithium-graphene foil, show it could enable batteries with close to twice the energy density of existing lithium batteries.

Lithium behaving badly

One obvious solution to increasing the amount of lithium in an electrode is simply to use lithium metal itself. But that’s not the easiest thing to do. Lithium metal is less reactive than the other members of its column of the periodic table (I’m looking at you, sodium and potassium), but it still reacts with air, water, and many electrolyte materials.

In addition, when lithium leaves the electrode and returns, there’s no way to control where it re-forms metal. After a few charge/discharge cycles, the lithium electrode starts to form sharp spikes that can ultimately grow large enough to short out the battery.

To have better control over how lithium behaves at the electrode, the Stanford group has looked into the use of some lithium-rich alloys. Lithium, for example, forms a complex with silicon where there are typically over four lithium atoms for each atom of silicon. When the lithium leaves the electrode, the silicon stays behind, providing a structure to incorporate the lithium when it returns on the other half of the charge/discharge cycle.

While this solves the problems with lithium metal, it creates a new one: volume changes. The silicon left behind when the lithium runs to the other electrode simply doesn’t take up as much volume as it does when the same electrode is filled with the lithium-silicon mix.

As a result, the electrode expands and contracts dramatically during a charge-discharge cycle, putting the battery under physical stress. (Mind you, a lithium metal electrode disappears entirely, possibly causing an even larger mechanical stress.)

And that would seem to leave us stuck. Limiting the expansion/contraction of the electrode material would seem to require limiting the amount of lithium that moves into and out of it. Which would, of course, mean limiting the energy density of the battery.

Between the sheets

In the new work, the researchers take their earlier lithium-silicon work and combine it with graphene. Graphene is a single-atom-thick sheet of carbon atoms linked together, and it has a number of properties that make it good for batteries. It conducts electricity well, making it easy to shift charges to and from the lithium when the battery charges and discharges. It’s also extremely thin, which means that packing a lot of graphene molecules into the electrode doesn’t take up much space. And critically for this work, graphene is mechanically tough.

To make their electrode material, the team made nanoparticles of the lithium-silicon material. These were then mixed in with graphene sheets in an eight-to-one ratio. A small amount of a plastic precursor was added, and the whole mixture was spread across a plastic block. Once spread, the polymer precursor created a thin film of polymer on top of the graphene-nanoparticle mix. This could be peeled off, and then the graphene-nanoparticle mix could be peeled off the block as a sheet.

The resulting material, which they call a foil, contains large clusters of the nanoparticles typically surrounded by three to five layers of graphene. Depending on how thick you make the foil, there can be several layers of nanoparticle clusters, each separated by graphene.

The graphene sheets make the material pretty robust, as you can fold and unfold it and then still use it as a battery electrode. They also help keep the air from reacting with the lithium inside. Even after two weeks of being exposed to the air, the foil retained about 95 percent of its capacity as an electrode. Lower the fraction of graphene used in the starting mix and air becomes a problem, with the electrode losing nearly half of its capacity in the same two weeks.

And it worked pretty well as an electrode. When the lithium left, the nanoparticles did shrink, but the graphene sheets held the structure together and kept it from shrinking. And it retained 98 percent of its original capacity even after 400 charge-discharge cycles. Perhaps most importantly, when paired with a vanadium oxide cathode, the energy density was just over 500 Watt-hours per kilogram. Current lithium-ion batteries top out at about half that.

Normally, work like this can take a while to get out of an academic lab and have a company start looking into it. In this case, however, the head of the research group Yi Cui already has a startup company with batteries on the market. So, this could take somewhat less time for a thorough commercial evaluation. The biggest sticking point may be the cost of the graphene. A quick search suggests that graphene is still thousands of dollars per kilogram, although it has come down, and lots of people are looking for ways to make it even less expensive.

If they succeed, then the rest of the components of this electrode are pretty cheap. And the process for making it seems pretty simple.

Nature Nanotechnology, 2017. DOI: 10.1038/NNANO.2017.129  (About DOIs).

Graphene girders extend the life of lithium-ion batteries


Nanoscale reinforcement with graphene girders boosts performance of silicon anodes, Warwick team discovers

When you want to make a structure stronger, put a girder across it. It’s a simple principle that every civil engineer knows well. But a team at Warwick Manufacturing Group has found that it applies just as well on very small scales as in megastructures. Melanie Loveridge and colleagues are studying methods for improving lithium-ion batteries, and have found that minute girders could provide an answer to a problem that has been plaguing the field.

Ever since their first introduction in the early 1990s, the anode of lithium batteries has been made of graphite. It has long been apparent that silicon would be a better material, as it can hold ten times more charge per gramme than carbon. But the mechanics of lithium ion batteries, where lithium ions are absorbed into the anode, create problems.

When silicon is lithiated, it expands. But it is an inelastic material, and repeated expansion and contraction — as happens during charge-discharge cycles — can lead to cracking and crumbling, which makes the capacity of the battery fade over time. Graphene has been tried as a reinforcing material for nanostructured silicon, but this has led to other problems.

Loveridge’s team is looking at a material known as FLG (few-layer graphene). As the name implies, this is composed of a few connected layers of single-atom-thick graphene sheets, which can be manipulated together.

In a paper in Nature Scientific Reports, the WMG team describes how FLG can improve the performance of anodes containing micron-sized particles of silicon. The team started with a mixture of 60 per cent micro-silicon, 16 per cent FLG, 14 per cent sodium/polyacrylic acid and 10 per cent carbon additives, and put these anodes through 100 charge-discharge cycles.

“The flakes of FLG were mixed throughout the anode and acted like a set of strong, but relatively elastic, girders. These flakes of FLG increased the resilience and tensile properties of the material greatly reducing the damage caused by the physical expansion of the silicon during lithiation. The graphene enhances the long range electrical conductivity of the anode and maintains a low resistance in a structurally stable composite,” Loveridge said.

Moreover, she added, the graphene girders keep the silicon particles apart. In their absence, the particles tend to ‘weld’ together, restricting lithium diffusion through the anode and reducing the surface area available for lithiation.

“The presence of FLG in the mixture tested by the WMG University of Warwick led researchers to hypothesise that this phenomenon is highly effective in mitigating electrochemical silicon fusion,” Loveridge stated.

The team is now working on scaling up their graphene girders discovery to produce pouch cells based on their reinforced anodes, as part of a two-year graphene flagship project along with Varta Micro-innovations, Cambridge University, CIC, Lithops and IIT (Italian Institute of Technology).

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Graphene Research and the World’s 5 Biggest Problems: From Clean Water and Healthcare to Energy and Infastructure – Solutions based in Graphene may Hold the Key


In September 2015, world leaders gathered at a historic UN summit to adopt the Sustainable Development Goals (SDGs). These are 17 ambitious targets and indicators that help guide and coordinate governments and international organizations to alleviate global problems. For example, SDG 3 is to “ensure healthy lives and promote well-being for all at all ages.” Others include access to clean water, reducing the effects of climate change, and affordable healthcare.

If you think these goals might be difficult to meet, you’re right. Reports show progress is lacking in many of the 17 categories, implying they may not be met by the target date of 2030. However, paired with progress in social and political arenas, advances in science and technology could be a key accelerant to progress too.

Just one example? Graphene, a futuristic material with a growing set of potential applications.

Graphene is comprised of tightly-knit carbon atoms arranged into a sheet only one atom thick. This makes it the thinnest substance ever made, yet it is 200 times stronger than steel, flexible, stretchable, self-healing, transparent, more conductive than copper, and even superconductive. A square meter of graphene weighing a mere 0.0077 grams can support four kilograms. It is a truly remarkable material—but this isn’t news to science and tech geeks.

Headlines touting graphene as the next wonder material have been a regular occurrence in the last decade, and the trip from promise to practicality has felt a bit lengthy.

But that’s not unexpected; it can take time for new materials to go mainstream. Meanwhile, the years researching graphene have yielded a long list of reasons to keep at it.

Since first isolated in 2004 at the University of Manchester—work that led to a Nobel Prize in 2010— researchers all over the world have been developing radical ways to use and, importantly, make graphene. Indeed, one of the primary factors holding back widespread adoption has been how to produce graphene at scale on the cheap, limiting it to the lab and a handful of commercial applications. Fortunately, there have been advances toward mass production.

Last year, for example, a team from Kansas State University used explosions to synthesize large quantities of graphene. Their method is simple: Fill a chamber with acetylene or ethylene gas and oxygen. Use a vehicle spark plug to create a contained detonation. Collect the graphene that forms afterward. Acetylene and ethylene are composed of carbon and hydrogen, and when the hydrogen is consumed in the explosion, the carbon is free to bond with itself, forming graphene. This method is efficient because all it takes is a single spark.

Whether this technique will usher in the graphene revolution, as some have claimed, remains to be seen. What’s more certain is there will be no shortage of problems solved when said revolution arrives. Here’s a look at the ways today’s research suggests graphene may help the UN meet its ambitious development goals.

Clean Water

SDG 6 is to “ensure availability and sustainable management of water and sanitation for all.” As of now, the UN estimates that “water scarcity affects more than 40 percent of the global population and is projected to rise.”

Graphene-based filters could very well be the solution. Jiro Abraham from the University of Manchester helped develop scalable graphene oxide sieves to filter seawater. He claims, “The developed membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes.”

Furthermore, researchers from Monash University and the University of Kentucky have developed graphene filters that can filter out anything larger than one nanometer. They say their filters “could be used to filter chemicals, viruses, or bacteria from a range of liquids. It could be used to purify water, dairy products or wine, or in the production of pharmaceuticals.”

Carbon Emissions

SDG 13 focuses on taking “urgent action to combat climate change and its impacts.”

Of course, one of the main culprits behind climate change is the excessive amount of carbon dioxide being emitted into the atmosphere. Graphene membranes have been developed that can capture these emissions.

Researchers at the University of South Carolina and Hanyang University in South Korea independently developed graphene-based filters that can be used to separate unwanted gases from industrial, commercial, and residential emissions. Henry Foley at the University of Missouri has claimed these discoveries are “something of a holy grail.”

With these, the world might be able to stem the rise of CO2 in the atmosphere, especially now that we have crossed the important 400 parts per million threshold.

Healthcare

Many around the world do not have access to adequate healthcare, but graphene may have an impact here as well.

First of all, graphene’s high mechanical strength makes it a perfect material for replacing body parts like bones, and because of its conductivity it can replace body parts that require electrical current, like organs and nerves. In fact, researchers at the Michigan Technological University are working on using 3D printers to print graphene-based nerves, and this team is developing biocompatible materials using graphene to conduct electricity.

Graphene can also be used to make biomedical sensors for detecting diseases, viruses, and other toxins. Because every atom of graphene is exposed, due to it being only one atom thick, sensors can be far more sensitive. Graphene oxide sensors, for example, could detect toxins at levels 10 times less than today’s sensors. These sensors could be placed on or under the skin and provide doctors and researchers with vast amounts of information.

Chinese scientists have even created a sensor that can detect a single cancerous cell. Further, scientists at the University of Manchester report graphene oxide can hunt and neutralize cancer stem cells.

Infrastructure

SDG 9 is to “build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation.” Graphene-enhanced composites and other building materials could bring us closer to meeting this goal.

Recent research shows that the more graphene is added, the better the composite becomes. This means graphene can be added to building materials like concrete, aluminum, etc., which will allow for stronger and lighter materials.

Resins are also getting better thanks to the addition of graphene. Research by Graphene Flagship, the EU’s billion-euro project to further graphene research, and their partner Avanzare suggests “graphene enhances the functionality of the resin, combining graphene’s electrical conductivity and mechanical strength with excellent corrosion resistance.” Some uses for this are making pipes and storage tanks corrosion-resistant, and making stronger adhesives.

Energy

SDG 7 is to “ensure access to affordable, reliable, sustainable and modern energy for all.” Because of its light weight, conductivity, and tensile strength, graphene may make sustainable energy cheaper and more efficient.

For example, graphene composites can be used to create more versatile solar panels. Researchers at MIT say, “The ability to use graphene…is making possible truly flexible, low-cost, transparent solar cells that can turn virtually any surface into a source of electric power.”

We’ll also be able to build bigger and lighter wind turbines thanks to graphene composites.

Further, graphene is already being used to enhance traditional lithium-ion batteries, which are the batteries commonly found in consumer electronics. Research is also being done into graphene aerogels for energy storage and supercapacitors. All of these will be essential for large-scale storage of renewable energy.

Over the next decade, graphene is likely to find more and more uses out in the real world, not only helping the UN and member states meet the SDGs, but enhancing everything from touch screens to MRI machines and from transistors to unknown uses as a superconductor.

New research is being published and new patents being filed regularly, so keep an eye out for this amazing material.

Manchester University: Photon-friendly graphene membranes mimic photosynthesis to produce hydrogen


Graphene membranes that mimic photosynthesis to produce hydrogen by harvesting solar energy could be developed following the discovery of a new effect.

Researchers at Manchester University have discovered that the rate at which graphene conducts protons increases 10 fold when it is illuminated with sunlight.

Dubbed the “photo-proton” effect, the finding could lead to graphene membranes being used to produce hydrogen from artificial photosynthesis, as well as for light-induced water splitting, photo-catalysis and in photodetectors.

Graphene – a one atom-thick sheet of carbon – is already known to be an extremely good conductor of electrons, and can absorb light of all wavelengths.

But it has also recently been found to be permeable to thermal protons, the nuclei of hydrogen atoms.

To discover how light affects the behaviour of these protons, the researchers fabricated graphene membranes and decorated them on one side with platinum nanoparticles.

When they illuminated the membrane with sunlight, they found the proton conductivity increased by 10 times, according to Dr Marcelo Lozada-Hidalgo, who led the research alongside Prof Sir Andre Geim.

“This is a new effect, it can only be found in graphene, there are no other materials that can use light to produce an enhancement in proton transport,” said Lozada-Hidalgo. “Scientifically this is a new physical phenomenon, which is quite remarkable.”

What’s more, when the researchers measured the photoresponsivity of the membrane using electrical measurements and mass spectrometry, they discovered that around 5,000 hydrogen molecules were being formed in response to every light particle. Existing photovoltaic devices need thousands of photons to produce a single hydrogen molecule.

“To put this in context, people have been developing silicon photodiodes for the best part of 50 years, while we did not expect this material to be responsive to light in the first place, and found that it outperforms pretty much everything that is out there,” said Lozada-Hidalgo.

The researchers have published their findings in Nature Nanotechnology. They now plan to investigate the addition of catalysts to the membrane, to enable it to split water molecules. This would allow it to act as a complete artificial leaf, said Lozada-Hidalgo.

“The goal of this project is to make an artificial leaf, to split water molecules and then use the protons to generate hydrogen,” he said. “What we’re missing is the bit to break the water in the first place, and for that we need another catalyst.”

Electrons in the water – Understanding the properties of water in reduction/oxidation reactions in aqueous solutions – widespread applications in chemistry and biology – Argonne National Laboratory


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It’s a popular tradition to throw coins into fountains in the hopes of having wishes granted. But what would happen if you could “throw” electrons into the water instead? That is, what happens shortly after an electron is injected into water?

This decades-old question now has an answer, thanks to an articlepublished in Nature Communications on January 16. The study is the result of collaboration among researchers at the University of Chicago, the U.S. Department of Energy’s (DOE) Argonne and Lawrence Livermore National Laboratories, and the University of California — San Diego.

“Knowing the electron affinity of liquid water is crucial to understanding and modeling processes involving electron transfer between solids and the liquid, … ” — Alex Gaiduk, postdoctoral fellow at the University of Chicago.

Until now, scientists faced technical challenges when they wanted to experimentally measure the electron affinity of water, said Professor Giulia Galli, Liew Family Professor at the Institute for Molecular Engineering at the University of Chicago and senior scientist at Argonne.

“Most of the results quoted in the literature as experimental numbers are actually values obtained by combining some measured quantities with crude theoretical estimates,” she said.

Accurate theoretical measurements, on the other hand, have been out of reach for some time due to the difficulty and high computational cost of simulating the interactions directly, said University of California-San Diego professor Francesco Paesani, a co-author of the study who has spent years developing an accurate potential for the modeling of liquid water.

The interaction potential between water molecules developed by Paesani was used to model the structure of both liquid water and the water’s surface. Once the structure was obtained, highly accurate theoretical methods and software to study excited states of matter, developed by Galli’s team, were used to understand what happens when an electron is injected into water.

Fundamentally, the researchers sought to understand whether the electron resides in the liquid and eventually participates in chemical reactions. The central question was, “Does the liquid bond with the electron right away?”

The researchers found that the electron binds with the water; however, its binding energy is much smaller than previously thought. This prompted the researchers to revisit a number of well-accepted data and models for the electron affinity of water.

Galli and her co-workers developed the methods for excited states used in this study over the years, in collaborations with T. A. Pham, from Lawrence Livermore, and Marco Govoni, from Argonne, both of whom are co-authors of this study.

“Using the software developed to study excited state phenomena in realistic systems (named Without Empty STates, or WEST) and the Argonne Leadership Computing Facility (ALCF), we were finally able to generate data for samples both large enough and on sufficiently long timescales to study the electron affinity of liquid water,” Govoni said.

“We found large differences between the affinity at the surface and in the bulk liquid. We also found values that were different from those accepted in the literature, which prompted us to revisit the full energy diagram of an electron in water,” Pham added.

This finding has important consequences, both for scientists who seek to fundamentally understand the properties of water and for those who want to describe reduction/oxidation reactions in aqueous solutions, which are widespread in chemistry and biology.

In particular, scientists often use information about the energy levels of water when they screen materials for photo-electrochemical cells. A reliable estimate of the water electron affinity (which the researchers of the study provided for both bulk water and its surface) will help scientists establish computational protocols that are more robust and more reliable, and improve computational screening of materials.

Funding for the work by Gaiduk and co-workers was provided by the DOE Office of Science through the Midwest Integrated Center for Computational Materials. Additional support was provided by the Natural Sciences and Engineering Research Council of Canada, the National Science Foundation and the Lawrence Fellowship. The researchers used the ALCF, a DOE Office of Science User Facility, for the study. Computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE), Extreme Science and Engineering Discovery Environment (XSEDE) and Lawrence Livermore National Laboratory Grand Challenge programs.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.