Sustainability: What can nano do for your car?
How nanotech power could replace internal combustion engines
In this feature Lesley Tobin, of the Institute of Nanotechnology, reviews the impact that nanotechnology is having on the development of electric vehicles.
Motor vehicles are the single biggest source of atmospheric pollution, accountable for almost 15% of the worlds carbon dioxide emissions from fossil fuel burning - a percentage that is progressively increasing 1.
It is estimated that by 2020 more than 1 billion vehicles will be competing for road space. The average car releases a concoction of at least 1,000 pollutants that contribute to a range of bronchial and respiratory diseases, as well as cancer, lead-poisoning and acid rain 2.
In confronting these problems, nanoscientists have been contributing to environmental sustainability by developing improved rechargeable batteries and supercapacitors. Both types of portable energy supply store electrical energy in a chemical form, with the market currently dominated by lithium-based rechargeable batteries.
The demand for a lasting, powerful portable energy supply has long been sustained by portable gadgets such as PMPs (portable media players), MP3 players, digital still cameras, laptops, digital video recorders, smart phones and GPS. However, in older battery technologies the graphite used in the anode could deteriorate. This deterioration could cause fragments of graphite to react with the lithium-particle bearing electrolyte, potentially making it unstable or even volatile 3. This could then spark off a thermal runaway reaction – the kind that famously led to Dell recalling laptop batteries because of fire and explosions.
Much work has gone into rectifying this. One of the first breakthroughs came from Sony, whose Nexelion family of hybrid Li-Ion battery offer 30% more lifespan than conventional lithium-ion batteries. Recharge time has also been improved, with 90% of the battery's capacity being recharged in approximately 30 minutes. Importantly, instead of using graphite-based materials for the anode, as found in conventional batteries, Sony incorporated a tin-based amorphous anode material - the lithium ion storage capacity per volume ratio increased by 50%, augmenting the overall battery capacity by 30% 4.
A distinct technology, developed by Altairnano in California , replaced graphite in the anode of the battery with engineered nanoparticles of lithium titanate. Previous development stages used larger-scale lithium titanate spinels, thus removing a risk of conflagration, but the result was a poorer performance. The nanotech-version frees the battery from the threat of volatility while at the same time providing a larger surface area for chemical reactions. The result? More power with more safety. When test-driven, the battery lived up to its expectations delivering a top speed of 177km/h and 0-to-96.5 km acceleration in less than 10 seconds. As for stability, during one trial a nail was hammered through the cell, which was then overcharged. It stayed stable 5.
Phoenix Motorcars, also a California-based company, plans to sell about 500 Sport Utility Vehicles (SUV) powered by Altairnano technology this year. Each vehicle requires only 6 or 7 hours of recharging and there is a 15-minute quick-charge option 6.
A123Systems, has also been adapting nanoscale materials to improve lithium-ion batteries . A spin-off from the Massachusetts Institute of Technology in 2001, A123Systems has taken a different approach to developing nano-enabled car batteries. The company began by making batteries for power tools manufacturers, such as Black & Decker, but meanwhile worked on more powerful prototypes for cars. The battery technology employed to eliminate the possibility of thermal runaway involves the use of a nanophosphate material modified with trace metals. While the technology differs from Altairnano's product, it nevertheless delivers a win-win performance: the increased surface area offered by the nanoparticles has proven to be a quicker source of greater power.
A123Systems has so far demonstrated a plug-in Toyota Prius that travels 48 to 56 km before recharging. The batteries, which are about 0.83 m wide, are stored under the boot. Now, the company is collaborating with General Motors to engineer the next generation of hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). So far it has shown that the A123 batteries for GM's Volt store enough energy for 64.3 km of driving, enough to cover daily runs. As a PHEV, on longer trips, the small petrol engine would kick in to recharge the battery, extending the range to more than 644 km.7.
Later this year, GM will evaluate A123Systems' batteries for a planned plug-in hybrid SUV, the Saturn Vue, Although more development is needed, it seems that A123Systems' batteries will make a mark on plug-in hybrid development, much the way they have in the power tools industry.
Powering the drive train in vehicles is not the only consideration, and other organizations are looking at smaller power supplies suitable for auxiliary systems and portable devices. mPhase/AlwaysReady successfully demonstrated their Lithium Smart NanoBattery at the recent NanoBusiness Alliance Conference. During the demonstration, a lithium pouch based reserve battery was mechanically activated, illuminating an LED light in front of a live audience (http://www.youtube.com/watch?v=uDhL--RLzoU ).
Following this, in a display at the company's office in New Jersey , mPhase/AlwaysReady activated several lithium battery prototypes, each of which provided 3 volts output and powered an LED. Dr. Fred Allen, President and CEO of AlwaysReady, commented:
"New portable electronic devices demand reliable power. Our lithium-based Smart NanoBattery makes sure power is there when you need it. Conventional batteries can corrode, discharge or die even before they are used. The Smart NanoBattery doesn't. It has a potentially infinite shelf life until you activate it. There are tremendous commercial and military applications that can benefit from our Smart NanoBattery, ranging from medical and health alert devices, unmanned sensors, emergency flashlights and backup power for cell phones." 8.
Meanwhile, in Europe , renewable energy is now an issue central to nano research and development. Since 2004, an integrated network of eighteen top research groups, accounting for about 60% of European Lithium battery research, has been amalgamating efforts within a virtual centre to place Europe in the driving seat of energy storage technology 9. The Advanced Lithium Energy Storage Systems (ALISTORE) network, has the goal of increasing energy density in rechargeable batteries through researching novel electrode materials such as iron fluoride, cobalt chloride, rubidium oxide, and nickel phosphide. The electrodes are “nanostructured” in place, rather than through compacting nanoparticles, a process which increases stability. The process also enhances discharge/charge rates, meaning more power can be delivered quickly.
In Scotland , the battery manufacturer Axeon has secured a series of contracts from vehicle makers across Europe for battery packs for electric vehicles. On May 21 st the company revealed that has won its first contract in America , supplying prototype battery packs for hybrid-engined buses10. This is evidence enough that on both sides of the Atlantic , manufacturers and drivers are rethinking their priorities.
Nevertheless, PHEVs are not the definitive solution to the environmental problem. Disadvantages include the co st, weight, and size of batteries. Acknowledging this, buyers of General Motors' Chevy Volt, for example, may be permitted to rent the car battery, but the need to recharge it exposes another drawback. Drivers living in flats, terraces and in houses with on-street parking would require access to electrical power supplies. New electrical outlets near their homes or in public car parks would need to be installed to enable battery recharging. To counter this, Mira – a UK developer of electric hybrid powertrain technology – are developing a removable battery pack that can also be recharged in-situ 11.
Looking at the big picture, will PHEVs really eradicate the pollution problem, or will emissions simply be concentrated around the electric plants? According to Dan Shapley in ‘The Daily Green', the good outweighs the bad:
"If 60% of drivers used plug-in hybrids, it would draw 7-8% of the electricity grid's load, and that would increase pollution from power plants if additional pollution controls aren't installed on them. But even with increased pollution from power plants, greenhouse gas emissions would decrease relative to the output of pollution from the fleet of cars now on the road"12.
Ford is approaching the problem from another perspective by examining how to reduce the amount of energy required by a vehicle. In a top-end application of nanotechnology, Ford is investigating paints, plastics, light metals and catalysts that allow a reduction in vehicle weight and an increase fuel economy without forgoing quality or compromising safety.
As Matthew Zaluzec, manager of the Materials Science & Nanotechnology Department for Ford Research and Advanced Engineering, said:
"Our challenge is to take those nanoparticles, separate them and disperse them into existing materials in a way that makes our vehicles lighter, more durable, and more fuel efficient." He added, "Many thought our aluminum engine technology was mature and fully optimized. Not until we looked at every aspect of the materials and manufacturing process were we able to pull out another 10 percent in structural performance out of our engines, which directly translates into weight and fuel economy savings year over year. It's nano at the working level" 13.
Without a doubt, diminishing the threat of vehicle use to environmental sustainability needs to encompass a multi-pronged approach that harnesses cheaper sources of power and renewable energy, combined with ecologically-aware vehicle and engine construction technology. If the developing nanotechnologies can really give drivers a run for their money, then electric vehicles could be a way forward.
The Institute of Nanotechnology puts significant effort into ensuring that the information provided on its news pages is accurate and up-to-date. However, we cannot guarantee absolute accuracy. Consequently, the Institute of Nanotechnology disclaims any and all responsibility for inaccuracy, omission or any kind of deficiency in relation to the news items and articles hosted herein.
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