“The energy-air-water-food nexus is the existential question of our times,” says Sanat Kumar, the Bykhovsky Professor of Chemical Engineering.
Recognizing the interdependence of the earth’s resources, Kumar believes developing affordable, sustainable energy solutions will be at the heart of increasing access to pure air, clean water, and food security for developing countries.
Advanced membranes will play a key role in this undertaking. For decades, membrane technology has been driving efficiencies in water purification, gas separation for more sustainable energy production systems, and ion separation for energy storage and batteries. Yet, the separation capabilities of standard polymer-based membranes (plastic films) are limited.
Kumar’s research group focuses on developing novel hybrid materials that combine polymers with nanoparticles to gain desired properties and improve separating abilities while reducing plastics consumption. Membranes perform best when the dispersion of nanoparticle fillers is uniform in the polymer matrix. His team has developed a process to chemically bond polymer chains to the fillers in such a way that they self-assemble into regular arrays, exhibiting the evenness needed for better performance.
To date, Kumar has developed materials that perform two to five times better than existing technologies for gas separation and has ideas for further improvements that could translate these methods for commercial use.
In another research thrust, his group seeks to improve the mechanical or electrical properties of polymeric membranes by drawing inspiration from nature, particularly nacre, commonly known as mother-of-pearl. Further advances in this area could lead to more sustainable, composite materials that are durable enough to replace structural materials in buildings and infrastructure.
With the potential for climate change to exacerbate social inequalities, Kumar feels a sense of urgency in bringing about sustainable technologies that will benefit all.
“It is our responsibility, especially as a school dedicated to engineering for humanity, to focus on the poor and provide them with the means to live their lives with dignity.”
New York, NY—April 22, 2019—The grand challenge to improve energy storage and increase battery life, while ensuring safe operation, is becoming evermore critical as we become increasingly reliant on this energy source for everything from portable devices to electric vehicles. A Columbia Engineering team led by Yuan Yang, assistant professor of materials science and engineering, announced today that they have developed a new method for safely prolonging battery life by inserting a nano-coating of boron nitride (BN) to stabilize solid electrolytes in lithium metal batteries. Their findings are outlined in a new study published by Joule.
While conventional lithium ion (Li-ion) batteries are currently widely used in daily life, they have low energy density, resulting in shorter battery life, and, because of the highly flammable liquid electrolyte inside them, they can short out and even catch fire. Energy density could be improved by using lithium metal to replace the graphite anode used in Li-ion batteries: lithium metal’s theoretical capacity for the amount of charge it can deliver is almost 10 times higher than that of graphite. But during lithium plating, dendrites often form and, if they penetrate the membrane separator in the middle of the battery, they can create short-circuits, raising concerns about battery safety.
“We decided to focus on solid, ceramic electrolytes. They show great promise in improving both safety and energy density, as compared with conventional, flammable electrolytes in Li-ion batteries,” says Yang. “We are particularly interested in rechargeable solid-state lithium batteries because they are promising candidates for next-generation energy storage.”
Most solid electrolytes are ceramic, and therefore non-flammable, eliminating safety concerns. In addition, solid ceramic electrolytes have a high mechanical strength that can actually suppress lithium dendrite growth, making lithium metal a coating option for battery anodes. However, most solid electrolytes are unstable against Li—they can be easily corroded by lithium metal and cannot be used in batteries.
“Lithium metal is indispensable for enhancing energy density and so it’s critical that we be able to use it as the anode for solid electrolytes,” says Qian Cheng, the paper’s lead author and a postdoctoral research scientist in the department of applied physics and applied mathematics who works in Yang's group. “To adapt these unstable solid electrolytes for real-life applications, we needed to develop a chemically and mechanically stable interface to protect these solid electrolytes against the lithium anode. It is essential that the interface not only be highly electronically insulating, but also ionically conducting in order to transport lithium ions. Plus, this interface has to be super-thin to avoid lowering the energy density of batteries.”
To address these challenges, the team worked with colleagues at Brookhaven National Lab and the City University of New York. They deposited 5~10 nm boron nitride (BN) nano-film as a protective layer to isolate the electrical contact between lithium metal and the ionic conductor (the solid electrolyte), along with a trace quantity of polymer or liquid electrolyte to infiltrate the electrode/electrolyte interface. They selected BN as a protective layer because it is chemically and mechanically stable with lithium metal, providing a high degree of electronic insulation. They designed the BN layer to have intrinsic defects, through which lithium ions can pass through, allowing it to serve as an excellent separator. In addition, BN can be readily prepared by chemical vapor deposition to form large-scale (~dm level), atomically thin scale (~nm level), and continuous films.
“While earlier studies used polymeric protection layers as thick as 200 µm, our BN protective film, at only 5~10 nm thick, is record-thin—at the limit of such protection layers—without lowering the energy density of batteries,” Cheng says. “It’s the perfect material to function as a barrier that prevents the invasion of lithium metal to solid electrolyte. Like a bullet-proof vest, we’ve developed a lithium-metal-proof ‘vest’ for unstable solid electrolytes and, with that innovation, achieved long-cycling lifetime lithium metal batteries.”
The researchers are now extending their method to a broad range of unstable solid electrolytes and further optimizing the interface. They expect to fabricate solid-state batteries with high performance and long-cycle lifetimes.
Columbia Engineering
Columbia Engineering, based in New York City, is one of the top engineering schools in the U.S. and one of the oldest in the nation. Also known as The Fu Foundation School of Engineering and Applied Science, the School expands knowledge and advances technology through the pioneering research of its more than 220 faculty, while educating undergraduate and graduate students in a collaborative environment to become leaders informed by a firm foundation in engineering. The School’s faculty are at the center of the University’s cross-disciplinary research, contributing to the Data Science Institute, Earth Institute, Zuckerman Mind Brain Behavior Institute, Precision Medicine Initiative, and the Columbia Nano Initiative. Guided by its strategic vision, “Columbia Engineering for Humanity,” the School aims to translate ideas into innovations that foster a sustainable, healthy, secure, connected, and creative humanity.
About the Study
The study is titled “Stabilizing Solid Electrolyte-Anode Interface in Li-Metal Batteries by Boron Nitride-Based Nanocomposite Coating.”
Authors are: Qian Cheng,1; Aijun Li,1,3,; Na Li,2; Kai Yan,4; Shuang Li,2; Amirali Zangiabadi,1; Tai-De Li,5; Wenlong Huang,1; Alex Ceng Li,1; Tianwei Jin,1; Qingquan Song,1; Weiheng Xu,1; Nan Ni,1; Haowei Zhai,1; Martin Dontigny,6; Karim Zaghib,6; Xiuyun Chuan,3; Dong Su,2; and Yuan Yang1,8.
1 Program of Materials Science and Engineering, Department of Applied Physics and Applied Mathematics, Columbia Engineering
2 Brookhaven National Laboratory
3 Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing
4 Amprius Inc., California
5 CUNY-Advanced Science Research Center, New York
6Centre of Excellence in Transportation Electrification and Energy Storage (CETEES), Hydro-Quebec, Canada
The study was supported by the Air Force Office of Scientific Research (FA9550-18-1-0410) and Research Corporation for Science Advancement (Award #26293), and the NSF MRSEC program through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634).
The authors declare no conflict of interest.
Conscientious consumers are always on the lookout for ways to limit carbon footprints, whether driving hybrids, installing solar panels or purchasing sustainably-sourced goods. But those results can be a drop in the bucket beside massive systemic emissions—measured in hundreds of billions of tons—stemming from key industrial sectors like construction and big data. Just cleaning up these two fields could be a game changer in the fight against climate change.
Take your home, for instance. Better insulation and more weather stripping are decent ways to increase a building’s efficiency after the fact, but by the time it’s been built tons of carbon emissions have already been baked in: conventional processes for manufacturing cement and steel currently account for 11% of all anthropogenic greenhouse gas emissions, and that’s likely to double by 2050 absent urgent innovation.
Ah-Hyung (Alissa) Park, Lenfest Earth Institute Associate Professor of Climate Change in earth and environmental engineering, as well as an associate professor in chemical engineering and director of the Lenfest Center for Sustainable Energy, is also cofounder of the Columbia startup GreenOre CleanTech. The company utilizes her patented methods for harvesting carbon and valuable chemical products from iron and steel waste known as slag. In addition to deploying their methods in China, where they have a commercial plant in the works, she and her team are also partnering with the state of Wyoming to replace standard cement production with a greener approach recycling ash from power plants into a variety of useful materials.
With cement processing alone generating around five percent of humans’ greenhouse gas emissions, going carbon-neutral would be transformative—but carbon-negative could be revolutionary. Professors Daniel Esposito and Shiho Kawashima are working on a new cement alternative that could help lay the foundation for a greener urban landscape. Synthesized from seawater, their material can withstand as much weight as the industry standard while absorbing substantial amounts of CO2. They’re currently translating their research into scalable production processes for future construction.
“We’re getting promising results in the lab, so we plan to do lifecycle analysis and techno-economic analysis to demonstrate our technology’s environmental benefits and economic viability,” Kawashima says.
While less conspicuous, data infrastructure is on pace to become another enormous source of emissions. Moving, storing, and particularly processing the trillions of gigabytes so effortlessly at our fingertips requires a vast amount of energy. If present trends continue, the information economy could soon produce half as many greenhouse gases as the entire transportation sector, with cloud computing consuming a fifth of the world’s electricity. As is, data centers already cause nearly two percent of our total carbon output—and that’s while we’re still at the dawn of artificial intelligence. Training algorithms require gigawatts of power, and the energy costs of rapidly proliferating AI could be staggering.
That’s partially because our wireless lifestyles actually rely on a vast tangle of inefficient electronic wiring, fundamentally the same materials we’ve been using since the 1940s. Professors Keren Bergman and Michal Lipson, however, are reconceiving the mechanics of computation using a whole new framework: frictionless optical components. Fiberoptics already use this principle to transfer data over long distances—but such bulky systems have proved incompatible with today’s data centers. Lipson and Bergman’s “photonic” elements neatly sidestep that issue by encoding data in the form of light directly on the chip.
Lipson’s group recently had a breakthrough pairing an optical funnel with optical fiber to achieve highly efficient high-bandwidth transmissions even when components weren’t in perfect alignment, while Bergman’s group in the Lightwave Research Laboratory just won a $4.8 million DARPA grant to develop efficient optical interconnects for feeding high-bandwidth signals from chips to anywhere in a computing system. Such advances could one day soon allow artificial intelligence to reach unlimited potential without consuming unreasonable amounts of energy.
Going Carbon Negative
Research Images
Electolite modulates degradation of battery
“Specifically, we found that potassium ions mitigate the formation of undesirable chemical compounds that deposit on the surface of lithium metal and prevent lithium ion transport during battery charging and discharging, ultimately limiting microstructural growth,” says the team’s PI Lauren Marbella, assistant professor of chemical engineering.
Her team’s discovery that alkali metal additives suppress the growth of non-conductive compounds on the surface of lithium metal differs from traditional electrolyte manipulation approaches, which have focused on depositing conductive polymers on the metal’s surface. The work is one of the first in-depth characterizations of the surface chemistry of lithium metal using NMR, and demonstrates the power of this technique to design new electrolytes for lithium metal. Marbella’s results were complemented with density functional theory (DFT) calculations performed by collaborators in the Viswanathan group in mechanical engineering at Carnegie Mellon University.
Next time Generation Lithium Batteries
Columbia chemical engineers find that alkali metal additives can prevent lithium microstructure proliferation during battery use; discovery could optimize electrolyte design for stable lithium metal batteries and enable lightweight, low-cost, long-lasting energy storage for EVs, houses, and more.
“Commercial electrolytes are a cocktail of carefully selected molecules,” Marbella notes. “Using NMR and computer simulations, we can finally understand how these unique electrolyte formulations improve lithium metal battery performance at the molecular level. This insight ultimately gives researchers the tools they need to optimize electrolyte design and enable stable lithium metal batteries.”
The team is now testing alkali metal additives that stop the formation of deleterious surface layers in combination with more traditional additives that encourage the growth of conductive layers on lithium metal. They are also actively using NMR to directly measure the rate of lithium transport through this layer.
Columbia Engineering
Columbia Engineering, based in New York City, is one of the top engineering schools in the U.S. and one of the oldest in the nation. Also known as The Fu Foundation School of Engineering and Applied Science, the School expands knowledge and advances technology through the pioneering research of its more than 220 faculty, while educating undergraduate and graduate students in a collaborative environment to become leaders informed by a firm foundation in engineering. The School’s faculty are at the center of the University’s cross-disciplinary research, contributing to the Data Science Institute, Earth Institute, Zuckerman Mind Brain Behavior Institute, Precision Medicine Initiative, and the Columbia Nano Initiative. Guided by its strategic vision, “Columbia Engineering for Humanity,” the School aims to translate ideas into innovations that foster a sustainable, healthy, secure, connected, and creative humanity.
ABOUT THE STUDY
The study is titled “Leveraging Cation Identity to Engineer Solid Electrolyte Interphases for Rechargeable Lithium Metal Anodes.” Authors are: Richard May 1; Yumin Zhang 1; Steven R. Denny 1; Venkatasubramanian Viswanathan 2,3; Lauren E. Marbella 1
- Department of Chemical Engineering, Columbia Engineering
- Department of Materials Science and Engineering, Carnegie Mellon University
- Department of Mechanical Engineering, Carnegie Mellon
The study was funded by the Alfred P. Sloan Foundation through a Scialog: Advanced Energy Storage Collaborative Innovation Award (2019-11419, LEM and VV). Richard May is supported by the U.S. Department of Defense through the National Defense Science & Engineering Graduate Fellowship Program.
The authors declare no competing interests.