Posts tagged thermal
CU scientists: New battery extends range and safety of electric-powered vehicles
Sep 22nd
A cutting-edge battery technology developed at the University of Colorado Boulder that could allow tomorrow’s electric vehicles to travel twice as far on a charge is now closer to becoming a commercial reality.
CU’s Technology Transfer Office has completed an agreement with Solid Power LLC—a CU-Boulder spinoff company founded by Se-Hee Lee and Conrad Stoldt, both associate professors of mechanical engineering—for the development and commercialization of an innovative solid-state rechargeable battery. Solid Power also was recently awarded a $3.4 million grant from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy for the purpose of creating a battery that can improve electric vehicle driving range.
The rechargeable batteries that are standard in today’s electric vehicles—as well as in a host of consumer electronics, such as mobile phones and laptops—are lithium-ion batteries, which generate electricity when lithium ions move back and forth between electrodes in a liquid electrolyte solution.
Engineers and chemists have long known that using lithium metal as the anode in a rechargeable battery—as opposed to the conventional carbon materials that are used as the anode in conventional lithium-ion batteries—can dramatically increase its energy density. But using lithium metal, a highly reactive solid, in conjunction with a liquid electrolyte is extremely hazardous because it increases the chance of a thermal runaway reaction that can result in a fire or an explosion.
Today’s lithium-ion batteries require a bulky amount of devices to protect and cool the batteries. A fire onboard a Boeing Dreamliner in January that temporarily grounded the new class of plane was linked to its onboard lithium-ion battery.
Lee and Stoldt solved the safety concerns around using lithium metal by eliminating the liquid electrolyte. Instead, the pair built an entirely solid-state battery that uses a ceramic electrolyte to separate the lithium metal anode from the cathode. Because the solid-state battery is far safer, it requires less protective packaging, which in turn could reduce the weight of the battery system in electric vehicles and help extend their range.
Research into the development of solid-state batteries has gone on for a couple of decades, but it has been difficult to create a solid electrolyte that allowed the ions to pass through it as easily as a liquid electrolyte.
“The problem has always been that solid electrolytes had very poor performance making their use in rechargeable batteries impractical,” Stoldt said. “However, the last decade has seen a resurgence in the development of new solid electrolytes with ionic conductivities that rival their liquid counterparts.”
The critical innovation added by Lee and Stoldt that allows their solid-state lithium battery to out-perform standard lithium-ion batteries is the construction of the cathode, the part of the battery that attracts the positively charged lithium ions once they’re discharged from the lithium metal. Instead of using a solid mass of material, Lee and Stoldt created a “composite cathode,” essentially small particles of cathode material held together with solid electrolyte and infused with an additive that increases its electrical conductivity. This configuration allows ions and electrons to move more easily within the cathode.
“The real innovation is an all-solid composite cathode that is based upon an iron-sulfur chemistry that we developed at CU,” Stoldt said. “This new, low-cost chemistry has a capacity that’s nearly 10 times greater than state-of-the-art cathodes.”
Last year, Lee and Stoldt partnered with Douglas Campbell, a small-business and early-stage product development veteran, to spin out Solid Power.
“We’re very excited about the opportunity to achieve commercial success for the all solid-state rechargeable battery,” said Campbell, Solid Power’s president. “We’re actively engaging industrial commercial partners to assist in commercialization and expect to have prototype products ready for in-field testing within 18 to 24 months.” Important to the early success of the company has been its incubation within CU-Boulder’s College of Engineering and Applied Science’s applied energy storage research center, a part of the college’s energy systems and environmental sustainability initiative.
Solid Power is a member of Rocky Mountain Innosphere, a nonprofit technology incubator headquartered in Fort Collins, Colo., with a mission to accelerate the development and success of high-impact scientific and technology startup companies.
“We’re very excited to be working with Solid Power’s team to get them to the next level,” said Mike Freeman, Innosphere’s CEO. “This is a big deal to Colorado’s clean-tech space. Solid Power’s batteries will have a huge impact in the EV market, and they have a potential $20 billion market for their technology.”
Learn more about Solid Power at http://www.solidpowerbattery.com.
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CU-Boulder team develops potential new hydrogen fuel technology
Aug 1st
The CU-Boulder team has devised a solar-thermal system in which sunlight could be concentrated by a vast array of mirrors onto a single point atop a central tower up to several hundred feet tall. The tower would gather heat generated by the mirror system to roughly 2,500 degrees Fahrenheit (1,350 Celsius), then deliver it into a reactor containing chemical compounds known as metal oxides, said CU-Boulder Professor Alan Weimer, research group leader.
As a metal oxide compound heats up, it releases oxygen atoms, changing its material composition and causing the newly formed compound to seek out new oxygen atoms, said Weimer. The team showed that the addition of steam to the system — which could be produced by boiling water in the reactor with the concentrated sunlight beamed to the tower — would cause oxygen from the water molecules to adhere to the surface of the metal oxide, freeing up hydrogen molecules for collection as hydrogen gas.
“We have designed something here that is very different from other methods and frankly something that nobody thought was possible before,” said Weimer of the chemical and biological engineering department. “Splitting water with sunlight is the Holy Grail of a sustainable hydrogen economy.”
A paper on the subject was published in the Aug. 2 issue of Science. The team included co-lead authors Weimer and Associate Professor Charles Musgrave, first author and doctoral student Christopher Muhich, postdoctoral researcher Janna Martinek, undergraduate Kayla Weston, former CU graduate student Paul Lichty, former CU postdoctoral researcher Xinhua Liang and former CU researcher Brian Evanko.
One of the key differences between the CU method and other methods developed to split water is the ability to conduct two chemical reactions at the same temperature, said Musgrave, also of the chemical and biological engineering department. While there are no working models, conventional theory holds that producing hydrogen through the metal oxide process requires heating the reactor to a high temperature to remove oxygen, then cooling it to a low temperature before injecting steam to re-oxidize the compound in order to release hydrogen gas for collection.
“The more conventional approaches require the control of both the switching of the temperature in the reactor from a hot to a cool state and the introduction of steam into the system,” said Musgrave. “One of the big innovations in our system is that there is no swing in the temperature. The whole process is driven by either turning a steam valve on or off.”
“Just like you would use a magnifying glass to start a fire, we can concentrate sunlight until it is really hot and use it to drive these chemical reactions,” said Muhich. “While we can easily heat it up to more than 1,350 degrees Celsius, we want to heat it to the lowest temperature possible for these chemical reactions to still occur. Hotter temperatures can cause rapid thermal expansion and contraction, potentially causing damage to both the chemical materials and to the reactors themselves.”
In addition, the two-step conventional idea for water splitting also wastes both time and heat, said Weimer, also a faculty member at CU-Boulder’s BioFrontiers Institute. “There are only so many hours of sunlight in a day,” he said.
The research was supported by the National Science Foundation and by the U.S. Department of Energy.
With the new CU-Boulder method, the amount of hydrogen produced for fuel cells or for storage is entirely dependent on the amount of metal oxide — which is made up of a combination of iron, cobalt, aluminum and oxygen — and how much steam is introduced into the system. One of the designs proposed by the team is to build reactor tubes roughly a foot in diameter and several feet long, fill them with the metal oxide material and stack them on top of each other. A working system to produce a significant amount of hydrogen gas would require a number of the tall towers to gather concentrated sunlight from several acres of mirrors surrounding each tower.
Weimer said the new design began percolating within the team about two years ago. “When we saw that we could use this simpler, more effective method, it required a change in our thinking,” said Weimer. “We had to develop a theory to explain it and make it believable and understandable to other scientists and engineers.”
Despite the discovery, the commercialization of such a solar-thermal reactor is likely years away. “With the price of natural gas so low, there is no incentive to burn clean energy,” said Weimer, also the executive director of the Colorado Center for Biorefining and Biofuels, or C2B2. “There would have to be a substantial monetary penalty for putting carbon into the atmosphere, or the price of fossil fuels would have to go way up.”
C2B2 is an arm of the Colorado Energy Research Collaboratory involving CU-Boulder, the Colorado School of Mines, Colorado State University and the National Renewable Energy Laboratory in Golden. The collaboratory works with industry partners, public agencies and other institutions to commercialize renewable energy technologies, support economic growth in the state and nation and educate the future workforce.
For more information on the chemical and biological engineering department visit http://www.colorado.edu/chbe/. For more information on C2B2 visit http://www.c2b2web.org. For more information on the Biofrontiers Institute visithttp://biofrontiers.colorado.edu.
Rodwin Architecture and Skycastle Construction
May 30th
We visit Rodwin Architecture and Skycastle Construction in Boulder and learn about their big commitment to sustainable design and green building and how they have brought together both the design and the build sides of creating an office building or home. Scott Rodwin – President, Brandon David – Construction Contractor and Kirsten Snobeck – Senior Designer all talk about some of the jobs they do and how they can save you time, money and help keep your carbon footprint low with their environmental design.