First-Principles Study of the Lithium/Sodium Storage Performance of Dirac Semimetal Carbon Materials Pmna-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.