Graphene and batteries

Graphene, a sheet of carbon atoms bound together in a honeycomb lattice pattern, is hugely recognized as a “wonder material” due to the myriad of astonishing attributes it holds. It is a potent conductor of electrical and thermal energy, extremely lightweight chemically inert, and flexible with a large surface area. It is also considered eco-friendly and sustainable, with unlimited possibilities for numerous applications.

In the field of batteries, conventional battery electrode materials (and prospective ones) are significantly improved when enhanced with graphene. Graphene can make batteries that are light, durable and suitable for high capacity energy storage, as well as shorten charging times. It will extend the battery’s life-time, which is negatively linked to the amount of carbon that is coated on the material or added to electrodes to achieve conductivity, and graphene adds conductivity without requiring the amounts of carbon that are used in conventional batteries.

Graphene can improve such battery attributes as energy density and form in various ways. Li-ion batteries can be enhanced by introducing graphene to the battery’s anode and capitalizing on the material’s conductivity and large surface area traits to achieve morphological optimization and performance.

It has also been discovered that creating hybrid materials can also be useful for achieving battery enhancement. A hybrid of Vanadium Oxide (VO2) and graphene, for example, can be used on Li-ion cathodes and grant quick charge and discharge as well as large charge cycle durability. In this case, VO2 offers high energy capacity but poor electrical conductivity, which can be solved by using graphene as a sort of a structural “backbone” on which to attach VO2 - creating a hybrid material that has both heightened capacity and excellent conductivity.

Another example is LFP ( Lithium Iron Phosphate) batteries, that is a kind of rechargeable Li-ion battery. It has a lower energy density than other Li-ion batteries but a higher power density (an indicator of of the rate at which energy can be supplied by the battery). Enhancing LFP cathodes with graphene allowed the batteries to be lightweight, charge much faster than Li-ion batteries and have a greater capacity than conventional LFP batteries.

In addition to revolutionizing the battery market, combined use of graphene batteries and supercapacitors could yield amazing results, like the noted concept of improving the electric car’s driving range and efficiency.

Battery basics

Batteries serve as a mobile source of power, allowing electricity-operated devices to work without being directly plugged into an outlet. While many types of batteries exist, the basic concept by which they function remains similar: one or more electrochemical cells convert stored chemical energy into electrical energy. A battery is usually made of a metal or plastic casing, containing a positive terminal (an anode), a negative terminal (a cathode) and electrolytes that allow ions to move between them. A separator (a permeable polymeric membrane) creates a barrier between the anode and cathode to prevent electrical short circuits while also allowing the transport of ionic charge carriers that are needed to close the circuit during the passage of current. Finally, a collector is used to conduct the charge outside the battery, through the connected device.

Eneloop battery design

When the circuit between the two terminals is completed, the battery produces electricity through a series of reactions. The anode experiences an oxidation reaction in which two or more ions from the electrolyte combine with the anode to produce a compound, releasing electrons. At the same time, the cathode goes through a reduction reaction in which the cathode substance, ions and free electrons combine into compounds. Simply put, the anode reaction produces electrons while the reaction in the cathode absorbs them and from that process electricity is produced. The battery will continue to produce electricity until electrodes run out of necessary substance for creation of reactions.

Battery types and characteristics

Batteries are divided into two main types: primary and secondary. Primary batteries (disposable), are used once and rendered useless as the electrode materials in them irreversibly change during charging. Common examples are the zinc-carbon battery as well as the alkaline battery used in toys, flashlights and a multitude of portable devices. Secondary batteries (rechargeable), can be discharged and recharged multiple times as the original composition of the electrodes is able to regain functionality. Examples include lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics.

Batteries come in various shapes and sizes for countless different purposes. Different kinds of batteries display varied advantages and disadvantages. Nickel-Cadmium (NiCd) batteries are relatively low in energy density and are used where long life, high discharge rate and economical price are key. They can be found in video cameras and power tools, among other uses. NiCd batteries contain toxic metals and are environmentally unfriendly. Nickel-Metal hydride batteries have a higher energy density than NiCd ones, but also a shorter cycle-life. Applications include mobile phones and laptops. Lead-Acid batteries are heavy and play an important role in large power applications, where weight is not of the essence but economic price is. They are prevalent in uses like hospital equipment and emergency lighting.

Lithium-Ion (Li-ion) batteries are used where high-energy and minimal weight are important, but the technology is fragile and a protection circuit is required to assure safety. Applications include cell phones and various kinds of computers. Lithium Ion Polymer (Li-ion polymer) batteries are mostly found in mobile phones. They are lightweight and enjoy a slimmer form than that of Li-ion batteries. They are also usually safer and have longer lives. However, they seem to be less prevalent since Li-ion batteries are cheaper to manufacture and have higher energy density.

Batteries and supercapacitors

While there are certain types of batteries that are able to store a large amount of energy, they are very large, heavy and release energy slowly. Capacitors, on the other hand, are able to charge and discharge quickly but hold much less energy than a battery. The use of graphene in this area, though, presents exciting new possibilities for energy storage, with high charge and discharge rates and even economical affordability. Graphene-improved performance thereby blurs the conventional line of distinction between supercapacitors and batteries.

Li-Polymer battery vs Supercapacitor structure

Commercial Graphene-enhanced battery products

Graphene-based batteries have exciting potential and while they are not commercially available yet, R&D is intensive and will hopefully yield results in the future.

In November 2016, Huawei unveiled a new graphene-enhanced Li-Ion battery that can remain functional at higher temperature (60° degrees as opposed to the existing 50° limit) and offers a longer operation time - double than what can be achieved with previous batteries. To achieve this breakthrough, Huawei incorporated several new technologies - including an anti-decomposition additives in the electrolyte, chemically stabilized single crystal cathodes - and graphene to facilitate heat dissipation. Huawei says that the graphene reduces the battery's operating temperature by 5 degrees.

In June 2014, US based Vorbeck Materials announced the Vor-Power strap, a lightweight flexible power source that can be attached to any existing bag strap to enable a mobile charging station (via 2 USB and one micro USB ports). the product weighs 450 grams, provides 7,200 mAh and is probably the world’s first graphene-enhanced battery.

In May 2014, American company Angstron Materials rolled out several new graphene products. The products, said to become available roughly around the end of 2014, include a line of graphene-enhanced anode materials for Lithium-ion batteries. The battery materials were named “NANO GCA” and are supposed to result in a high capacity anode, capable of supporting hundreds of charge/discharge cycles by combining high capacity silicon with mechanically reinforcing and conductive graphene.

Graphene batteries market report

Developments are also made in the field of graphene batteries for electric vehicles. Henrik Fisker, who announced its new EV project that will sport a graphene-enhanced battery, unveiled in November 2016 what is hoped to be a competitor to Tesla. Called EMotion, the electric sports car will reportedly achieve a 161 mph (259 kmh) top speed and a 400-mile electric range.

Graphene Nanochem and Sync R&D’s October 2014 plan to co-develop graphene-enhanced Li-ion batteries for electric buses, under the Electric Bus 1 Malaysia program, is another example.

In August 2014, Tesla suggested the development of a "new battery technology" that will almost double the capacity for their Model S electric car. It is unofficial but reasonable to assume graphene involvement in this battery.

UK based Perpetuus Carbon Group and OXIS Energy agreed in June 2014 to co-develop graphene-based electrodes for Lithium-Sulphur batteries, which will offer improved energy density and possibly enable electric cars to drive a much longer distance on a single battery charge.

Another interesting venture, announced in September 2014 by US based Graphene 3D Labs, regards plans to print 3D graphene batteries. These graphene-based batteries can potentially outperform current commercial batteries as well as be tailored to various shapes and sizes.

Other prominent companies which declared intentions to develop and commercialize graphene-enhanced battery products are: Grafoid, SiNode together with AZ Electronic Materials, XG Sciences, Graphene Batteries together with CVD Equipment and CalBattery.

Further reading

Latest Graphene Batteries news

Researchers succeed in imaging how electrons move in graphene

Apr 27, 2017

Researchers at the University of Melbourne succeeded in imaging how electrons move in 2D graphene, an achievement which may boost the development of next-generation electronics. The new technique overcomes usual limitations of existing methods for understanding electric currents in devices based on ultra-thin materials, and so it is capable of imaging the behavior of moving electrons in structures only one atom in thickness.

Mapping electrons in graphene using diamonds image

The team used a special quantum probe based on an atomic-sized 'color center' found only in diamonds to image the flow of electric currents in graphene. The technique could be used to understand electron behavior in a variety of new technologies.

Defects in graphene membranes enable selective passage of molecules

Apr 26, 2017

Researchers from the Clemson Nanomaterials Institute and the Ural Federal University in Russia have discovered a way to make an extremely thin oxygen selective membrane using graphene. Such membranes allow only oxygen into Li-O2 batteries while stopping or slowing water vapor intake. This could impede corrosion caused by ambient water vapor from air and push forward the usability of much-awaited Li-O2 batteries in electric vehicles and more.

Graphene membrane defects to aid batteries image

The team has developed an in situ technique to induce pores in graphene by doping it with nitrogen during the growth process. Doping the graphene sheet with nitrogen inevitably breaks some carbon bonds in graphene, opening nanoscopic pores. The researchers observed that such pores in doped graphene selectively allow oxygen, leading to oxidation of the underlying copper foil, unlike pristine graphene.

Graphene Investment Guide

Graphene-based "sponge" can improve Li-ion batteries

Apr 25, 2017

Researchers from Nec Corporation have developed a graphene-based porous material, dubbed "Magic G", that can reportedly be used in both the anode and the cathode of a lithium-ion battery, as an additive, to increase its performance.

Both the precursor and the final Magic G product were characterized through commercially available machines and methods, including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR), Raman spectroscopy (NRS-7000), gas adsorption and temperature programmed desorption–mass spectrometry (TPD-MS) (Shimadzu GC/MS- QP2010 Plus). Both the anode and cathode of the cell showed a much greater performance and charge rate after the incorporation of Magic G.

Saint Jean Carbon provides phase one results of graphene-based battery project

Apr 23, 2017

Saint Jean Carbon has reported the results of the first phase of its graphene battery project, announced in January, 2017. According to SJC, while primary at this point, the graphene battery has outperformed the graphite battery, as shown by a greater discharge capacity of about 30%. Both batteries were manufactured with the same material, battery “A” graphite anode and “B” graphene anode.

The company supplied performance results, among which are the graphite anode’s theoretical capacity of 372 mAh/g and the theoretical capacity of the graphene anode of 700 mAh/g. Beyond 100 cycles the discharge capacity for the graphite was 200 to 220 mAh/g and for the graphene 310 to 330 mAh/g. The testing processes included charging to 3V at 500 mA/g and discharging to 0.05V at 100 mA/g. SJC said that neither the graphene nor graphite was enhanced so the variations in the results have to be additionally tested.

HKG plans to manufacture cars with graphene-enhanced batteries

Apr 20, 2017

China's Hybrid Kinetic Group, a producer of lithium-ion batteries and hybrid vehicles, announced its aim to build car assemblies in three to five locations across China, with an initial production capacity of 300,000 units within three years, eventually expanding the capacity to 1 million units. While not many details were given, it was said that some of the models are to be powered by a 30 kilowatt battery using graphene with a 60 kw micro turbine power generator that theoretically can extend the battery’s range to 1,000 kilometers on each charge.

HKG's car with graphene battery imageThe H600 prototype by HKG

HKG is using US technology, and has commissioned designs by the Mahindra Group’s design studio Pininfarina. The company stated that “expansion of the production will depend on the market reactions”. and that “negotiations with car part makers are going on smoothly.”