Dr. Yi Cui is a Stanford University associate professor of materials science and engineering and a member of the Stanford Institute for Materials and Energy Sciences, a joint institute with SLAC, the National Acceleration Laboratory. He has spoken at three Electric Aircraft Symposiums, and has worked for at least the last decade on various technologies and tactics to bring battery science to a high level. His latest effort involves “a low-cost, long-life battery that could enable solar and wind energy to become major suppliers to the electrical grid,” according to a press release from SLAC. Dr. Cui says, “We believe our new battery may be the best yet designed to regulate the natural fluctuations of these alternative energies.” Of concern to drivers of electric vehicles and future pilots, the electrical grid may have trouble keeping up with recharging needs of large numbers of cars, buses and even Boeing SUGAR (Subsonic Ultra Green Aircraft Research) Liners. Wind and solar have the …
Dr. Cui’s Pomegranate-inspired Battery Bears Fruit
Dr. Yi Cui seems to get inspiration from food. A few years ago, his research team came up with a “yolk-shell structure” that helped contain the high amount of lithium that silicon anodes were able to absorb. That battery design promised much, and an embellishment of that design seems to hold even greater promise. His newest effort, working at Stanford University with the Department of Energy’s SLAC National Accelerator Laboratory, features an electrode “designed like a pomegranate – with silicon nanoparticles clustered like seed in a tough carbon rind.” This approach, according to its inventors, overcomes several remaining obstacles to the use of silicon in a new generation of lithium-ion batteries. Yi said the battery’s efficiency and longevity are promising. “Experiments showed our pomegranate-inspired anode operates at 97 percent capacity even after 1,000 cycles of charging and discharging, which puts it well within the desired range for commercial operation.” Cui’s team has been working on preventing anode breakup for the …
Free Battery Software May Free Battery Designers
Your editor used to teach a class on technical writing. One of its premises was that good technical writing should be so clear it helps us see the error of our ways. If the knights in Monty Python and the Holy Grail had done a brief description and a few simple drawings before catapulting cows over their enemy’s walls, they might have realized that they had supplied bovine bombs for the enemy to catapult back. To avoid similar defeats on the stored energy front, engineers at Washington University in St. Louis have cooked up a Cliff’s Notes of how different battery chemistries will behave when being charged. This “back of the envelope calculation,” as Venkat Subramanian, PhD, associate professor of energy, environmental & chemical engineering and his team think of it, is an early predictor of success. Best of all, “The team developed a freely available code that battery developers can use as a model to determine the optimal profile …
Batteries That Heal Themselves
Alert reader Colin Rush provided this breaking development in battery science. Regular readers will remember Dr. Yi Cui’s name. He’s a Stanford University scientist who has worked with paper batteries, much more powerful electrodes, and means of helping batteries stay together under the continuous strain of expanding and contracting during charging and discharging. He explained that at the third annual Electric Aircraft Symposium at the Hiller Aviation Museum, and has since adopted several tactics to overcome that problem. One commercial outgrowth of his work, Amprius, is working on commercial production that benefits from his insights. Since that internal flexing eventually leads to cracking of electrodes, Dr. Cui’s latest announcement brings some hope that such things can not only be overcome, but literally healed. Just as our bodies have internal resources to fight diseases and repair muscle and bone, batteries can be made to be self-healing. Dr. Cui has been a proponent of using silicon as a major component in electrodes, …
Breaking Up Isn’t So Hard to Do
A great deal of the research on lithium batteries goes into figuring out how to keep them together for the greatest number of charge-discharge cycles. Unfortunately, the active compounds in these batteries that give the greatest energy storage capacity or power output, also tend to be those compounds that come unglued under stress. Taking high-resolution 3D movies with X-ray tomography (somewhat like the CAT scans used on human subjects), researchers at the Swiss Light Source, a mecca for seeing the unseeable, have witnessed the expansion and contraction of the internal structure of lithium-ion batteries, while the batteries are operating. Stanford University’s Dr. Cui has explained that the expansion and contraction of batteries leads to their eventual failure, but until now, there has been no real-time observation of these internal reactions. Martin Ebner, a Ph.D. candidate at the Laboratory for Nanoelectronics in the Department of Information Technology and Electrical Engineering (D-ITET) at ETH (Eidgenössische Technische Hochschule) and Professor Vanessa Wood, head of the …
Lithium Gets a Good Wrap
Shadi Dayeh, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering, has been designing new electrode architectures that could solve one of lithium batteries’ biggest problems. When lithium diffuses across the surface of a lithium-ion battery electrode, it causes the electrode to expand and contract depending on its charging or discharging. This eventually leads to cracking and ultimate disintegration of the anode or cathode – weakening and finally disabling the battery. Dayeh, working with colleagues at the University and Sandia and Los Alamos National Laboratories, came up with nanowires that, “Block diffusion of lithium (Li) across their silicon surface and promote layer-by-layer axial lithiation of the nanowire’s germanium core.” Seeing possibilities beyond his current research, Dayeh says the work could lead to, “An effective way to tailor volume expansion of lithium ion battery electrodes which could potentially minimize their cracking, improve their durability, and perhaps influence how one could think about …
A Milestone on the Road to Dr. Cui’s 10X Battery
Seeing the Amprius web site, one would never know that some “dramatic improvements” promised in the terse announcement might mean so much in terms of true breakthroughs. Neatly centered, Amprius’ total web site is a few lines of discrete text. Amprius is a leading Lithium-Ion battery developer Amprius’s silicon technology was originally developed at Stanford University and enables dramatic improvements in the energy density and specific energy of Lithium-Ion batteries. Amprius is backed by some of the world’s leading investors, including Trident Capital, VantagePoint Venture Partners, IPV Capital, Kleiner Perkins Caufield & Byers, and Dr. Eric Schmidt. Amprius, Inc., 225 Humboldt Ct. Sunnyvale, CA 94089 But the battery manufacturer has two first-generation product offerings with volumetric energy densities of 580 Watt-hours and 600 Watt-hours per liter. Most lithium batteries fall into a range from 250-500 Wh/l., putting the new cells at the upper limit of such batteries. Both Amprius batteries are now in production and available to original equipment manufacturers, …
That’s No Yolk!
Dr. Cui is at it again! In a seemingly endless stream of announcements, his work with silicon anodes keeps promising improvements in battery capacity and longevity. The Stanford professor and his team, Stanford’s National Accelerator Laboratory (Formerly the Stanford Linear Accelerator Center), and the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory all published papers on their latest joint accomplishment. Conceptual drawing of silicon filling carbon shell, TEM photo of actual expansion, and life cycle analysis for yolk-shell batteries Expansion and contraction of anodes and cathodes during charging and discharging of batteries causes flexing and eventual breakdown of a battery’s internal components. Cui and other researchers have tried various strategies to mitigate or eliminate this flexing, but the latest tactic seems to promise longer battery life and greater power and energy. Calling it a “yolk-shell structure,” researchers seal commercially available single silicon nanoparticles in “conformal, thin, self-supporting carbon shells, with rationally-designed void space between the particles and the …
Dipping and Coating for Better Batteries
Could dipping electrodes in a secret sauce improve supercapacitor and battery endurance and power? Could coating cell internals be the flavor of the month? These recipes for better batteries may improve things at a better than normal rate, if California researchers have anything to say about it. Working with his compatriot Dr. Jaephil Cho in South Korean, Dr. Cui of Stanford University has been a leader in developing improved battery technology, even developing a painted paper battery. In an appearance at the 2009 Electric Aircraft Symposium, Cui explained a basic truth of battery development – that improvements generally created about eight percent greater power or endurance in cells every year, leading to a doubling of battery capabilities every seven and one-half years. He aims to improve that rate of change in batteries and ultracapacitors. Although ultracapacitors are able to charge and discharge rapidly, they are only about one-tenth as energy dense as batteries of equivalent mass. Cui and colleague Zhenan Bao …
Power Spraying Takes on a Whole New Meaning
Several news sources, apparently using the same press release from Mitsubishi Chemical Corp., have announced a spray-on solar cell, which can be applied in the same fashion as paint – to “buildings, vehicles and even clothing.” This “means that the places where energy from the sun can be harvested are almost limitless.” Less than one millimeter thick and capable of 10.1-percent efficiency, the new material is said to have a weight one-tenth of traditional silicon cells. Mitsubishi says these are prototype materials, and that they hope to achieve 15-percent efficiency by 2015, with 20 percent as a more distant possibility. Mitsubishi is a bit soft on details, but says, “The new solar cells utilize carbon compounds which, when dried and solidified, act as semiconductors and generate electricity in reaction to being exposed to light. Most existing solar cell technology requires crystalline silicon to be sandwiched between glass sheets and positioned on the roofs of homes and office buildings, or in space-consuming …