A research team has introduced a budget-friendly iron chloride cathode for all-solid-state lithium-ion batteries, which has the potential to lower costs and enhance performance for electric vehicles and large-scale energy storage solutions.
A collaborative research effort spearheaded by Hailong Chen from Georgia Tech has created an innovative, cost-effective cathode that could dramatically enhance lithium-ion batteries (LIBs), potentially revolutionizing the market for electric vehicles (EVs) and extensive energy storage systems.
“For a long time, people have been searching for a more affordable, sustainable replacement to current cathode materials. I believe we’ve found one,” stated Chen, who is an associate professor in both the George W. Woodruff School of Mechanical Engineering and the School of Materials Science and Engineering.
This groundbreaking material, iron chloride (FeCl3), costs only 1-2% of conventional cathode materials while being capable of storing an equivalent amount of energy. The choice of cathode materials is crucial as it influences a battery’s capacity, energy output, efficiency, along with its overall performance, lifespan, and cost-effectiveness.
“Our cathode could truly be a game-changer,” asserted Chen, whose team has detailed their findings in Nature Sustainability. “It would significantly benefit the EV market and enhance the entire lithium-ion battery sector.”
Originally commercialized by Sony in the early 1990s, LIBs led to a surge in personal electronic devices, including smartphones and tablets. Over time, this technology evolved to power electric vehicles, delivering a reliable, rechargeable, and high-density energy source. However, unlike consumer electronics, large-scale energy consumers like EVs are particularly sensitive to the costs associated with LIBs.
Currently, batteries account for about 50% of an EV’s overall cost, making these environmentally-friendly vehicles pricier compared to conventional internal combustion engines that emit greenhouse gases. The innovation from Chen’s team could shift this paradigm.
Creating Superior Batteries
When compared to traditional alkaline and lead-acid batteries, LIBs provide a more compact energy storage solution that lasts longer between charges. However, LIBs require expensive metals, incorporating rare elements like cobalt and nickel which contribute to high production costs.
To date, only four types of cathodes have been successfully commercialized for LIBs. Chen’s development would mark the fifth type and signify a major advancement toward all-solid-state LIB technology.
Standard LIBs rely on liquid electrolytes for the movement of lithium ions that store and release energy, which places strict limits on energy storage capacity and raises risks of leakage and fire. Conversely, all-solid-state LIBs utilize solid electrolytes, significantly enhancing battery efficiency, reliability, and safety while enabling higher energy storage capabilities. These new batteries, still under development and testing, promise notable improvements.
As researchers and manufacturers worldwide endeavor to create practical all-solid-state technology, Chen and his team have introduced an economical and sustainable option. With the FeCl3 cathode, a solid electrolyte, and a lithium metal anode, their complete battery system costs only 30-40% of the current LIBs on the market.
“This could not only make EVs much more affordable than traditional combustion vehicles, but it also introduces a promising solution for large-scale energy storage, thereby strengthening the electrical grid’s resilience,” said Chen. “Moreover, our cathode would significantly enhance the sustainability and reliability of the supply chain within the EV sector.”
A Solid Beginning to a New Discovery
Chen’s interest in FeCl3 as a cathode material stemmed from his lab’s exploration of solid electrolyte substances. Beginning in 2019, his team attempted to create solid-state batteries using chloride-based solid electrolytes but faced challenges when pairing them with traditional commercial oxide-based cathodes.
Researchers believed a chloride-based cathode might work better with the chloride electrolyte, ultimately delivering enhanced battery performance.
“We identified FeCl3 as a fitting option to explore further, as its crystal structure shows potential for effectively storing and transferring lithium ions, and luckily, it performed as we anticipated,” explained Chen.
Currently, the most commonly used cathodes in EVs are oxides, which necessitate large quantities of costly nickel and cobalt—heavy metals that can be toxic and pose environmental issues. In contrast, the cathode developed by Chen’s team consists solely of iron (Fe) and chlorine (Cl)—ubiquitous, cost-effective elements found in steel and table salt.
Initial tests revealed that FeCl3 performed on par with or outperformed other, more expensive cathode options. For instance, it boasts a higher operational voltage compared to the popular LiFePO4 (lithium iron phosphate, or LFP) cathode, which relates to the battery’s electrical output when connected to a device, akin to water pressure flowing through a garden hose.
This technology may be commercialized for use in EVs within the next five years. For the moment, the team will continue exploring FeCl3 and similar materials, as stated by Chen. The research was led by Chen and postdoctoral fellow Zhantao Liu (the primary author of the study), with collaboration from colleagues at Georgia Tech’s Woodruff School (Ting Zhu) and the School of Earth and Atmospheric Sciences (Yuanzhi Tang), in addition to researchers from Oak Ridge National Laboratory (Jue Liu) and the University of Houston (Shuo Chen).
“Our goal is to refine the materials to perfection in the lab and comprehend the fundamental mechanisms at play,” Chen elaborated. “We remain open to opportunities for scaling up the technology and advancing it towards commercial applications.”
