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New Graphene Supercapacitor Materials Offer Fast Charging for Electric Vehicles

Posted By Graphene Council, Monday, May 18, 2020
Introduction

Picture the scene, you are driving to a meeting and running late. The new company car is an electric vehicle (EV), power is running low and range anxiety is setting in. You pull into the service station on the motorway and head straight to the charging station. Instead of taking hours to charge, the car is fully charged in minutes. You pay at the fuel court and back on your way to the meeting in under 5 minutes. Welcome to the future.  Welcome to the world of graphene supercapacitors.

Batteries

We have seen dramatic improvements in battery technologies over recent years but range anxiety and the need for large battery powertrains for performance and commercial vehicles means that EV’s still have some way to go before they are universally accepted. EV’s are calling out for lightweight and more powerful powertrains. Capacitors and supercapacitors could be the answer.

Capacitors and Supercapacitors

Batteries provide high energy density, which means that they have the ability to provide power over a longer period, but they have low power density. Capacitors have a lower energy density but have a high power density and can charge and discharge very quickly providing high bursts of power when required.  In short, batteries are able to store more energy but capacitors can release energy more quickly.

Supercapacitors are generally categorised into three groups : electrostatic double-layer capacitors (EDLCs) using carbon electrodes, electrochemical pseudo-capacitors which use metal oxide or conducting polymer electrodes and hybrid capacitors such as the lithium-ion capacitor.  These differing electrodes – the first exhibiting mostly electrostatic capacitance and the others offer some chemical performance.

Supercapacitors, or ultracapacitors as they are sometimes called could be used in conjunction with batteries to provide powertrains at a reduced weight. Supercapacitors have the ability to tolerate high charge and discharge cycles and are capable of storing and discharging energy very quickly and effectively.  They can hold a much higher charge than traditional capacitors.  In vehicles, supercapacitors are predominantly used for regenerative braking.

Why are supercapacitors becoming important?

Lithium-ion battery technology has made huge advances and industry continues to make incremental improvements however, these do not meet the needs of the electric vehicle industry in terms of range, weight and cost. Supercapacitors can complement the chemical battery by providing bursts of energy when required, such as moving a large truck from a standing stop or short-term surge of power to accelerate a high-performance sports car.  Combining both battery and supercapacitor technologies into a new hybrid battery could satisfy both short and long-term power needs, reducing stress on the battery at peak loads, leading to longer service life.  Potentially, this could lead to smaller, lighter battery packs and vehicles due to supercapacitors taking part of the load and extending the range of EV’s.

Examples of Supercapacitor Applications

• Private and public electrical vehicles
• Port-cranes
• Automotives
• Rail sectors
• Grid energy storage
• Smart phones
• Other consumer electronics
• Sensors
• Wireless sensor networks
• Stationary storage
• Renewables integration
• Industrial vehicles
• Electric & hybrid buses
• Replacement for lead-acid batteries in trucks
• Provide burst of power in lifting operations – cranes, diggers etc.
• Provide fast flow of energy to data centres between power failures and initiation of backup power systems
• Uninterruptible Power Systems (UPS) – for back-up power systems, for example in data centres
• Actuators (Aircraft emergency doors)
• Work in conjunction with lithium-ion batteries or lead-acid batteries in vehicles like forklifts

Why Graphene-based supercapacitors?

It is clear that supercapacitors are a promising supplement to lithium-ion batteries, offering significantly high-power densities, resilience to multiple charge/discharge cycles and short charging times. However, growth in the supercapacitor market may be stifled by the limited capacitance of current materials and the inability of suppliers to effectively scale-up production. Graphene-based materials are a highly suitable alternative to these technologies.

Graphene-based capacitors are lightweight and have a relatively low-cost vs performance ratio.  Graphene lends far more strength compared with activated carbon.  In addition, graphene has a surface area even larger than that of activated carbon used to coat the plates of traditional supercapacitors, enabling better electrostatic charge storage. Graphene-based supercapacitors can store almost as much energy as lithium-ion batteries, charge and discharge in seconds and maintain these properties through tens of thousands of charging cycles.

Professors at the University of Manchester have developed an electrochemical process that enables the production of microporous, metal oxide-decorated graphene materials from graphite. Conventional activated carbon has a gravimetric capacitance of 50-150 Farads per gram, whereas laboratory trials show that these new graphene materials demonstrate a gravimetric capacitance of up to 500 Farads per gram.

Tags:  Batteries  electric vehicle  Graphene  Graphite  Li-ion batteries  supercapacitors  University of Manchester 

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Talga Resources : in Bentley Motors Electric Drive Project

Posted By Graphene Council, Monday, April 27, 2020
Battery anode and graphene additives provider Talga Resources Ltd is pleased to announce it has been approved for Innovate UK co-funding to support development of an e-axle designed for Bentley Motors.

The OCTOPUS project aims to deliver the ultimate single unit e-axle solution designed specifically to meet Bentley Motors performance specifications via optimised motor and power electronics technology and materials. The project is funded under the Office for Low Emission Vehicles' and Innovate UK's 'IDP15: The Road to Zero Emission Vehicles' competition.

Under the project Talga will develop and provide graphene materials for the high performance electric motor windings to deliver an aluminium-based solution aimed at outperforming, and ultimately replacing, the copper windings currently used.

The improved motor windings form part of the project's aim of developing next generation lightweight high performance component systems that integrate the latest advanced materials and manufacturing techniques. The components are to be tested at sub-system and system level for an integration route into future e-axle designs.

Talga Managing Director, Mark Thompson: 'We are delighted to engage in jointly developing Bentley Motors' e-axle concept with our consortium partners and are honoured to have earned Innovate UK's continued support.

The successful use of Talga graphene material to lend aluminium the properties required to outperform copper in electric motors would be a big advancement. For automotive manufacturers this could reduce vehicle weight and increase performance, safety and driving range while retaining sustainability and economics. Lightweight and high performance automotive components perfectly complement our Li-ion battery anode products, and the advancement could pave the way for opportunities to replace copper wire in many large-scale applications globally.'

Tags:  Bentley Motors  Electric Vehicle  Graphene  Li-ion Batteries  Mark Thompson  Talga Resources 

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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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High-performance anode for all-solid-state Li batteries is made of Si nanoparticles

Posted By Graphene Council, Tuesday, December 31, 2019
A new study led by NIMS researchers reveals that, in solid electrolytes, a Si anode composed only of commercial Si nanoparticles prepared by spray deposition -- the method is a cost-effective, atmospheric technique -- exhibits excellent electrode performance, which has previously been observed only for film electrodes prepared by evaporation processes. This new result therefore suggests that a low-cost and large-scale production of high-capacity anodes for use in all-solid-state Li batteries is possible.

Si has a theoretical capacity of ~4,200 mAh/g, which is approximately 11 times higher than that of the graphite commonly used as the anode-active material in commercial Li-ion batteries. Replacing the traditional graphite by Si can extend significantly the driving range per charge of electric vehicles. However, its huge volume change (~300%) during lithiation and delithiation -- charge and discharge -- hinders its practical application in the batteries. In conventional liquid electrolytes, the use of polymeric binders is necessary to hold the active material particles in the electrode together and maintain their adhesion to the surface of metal current collectors. The repeated huge volume change of Si causes the particle isolation and thus leads to losing the active material, which results in a continuous capacity loss. In solid-state cells, the active material is placed between two solid components -- solid electrolyte separator layer and metal current collector --, which enables avoidance of tackling the problem -- electrical isolation of the active material --. In fact, as reported previously by the team of NIMS researchers, the sputter-deposited pure Si films delivering practical areal capacities exceeding 2.2 mAh/cm2 exhibit excellent cycling stability and high-rate discharge capabilities in solid electrolytes. Nonetheless, cost-effective and industrially scalable synthesis of the anode for all-solid-state Li batteries remains a great challenge.

The team of NIMS researchers has taken another synthesis approach toward develop the high-performance anode for all-solid-state Li batteries with commercial Si nanoparticles, and found a unique phenomenon to the nanoparticles in the solid-state cell: upon lithiation, they undergo volume expansion, structural compaction, and appreciable coalescence in the confined space between the solid electrolyte separator layer and metal current collector to form a continuous film similar to that prepared by the evaporation process. The anode composed of nanoparticles prepared by spray deposition therefore exhibits excellent electrode performance, which has previously been observed only for sputter-deposited film electrodes. The spray deposition method is a cost-effective, atmospheric technique that can be used for large-scale production. Hence, the findings will pave the way for low-cost and large-scale production of high-capacity anodes for use in all-solid-state Li batteries.

Continuing efforts by the team of NIMS researchers to improve the cyclability in the anode having the increased areal mass loading of nanoparticles are in progress to meet the requirements of electric vehicles.

Tags:  Electric Vehicle  Graphene  Graphite  Li-ion batteries  nanoparticles  National Institute for Materials Science 

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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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