A multi-institutional research team led by Hailong Chen of Georgia Institute of Technology has developed a new, cost-effective cathode that is expected to significantly improve the performance of lithium-ion batteries (LIB) and revolutionize the electric vehicle (EV) market and large-scale energy storage systems.
"People have long been looking for a lower-cost, more sustainable cathode material to replace existing cathode materials. I think we have found one," said Chen, an associate professor in the George Woodruff School of Mechanical Engineering and the School of Materials Science and Engineering.
This revolutionary material is ferric chloride (FeCl3), which costs only 1-2% of typical cathode materials but can store the same amount of electricity. Cathode materials affect capacity, energy and efficiency and play an important role in battery performance, longevity and economics.
"Our cathode is a game-changer that will greatly improve the electric vehicle market -- and the overall lithium-ion battery market," said Chen. His team presented their work in Nature Sustainability.
Sony first commercialized lithium-ion batteries in the early 1990s, triggering an explosion in personal electronics such as smartphones and tablets. The technology eventually developed into fuel for electric vehicles, providing a reliable, rechargeable, high-density energy source. But unlike personal electronics, large energy users such as electric vehicles are particularly sensitive to the cost of lithium batteries.
Batteries currently account for about 50% of the total cost of electric vehicles, making these clean-energy vehicles more expensive than their internal combustion, greenhouse gas-emitting counterparts. The invention of Dr. Chen's team can change this situation.
Make better batteries
Compared with older alkaline and lead-acid batteries, lithium-ion batteries store more energy in a smaller volume and can power devices for longer between charges. However, lithium batteries contain expensive metals, including semi-precious metal elements such as cobalt and nickel, and their manufacturing costs are high.
To date, only four types of cathodes have been successfully commercialized for lithium batteries. Dr. Chen's technology will be the fifth, and it represents a major step forward in battery technology: the development of all-solid-state lithium-ion batteries.
Traditional lithium-ion batteries use a liquid electrolyte to transport lithium ions to store and release energy. Liquid lithium-ion batteries have strict limits on the amount of energy they can store and can leak and catch fire. But all-solid-state lithium batteries use solid electrolytes, which greatly improves the efficiency and reliability of the battery, making it safer and capable of storing more energy. This battery is still in the development and testing stages, but will be a major improvement.
As researchers and manufacturers around the world scramble to bring all-solid-state technology to life, Chen and his collaborators have developed an affordable and sustainable solution. With a ferric chloride cathode, solid electrolyte and lithium metal anode, their entire battery system costs only 30-40% of current lithium batteries.
"This will not only make electric vehicles much cheaper than internal combustion vehicles, but also provide a new and promising form of large-scale energy storage that enhances the resilience of the grid. In addition, our cathode will greatly improve the sustainability and supply chain stability of the electric vehicle market," Chen said.
A solid starting point for new discoveries
Chen's interest in FeCl3 as a cathode material stems from his laboratory's research on solid electrolyte materials. Starting in 2019, his lab tried to create solid-state batteries using chloride-based solid electrolytes and traditional commercial oxide-based cathodes. The results were not smooth—the cathode and electrolyte materials were not compatible.
The researchers believe that a chloride-based cathode could pair better with a chloride electrolyte, providing better battery performance. "We found a candidate material (FeCl3) that was worth trying because its crystal structure might be suitable for storing and transporting lithium ions, and fortunately, it functioned as we expected," Chen said.
Currently, the most commonly used cathodes in electric vehicles are oxides, which require large amounts of expensive nickel and cobalt. These heavy elements can be toxic and pose environmental challenges. In contrast, Dr. Chen's team's cathode contained only iron (Fe) and chlorine (Cl) - elements that are abundant, cheap and widely used in steel and table salt.
In their preliminary tests, they found that FeCl3 performed as well as or better than other, much more expensive cathodes. For example, it operates at a higher voltage than the commonly used cathode LiFePO4 (lithium iron phosphate, or LFP), which is the power the battery provides when connected to a device, similar to the water pressure of a garden hose.
The technology is likely less than five years away from the commercialization of electric vehicles. For now, the research team will continue to study ferric chloride and related materials. The work was led by Chen and postdoc Liu Zhantao, the study's first author. Collaborators include researchers from Georgia Tech's Woodruff School (Ting Zhu) and School of Earth and Atmospheric Sciences (Yuanzhi Tang), as well as researchers from Oak Ridge National Laboratory (Jue Liu) and the University of Houston (Shuo Chen).
"We want to make the material as perfect as possible in the laboratory and understand its basic operating mechanisms," Chen said. "But we are open to opportunities to scale the technology and advance it to commercial applications."
Compiled from /ScitechDaily
DOI:10.1038/s41893-024-01431-6