Spinoff from Argonne-led innovation hub opens new frontier for batteries
Blue Current achieves success with a breakthrough material originally discovered by the Joint Center for Energy Storage Research.
There is broad consensus that there is no silver bullet for climate change. Rather, many solutions will be required. What makes the challenge particularly daunting is the enormous reductions in greenhouse gas emissions needed in a short period of time. Some experts are concerned that there is not enough time to turn breakthrough scientific discoveries into the revolutionary products necessary to achieve aggressive decarbonization goals.
The Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory, recognized this dilemma when it launched in 2012. JCESR brings together more than 150 researchers from 20 institutions — including national laboratories, universities and industry — to build materials to enable breakthrough batteries.
“JCESR creates and proves the ideas that eventually go commercial,” said George Crabtree, JCESR’s director and an Argonne senior scientist. “These are the riskier ideas that no investors would fund — and that companies are unlikely to pursue — because the outcome is so uncertain. If proven, these ideas can drive the rapid progress on climate change that we need.”
“JCESR put resources behind composites because the materials had potential to address a market need for safe, solid-state batteries while solving important technical challenges. By proving these materials, JCESR made it a lot easier for us to move forward with the technology.” — Kevin Wujcik, Blue Current’s chief technology officer
The successful trajectory of JCESR spinoff company Blue Current points to the wisdom of this approach. In 2015, one of JCESR’s laboratories discovered a promising new battery material, known as a “composite,” that can make batteries dramatically safer. Inspired by the composite’s potential, Blue Current developed it further. Now, Blue Current is ramping up production of its battery cells. What’s more, an arm of Koch Industries has invested $30 million in the company to build its first megawatt-scale pilot factory in Hayward, California.
A focus on safety from the start
Safety is an important issue with batteries. When batteries are charged and discharged, substances known as electrolytes carry charge between the positive and negative electrodes. The liquid electrolytes found in many commercial lithium-ion batteries are flammable.
Since its founding, Blue Current’s top priority has been to develop a completely safe battery. At the same time, it has gone to great lengths to avoid the safety related design compromises that other battery companies have made. Its primary target market is electric vehicles (EVs).
“Helping the transition to sustainable energy is part of our core mission, and EVs provide the biggest platform to do that,” said Kevin Wujcik, Blue Current’s chief technology officer. Wujcik was on the JCESR research team that discovered the composite material. At the time, he was pursuing his Ph.D. studies at University of California, Berkeley.
Developing batteries for EVs is particularly challenging because many needs have to be met at once. “An EV battery has to be both a marathon runner and a sprinter,” said Wujcik. “It has to have a very long driving range and operate for a long time. But it also has to be able to charge very quickly. And it needs to work well in low and high temperatures.”
Two internationally recognized battery researchers founded Blue Current in 2014. Nitash Balsara is a JCESR scientist, a professor of chemical engineering at the University of California, Berkeley and a senior faculty scientist at Lawrence Berkeley National Laboratory. Joseph DeSimone, who was a chemistry professor at the University of North Carolina at Chapel Hill in 2014, is a Stanford chemical engineering professor today.
An early pivot
Solid-state batteries, which contain solid electrolytes, are much less flammable than liquid batteries. That’s why many battery developers view solid-state technologies as key to developing completely safe batteries. But solid electrolytes face many technical challenges, and no company has successfully commercialized a solid-state battery to date.
A crystalline class of solids known as glass ceramics have good conductivity, which is the ability to move lithium ions quickly. But they lack the ability to stick to the chemically active materials in battery electrodes that store lithium ions.
Another class of materials known as polymers — large molecules with repeating chemical units — are effective at sticking to electrodes. But they have low conductivity.
Initially, Blue Current focused on developing a battery cell with a nonflammable liquid electrolyte. Then, in 2015, as part of JCESR-sponsored research, Balsara’s lab made a breakthrough discovery that turned out to be a key formative event for Blue Current. The lab addressed the shortcomings of glass ceramics and polymers by bonding them together. The resulting composite solid electrolyte demonstrated good conductivity and good stickiness. Recognizing the composite’s potential to address key challenges with solid-state batteries, Blue Current pivoted to the solid-state field in 2016.
“By combining these materials, the JCESR discovery solved the challenges that each material faced on its own,” said Wujcik. “We decided that using composites was the best way to make the safest battery possible.”
“Getting the science right”
Initially, the anode (negative electrode) of Blue Current’s battery cell was made of lithium metal. Then, in 2018, the company decided to use silicon as the chemically active anode material. One reason for the switch was safety: Lithium metal is highly reactive and flammable, even in solid-state batteries.
Since 2018, the company has refined its composite electrolytes, silicon anode and other battery materials, with an aim of solving the technical challenges of solid-state technology.
“We have focused on getting the science right,” said Wujcik.
One solid-state challenge involves the amount of pressure needed for good battery performance. To help solid electrolytes stick to electrodes, some companies add heavy metal plates and bolts that put battery cells under high pressure. These fixtures increase manufacturing costs while reducing energy density — the amount of energy that can be stored in batteries per unit weight or volume. Lower energy density in EV batteries translates into shorter driving ranges unless the manufacturer increases the size and weight of the batteries. Shorter driving ranges tend to make EVs less attractive to consumers.
Blue Current’s vision has been to use the adhesiveness and elasticity of its composite electrolyte to lower the amount of pressure required for cells to operate. The composite is able to maintain good contact with silicon particles in the anode — without the use of heavy metal plates. This is an impressive achievement: Silicon expands and contracts as a battery cell charges and discharges, which makes it particularly difficult for solid electrolytes to maintain contact.
A second challenge that Blue Current has overcome involves temperature. Because polymer electrolytes have low conductivity, many solid-state battery developers use heating elements to raise the temperature of the cells. While the heat improves the polymers’ conductivity, it requires energy, reducing the battery’s cost-effectiveness. As a result, this approach is not viable for many commercial applications. Today, the high conductivity of Blue Current’s composite electrolytes enables its cells to operate effectively at room temperature.
Solid-state battery developers often struggle to design cost-effective, large-scale manufacturing processes. For example, solid-state cells with lithium metal anodes require specialized manufacturing equipment to avoid formation of dendrites during battery operation. Dendrites are needle-like lithium structures that make batteries less safe and less durable.
Blue Current has overcome this barrier by selecting affordable, abundant silicon anode materials. Additionally, it has designed its components so that they can be processed with the same equipment used by high-volume, lithium-ion battery manufacturers today.
Blue Current’s cells have demonstrated excellent performance. As part of rigorous safety testing, the company subjected its cells to harsh conditions that EVs could encounter in the real world, including crushing, puncturing and overcharging. Thermal runaway — an overheating event in batteries that can lead to fires — never occurred.
“If you get rid of thermal runaway, you make the battery a lot safer,” said JCESR’s Crabtree. “This is especially important in EVs. The batteries are located under the passenger seats.”
In other recent tests, Blue Current’s cells retained 85% of their energy capacity after more than 1,000 charge-discharge cycles — the equivalent of driving hundreds of thousands of miles. It’s a promising sign that the cells will last a long time. According to an EV industry rule-of-thumb, 80% capacity retention is excellent.
The path forward
Blue Current is currently outfitting its Hayward pilot manufacturing plant with high-volume manufacturing equipment. When completed in 2023, the plant will have an annual production capacity of 1–2 megawatt-hours. Here, it will develop the specifications for manufacturing even higher volumes. “The plant is going to lay the groundwork for the next facility,” said Wujcik.
Blue Current also plans to remain focused on research and development. “We’re seeing the battery industry shifting towards the use of silicon anodes to improve the performance of both traditional lithium-ion batteries and next-generation, solid-state batteries,” said Wujcik. “Because the solid-state silicon field is still in an early stage, it’s essential for us to continue our efforts developing new materials.”
Indeed, Blue Current’s success with solid-state silicon batteries opens up a new field for researchers and other companies to explore. “There’s a lot of work that can be done in this space,” said Wujcik. “Researchers can investigate which solid electrolytes and silicon materials to use and how composite electrolytes stick to anode materials.”
Wujcik expressed appreciation for JCSER’s important role in Blue Current’s success.
“The idea of using composites in batteries was new and unproven prior to the JCESR program,” he said. “JCESR put resources behind composites because the materials had potential to address a market need for safe, solid-state batteries while solving important technical challenges. By proving these materials, JCESR made it a lot easier for us to move forward with the technology.”
The Joint Center for Energy Storage Research (JCESR), a DOE Energy Innovation Hub, is a major partnership that integrates researchers from many disciplines to overcome critical scientific and technical barriers and create new breakthrough energy storage technology. Led by the U.S. Department of Energy’s Argonne National Laboratory, partners include national leaders in science and engineering from academia, the private sector, and national laboratories. Their combined expertise spans the full range of the technology-development pipeline from basic research to prototype development to product engineering to market delivery.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
Researchers zoom in on battery wear and tear
Peer-Reviewed PublicationIMAGE: PME RESEARCHERS COLLECTED DATA ON HOW DIFFERENT COMPONENTS OF A THICK LITHIUM ION BATTERY ELECTRODE EVOLVE AFTER SUCCESSIVE CYCLES (ONE SNAPSHOT OF THE MICROSCOPY DATA SHOWN ON THE LEFT). THEN, THEY USED THIS DATA TO CREATE A COMPUTATIONAL MODEL (RIGHT) ILLUSTRATING THE DEGRADATION AND POINTING TOWARD HOW TO IMPROVE THE LIFESPAN OF THE BATTERIES. view more
CREDIT: IMAGE COURTESY OF THE LABORATORY FOR ENERGY STORAGE AND CONVERSION.
From the moment you first use it, a new lithium-ion battery is degrading. After a few hundred charge cycles, you’ll notice — your phone, laptop or electric car battery wears out more quickly. Eventually, it stops holding a charge at all.
Researchers at the University of Chicago’s Pritzker School of Molecular Engineering (PME) have now used a combination of high-powered electron microscopy and computational modeling to understand, at an atomic level, exactly what occurs when lithium-ion batteries degrade. Their research points toward one approach to designing longer-lasting lithium-ion batteries — by focusing on an oft-ignored structural component, the carbon binder domain (CBD).
“To tackle many of the world’s energy storage and conversion challenges over coming decades, we need to keep innovating and improving batteries,” said Prof. Y. Shirley Meng, who led the research, published in the journal Joule. “This work is one step toward more efficient and sustainable battery technology.”
Limited Charge Cycles
The widespread commercialization of lithium-ion batteries at the end of the twentieth century played a role in the advent of lightweight, rechargeable electronics. Lithium is the lightest metal and has a high energy density-to-weight ratio. When a lithium-ion battery is charged, lithium ions move from a positively charged cathode to a negatively charged anode. To release energy, those ions flow back from the anode to the cathode.
Throughout charging cycles, the active materials of the cathode and anode expand and contract, accumulating “particle cracks” and other physical damage. Over time, this makes lithium-ion batteries work less well.
Researchers have previously characterized the particle cracking and degradation that occurs in small, thin electrodes for lithium-ion batteries. However, thicker, more energy-dense electrodes are now being developed for larger batteries — with applications such as electric cars, trucks and airplanes.
“The kinetics of a thick electrode are quite different from those of a thin electrode,” said project scientist Minghao Zhang of the University of California San Diego, a co-first author of the new paper. “Degradation is actually much worse in thicker, higher-energy electrodes, which has been a struggle for the field.”
It’s also harder to quantitatively study thick electrodes, Zhang pointed out. The tools that previously worked to study thin electrodes can’t capture the structures of larger, denser materials.
Combining Microscopy and Modeling
In the new work, Meng, Zhang and collaborators from Thermo Fisher Scientific turned to Plasma focused ion beam-scanning electron microscopy (PFIB-SEM) to visualize the changes that occur inside a thick lithium-ion battery cathode. PFIB-SEM uses focused rays charged ions and electrons to assemble an ultra-high-resolution picture of a material’s three-dimensional structure.
The researchers used the imaging approach to collect data on a brand new cathode as well as one that had been charged and depleted 15 times. With the data from the electron microscopy experiments, the team built computational models illustrating the process of degradation in the batteries.
“This combination of nanoscale resolution experimental data and modeling is what allowed us to determine how the cathode degrades,” said PME postdoctoral research fellow Mehdi Chouchane, a co-first author of the paper. “Without the modeling, it would have been very hard to prove what was happening.”
The researchers discovered that variation between areas of the battery encouraged many of the structural changes. Electrolyte corrosion occurred more frequently with a thin layer at the surface of the cathode. This top layer therefore developed a thicker resistive layer, which led the bottom layer to expand and contract more than other parts of the cathode, leading to faster degradation.
The model also pointed toward the importance of CBD — a porous grid of fluoropolymer and carbon atoms that holds the active materials of an electrode together contribute and helps conduct electricity through the battery. Previous research has not characterized how the CBD degrades during battery use, but the new work suggested that the weakening of contacts between the CBD and active materials of the cathode directly to the decline in performance of lithium-ion batteries over time.
“This change was even more obvious than the cracking of the active material, which is what many researchers have focused on in the past,” said Zhang.
Batteries of the Future
With their model of the cathode, Meng’s group studied how tweaks to the electrode design might impact its degradation. They showed that changing the CBD structure network could help prevent the worsening of contacts between the CBD and active materials, making batteries last longer — a hypothesis that engineers can now follow up with physical experiments.
The group is now using the same approach to study even thicker cathodes, as well as carrying out additional modeling on how to slow electrode degradation.
Said Dr. Zhao Liu, senior manager for battery market development at Thermo Fisher Scientific, who contributed to the research, “This study develops a methodology of how to design electrodes to enhance future battery performance.”
JOURNAL
Joule
METHOD OF RESEARCH
Computational simulation/modeling
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Coupling of multiscale imaging analysis and computational modeling for understanding thick cathode degradation mechanisms
ARTICLE PUBLICATION DATE
22-Dec-2022
