Graphite synthesis for batteries and fuel cells

Graphite is critical for lithium-ion batteries making up approximately a quarter of the battery and is where the lithium is safely stored during charging. Some fuel cell vehicles contain even more graphite than battery electric in their fuel cells. A better understanding of graphite synthesis is critical for the green transition.

Half of the graphite used in lithium-ion batteries is synthetic graphite that requires hours to days to reach the 3000 °C required to make the graphite. There is considerable interest in understanding how graphite forms and how to reduce the energy requirements to manufacture it.

We developed a method to use the graphite furnace within an atomic absorption spectrometer for heating materials to 3000 °C. This small tube furnace can heat milligrams of material to 3000 °C and cool to room temperature in seconds.

This allows for rapid testing of materials propensity to transform into graphite to be assessed as well as the time to graphitisation to be quantified. We have used this furnace to establish the time scale for graphite formation and study the key defects involved. We found that screw defects are the key defect that inhibit graphite formation. By targeting these defects, we aim to lower the cost of graphite synthesis and thereby reduce the cost of lithium-ion batteries.

Francas, G. R., Martin, J. W., Suarez-Martinez, I., & Marks, N. A. (2023). Topological defects and anisotropic development during pre-graphitization. Carbon, 213, 118251.

Martin, J. W., Fogg, J. L., Francas, G. R., Putman, K. J., Turner, E. P., Suarez-Martinez, I., & Marks, N. A. (2023). Graphite rapidly forms via annihilation of screw dislocations. Carbon, 215, 118386.

Fogg, J. L., Putman, K. J., Zhang, T., Lei, Y., Terrones, M., Harris, P. J., ... & Suarez-Martinez, I. (2020). Catalysis-free transformation of non-graphitising carbons into highly crystalline graphite. Communications Materials, 1(1), 47.

Putman, K. J., Sofianos, M. V., Rowles, M. R., Harris, P. J. F., Buckley, C. E., Marks, N. A., & Suarez-Martinez, I. (2018). Pulsed thermal treatment of carbon up to 3000 C using an atomic absorption spectrometer. Carbon, 135, 157-163.