Better Batteries or No Batteries at All

Stephen DeAngelis

February 25, 2010

The information age is as much an age of electricity as it is an age of digitization — and that is probably not going to change. Cars are becoming more electrified. The world is becoming more mobile and that mobility is fostered by battery-powered devices of all sorts. As Curt Suplee observes, “Since the opening bell of the wonder-stuffed 21st century, consumer technologies have evolved at an electrifying pace … batteries not included” [“Talk about battery life! Old device, new tricks.” Washington Post, 20 October 2009]. When you think about it, Suplee is correct. Battery technology has changed much more slowly than other technologies — even though the world is becoming more dependent on them. Suplee explains why this is so:

“Despite the promotional zeal of those drum-toting bunnies, the alkaline battery that powers most of our portable gizmos is not different in principle from the model that Alessandro Volta created in 1800. That fabled ‘voltaic pile’ — a stack of alternating zinc and copper disks separated by layers of brine-sodden-paper — didn’t look much like today’s sleek cylinders. But it was the first battery as we understand the term — that is, a device that turns stored chemical energy into electrical energy. And its successors are still using the same kind of system. Is this retro-electro condition a failure of modern science? Well, no, for two reasons. The first is that the newest versions of Volta’s pile produce amazing boing for the buck and are poised to get better. The second and most important reason that battery tech may seem to be lagging is that beyond a certain point you can’t shrink chemistry. Digital data are almost infinitely compressible because the information is not a physical object. It can be embodied in the smallest difference between any two conditions — on or off, 0 or 1 — way down to subatomic scale. But batteries aren’t digital. ‘Energy is stored on stuff — atoms, ions and so forth,’ says MIT professor Gerbrand Ceder. ‘This is done by transferring electrons from one atom to another. Their energy difference is the energy stored. That’s why batteries will never scale in performance the way, say, semiconductors have done.'”

Normally when we think about batteries, we think about cylinders or cubes that go inside devices or vehicles. But that could change. A British university is developing a material that could perform as both a covering and a battery [“Future cars: Auto bodywork composite doubles as a battery,” by Tannith Cattermole, Gizmag, 7 February 2010]. Because the new battery does not rely on chemical reactions, it offers a revolutionary way forward. Cattermole reports:

“The problem is clear. Hybrid cars and EVs rely on batteries for power, but batteries are bulky and heavy, causing the car to use up more energy. But what if a car’s bodywork was made of a strong, lightweight material that could store and discharge electrical energy just as a conventional battery does? In pursuing this goal, researchers at the Imperial College London are developing a key building block for the hybrid car of the future, and the implications go way beyond automobiles – think wafer thin mobile phones and laptops that don’t need a separate battery because they draw power from their casing. Imperial College has been working on the idea as part of a €3.4 million 3 year European Union-funded project which includes researchers from a number of European partners, including automotive firm Volvo. The prototype material is a composite of carbon fibers and a polymer resin which can store and discharge large amounts of energy much faster than conventional batteries. Unlike these there is little degradation in the material over time because there is no chemical process involved, and this also aids more rapid recharging. It is lightweight and strong enough to make car body parts, and could be plugged into the household power supply for recharging.”

At the moment, the material is still in the research and development phase.

“Researchers say the next stage is to further develop the composite in order to store more energy. This may be achieved by growing carbon nanotubes on the surface of the carbon fibers which will increase the surface area, thus improving its storage capacity. They also hope to find alternative options for recharge such as recycling energy created during braking while the car is on the move. Their first test in-situ will be to exchange the metal floor in the car boot, or wheel well, for the composite, and Volvo is investigating the possibility of rolling this out in prototype cars for testing purposes. The addition of the composite combined with a reduced need for heavy batteries could see the car’s overall weight drop by up to 15%, consequently increasing the range of future hybrids.”

As I’ve noted in previous posts, for a concept to move from being an idea to an innovation, it must actually be produced and widely used. Once the material is perfected, manufacturing it becomes the next big hurdle. Cattermole concludes:

“The most effective method for manufacturing the composite material at an industrial level is also being investigated. Project co-coordinator, Dr Emile Greenhalgh, from the Department of Aeronautics at Imperial College London, says: ‘We are really excited about the potential of this new technology. We think the car of the future could be drawing power from its roof, its bonnet or even the door, thanks to our new composite material. Even the Sat Nav could be powered by its own casing. The future applications for this material don’t stop there – you might have a mobile phone that is as thin as a credit card because it no longer needs a bulky battery, or a laptop that can draw energy from its casing so it can run for a longer time without recharging. We’re at the first stage of this project and there is a long way to go, but we think our composite material shows real promise.’ The future for the Hybrid car looks bright … and batteries are definitely not included.”

Although batteries remain the most likely source of power for mobile devices in the future, they may not be the only option. American researchers are developing a material that harnesses body motion to generate electrical power [“Rubber sheets harness body movement to power electrical devices,” by Darren Quick, Gizmag, 27 January 2010]. Like the carbon material discussed above, the new material doesn’t use chemical reactions to do its job. Quick reports:

“Engineers from Princeton University have developed power-generating rubber films that could be used to harness natural body movements such as breathing or walking in order to power electronic devices such as pacemakers or mobile phones. The material, which is composed of ceramic nanoribbons embedded onto silicone rubber sheets, generates electricity when flexed and is highly efficient at converting mechanical energy into electrical energy. Its developers say shoes made of the material could harvest the pounding of walking or running to power mobile electrical devices and, when placed against the lungs, sheets of the material could use the raising and falling breathing motions of the chest to power pacemakers. This would negate the current need for surgical replacement of the batteries which power the devices. Plus, because the silicone is biocompatible and is already used for cosmetic implants and medical devices, ‘the new electricity-harvesting devices could be implanted in the body to perpetually power medical devices, and the body wouldn’t reject them,’ said Michael McAlpine, a professor of mechanical and aerospace engineering, at Princeton, who led the project to develop the material.”

Quick reports that nanotechnology is also involved in the production of the Princeton material. He continues:

“To produce the material the researchers first fabricated lead zirconate titanate (PZT) nanoribbons in strips so narrow that 100 fit side by side in a space of a millimeter. PZT is a ceramic material that is piezoelectric, meaning it generates an electrical voltage when pressure is applied to it. Of all piezoelectric materials, PZT is the most efficient, able to convert 80% of the mechanical energy applied to it into electrical energy. ‘PZT is 100 times more efficient than quartz, another piezoelectric material,’ said McAlpine. ‘You don’t generate that much power from walking or breathing, so you want to harness it as efficiently as possible.’ In a separate process, the team then embedded these ribbons into clear sheets of silicone rubber, creating what they call ‘piezo-rubber chips.’ The Princeton team is the first to successfully combine silicone and nanoribbons of PZT. In addition to generating electricity when it is flexed, the opposite is true: the material flexes when electrical current is applied to it. This opens the door to other kinds of applications, such as use for microsurgical devices, McAlpine said. ‘The beauty of this is that it’s scalable,’ said Yi Qi, a postdoctoral researcher who works with McAlpine. ‘As we get better at making these chips, we’ll be able to make larger and larger sheets of them that will harvest more energy.'”

Progress is being made in a number of areas related to flexible materials that can harvest energy. For example, “The New York-based Center for Architectural Science and Ecology CASE has unveiled a new Integrated Concentrating (IC) Dynamic Solar Facade which does just that – and it looks great!” [“Solar glazing chases sun from dawn until dusk,” by Tannith Cattermole, Gizmag, 3 February 2010]. The CASE system uses a miniaturized concentrator solar cell, a tracking system, and a glass pyramid shape to track “the sun’s progress across the sky, maximizing light gain all day long. The glass pyramid shape magnifies the light available and additionally serves to capture thermal energy.” Cattermole continues:

“This advanced technology provides a number of advantages over current BIPV [Building integrated photovoltaic] systems according to CASE. Not only does IC use as much sunlight as possible in the production of electricity, it also allows greater diffuse light to enter the building reducing the need for artificial light. Additionally it can be applied to both retrofit applications and new construction, requires little maintenance and is modern and aesthetically pleasing. And what’s more, the thermal energy trapped by the glass pyramid design is funneled for use in the building’s heating or cooling systems. Incorporating these types of arrays could see solar energy becoming an increasingly viable option that is competitive with other energy sources, reducing our dependency on fossil fuels.”

Other advances reported by Gizmag over the past few years include: flexible solar panels [“Flexible Cells to expand Solar Energy applications,” by Mike Hanlon, 2003]; flexible panels that could be used on the outside of buildings [“Flexible modules could transform windows and buildings into solar panels,” by Emily Clark, 10 October 2007]; solar bricks [“Solar brick provides integrated outdoor lighting solution,” by Emily Clark, 22 September 2008]; and semi-transparent solar windows [“RSi unveils semi-transparent solar window,” by Emily Clark, 14 December 2008]. All of these items are intended to be visible to the public, rather than hidden inside objects like batteries. Tomorrow I will discuss other creative ways that are being developed to make power more portable. Comedian Stephen Wright once remarked, “I bought some batteries, but they weren’t included.” In the future, Mr. Wright could just be correct.