First-Principles Study of the Lithium/Sodium Storage Performance of Dirac Semimetal Carbon Materials <i>Pmna</i> -C20/C56

Topological semimetals (TSMs) have wide application potential as new electrode materials for metal-ion batteries. Two Dirac semimetal carbon materials Pmna-C20 and Pmna-C56 with Pmna space group have attracted attention in the field of topological quantum materials due to their special topological properties. However, the exploration of their electrochemical properties is still lacking in existing research. This study investigates the lithium/sodium storage performance of two Dirac semimetal carbon materials, Pmna-C20 and Pmna-C56, using first-principles calculations. First, it was verified that the band structures of the two materials exhibit crossing and linear dispersion between the conduction and valence bands near the Fermi level, and there is a quadruple degenerate Dirac point with high electronic conductivity. For lithium-ion batteries (LIBs), Pmna-C20 exhibits high theoretical capacity (893.4 mA h g–1), low diffusion barrier (0.40 eV), and suitable open-circuit voltage (1.04 V), which is superior to the performance of existing three-dimensional carbon materials; In sodium-ion batteries (SIBs), Pmna-C56 exhibits a high theoretical capacity of 199.4 mA h g–1, a low diffusion barrier of 0.16 eV, and a low open-circuit voltage of 0.52 V. Overall, Pmna-C20 and Pmna-C56 have broad application prospects in the field of LIBs and SIBs anode materials, respectively. This study fills the gap in the electrochemical performance research of Pmna-C20 and Pmna-C56 carbon materials, providing a theoretical basis for the development of new efficient and stable anode materials for metal-ion batteries.