An international team of scientists has for the first time observed carbon dioxide converting into solid carbon inside molten salt at roughly 500 degrees Celsius, a step toward lower-cost graphite for electric vehicle batteries.
The work was carried out by researchers from Lawrence Berkeley National Laboratory, the University of California Berkeley, and the National Institute of Chemical Physics and Biophysics in Estonia.
The technique uses molten-salt electrolysis: an electric current strips oxygen from CO2 molecules, and the remaining carbon deposits as a solid on the cathode. Observing this directly had previously been impossible because the hot salt destroys conventional optical equipment. The team solved this by building a reaction chamber fitted with heat-resistant lenses.
The experiment showed that conversion unfolds in two stages, with an intermediate compound forming before solid carbon appears. The researchers also found that adjusting the melt composition and electrode materials can control the structure of the carbon produced, which affects how efficiently lithium ions move through battery anodes.
Industrial application remains distant. The process requires sustained temperatures of about 500 degrees Celsius, and engineers still need to optimize salt mixtures, electrode materials, energy consumption, and heat distribution at larger scale.
