I just became a little more hopeful for the future of battery technology. Scientists at the University of Kiel in Germany have developed a carbon material called aerographite with some very intriguing properties. The most promising application for this at the moment appears to be exceptionally lightweight lithium-ion batteries. If this can become commercially viable, aerographite has the potential to be a game changer.
Aerographite: What is it?
It earns the title of “lightest material on earth” at .0002 grams per cubic centimeter. That is 1/6 the density of air and 1/4 that of the previous record holder, nickel microlattices. A black freestanding mesh of tiny carbon tubes, aerographite is not only light, but is also flexible, waterproof, highly resilient in tension and compression (able to spring back to its original form after being compressed 95%), and electrically conductive. That combination opens up some exciting possibilities, including the development of much lighter batteries for electronic devices. Perhaps the most important of these devices: hybrid and electric vehicle batteries.
Aerographite Batteries: What’s the big deal?
Electrically powered vehicles have been slow to gain acceptance for a variety of reasons. Political, economic, cultural, and technological obstacles have all contributed to the small market share EV’s enjoy. As an engineer, my interest has always been with the last item on that list… battery technology has simply been unable to effectively compete with the energy density and convenience of fossil fuels powering internal combustion engines. All the recent development in hybrid vehicles and pure EV’s has certainly improved their practicality, but they are still a long way from supplanting your standard ICE car.
Challenges for Battery-Powered Automobiles
The biggest problem is energy density. Gasoline has an energy density of 13,111 W-h/kg. A typical lithium-ion battery stores about 200 W-h/kg. The result is that you have to tote an awful lot of battery in your car to store enough energy for practical transportation ranges. The Nissan Leaf carries almost 400 pounds of battery to power its 73 mile range. The Chevy Volt hybrid hauls a 435 pound battery pack as well, and even though it can switch to gasoline when the battery is depleted, that additional dead weight takes a toll on fuel efficiency. The Tesla Roadster, the rockstar of EV’s, carries 992 pounds of batteries to travel 220+ miles. Given that the entire car is 2,700 pounds, the batteries comprise a staggering 37% of the total vehicle weight. Your typical seventeen gallon gas tank holds about 103 pounds of fuel when full and just gets lighter as you consume the gasoline. That is a pretty huge disadvantage for the battery-powered cars.
How Would Aerographite Change Things?
Since this material is still in its infancy, the application has a long way to go, but Dr. Rainer Adelung calls it the “Holy Grail” for battery development. According to the release from the University of Kiel, aerographite could be applied to the electrodes of lithium-ion batteries and greatly reduce the amount of electrolyte needed, resulting in a much lighter battery cell. No specific numbers have been projected in terms of mass reduction, but this does put the industry on a path to address a major drawback of battery power storage. The battery being lighter could allow the same power capacity to take the driver farther on a single charge since the car would be carrying less weight, or the range could be dramatically increased by packing more cells into the vehicle without increasing the curb weight.
What Else Can You Do With It?
The scientists keep coming up with new ways to exploit the properties of aerographite for things like low static plastic parts, vibration resistant aerospace electronics, and new applications of wearable computing. Given the strength, resilience, and large carbon surface area, this could push the frontiers of filtration. Water and air purification could see huge gains if the carbon foam performs as they hope. It is an exciting time for material science, but for now we wait and see what develops.
Aerographite: Some Final Thoughts
When the options for fully electric vehicles consist of cars with a range that couldn’t get me from Dallas to Fort Worth and back or supercars that seem reserved (both in price and scarcity) for Internet millionaires, the general populace doesn’t have a very compelling choice. Hybrids are a decent step, but as previously mentioned, the mass of the batteries holds them back. In fact, there are still several fossil fuel-only cars on the road that will outperform most non-plug-in hybrids in terms of gas mileage. Having heard countless people asking when electric cars will be the standard, my answer has always been, “After we have a quantum leap in battery technology.” It is far too early to know for certain, but hopefully this discovery is the first stage of that leap.