Paper-based Supercapacitor uses metal Nanoparticles to Boost Energy Density


GIT Paper SuperCap 171005121053_1_540x360Images show the difference between paper prior to metallization (left) and the paper coated with conductive nanoparticles. Credit: Ko et al., published in Nature Communications

Using a simple layer-by-layer coating technique, researchers from the U.S. and Korea have developed a paper-based flexible supercapacitor that could be used to help power wearable devices. The device uses metallic nanoparticles to coat cellulose fibers in the paper, creating supercapacitor electrodes with high energy and power densities — and the best performance so far in a textile-based supercapacitor.

By implanting conductive and charge storage materials in the paper, the technique creates large surface areas that function as current collectors and nanoparticle reservoirs for the electrodes. Testing shows that devices fabricated with the technique can be folded thousands of times without affecting conductivity.

“This type of flexible energy storage device could provide unique opportunities for connectivity among wearable and internet of things devices,” said Seung Woo Lee, an assistant professor in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “We could support an evolution of the most advanced portable electronics. We also have an opportunity to combine this supercapacitor with energy-harvesting devices that could power biomedical sensors, consumer and military electronics, and similar applications.”

The research, done with collaborators at Korea University, was supported by the National Research Foundation of Korea and reported September 14 in the journal Nature Communications.

Energy storage devices are generally judged on three properties: their energy density, power density and cycling stability. Supercapacitors often have high power density, but low energy density — the amount of energy that can be stored — compared to batteries, which often have the opposite attributes. In developing their new technique, Lee and collaborator Jinhan Cho from the Department of Chemical and Biological Engineering at Korea University set out to boost energy density of the supercapacitors while maintaining their high power output.

The researchers began by dipping paper samples into a beaker of solution containing an amine surfactant material designed to bind the gold nanoparticles to the paper. Next they dipped the paper into a solution containing gold nanoparticles. Because the fibers are porous, the surfactants and nanoparticles enter the fibers and become strongly attached, creating a conformal coating on each fiber.

By repeating the dipping steps, the researchers created a conductive paper on which they added alternating layers of metal oxide energy storage materials such as manganese oxide. The ligand-mediated layer-by-layer approach helped minimize the contact resistance between neighboring metal and/or metal oxide nanonparticles. Using the simple process done at room temperatures, the layers can be built up to provide the desired electrical properties.

“It’s basically a very simple process,” Lee said. “The layer-by-layer process, which we did in alternating beakers, provides a good conformal coating on the cellulose fibers. We can fold the resulting metallized paper and otherwise flex it without damage to the conductivity.”

Though the research involved small samples of paper, the solution-based technique could likely be scaled up using larger tanks or even a spray-on technique. “There should be no limitation on the size of the samples that we could produce,” Lee said. “We just need to establish the optimal layer thickness that provides good conductivity while minimizing the use of the nanoparticles to optimize the tradeoff between cost and performance.”

The researchers demonstrated that their self-assembly technique improves several aspects of the paper supercapacitor, including its areal performance, an important factor for measuring flexible energy-storage electrodes. The maximum power and energy density of the metallic paper-based supercapacitors are estimated to be 15.1mWcm?2 and 267.3 ?Wh cm?2, respectively, substantially outperforming conventional paper or textile supercapacitors.

The next steps will include testing the technique on flexible fabrics, and developing flexible batteries that could work with the supercapacitors. The researchers used gold nanoparticles because they are easy to work with, but plan to test less expensive metals such as silver and copper to reduce the cost.

During his Ph.D. work, Lee developed the layer-by-layer self-assembly process for energy storage using different materials. With his Korean collaborators, he saw a new opportunity to apply that to flexible and wearable devices with nanoparticles.

“We have nanoscale control over the coating applied to the paper,” he added. “If we increase the number of layers, the performance continues to increase. And it’s all based on ordinary paper.”

Story Source:

Materials provided by Georgia Institute of TechnologyNote: Content may be edited for style and length.


Journal Reference:

  1. Yongmin Ko, Minseong Kwon, Wan Ki Bae, Byeongyong Lee, Seung Woo Lee, Jinhan Cho. Flexible supercapacitor electrodes based on real metal-like cellulose papersNature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00550-3
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The Future of Batteries, from Human Power to a Wireless Grid


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Extending the battery life of our tech is something that preoccupies manufacturers and consumers alike. With every new phone launch we’re treated to new features, such as increasingly high-res displays and better cameras, but it’s longer battery life we all want. For most of us, being able to use our phone for a full day still means charging it every night, or lugging your charger around all day and hunting for a power socket. And when the electric car revolution reaches full speed, fast-charging, long-life batteries are going to be essential.

Advances in battery life are being made all the time, even if we’re yet to see the full benefits in our day-to-day gadgets.

But what’s beyond that? Wireless power. And we don’t mean laying our phone on a charging pad – we’re talking about long-range wireless power. If this is cracked we could have all our devices at full juice all the time, no matter where we are.

The current tech

The batteries in your current phone, and in electric cars, are lithium-ion. These  charge quickly, last for plenty of cycles and offer decent capacity. But devices are more juice-hungry than ever, and with cars in particular fast charging needs to become more effective, because batteries aren’t going away any time soon.

While wireless power could be a viable option in the future, in the short-to-medium term we need to enhance batteries so that individuals and energy providers can first transition from fossil fuels to green renewable power.

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The battery tech in our smartphones has changed little, even as other features have seen dramatic advances

Louis Shaffer of power management solutions firm Eaton tells TechRadar: “We constantly hear about battery breakthroughs but still have the same lithium-ion batteries in our phones. Innovation takes time. It took over 30 years for li-ion batteries to enter the mainstream, from their invention in the 1980s to featuring in iPhones.”

Another factor in slowing this progress is highlighted by Chris Slattery, product manager at smart lighting manufacturer Tridonic. “The interesting point with mobile phones is that one of the major factors for upgrading your phone is the degradation of the current phone’s battery life,“ he says.

“Increasing the life of these batteries removes a major reason for upgrading to the latest smartphone when the feature set itself doesn’t change that greatly.”

Ultracapacitors

Ultracapacitors are seen by many as the future of energy storage, as they store energy in an electric field, rather than in a chemical reaction as a battery does, meaning they can survive hundreds of thousands more charge and discharge cycles than a battery can.

Taavi Madiburk is CEO of Skeleton Technologies, a global leader in ultracapacitor-based storage solutions. He says: “The future, we believe, lies not in replacing lithium-ion, but coupling this technology with ultracapacitors in a hybrid approach.

“In doing so, it is possible to benefit from both the high energy density of batteries, and the high power density and output of ultracapacitors.

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Advances is energy storage and fast-charging tech are urgently needed if electric car use is to become practicable on a large scale

“Ultracapacitors can be re-charged in a matter of 2-3 seconds, providing one million deep charge/discharge cycles. Also, with ultracapacitors protecting batteries from high power surges, the lifetime of the battery pack is increased by 50% and the range by 10%.

Skeleton is already working to improve power grids to cater for the growing number of electric cars. It sees current large-scale electrical grids being replaced in certain areas by smaller, less centralized grids called microgrids, and, Madiburk adds, “We’re currently working on with ultracapacitors as a piece of that puzzle.”

Solid state batteries

One of the major advances in battery tech right now sticks with good old lithium.

Solid-state lithium batteries dispense with the electrolyte liquid that transfers charged particles, making them safer than current batteries yet still able to operate at super-capacitor levels, meaning that charging and discharging can happen faster.

This is great for car batteries, as it means more power can be utilized by the car for quick pull-away speed, but fast charging will mean drivers need to spend less time at charging stations.

One example of this, from Toyota scientists, is a battery that can be fully charged from empty in just seven minutes.

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Toyota is a the forefront of the development of high-capacity, fast-charging batteries for electric cars

Another promising area is aluminium-air batteries, which have been placed in a car to deliver a whopping 1,100 miles on a single charge. Then there are sand-based batteries, which – while still lithium-ion – manage to offer three times better performance than lithium-ion while being cheaper to make, non-toxic and environmentally friendly.

Whisper it, but one of the big hopes for improved batteries for a while now has been graphene. The Grabat battery from Graphenano charges 33 times faster than lithium-ion units, and can deliver high power too, making it ideal for cars.

Battery-free phones

One way to go without batteries is to make gadgets super-low power consuming. A phone has been built that doesn’t even require a battery, so low are its power needs – and it was achieved using components that are available to anyone.

Engineers at the University of Washington designed the phone, which is able to pull power from the environment, with radio signals and light harvested by an antenna and tiny solar cell.

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Engineers at the University of Washington have developed a phone that doesn’t need a battery

The result is enough power to run the 3.5 microwatt-consuming phone. You’re limited to making calls only, but the idea having a tiny credit card-sized backup phone in your wallet will appeal to everyone from constantly on-the-move workers who need to stay in touch, to hikers.

Ambient power

Other breakthroughs have also been based on drawing ambient power from the world around us. One such technology uses sound and nanogenerators, so that simply talking into your phone generates power to charge it.

MIT scientists, meanwhile, have shown off a way to harvest power from water dew in the air; they’ve only been able to create a potential one microwatt so far, but combine these methods, throw in a bit more evolution and we could be looking at a battery-free future.

Over the air power

The dream of transmitting power over the air has existed since the days of the legendary inventor and electrical engineer Nikolas Tesla, but it’s only recently started to become a reality. One company that claims to have mastered the technology, taking it beyond the close-range Qi wireless charging now found in many smartphones, is uBeam.

The uBeam system was cracked by 25-year-old astrobiology grad Meredith Perry, who has since received over $28 million in funding.

This system uses microwaves to transmit energy several metres across a room to power devices. Perry has shown it off charging phones, but says it could be applied to TVs, computers and even cars.

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The uBeam system is capable of charging devices over distances of several meters, but such technology is still in its infancy

It uses a lot of power, costs a lot to manufacture and offers a pretty slow charging rate; but there are no wires to be seen, and this way of delivering power could hail a future without batteries.

If it could be made efficient on a large scale, in a similar way to mobile phone networks, all our devices could draw power from such a system. Imagine phones and electric cars that never need charging.

But is this future as close as uBeam would have its investors and us believe? Probably not.

Human power

This is where things get really interesting – harnessing the power of human beings. Not like in The Matrix, where we’re reduced to a glorified battery, but through friction generated by movement.

Scientists have shown off the tech in action, powering 12 LED bulbs. That’s not going to change the way you use your gadgets right now, but it’s a step in the right direction.

The technology uses a 50nm thin gold film sitting under silicone rubber nanopillars which create maximum surface area with the skin. The result is lots of friction, and all the user has to do is strap the unit on, making it ideal for wearables.

And the Bill Gates Foundation has even developed a process that harvests enough power from our urine to charge a phone, dubbed the Microbial Fuel Cell; that’s pretty much the definition of sustainable power.

GNT New Thumbnail LARGE 2016Watch Our ‘Current’ Video: “Nano Enabled Super Capacitors and Batteries”

 

 

Read More: Super Capacitor Assisted Silicon Nanowire Batteries for EV and Small Form Factor Markets. A New Class of Battery /Energy Storage Materials is being developed to support the High Energy – High Capacity – High Performance High Cycle Battery Markets. “Ultrathin Asymmetric Porous-Nickel Graphene-Based Supercapacitor with High Energy Density and Silicon Nanowire,”

A New Generation Battery that is:

 Energy Dense   High Specific Power

 Simple Manufacturing Process  Low Manufacturing Cost

 Rapid Charge/ Re-Charge  Flexible Form Factor

 Long Warranty Life  Non-Toxic

 Highly Scaleable Key Markets & Commercial Applications

 EV –  (18650 & 21700); Drone and Marine Batteries

 Wearable Electronics and The Internet of Things

 Estimated $112B Market by 2025

MIT: Researchers clarify mystery about proposed battery material – More “Energy Per Pound”- EV’s and Lithium-Air Batteries


MIT-Lithium-i-1_0Study explains conflicting results from other experiments, may lead to batteries with more energy per pound.

Battery researchers agree that one of the most promising possibilities for future battery technology is the lithium-air (or lithium-oxygen) battery, which could provide three times as much power for a given weight as today’s leading technology, lithium-ion batteries. But tests of various approaches to creating such batteries have produced conflicting and confusing results, as well as controversies over how to explain them.

Now, a team at MIT has carried out detailed tests that seem to resolve the questions surrounding one promising material for such batteries: a compound called lithium iodide (LiI). The compound was seen as a possible solution to some of the lithium-air battery’s problems, including an inability to sustain many charging-discharging cycles, but conflicting findings had raised questions about the material’s usefulness for this task. The new study explains these discrepancies, and although it suggests that the material might not be suitable after all, the work provides guidance for efforts to overcome LiI’s drawbacks or find alternative materials.battery-5001

The new results appear in the journal Energy and Environmental Science, in a paper by Yang Shao-Horn, MIT’s W.M. Keck Professor of Energy; Paula Hammond, the David H. Koch Professor in Engineering and head of the Department of Chemical Engineering; Michal Tulodziecki, a recent MIT postdoc at the Research Laboratory of Electronics; Graham Leverick, an MIT graduate student; Yu Katayama, a visiting student; and three others.

The promise of the lithium-air battery comes from the fact one of the two electrodes, which are usually made of metal or metal oxides, is replaced with air that flows in and out of the battery; a weightless substance is thus substituted for one of the heavy components. The other electrode in such batteries would be pure metallic lithium, a lightweight element.

But that theoretical promise has been limited in practice because of three issues: the need for high voltages for charging, a low efficiency with regard to getting back the amount of energy put in, and low cycle lifetimes, which result from instability in the battery’s oxygen electrode. Researchers have proposed adding lithium iodide in the electrolyte as a way of addressing these problems. But published results have been contradictory, with some studies finding the LiI does improve the cycling life, “while others show that the presence of LiI leads to irreversible reactions and poor battery cycling,” Shao-Horn says.

Previously, “most of the research was focused on organics” to make lithium-air batteries feasible, says Michal Tulodziecki, the paper’s lead author. But most of these organic compounds are not stable, he says, “and that’s why there’s been a great focus on lithium iodide [an inorganic material], which some papers said helps the batteries achieve thousands of cycles. But others say no, it will damage the battery.” In this new study, he says, “we explored in detail how lithium iodide affects the process, with and without water,” a comparison which turned out to be significant.

lithium-air-battery (1)

The team looked at the role of LiI on lithium-air battery discharge, using a different approach from most other studies. One set of studies was conducted with the components outside of the battery, which allowed the researchers to zero in on one part of the reaction, while the other study was done in the battery, to help explain the overall process.

They then used ultraviolet and visible-light spectroscopy and other techniques to study the reactions that took place. Both of these processes foster the production of different lithium compound such as LiOH (lithium hydroxide) in the presence of both LiI and water, instead of Li2O(lithium peroxide).  LiI can enhance water’s reactivity and make it lose protons more easily, which promotes the formation of LiOH in these batteries and interferes with the charging process. These observations show that finding ways to suppress these reactions could make compounds such as LiI work better.

This study could point the way toward selecting a different compound instead of LiI to perform its intended function of suppressing unwanted chemical reactions at the electrode surface, Leverick says, adding that this work demonstrates the importance of “looking at the detailed mechanism carefully.”

Shao-Horn says that the new findings “help get to the bottom of this existing controversy on the role of LiI on discharge. We believe this clarifies and brings together all these different points of view.”

But this work is just one step in a long process of trying to make lithium-air technology practical, the researchers say. “There’s so much to understand,” says Leverick, “so there’s not one paper that’s going to solve it. But we will make consistent progress.”

“Lithium-oxygen batteries that run on oxygen and lithium ions are of great interest because they could enable electric vehicles of much greater range. However, one of the problems is that they are not very efficient yet,” says Larry Curtiss, a distinguished fellow at Argonne National Laboratory, who was not involved in this work. In this study, he says, “it is shown how adding a simple salt, lithium iodide, can potentially be used to make these batteries run much more efficiently. They have provided new insight into how the lithium iodide acts to help break up the solid discharge product, which will help to enable the development of these advanced battery systems.”Nissan-Leaf

Curtiss adds that “there are still significant barriers remaining to be overcome before these batteries become a reality, such as getting long enough cycle life, but this is an important contribution to the field.”

The team also included recent MIT graduates Chibueze Amanchukwu PhD ’17 and David Kwabi PhD ’16, and Fanny Bardé of Toyota Motor Europe. The work was supported by Toyota Motor Europe and the Skoltech Center for Electrochemical Energy Storage, and used facilities supported by the National Science Foundation.

Graphene-MoS2 Hybrid Material for Energy Storage and Transfer Applications



The exponential growth rates of population density and the worldwide economy has required a significant investment in energy storage devices, particularly those which are portable and can be used for future flexible electronics.

To meet the increasing energy demands of a growing population, not only are new ways of creating the energy being devised, but so are new ways of storing this that energy. 

A team of Researchers from India have developed a hybrid nanomaterial composed of graphene and flower-shaped MoS2 nanostructures to store energy in a prototype supercapacitor.



As a result of an ever-expanding population and its associated energy consumption, there is a projection that the demand for energy in 2050 will exceed 40 terawatts (TW). 




Because of the requirements for a high amount of energy, new ways of producing renewable energy are being researched and implemented, as current non-renewable fuels will eventually run out.

Due to both the energy increase and nature of the produced energy, new materials are also being developed that can store this energy efficiently.

At present, such storage capabilities are not even close to meeting the energy demands set out in future predictions. Current devices can only store 1% of renewable energy that storage devices do for fossil fuels.

As such, there is a great need to not only create materials which can store renewable energy, but to also produce materials with a real-world function that can rival non-renewable storage options, potentially as a variant of Li-ion and Na-air batteries that can hold renewable-produced energy.



The team of Researchers have created a hybrid nanomaterial composed of flower-like MoS2 nanostructures and 3D graphene heterostructures to be used as an active material in energy storage and transfer devices.
 

The Researchers also tested and employed the material in a solid-state supercapacitor, where the 3D graphene-MoS2 material was used with a graphite current collector.

To create the active material, the Researchers first created MoS2 nanospheres through a hydrothermal method using ammonium molybdate and thiourea. 

A modified hydrothermal method was then utilized to deposit 3D graphene oxide onto a graphite electrode using a series of wet synthetic steps.

The MoS2 nanostructures were then also deposited onto the graphene sheets. To create the supercapacitor, the Researchers, alongside the electrodes, used a polyvinyl acetate (PVA) gel and a gel-soaked whatman filter paper as part of the internal components. A drying time of 12 hours was required for the device to be fully fabricated.

Electrodes Push Charging Rate Limits in Energy Storage: Using MXene in Electrode Design: Drexel University


Drexel Energy Storage Electrodes Key rd1707_MXene-electrode-crop

Drexel researchers developed electrode designs using MXene that allow for much faster charging because they open up paths for ions to quickly travel within the material. Source: Drexel University

 

Can you imagine fully charging your cell phone in just a few seconds? Researchers in Drexel University’s College of Engineering can, and they took a big step toward making it a reality with their recent work unveiling of a new battery electrode design in the journal Nature Energy.

The team, led by Yury Gogotsi, PhD,Distinguished University and Bach professor in Drexel’s College of Engineering, in the Department of Materials Science and Engineering, created the new electrode designs from a highly conductive, two-dimensional material called MXene. Their design could make energy storage devices like batteries, viewed as the plodding tanker truck of energy storage technology, just as fast as the speedy supercapacitors that are used to provide energy in a pinch — often as a battery back-up or to provide quick bursts of energy for things like camera flashes.

“This paper refutes the widely accepted dogma that chemical charge storage, used in batteries and pseudocapacitors, is always much slower than physical storage used in electrical double-layer capacitors, also known as supercapacitors,” Gogotsi said. “We demonstrate charging of thin MXene electrodes in tens of milliseconds. This is enabled by very high electronic conductivity of MXene. This paves the way to development of ultrafast energy storage devices than can be charged and discharged within seconds, but store much more energy than conventional supercapacitors.”

The key to faster charging energy storage devices is in the electrode design. Electrodes are essential components of batteries, through which energy is stored during charging and from which it is disbursed to power electronic devices. So the ideal design for these components would be one that allows them to be quickly charged and store more energy.

To store more energy, the materials should have places to put it. Electrode materials in batteries offer ports for charge to be stored. In electrochemistry, these ports, called “redox active sites” are the places that hold an electrical charge when each ion is delivered. So if the electrode material has more ports, it can store more energy — which equates to a battery with more “juice.”

Collaborators Patrice Simon, PhD, and Zifeng Lin, from Université Paul Sabatier in France, produced a hydrogel electrode design with more redox active sites, which allows it to store as much charge for its volume as a battery. This measure of capacity, termed “volumetric performance,” is an important metric for judging the utility of any energy storage device.

To make those plentiful hydrogel electrode ports even more attractive to ion traffic, the Drexel-led team, including researchers Maria Lukatskaya, PhD, Sankalp Kota, a graduate student in Drexel’s MAX/MXene Research Group led by Michel Barsoum, PhD,distinguished professor in the College of Engineering; and Mengquiang Zhao, PhD, designed electrode architectures with open macroporosity — many small openings — to make each redox active sites in the MXene material readily accessible to ions.

Mxene 2 containingou“In traditional batteries and supercapacitors, ions have a tortuous path toward charge storage ports, which not only slows down everything, but it also creates a situation where very few ions actually reach their destination at fast charging rates,” said Lukatskayathe first author on the paper, who conducted the research as part of the A.J. Drexel Nanomaterials Institute. “The ideal electrode architecture would be something like ions moving to the ports via multi-lane, high-speed ‘highways,’ instead of taking single-lane roads. Our macroporous electrode design achieves this goal, which allows for rapid charging — on the order of a few seconds or less.”

The overarching benefit of using MXene as the material for the electrode design is its conductivity. Materials that allow for rapid flow of an electrical current, like aluminum and copper, are often used in electric cables. MXenes are  conductive, just like metals, so not only do ions have a wide-open path to a number of storage ports, but they can also move very quickly to meet electrons there. Mikhael Levi, PhD, and Netanel Shpigel, research collaborators from Bar-Ilan University in Israel, helped the Drexel group maximize the number of the ports accessible to ions in MXene electrodes.mxene-polymer-nanocomposite-material

Use in battery electrodes is just the latest in a series of developments with the MXene material that was discovered by researchers in Drexel’s Department of Materials Science and Engineering in 2011. Since then, researchers have been testing them in a variety of applications from energy storage to electromagnetic radiation shielding, and water filtering. This latest development is significant in particular because it addresses one of the primary problems hindering the expansion of the electric vehicle market and that has been lurking on the horizon for mobile devices.

“If we start using low-dimensional and electronically conducting materials as battery electrodes, we can make batteries working much, much faster than today,” Gogotsi said. “Eventually, appreciation of this fact will lead us to car, laptop and cell-phone batteries capable of charging at much higher rates — seconds or minutes rather than hours.”

This research was supported by Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy’s Office of Science and Office of Basic Energy Sciences; as well as the National Science Foundation and Binational Science Foundation, which supported collaborations with France and Israel, respectively.

What are MXenes ?

MXenes are a new family of two-dimensional (2D) transition metal carbides, carbonitrides and nitrides that were discovered and developed in collaboration with Prof. Barsoum’s group, that can be used in many applications. These applications include lithium-ion and sodium-ion energy storage systems, electromagnetic interference (EMI) shielding, and water purification. MXenes are highly desirable in EMI shielding due to their good flexibility, easy processing, and high conductivity with minimal thickness, having the highest EMI shielding effectiveness of all synthetic materials of similar thickness. MXenes are also promising antibacterial agents, with higher efficiency than graphene oxide in diminishing bacterial cell viability.

 

 

AE_Nanomaterials_Figure 1Read More: 2D Carbides and Nitrides (MXenes)

EPPL Creates a low-cost system for splitting carbon dioxide – Turning Renewable Energy into Fuel


Ball-and-stick model of carbon dioxide. Credit: Wikipedia

Using Earth-abundant materials, EPFL scientists have built the first low-cost system for splitting CO2 into CO, a reaction necessary for turning renewable energy into fuel.
The future of clean energy depends on our ability to efficiently store energy from renewable sources and use it later. 


A popular way to do this is to electrolyze carbon dioxide to carbon monoxide, which is then mixed with hydrogen to produce liquid hydrocarbons like gasoline or kerosene that can be used as fuel. 

However, we currently lack efficient and Earth-abundant catalysts for the initial splitting of CO2 into CO and oxygen, which makes the move into renewable energy expensive and prohibitive. 

EPFL scientists have now developed an Earth-abundant catalyst based on copper-oxide nanowires modified with tin oxide. 
The system can split CO2 with an efficiency of 13.4%. 
The work is published in Nature Energy, and can help worldwide efforts to synthetically produce carbon-based fuels from CO2 and water.

The research was carried out by the lab of Michael Grätzel at EPFL. Grätzel is known worldwide for the invention of the first ever dye-sensitized solar cells (or “Grätzel cells”). 

The catalyst, developed by PhD student Marcel Schreier and postdoc Jingshan Luo, is made by depositing an atomic layer of tin oxide on copper oxide nanowires

By using such Earth-abundant materials, the design keeps the cost of the catalyst low while significantly increasing the yield of CO, as opposed to the other products that are generated from CO2 electrocatalysis.
The catalyst was integrated into a CO2 electrolysis system and linked to a triple-junction solar cell (GaInP/GaInAs/Ge) to make a CO2 electrolyzer. 

The system uses the catalyst as a bifunctional electrode that both reduces CO2 into CO and produces oxygen through what is known as the “oxygen evolution” reaction. The two products are separated with a bipolar membrane.

Using solar energy, the system was able to selectively convert CO2 to CO with an efficiency of 13.4%, and do so with a Faradaic efficiency up to 90%—this describes how efficiently electrical charge is transferred in a electrocatalysis system like the one developed here. “The work sets a new benchmark for solar-driven CO2 reduction,” says Luo.

“This is the first time that such a bi-functional and low-cost catalyst is demonstrated,” adds Schreier. “Very few catalysts—except expensive ones, like gold and silver—can selectively transform CO2 to CO in water, which is crucial for industrial applications.”

 
More information: Marcel Schreier, Florent Héroguel, Ludmilla Steier, Shahzada Ahmad, Jeremy S. Luterbacher, Matthew T. Mayer, Jingshan Luo, Michael Grätzel. Solar conversion of CO2 to CO using Earth-abundant electrocatalysts prepared by atomic layer modification of CuO. Nature Energy 2, 17087 (05 June 2017). nature.com/articles/doi:10.1038/nenergy.2017.87
Provided by: Ecole Polytechnique Federale de Lausanne

A Holey Graphene Electrode framework that enables highly efficient charge delivery – Making Better Batteries for the Future


Holey Graphene II grapheneThis visualisation shows layers of graphene used for membranes. Credit: University of Manchester

A team of researchers affiliated with institutions in the U.S., China and the Kingdom of Saudi Arabia has developed a new type of porous graphene electrode framework that is capable of highly efficient charge delivery. In their paper published in the journal Science, the group describes how they overcame traditional conflicts arising between trade-offs involving density and speed to produce an electrode capable of facilitating rapid ion transport. Hui-Ming Cheng and Feng Li with the Chinese Academy of Sciences offer a Perspective piece on the work done by the team in the same journal issue, and include some opinions of their own regarding where such work is likely heading.

In a perfect world, batteries would have unlimited energy storage delivered at speeds high enough to power devices with unlimited needs. The phaser from Star Trek, for example, would require far more power and speed than is possible in today’s devices.

While it is unlikely that such technology will ever come about, it does appear possible that batteries of the future will perform much better than today, likely due to nano-structured materials—they have already shown promise when used as material due to their unique properties. Unfortunately, their use has been limited thus far due to the ultra-thin nature of the resulting electrodes and their extremely low mass loadings compared to those currently in use. In this new effort, the researchers report on a new way to create an electrode using that overcomes such limitations.

The electrode they built is porous, which in this case means that it has holes in it. Those holes, as Cheng and Li note, allow better charge transport while also offering improved capacity retention density. The graphene framework they built, they note, offers a superior means of electron transport and its porous nature allows for a high ion diffusion rate—the holes force the ions to take shortcuts, reducing diffusion.

Cheng and Li suggest the new work is likely to inspire similar designs in the search for better electrode materials, which they further suggest appears likely to lead to new electrodes that are not only practical, but have high mass loadings.

Explore further: New graphene framework bridges gap between traditional capacitors, batteries

More information: Hongtao Sun et al. Three-dimensional holey-graphene/niobia composite architectures for ultrahigh-rate energy storage, Science (2017). DOI: 10.1126/science.aam5852

Abstract
Nanostructured materials have shown extraordinary promise for electrochemical energy storage but are usually limited to electrodes with rather low mass loading (~1 milligram per square centimeter) because of the increasing ion diffusion limitations in thicker electrodes.

We report the design of a three-dimensional (3D) holey-graphene/niobia (Nb2O5) composite for ultrahigh-rate energy storage at practical levels of mass loading (>10 milligrams per square centimeter). The highly interconnected graphene network in the 3D architecture provides excellent electron transport properties, and its hierarchical porous structure facilitates rapid ion transport.

By systematically tailoring the porosity in the holey graphene backbone, charge transport in the composite architecture is optimized to deliver high areal capacity and high-rate capability at high mass loading, which represents a critical step forward toward practical applications.

 

“Holey” graphene improves battery electrodes – May be ‘The Holy Grail’ of Next Generation Batteries 



May 12, 2017

Electrodes containing porous graphene and a niobia composite could help improve electrochemical energy storage in batteries. This is the new finding from researchers at the University of California at Los Angeles who say that the nanopores in the carbon material facilitate charge transport in a battery.

By fine tuning the size of these pores, they can not only optimize this charge transport but also increase the amount of active material in the device, which is an important step forward towards practical applications.


Niobia and holey graphene composite with tailored nanopores

Batteries and supercapacitors are two complementary electrochemical energy-storage technologies. They typically contain positive and negative electrodes with the active electrode materials coated on a metal current collector (normally copper or aluminium foil), a separator between the two electrodes, and an electrolyte that facilitates ion transport.

The electrode materials actively participate in charge (energy) storage, whereas the other components are passive but nevertheless compulsory for making the device work.

Batteries offer high energy density but low power density while supercapacitors provide high power density with low energy density.

Although lithium-ion batteries are the most widely employed batteries today for powering consumer electronics, there is a growing demand for more rapid energy storage (high power) and higher energy density. Researchers are thus looking to create materials that combine the high-energy density of battery materials with the short charging times and long cycle life of supercapacitors.

Such materials need to store a large number of charges (such as Li ions) and have an electrode architecture that can quickly deliver charges (electrons and ions) during a given charge/discharge cycle.

Increasing the mass loading of niobia in electrodes

Nanostructured materials fit the bill here, but unfortunately only for electrodes with low areal mass loading of the active materials (around 1 mg/cm2). “This is much lower than the mass of the passive components (around 10 mg/cm2 or greater),” explains team leader Xiangfeng Duan. “As a result, in spite of the high intrinsic capacity or rate capability of these new nanostructured materials, the scaled area capacity or areal current density of nanostructured electrodes rarely exceeds those of today’s Li-ion batteries.

Thus, these electrodes have not been able to deliver their extraordinary promise in practical commercial devices.

“To take full advantage of these new materials, we must increase the mass loading to a level comparable to or higher than the mass of the passive components. To satisfy the energy storage requirement of an electrode with 10 times higher mass loading requires the rapid delivery of 10 times more charge over a distance that is 10 times greater within a given time. This is a rather challenging task and has proven to be a critical roadblock for new electrode materials.

“We have now addressed this very issue of how we can increase the mass loading of niobia (Nb2O5) in electrode structures without compromising its merit for ultrahigh-rate energy storage,” he continues. “Electrodes with intrinsically high capacity or high rate capability in practical devices require a new architecture that can efficiently deliver sufficient electrons or ions.

We have designed a 3D holey-graphene-Nb2O5 composite with excellent electron and ion transport properties for ultrahigh-rate energy storage at practical levels of mass loading (greater than 10 mg/cm2).”

Porous structure facilitates rapid ion transport

“The highly interconnected graphene network in the 3D architecture provides excellent electron transport properties and its hierarchical porous structure facilitates rapid ion transport,” he adds. “What is more, by systematically tailoring the porosity in the holey graphene backbone, we optimize charge transport in the composite architecture to simultaneously deliver areal capacity and high-rate capability at practical levels of mass loading – something that is a critical step forward towards commercial applications.”

The researchers made their mechanically strong 3D porous composites in a two-step synthesis technique. “We uniformly decorate Nb2O5

Decreasing the fraction of inactive materials

The in-plane pores in the holey graphene sheet function as ion transport “shortcuts” in the hierarchical porous structure to facilitate rapid ion transport throughout the entire 3D electrode and so greatly improve ion transport kinetics and access to ions on the surface of the electrode, Duan tells nanotechweb.org.

Spurred on by these results, the researchers say they will now try to incorporate high-capacity active materials such as silicon and tin oxide to further increase output energy levels in electrochemical cells. “Extremely high mass-loaded electrodes (for example, five times that of practical mass loading, or 50 mg/cm2) could also help decrease the fraction of inactive materials in a device and so simplify the process to make these cells.”


So What’s Next?

Team GNT writes: For the Researchers to take ‘the next step’ further exploration of best outcome and integration of new structured  materials must be completed. And then …

  • Proof of Concept
  • Proof of Scalability 
  • Competitive Market Integration Analysis
  • Manufacturing Platform and Market Distribution 

A lot of hard work! But work that will be well worth the effort if the emerging technology can meet all of the required. Milestones! The current rechargeable battery market is a $112 Billion Market!



The research is detailed in Science DOI: 10.1126/science.aam5852.
Belle Dumé is contributing editor at nanotechweb.org

New battery technology that could run for more than a decade could revolutionize renewable energy – Harvard University


Harvard Battery Research aziz_650

The race is on to build the next-generation battery that could help the world switch over to clean energy. But as Bill Gates explained in his blog last year: “storing energy turns out to be surprisingly hard and expensive”.

 

Now Harvard researchers have developed a cheap, non-toxic battery that lasts more than 10 years, which they say could be a game changer for renewable energy storage.

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016.  Picture taken October 14, 2016.      REUTERS/Mike Blake - RTX2QGWW

Image: REUTERS/Mike Blake

The researchers from the John A. Paulson School of Engineering and Applied Sciences published a paper in the journal ACS Energy Letters saying that they have developed a breakthrough technology.

 

Their new type of battery stores energy in organic molecules dissolved in neutral pH water. This makes the battery non-toxic and cheaper. It’s suitable for home storage and lasts for more than a decade. “This is a long-lasting battery you could put in your basement,” Roy Gordon, a lead researcher and the Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science, said in a Harvard news article.

“If it spilled on the floor, it wouldn’t eat the concrete and since the medium is non-corrosive, you can use cheaper materials to build the components of the batteries, like the tanks and pumps.”

 

The energy storage problem

There’s a big problem with renewable energy sources: Intermittency. In other words, how to keep the lights on when the sun isn’t shining or the wind isn’t blowing.

 Image 2

 Image: International Energy Agency

In recent years, universities and the tech sector have been working on better batteries that they hope could help solve the energy storage problem. Despite significant improvements though, batteries are riddled with issues such as high cost, toxicity and short lifespan.

 

Solar power customers usually have two options to store power: lithium-ion batteries such as the ones found in electronics, which are still very expensive; or lead-acid batteries. These cost half as much, but need a lot of maintenance and contain toxic materials.

 Image 3

Image: Bloomberg New Energy Finance

In one emerging and promising technology is the “v-flow” battery, which uses vanadium in large external tanks of corrosive acids. 

The bigger the tanks, the more energy they store. But there’s a catch: vanadium is an expensive metal and like all other battery technologies, v-flow batteries lose capacity after a few years.

The quest for the next-generation battery

The US Department of Energy has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour, which would make stored wind and solar energy competitive with energy produced from traditional power plants.

 

The Harvard researchers say their breakthrough puts them within sight of this goal.

“If you can get anywhere near this cost target then you change the world,” said Michael Aziz, lead researcher and professor of Materials and Energy Technologies at Harvard. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”

 

energy_storage_2013-042216-_11-13-1

Video: Next Generation Silicon-Nanowire Batteries

 

A new company has been formed to exploit and commercialize the Next Generation Super-Capacitors and Batteries. The opportunity is based on Technology & Exclusive IP Licensing Rights from Rice University, discovered/ curated by Dr. James M. Tour, named “One of the Fifty (50) most influential scientists in the World today”

The Porous Silicon Nanowires & Lithium Cobalt Oxide technology has been advanced to provide a New Generation Battery that is:

 Energy Dense
 High Specific Power
 Affordable Cost
 Low Manufacturing Cost
 Rapid Charge/ Re-Charge
 Flexible Form Factor
 Long Warranty Life
 Non-Toxic
 Highly Scalable

Key Markets & Commercial Applications

 Motor Cycle/ EV Batteries
 Marine and Drone Batteries
 Medical Devices and
 Power Banks
 Estimated $112 Billion Market for Rechargeable Batteries by 2025

 

 

An EV Battery That Charges Fully In 5 Minutes? Commercialization Step-Up Could Come Soon


storedot-ev-battery-21-889x592 (1)

Electric vehicles now comprise a substantial part of the automotive market. But the fact remains that despite the increasing number of charging stations, it is still inconvenient to charge a car in comparison to getting a tank full of gas.

StoreDot, an Israeli startup, might have the solution to the woes of electric vehicle (EV) owners, with a new battery it claims can fully charge in five minutes and drive the EV 300 miles on a single charge.

StoreDot aa8b81a83f20b19b089ceb4e4a25e036

 

Read About the Company: Enabling the Future of Charging

The battery is made of nano-materials in a layered structure, made of special organic compounds manufactured by the company. This, the company said, is a massive improvement over traditional lithium-ion battery.

The company first demonstrated the technology at Microsoft Think Next in 2015. The company says the batteries are in the “advanced stages of development” and might be integrated into electric vehicles in the next three years. It also says that its chemical compound is not flammable and has a higher level of combustion, reducing the level of resistance in the batteries making it safe for use in cars.

The batteries won’t be too difficult to manufacture either — the company estimates that 80 percent of the manufacturing process is the same as regular lithium-ion batteries.

StoreDot specializes in battery technology. Last year, it showcased a smartphone battery capable of fully charging within 30 seconds. The EV battery is a scaled up version of this battery which has multi-function electrodes, a combination of polymer and metal oxide.

Watch the Video

 

Read More

 

An electric car battery that could charge in just five minutes ~ Where is the Israeli Start-Up “+StoreDot” One Year Later? +Video

storedot-ev-battery-21-889x592 (1)