Researchers at Lawrence Berkeley National Laboratory, UC Berkeley, and Estonia’s National Institute of Chemical Physics and Biophysics have converted atmospheric carbon dioxide into graphite using molten-salt electrolysis, according to reporting from Berkeley Lab. The work, published recently in Nature Communications, demonstrates a potential alternative to traditional mining for a critical mineral required in batteries, smartphones, laptops, and industrial power equipment. United States industries currently rely on imported and processed graphite for these technologies.
To study the conversion, researchers constructed a custom microscope setup to observe molten-salt electrolysis as it occurred. The technique applies electricity to hot liquid salts, converting carbon dioxide gas into solid carbon. The custom instrumentation allowed the team to monitor the process in real time inside corrosive liquid salts heated to 500 degrees Celsius while the system operated.
Molecular observations
The real-time tracking revealed an unexpected two-step reaction at the molecular level, resolving a long-standing question regarding how the conversion occurs. Researchers observed that the core chemical reaction remained constant even when altering the materials used for the electrodes or the molten salts. Adjusting these materials changes the resulting carbon structures, offering a method to tune the process to produce battery-grade graphite.
“This is a major win in a larger effort of synthesizing critical materials and battery materials using molten salts,” said Mike Whittaker, a Berkeley Lab scientist who worked on the project. Whittaker noted that running the process at low temperatures with low-cost salts could allow wide deployment and supply graphite directly into battery supply chains.
Next steps and funding
The project demonstrated a new approach for studying chemistry inside molten-salt environments, which have historically proven difficult to probe directly due to harsh operational conditions. Future research will focus on identifying ideal combinations of molten salts, electrode materials, temperatures, and voltages. The team must also scale up the approach to produce industrially useful quantities of carbon materials.
The research was conducted under the MINerals for Energy Storage Synthesis (MINES) program, funded by the Department of Energy’s Basic Energy Sciences program. Berkeley Lab was founded in 1931, is managed by the University of California for the U.S. Department of Energy’s Office of Science, and has had its scientists recognized with 17 Nobel Prizes.
