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POSITION AVAILABLE: Conductive Ink Formulation Scientist

Posted By Graphene Council, Tuesday, February 25, 2020

Nanotech Energy is developing cutting-edge energy storage solutions for the electric and portable electronics markets. This technology is based on the wonder material graphene that is established as the thinnest, strongest and most conductive material. Our mission at Nanotech Energy is to harness the power of graphene into world-changing battery solutions. We also take advantage of the outstanding structural, mechanical and electronic properties of graphene to develop conductive inks and adhesives as well as electromagnetic interference shielding materials with unparalleled performance. Nanotech Energy seeks talented scientists and engineers to join the expanding development and production teams. Choosing where to start and grow your career has a major impact on your professional and personal life. Nanotech Energy is home for cutting-edge graphene and nanomaterials technology and our scientists develop solutions that impact our community and the world. We offer you a chance to join a high-growth company at an early stage and shape the direction of our culture.

Position Summary :

Nanotech Energy, Inc. is seeking a talentedInk Formulation Scientist to join our expanding team located in Northern California. As a leading company in the manufacture of graphene oxide, silver nanoparticles and nanowires, we plan to offer our customers a full spectrum of conductive inks for a wide range of applications.

The successful candidate will work with our chemistry team and analytical scientists to develop conductive inks for the growing markets of printed electronics and smart packaging.You will use your knowledge in conductive ink formulations to develop, validate and implement inkjet, aerosol and screen printing inks. This job requires a strong hands-on experience in a variety of printing processes and ink formulations and the ability to work independently with little supervisions, yet also be an integral team member. As our residential expert in conductive inks, you will coordinate ink development with cross-functional teams to meet our engineering and customer needs. You will also be responsible for facilitating the transition of our inks from development to manufacturing. Nanotech Energy is made up of amazing individuals but it’s only through teamwork that we achieve greatness. At Nanotech Energy, you will be given the opportunity to participate and join in the growth stage of a startup company and contribute at all levels to make an impact.

Job Type: Full-time

Job level: Senior level 

Responsibilities and Duties

• Lead technical and quality needs for our conductive inks projects to address immediate and strategic problems of the company.
• Contribute to the continuous improvement of processes and capabilities in the company.
• Participate in the design and development ofa new laboratory for inkjet, aerosol and screen printing applications. 
• Develop or improve existing products and processes to prepare dispersions and inks and help to implement in production. 
• Synthesize and characterize new products, components, and formulations. 
• Assist in collecting data and writing of patent inventions associated with the development of new products. 
• Apply knowledge to provide customer support and troubleshooting in the application of commercial products.
• Assist our engineers and plant production personnel in scaling up the technology from bench to manufacturing.
• Review and write standard operating procedures for analytical development.
• Conduct experiments to test the long-term stability of our inks. Analyze results of experiments and trials and write reports. 
• Assist in the supervision of less experienced chemists and technicians in the team. Provide other support as needed to help maintain an efficientdevelopment lab.
• Communicate ideas and results internally across multiple teams. 

Education and Qualifications

• Bachelor degree in chemistry, materials science, chemical engineering or related field. PhD degree with relevant experience is also acceptable. 
• Experience in the preparation, processing and characterization of conductive inks for printed and flexible electronics. 
• Knowledge of fluid dynamics, rheology, and fluid development is required. 
• Demonstrated history of solving problems with a chemical and analytical approach.
• Strong background in colloidal and surface chemistry and surface treatment through material design, synthesis, and characterization. 
• Experience with the development of transparent conducting electrodes with different surface properties is highly desirable. 
• Examples of instrumentation / techniques: Viscometry, goniometry (with tensiometry), DLS, zeta potential, SEM, TEM
• Knowledge of nanocolloidal system stability; nanoparticle synthesis experience is a plus 
• Scale up experience with nanocolloidal systems
• Experience with at least one printing process is required.
• Experience with nanomaterial surface coatings for added functions is a plus. 
• 3-5 years of industry experience (less for candidates with advanced degrees).

Professional Skills

• Ability to respond to multiple priorities simultaneously; ability to coordinate team and projects to meet the company needs and deadlines. 
• Strong project management skills.
• Skilled in troubleshooting and analytical thinking with an interest in solving complex problems. 
• Ability to deal with a variety of abstract and concrete variables and to conduct studies using the scientific method
• Demonstrated understanding of analytical chemistry and materials science, especially in rheology, polymer, and thermal analysis. 
• Demonstrated ability to communicate effectively in both verbal and written formats; ability to work effectively with team members and management. 
• Competency level should allow the employee to author internal reports, reports to customers, or articles for ink industry publications.
• Experience in 3D printing and thermal inkjet is a plus. 

Work authorization / location:
• United States (Required)

Contact
Scott Jacobson
Director of Business Development
scottjacobson@nanotechenergy.com

Tags:  Battery  Energy Storage  Graphene  nanomaterials  Nanotech Energy  Scott Jacobson 

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Fast-charging, long-running, bendy energy storage breakthrough

Posted By Graphene Council, Wednesday, February 19, 2020
A new bendable supercapacitor made from graphene, which charges quickly and safely stores a record-high level of energy for use over a long period, has been developed and demonstrated by UCL and Chinese Academy of Sciences researchers.

While at the proof-of-concept stage, it shows enormous potential as a portable power supply in several practical applications including electric vehicles, phones and wearable technology.

The discovery, published today in Nature Energy, overcomes the issue faced by high-powered, fast-charging supercapacitors – that they usually cannot hold a large amount of energy in a small space.

First author of the study, Dr Zhuangnan Li (UCL Chemistry), said: “Our new supercapacitor is extremely promising for next-generation energy storage technology as either a replacement for current battery technology, or for use alongside it, to provide the user with more power.

“We designed materials which would give our supercapacitor a high power density – that is how fast it can charge or discharge – and a high energy density – which will determine how long it can run for. Normally, you can only have one of these characteristics but our supercapacitor provides both, which is a critical breakthrough.

“Moreover, the supercapacitor can bend to 180 degrees without affecting performance and doesn’t use a liquid electrolyte, which minimises any risk of explosion and makes it perfect for integrating into bendy phones or wearable electronics.”

A team of chemists, engineers and physicists worked on the new design, which uses an innovative graphene electrode material with pores that can be changed in size to store the charge more efficiently. This tuning maximises the energy density of the supercapacitor to a record 88.1 Wh/L (Watt-hour per litre), which is the highest ever reported energy density for carbon-based supercapacitors.

Similar fast-charging commercial technology has a relatively poor energy density of 5-8 Wh/L and traditional slow-charging but long-running lead-acid batteries used in electric vehicles typically have 50-90 Wh/L.

While the supercapacitor developed by the team has a comparable energy density to state-of-the-art value of lead-acid batteries, its power density is two orders of magnitude higher at over 10,000 Watt per litre.

Senior author and Dean of UCL Mathematical & Physical Sciences, Professor Ivan Parkin (UCL Chemistry), said: “Successfully storing a huge amount of energy safely in a compact system is a significant step towards improved energy storage technology. We have shown it charges quickly, we can control its output and it has excellent durability and flexibility, making it ideal for development for use in miniaturised electronics and electric vehicles. Imagine needing only ten minutes to fully-charge your electric car or a couple of minutes for your phone and it lasting all day.”

The researchers made electrodes from multiple layers of graphene, creating a dense, but porous material capable of trapping charged ions of different sizes. They characterised it using a range of techniques and found it performed best when the pore sizes matched the diameter of the ions in the electrolyte.

The optimised material, which forms a thin film, was used to build a proof-of-concept device with both a high power and high energy density.

The 6cm x 6cm supercapacitor was made from two identical electrodes layered either side of a gel-like substance which acted as a chemical medium for the transfer of electrical charge. This was used to power dozens of light-emitting diodes (LEDs) and was found to be highly robust, flexible and stable.

Even when bent at 180 degrees, it performed almost same as when it was flat, and after 5,000 cycles, it retained 97.8% of its capacity.

Senior author, Professor Feng Li (Chinese Academy of Sciences), said: “Over the next thirty years, the world of intelligent technology will accelerate, which will greatly change communication, transportation and our daily lives. By making energy storage smarter, devices will become invisible to us by working automatically and interactively with appliances. Our smart cells are a great example of how the user experience might be improved and they show enormous potential as portable power supply in future applications.”

Tags:  Chinese Academy of Sciences  Electric Vehicle  Energy Storage  Feng li  Graphene  Ivan Parkin  Supercapacitor  University College London  Zhuangnan Li 

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Global Graphene Group Named R&D 100 Award Finalist

Posted By Graphene Council, Friday, January 17, 2020
Global Graphene Group (G3) was honored recently by R&D World, naming G3’sgraphene-protected lithium metal anode for rechargeable metal batteries solution (HELiX™) a finalist for the 2019 R&D100 Award. The R&D 100 Awards recognize the top 100 most technologically significant new products of the year. 

HELiX is a single-layer graphene-protected lithium metal technology making high-energy rechargeable metal batteries viable. It allows extremely low anode usage (anode/cathode ratio ≤ 10%), creating an energy density over 350 Wh/kg and 1,000 Wh/L, which yields a 60-80% improvement over current lithium-ion batteries. This offers unprecedented opportunities for advanced portable devices/electric vehicles.

HELiX is a readily available, drop-in, graphene-enabled anode solution for all types of high-energy, lithium metal batteries (e.g. advanced Li-ion, all solid-state batteries, Li-S, Li-Se, and Li-air cells). It adds immediate value to any rechargeable battery, including, but not limited to power drones, renewable energy storage systems, aerospace applications, unmanned vehicles, and electric vehicles (EVs). Additionally, due to its performance, batteries can be reduced in size by 30-40% while still providing the required energy. This provides room for other components or allows for significant reductions in size and weight.  The most promising opportunity for HELiX graphene-enabled anode solutions is inEV batteries, where it can replace incumbent (graphite) technology today and drive an accelerated adoption of EVs due to improved cost and performance. 

“Rechargeable lithium metal batteries for next-generation portable devices and EVs must meet several challenging requirements: safety, high energy density, long cycle life, and low cost.This is the end-goal laid out by nearly every EV manufacturer for the foreseeable future,” said Dr. Aruna Zhamu, VP of New Product / Process Development at G3. 

“Global Graphene Group has developed an enabling anode-protecting technology that is essential to successful operation of safe, high-energy and long-cycle-life lithium metal batteries working with liquid, quasi-solid, or solid electrolytes,” continued Dr. Zhamu.“This HELiX product has overcome the long-standing issues thus far impeding successful commercialization of all the rechargeable batteries that make use of lithium metal as the anode material. OurHELiX technology is available and offers a drop-in, scalable, facile, cost reducing improvement over current solutions. It lowers the battery cost to less than$100 US$/kWh.”

G3 developed and produces the HELiX solution in its Dayton, Ohio, facilities. G3 was named an R&D 100 winner in 2018 for its graphene-enabled silicon anode (GCATM).

Tags:  Aruna Zhamu  Batteries  electric vehicle  Energy Storage  Global Graphene Group  Graphene  Li-Ion batteries  Lithium 

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XG Sciences and Perpetuus Partner to Supply Graphene to the North American Tire Markets

Posted By Graphene Council, Wednesday, December 11, 2019
XG Sciences, Inc., a market leader in the design and manufacture of graphene nanoplatelets and advanced materials containing graphene nanoplatelets, announced it has  entered into Commercialization and License Agreements with Perpetuus Advance Materials, a market leader in the production of dispersible, surface-modified graphene to optimize their performance in a range of matrices and end-use markets.

The Agreements provide the commercial framework allowing the two companies to more closely collaborate in the exclusive supply of functionalized graphene into the North American market and to also collaboratively develop applications for the global marketplace.  Initially, the Companies will focus efforts on elastomers, with an emphasis on tires and related applications, but may expand the relationship over time to include other markets and applications.  Under the Agreements, Perpetuus will locate one or more of its patented, plasma-based surfaces-modification production plants in the U.S. near one of XG Sciences’ graphene nanoplatelet production facilities.  The collaboration contemplates both product development collaboration and high-volume commercial supply.

First isolated and characterized in 2004, graphene is a single layer of carbon atoms. Among many noted properties, monolayer graphene is harder than diamonds, lighter than steel but significantly stronger, and conducts electricity better than copper. Graphene nanoplatelets are particles consisting of multiple layers of graphene with unique capabilities for energy storage, thermal conductivity, electrical conductivity, barrier properties, lubricity and the ability to impart physical property improvements when incorporated into plastics, metals or other matrices.

“We have been working with Perpetuus in various commercial and development efforts for the past several years.  This Agreement represents a key milestone in the commercial adoption of graphene and establishes XG Sciences and Perpetuus as marque players in the supply of graphene for use in tire elastomers and other applications,” said Dr. Philip Rose, CEO, XG Sciences. “The North American elastomer market, especially those used in tires is substantial.   Perpetuus has unique technology with demonstrated performance enhancements when incorporated into tires.  Tires will likely represent one of the break-out applications for graphene and we are now well-positioned with Perpetuus to deliver solutions to the elastomer market,” said Bamidele Ali, Chief Commercial Officer, XG Sciences.

“XG Sciences is a well-known leader in the graphene field and is an ideal choice with whom to partner to bring our technology to this important market,” said John Buckland, CEO, Perpetuus.

“We are familiar with XG Sciences’ graphene nanoplatelets and we have been utilizing them as input materials to our patented, surface-modification process and supplying the resulting high-performance graphenes to both commercial and developmental customers in a range of applications and markets.  It is a natural fit to partner our two Companies and leverage our respective capabilities to serve the North American market for elastomers,” said Ian Walters, Director and COO, Perpetuus.

Tags:  Bamidele Ali  energy storage  Graphene  Perpetuus Advanced Materials  Philip Rose  Tires  XG Sciences 

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Robust electrodes could pave the way to lighter electric vehicles

Posted By Graphene Council, Tuesday, December 3, 2019
One of the biggest remaining problems facing electric vehicles – whether they are road-going, waterborne or flying – is weight. Vehicles must carry their energy storage, and in the case of electric vehicles this inevitably means batteries.

No matter how many advances electrical engineers make in improving energy density, batteries remain dense and heavy components, and this is a drag on vehicle performance.

One approach to reducing the weight of electric vehicles might be to incorporate energy storage into the structure of the vehicle itself, thereby distributing the mass all over the vehicle and reducing the need for a single large battery or even eliminating it altogether.

The stumbling block to this approach is that materials that are good for energy storage and release tend to have properties that are not useful for structural applications: they are often brittle, which has obvious safety implications.

A team led by a Texas A&M University chemical engineer, Jodie Lutkenhaus, now claims to have made progress towards solving this problem using an approach inspired by brain chemistry and a trick employed by shellfish to stick themselves to rocks.

In a paper in the journal Matter, Lutkenhaus and her colleagues explain how their studies of redox active polymers for energy storage led them to investigate the properties of dopamine, most familiar as a signal-carrying molecule in the brain involved in movement, but also a very sticky substance that mimics proteins found in the material that mussels use to fasten themselves tightly to any surface underwater.

The team used dopamine to functionalise – that is, chemically bond to – graphene oxide, and then combine this material into a composite with aramid fibres, better known as Kevlar. This composite is both strong and tough, with a structure and properties similar to the famously tough natural material nacre or mother-of-pearl, and the graphene in its structure conveys both lightness and electrical properties that make it useful as an electrode.

The researchers describe using this material to form the electrodes for a super capacitor, a kind of energy storage device which can be charged and discharged very quickly.

The paper reports the highest ever multifunctional efficiency (a metric which evaluates material based on both its mechanical and electrochemical performance) for graphene-based materials.

Tags:  batteries  electric vehicle  energy storage  Graphene  graphene oxide  Jodie Lutkenhaus  Journal Matter  mimics proteins  polymers  super capacitor  Texas A&M University 

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ZEN Graphene Solutions Reports Preliminary Results for Graphene Aerogel Battery Tests

Posted By Graphene Council, Tuesday, November 26, 2019
Updated: Tuesday, November 26, 2019
ZEN Graphene Solutions and its research partner, Deutsches Zentrum fur Luft- und Raumfahrt are pleased to report on additional encouraging results from their battery development program led by Dr. Lukas Bichler and his team at the University of British Columbia, Okanagan Campus (UBC-O). UBC-O has created a Graphene Aerogel composite anode material using a proprietary aerogel formulation containing doping with either ZEN’s reduced Graphene Oxide (rGO) or Graphene Preliminary results indicate that relatively low loadings (<5 wt.%) of graphene-based material, combined with this proprietary aerogel structure, can result in an anode with a significant specific discharge capacity. 

Preliminary best results were achieved with a 2 wt.% loading of Graphene dispersed in aerogel and resulted in an initial specific discharge capacity of 2800 mAh/g and a discharge capacity of 1300 mAh/g after 50 cycles at a current capacity of 186 mA/g. These unoptimized results are believed to be better than those currently reported in the literature for Graphene Aerogel batteries. DLR and ZEN will present a poster of the battery results at the Batterieforum in Berlin, Germany in January 2020. Graphene-containing aerogels could have the potential to be a low-cost, low-weight, high-performance composite materials for near future energy storage applications.

DLR has applied for and received federal funding from the Helmholtz Association to create a new Helmholtz Innovation Lab, called ZAIT, or the Center for Aerogels in Industry and Technology, which will be working together with industrial partners on the development of Aerogels. ZEN supported this application with a letter of intent indicating the Company would continue to collaborate with DLR in developing graphene-based aerogel batteries and other graphene-based products.

“Our work with the team at DLR has led to very promising research and we look forward to continuing this research both at UBC-O and within the new Center for Aerogels in Industry and Technology (ZAIT), a Helmholtz Innovation Lab” commented ZEN CEO Dr. Francis Dubé. Also, Dr. Bichler indicated that “this partnership brings together expertise from Canada and Germany to jointly develop high-tech energy storage systems, which are currently not available on the market”.

Tags:  Batteries  Deutsches Zentrum fur Luft- und Raumfahrt  Energy Storage  Francis Dubé  Graphene  graphene oxide  Lukas Bichler  University of British Columbia  ZEN Graphene Solutions 

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First Graphene to develop graphene-based energy storage materials for supercapacitors

Posted By Graphene Council, Tuesday, September 24, 2019
First Graphene has signed an exclusive worldwide licensing agreement with the University of Manchester to develop graphene-hybrid materials for use in supercapacitors. The licencing agreement is for patented technology for the manufacture of metal oxide decorated graphene materials, using a proprietary electrochemical process.

The graphene-hybrid materials will have the potential to create a new generation of supercapacitors, for use in applications ranging from electric vehicles to elevators and cranes. Supercapacitors offer high power-density energy storage, with the possibility of multiple charge/discharge cycles and short charging times. The market for supercapacitor devices is forecast to grow at 20% per year to approximately USD 2.1 billion by 2022. Growth may, however, be limited by the availability of suitable
materials.

Supercapacitors typically use microporous carbon nanomaterials, which have a gravimetric capacitance between 50 and 150 Farads/g. Research carried out by the University of Manchester shows that high capacitance materials incorporating graphene are capable of reaching up to 500 Farads/g. This will significantly increase the operational performance of supercapacitors in a wide range of applications, as well as increasing the available supply of materials.

Published research1 by Prof. Robert Dryfe and Prof. Ian Kinloch of The University of Manchester reveals how high capacity, microporous materials can be manufactured by the electrochemical processing of graphite raw materials. These use transition metal ions to create metal oxide decorated graphene materials, which have an extremely high gravimetric capacitance, to 500 Farads/g.

Prof. Dryfe has secured funding from the UK EPSRC (Engineering and Physical Sciences Council) for further optimisation of metal oxide/graphene materials. Following successful completion of this study, FGR is planning to build a pilot-scale production unit at its laboratories within the Graphene Engineering and Innovation Centre (GEIC). It is anticipated that this will be the first step in volume production in the UK, to enable the introduction of these materials to supercapacitor device manufacturers.

Andy Goodwin, Chief Technology Officer of First Graphene Ltd says: “This investment is a direct result of our presence at the Graphene Engineering and Innovation Centre. It emphasises the importance of effective external relationships with university research partners. The programme is also aligned with the UK government’s industrial strategy grand challenges and we’ll be pursuing further support for the development of our business within the UK.”

James Baker, Chief Executive of Graphene@Manchester, added: “We are really pleased with this further development of our partnership with First Graphene. The University’s Graphene Engineering Innovation Centre is playing a key role in supporting the acceleration of graphene products and applications through the development of a critical supply chain of material supply and in the development of applications for industry. This latest announcement marks a significant step in our Graphene City developments, which looks to create a unique innovation ecosystem here in the Manchester city-region, the home of graphene.”

Tags:  Andy Goodwin  Energy Storage  First Graphene  Graphene  Graphene Engineering and Innovation Centre  Ian Kinloch  James Baker  nanomaterials  Robert Dryfe  supercapacitors  University of Manchester 

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High-safety, flexible and scalable Zn//MnO2 rechargeable planar micro-batteries

Posted By Graphene Council, Thursday, July 18, 2019
Updated: Monday, July 15, 2019
Increasing development of micro-scale electronics has stimulated demand of the corresponding micro-scale power sources, especially for micro-batteries (MBs). However, complex manufacturing process and poor flexibility of the traditional stacked batteries have hindered their practical applications.

Planar MBs have recently garnered great attention due to their simple miniaturization, facile serial/parallel integration and capability of working without separator membranes. Furthermore, planar geometry has extremely short ion diffusion pathway, which is attributed to full integration of printed electronics on a single substrate. Also, in order to get rid of the safety issues induced by the flammable organic electrolyte, the aqueous electrolyte, characterized by intrinsic nonflammability, high ionic conductivity, and nontoxicity, is a promising candidate for large-scale wearable and flexible MB applications. As the consequence, various printing techniques have been used for fabricating planar aqueous MBs. "In particular, screen printing can effectively control the precise pattern design with adjustable rheology of the inks, and is very promising for large-scale application." The author said.

In a new article published in Beijing-based National Science Review, Zhong-Shuai Wu at Dalian Institute of Chemical Physics, Chinese Academy of Sciences, constructed aqueous rechargeable planar Zn//MnO2 batteries by an applicable and cost-effective screen printing strategy. "The planar Zn//MnO2 micro-batteries, free of separators, were manufactured by directly printing the zinc ink as the anode and γ-MnO2 ink as the cathode, high-quality graphene ink as metal-free current collectors, working in environmentally benign neutral aqueous electrolytes of 2 M ZnSO4 and 0.5 M MnSO4." The author stated. Diverse shapes of Zn//MnO2 MBs were fabricated onto different substrates, implying the potential for widespread applications.

The planar separator-free Zn//MnO2 MBs, tested in neutral aqueous electrolyte, deliver high volumetric capacity of 19.3 mAh/cm3 (corresponding to 393 mAh/g), at 7.5 mA/cm3, and notable volumetric energy density of 17.3 mWh/cm3, outperforming lithium thin-film batteries (<=10 mWh/cm3). Moreover, The Zn//MnO2 planar MBs present long-term cyclability, holding high capacity retention of 83.9% after 1300 times at 5 C, superior to stacked Zn//MnO2 MBs reported. Also, Zn//MnO2 planar MBs exhibit exceptional flexibility without observable capacity decay under serious deformation, and remarkable serial and parallel integration of constructing bipolar cells with high voltage and capacity output.

This satisfactory result will open numerous intriguing opportunities in various applications of intelligent, printed and miniaturized electronics. Also, this work will inspire scientists working in nanotechnology, chemistry, material science and energy storage, and may have significant impact on both future technological development of planar micro-scale energy-storage devices and research of graphene based materials.

Tags:  Batteries  Dalian Institute of Chemical Physics  Energy Storage  Graphene  Zhong-Shuai Wu 

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SOLAR-POWERED SUPERCAPACITORS COULD CREATE FLEXIBLE, WEARABLE ELECTRONICS

Posted By Graphene Council, Wednesday, February 27, 2019
Updated: Wednesday, February 27, 2019
A breakthrough in energy storage technology could bring a new generation of flexible electronic devices to life, including solar-powered prosthetics for amputees.

In a new paper published in the journal Advanced Science, a team of engineers from the University of Glasgow discuss how they have used layers of graphene and polyurethane to create a flexible supercapacitor which can generate power from the sun and store excess energy for later use.

They demonstrate the effectiveness of their new material by powering a series of devices, including a string of 84 power-hungry LEDs and the high-torque motors in a prosthetic hand, allowing it to grasp a series of objects.

The research towards energy autonomous e-skin and wearables is the latest development from the University of Glasgow’s Bendable Electronics and Sensing Technologies (BEST) research group, led by Professor Ravinder Dahiya.

The top touch sensitive layer developed by the BEST group researchers is made from graphene, a highly flexible, transparent ‘super-material’ form of carbon layers just one atom thick.

Sunlight which passes through the top layer of graphene is used to generate power via a layer of flexible photovoltaic cells below. Any surplus power is stored in a newly-developed supercapacitor, made from a graphite-polyurethane composite.

The team worked to develop a ratio of graphite to polyurethane which provides a relatively large, electroactive surface area where power-generating chemical reactions can take place, creating an energy-dense flexible supercapacitor which can be charged and discharged very quickly.

Similar supercapacitors developed previously have delivered voltages of one volt or less, making single supercapacitors largely unsuited for powering many electronic devices. The team’s new supercapacitor can deliver 2.5 volts, making it more suited for many common applications.

In laboratory tests, the supercapacitor has been powered, discharged and powered again 15,000 times with no significant loss in its ability to store the power it generates.

Professor Ravinder Dahiya, Professor of Electronics and Nanoengineering at the University of Glasgow’s School of Engineering, who led this research said: “This is the latest development in a string of successes we’ve had in creating flexible, graphene based devices which are capable of powering themselves from sunlight.

“Our previous generation of flexible e-skin needed around 20 nanowatts per square centimetre for its operation, which is so low that we were getting surplus energy even with the lowest-quality photovoltaic cells on the market.

“We were keen to see what we could do to capture that extra energy and store it for use at a later time, but we weren’t satisfied with current types of energy storages devices such as batteries to do the job, as they are often heavy, non-flexible, prone to getting hot, and slow to charge.

“Our new flexible supercapacitor, which is made from inexpensive materials, takes us some distance towards our ultimate goal of creating entirely self-sufficient flexible, solar-powered devices which can store the power they generate.

“There’s huge potential for devices such as prosthetics, wearable health monitors, and electric vehicles which incorporate this technology, and we’re keen to continue refining and improving the breakthroughs we’ve made already in this field.”

The team’s paper, titled ‘Graphene-Graphite Polyurethane Composites based High-Energy Density Flexible Supercapacitors’, is published in Advanced Science. The research was funded by the Engineering and Physical Sciences Research Council (EPSRC).

Tags:  energy storage  Graphene  Ravinder Dahiya  University of Glasgow 

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Graphene Lays Foundation for Fast Charging High Capacity Li-ion Batteries

Posted By Dexter Johnson, IEEE Spectrum, Thursday, June 14, 2018

Prof. Dina Fattakhova-Rohlfing. (Image: FZ Juelich)

Graphene has been earmarked for energy storage applications for years. The fact that graphene is just surface area is very appealing to battery applications in which anodes and electrodes store energy in the material that covers them.

With lithium ion (Li-ion) batteries representing the most ubiquitous battery technology, with uses ranging from our smart phones to electric cars, increasing their storage capacity and shortening their charging times with graphene has been a big research push. 

Unfortunately, the prospects for graphene in energy storage have been stalled for years. This is in part due to the fact that while graphene is all surface area, in order to get anywhere near the kind of storage capacity of today’s activated carbon you need to layer graphene. The result after enough layering is you end up back with graphite, defeating the purpose of using graphene in the first place.

Now a team of German researchers has developed an approach for improving the anodes of Li-ion batteries that uses graphene in support of tin oxide nanoparticles.

"In principle, anodes based on tin dioxide can achieve much higher specific capacities, and therefore store more energy, than the carbon anodes currently being used. They have the ability to absorb more lithium ions," said Dian Fattakhova-Rohlfing, a researcher at Forschungszentrum Jülich research institute in Germain, in a press release. "Pure tin oxide, however, exhibits very weak cycle stability – the storage capability of the batteries steadily decreases and they can only be recharged a few times. The volume of the anode changes with each charging and discharging cycle, which leads to it crumbling."

The research described in the Wiley journal Advanced Functional Materials, uses graphene as a base layer in a hybrid nanocomposite in which the tin oxide nanoparticles enriched with antimony are layered on top of the graphene. The graphene provides structural stability to the nanocomposite material.

The combination of the tin oxide nanoparticle being enriched with antimony makes them extremely conductive, according to Fattakhova-Rohlfing. "This makes the anode much quicker, meaning that it can store one-and-a-half times more energy in just one minute than would be possible with conventional graphite anodes. It can even store three times more energy for the usual charging time of one hour."

The scientists found that in contrast to most batteries the high energy density did not have to come with very slow charging rates. Anybody who has a smartphone knows how long it takes to charge it to 100 percent.

"Such high energy densities were only previously achieved with low charging rates," says Fattakhova-Rohlfing. "Faster charging cycles always led to a quick reduction in capacity."

In contrast, the research found that their antimony-doped anodes retain 77 percent of their original capacity even after 1,000 cycles.

Because tin oxide is abundant and cheap, the scientists claim that the nanocomposite anodes can be produced in an easy and cost-effective way.

Fattakhova-Rohlfing added: "We hope that our development will pave the way for lithium-ion batteries with a significantly increased energy density and very short charging time."

Tags:  energy storage  Li-ion batteries  nanocomposites  nanoparticles 

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