Molten salt electrochemical upcycling of CO2 to graphite for high performance battery anodes

The efficient transformation of CO2 into a value-added material is a potential strategy to help mitigate climate effects caused by CO2 emissions. One potential CO2 conversion product is graphite which is an important and versatile material extensively used in many applications including as an anode for lithium-ion batteries (LIBs). Commercial graphite, however, is traditionally synthesized via the energy intensive Acheson process (>3000 °C) and the performance of such graphite can be limited under fast charging conditions which is important for vehicle electrification. Herein, we report the electrochemical transformation of CO2 to highly crystalline nano-graphite with a controlled microstructure in a carbonate molten salt at 780 °C. The use of a nickel foam electrode and controlled electrochemical parameters during the molten salt conversion process yielded pure graphite at a lower temperature compared to the Acheson process. Moreover, when investigated as an anode material for LIBs, the CO2-converted graphite exhibited high reversible capacity, long cycle life, and excellent rate capability even under fast charging conditions. This process provides a way to potentially reduce carbon emissions through the utilization of waste CO2 by converting it into value-added graphite suitable for fast charging, high-energy-density batteries for vehicle electrification.