Researchers achieved a complete transition from 3R to 2H at about 350 degrees C.
Graphite is a critical element for lithium battery anode preparation. It can exist in two phases: the Bernal (2H) phase and the rhombohedral (3R) phase. The 2H phase has relatively low energy and high proportion in graphite powder, while the 3R phase is opposite to this. Research works suggest the transition from 3R phase to 2H phase is usually observed under high temperature over 1,000 degrees C through Joule or laser heating, which is inappropriate and unfeasible.
Researchers from University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) have achieved complete transition from 3R to 2H at about 350 degrees C by annealing graphite in the presence of α-Li3N (lithium nitride), which is a promising candidate for catalysis and energy applications.
The lithium nitride injects charge to the conjugated π bond of graphite, allowing a lower phase transition temperature from 3R to 2H in graphite.
According to the researchers, the study provides a way to control the stacking configuration and other properties of graphite through regulating the conjugated π bond, also making it attractive for future carbon material preparation.