Tesla Developing 500-mile Graphene Battery?

Elon Musk has bet his fortune on the future electric cars, and he knows that Tesla has to stay on the forefront of battery technology. One of the most promises advancements in battery tech is graphene-based anodes, which have been proven to more than quadruple lithium-ion battery density.

A report from China’s Xinhua news agency claims that Tesla is working on a new graphene battery that could almost double the range of the Model S to some 500 miles. This follows up on Musk’s assertion that Tesla could offer a 500-mile battery “soon”, but only if it makes financial sense.

Graphene could be what makes long-range EVs finally viable, though the technology has been in the works for some time now. As well as increasing energy density, graphene also allows for faster charging of batteries, opening the ion-highway to faster fill-ups. Whichever company can come up with a long-range, fast-charging, and (most importantly) fiscally viable electric car battery will be at a huge advantage going forward. Tesla needs to be that company if the $5 billion battery Gigafactory is going to be the game changer Musk thinks it will be.

A 500-mile Tesla Model S would all but eliminate the effects of range anxiety and could give Tesla the means to dominate the growing electric car market. That would be more driving range than even most conventional cars offer, though the price would likely be in the six-digits…at least at first. The average driver rarely exceeds 100 miles of total driving per day, and 200 miles per charge seems to be the magic number the Tesla Model III is aiming for. Then again, Musk seems confident that there hasn’t been a legitimate battery advancement yet, and that when it does comes, Tesla will know about it first.

Could a graphene-anode battery be the technology that puts Tesla at its place on top of the EV market? Or is there another technology (like aluminum-air batteries) that Tesla is trying to develop?

Source: Gas2

South Korean engineers find graphene electrodes can recharge in 16 seconds

Yes, one day, you too may be able to fully recharge your plug-in vehicle's battery in the amount of time it takes to decelerate down one of those runaway truck ramps. Assuming your brakes actually work, of course.

Engineers at South Korea's Gwangju Institute of Science and Technology are researching the concept ofgraphene supercapacitors and how they can be applied to plug-in vehicle technology, Technology Reviewsays. A simplified explanation is that the engineers have created an extremely porous version of graphene, turned it into a powder (which makes its surface area larger) and packed the powder into a cell.

The fun part is that the new graphene electrode was tested to provide almost as much charge as a fully recharged lithium-ion battery, with the amazing benefit of only needing about 16 seconds to recharge, raising interesting possibilities for applying the technology to a regenerative braking system. And the electrode was tested 10,000 times and didn't suffer capacity reduction. Cornell University published a version of the studyhere.

The idea of using graphene, a crystalline form of carbon, for automotive technology, is continuously being researched. Earlier this year, researchers from South Korea, Case Western University and University of North Texas said they discovered that a graphene-coated cathode may generate a greater battery current than a cathode covered with the more expensive but more traditional platinum. And in 2011, University of Technology Sydney researchers created a type of graphene "paper" that is stronger, lighter and less dense than steel. Such widespread use would enable automakers to cut vehicle weight and boost fuel efficiency as a result.

News Source: Technology Review

Image Credit: Flickr

Monash University team develops graphene-based supercapacitor with energy density of 60 Wh/L

A research team at Monash University (Australia) led by Professor Dan Li of the Department of Materials Engineering has developed a new strategy to engineer graphene-based supercapacitors (SC), resulting in an energy density of 60 Wh/liter—comparable to lead-acid batteries and around 12 times higher than commercially available SCs.

The approach could make SCs more viable for widespread use in renewable energy storage, portable electronics and electric vehicles. A paper on the work is published in Science.

SCs are generally made of highly porous carbon impregnated with a liquid electrolyte to transport the electrical charge. Known for their almost indefinite lifespan and the ability to re-charge in seconds, the drawback of existing SCs is their low energy density. With a low energy density of 5-8 Wh/liter, SCs are unfeasibly large or must be re-charged frequently.

It has long been a challenge to make SCs smaller, lighter and compact to meet the increasingly demanding needs of many commercial uses.

—Professor Li

Graphene, which is formed when graphite is broken down into layers one atom thick, is very strong, chemically stable and an excellent conductor of electricity.

To make the compact electrode, Professor Li’s team exploited an adaptive graphene gel film they had developed previously. They used liquid electrolytes—generally the conductor in traditional SCs—to control the spacing between graphene sheets on the sub-nanometer scale. In this way the liquid electrolyte played a dual role: maintaining the minute space between the graphene sheets and conducting electricity. Unlike in traditional hard porous carbon, where space is wasted with unnecessarily large pores, density is maximized without compromising porosity.

Porous yet densely packed carbon electrodes with high ion-accessible surface area and low ion transport resistance are crucial to the realization of high-density electrochemical capacitive energy storage but have proved to be very challenging to produce. Taking advantage of chemically converted graphene’s intrinsic micro-corrugated two-dimensional configuration and self-assembly behavior, we show that such materials can be readily formed by capillary compression of adaptive graphene gel films in the presence of a nonvolatile liquid electrolyte. This simple soft approach enables sub-nanometer scale integration of graphene sheets with electrolytes to form highly compact carbon electrodes with a continuous ion transport network. Electrochemical capacitors based on the resulting films can obtain volumetric energy densities approaching 60 watt-hours per liter.

—Yang et al.

To create their material, the research team used a method similar to that used in traditional paper making, meaning the process could be easily and cost-effectively scaled up for industrial use.

We have created a macroscopic graphene material that is a step beyond what has been achieved previously. It is almost at the stage of moving from the lab to commercial development.

—Professor Li

The work was supported by the Australian Research Council.

Resources

• Xiaowei Yang, Chi Cheng, Yufei Wang, Ling Qiu, and Dan Li (2013) Liquid-Mediated Dense Integration of Graphene Materials for Compact Capacitive Energy Storage. Science 341 (6145), 534-537 doi: 10.1126/science.1239089
  
  
  
  
  Source: Green Car Congress

Graphene Can Create "Hot Carrier" Cells for Photovoltaics

Graphene’s potential applications in photovoltaics (PVs) have remained fairly limited. Nanomaterials of nearly every stripe, including quantum dots, nanowires and carbon nanotubes, have offered alternatives in the solar collecting cells of PVs. But research has really only offered graphene as a replacement to indium-tin-oxide (ITO) used in the electrodes for organic solar cells.

Now researchers at the Barcelona, Spain-based Institute of Photonic Science (ICFO), in collaboration with the Massachusetts Institute of Technology, Max Planck Institute for Polymer Research in Germany and Graphenea S.L. Donostia-in San Sebastian, Spain have taken some initial steps in using graphene in the conversion and the conduction layers of a PV cell.

The research, which was published in the journal Nature Physics (“Photoexcitation cascade and multiple hot-carrier generation in graphene”), has demonstrated that graphene is capable of converting one photon into multiple electrons, leading to electric current. Until now, researchers had been looking at quantum dots to generate electron multiplication or creating so-called “hot carrier” cells in PVs.  While this line of research has gained some skeptics, it has been pursued for nearly a decade. The international team in this latest research has demonstrated that graphene can be used to create these hot carrier cells. “In most materials, one absorbed photon generates one electron, but in the case of graphene, we have seen that one absorbed photon is able to produce many excited electrons, and therefore generate larger electrical signals" explains Frank Koppens, group leader at ICFO in a press release.

In their experiments, the researchers excited the graphene by exposing it to photons of different energies (colors). They then measured the resulting hot-electron distribution with a Terahertz pulse and determined that higher photon energies (violet) resulted in higher numbers of hot electrons than lower photon energies (infrared). “The observed relation between the photon energy and the number of generated excited electrons shows that graphene converts light into electricity with very high efficiency,” says Klaas-Jan Tielrooij, one of the researchers in Koppen’s group at ICFO, in a press release. “Even though it was already speculated that graphene holds potential for light-to-electricity conversion, it now turns out that it is even more suitable than expected."

The problem with graphene in this area of PVs remains its low absorption. However, the researchers are encouraged to tackle this issue, because of the success they had in getting high-energy conversion figures out of the material. Koppens adds: “Now we know that once the material has absorbed light, the energy conversion efficiency is very high. Our next challenge will be to find ways of extracting the electrical current and enhance the absorption of graphene. Then we will be able to design graphene devices that detect light more efficiently and could potentially even lead to more efficient solar cells."



Image:  ICFO The Institute of Photonic Sciences

Graphene Supercapacitors Offer Blistering Performance and Charge in a Couple of Minutes

Researchers at the University of California are developing graphene supercapacitors that can charge and discharge in a couple of minutes. The ability to discharge in a couple of minutes means that they are extremely powerful. More importantly though, these researchers developed a technique for printing graphene supercapacitors using a DVD burner.

The researchers dissolved graphite oxide in water and heated it with a laser from a standard DVD burner to obtain flexible graphene sheets. These graphene sheets are one-atom thick, yet can hold a remarkable amount of energy, while being charged or discharged in very little time compared to standard batteries.

Ultracapacitors have tremendous advantages over typical lithium-ion batteries, some of which are of paramount importance to the adoption of electric cars, such as their ability to charge in as little as 1 second, and last 20 years (easily, and with very heavy usage). While this technology could mean ever-smaller handheld electronic devices, the real beneficiaries could be electric cars. If supercapactiors replace batteries as the primary energy storage method on EVs, it could mean much faster charge times, and much longer range. This graphene sheet method could also make EVs a lot more affordable, thanks to this cost-effective method.

Will supercapacitors save the electric car?

Source: Science Daily