Two-dimensional C₅₆₇₈: a promising carbon-based high-performance lithium-ion battery anode

Abstract

A two-dimensional structurally stable carbon allotrope C5678 as a promising electrode for lithium-ion batteries was predicted.

Hd-Graphene: A Hexagon-Deficient Carbon-Based Anode for Metal-Ion Batteries with High Charge/Discharge Rates

“…Both sides of the adsorption mode were 36 in LIBs. Furthermore, although these values are smaller than that of reported highest theoretical capacity of Be-doped graphene (2303 mA h/g), 73 they are much larger than those of well-known phagraphene (558 mA h/g), 44 bco-C 16 (558 mA h/g), 74 planar net-τ graphene (558 mA h/g), 32 and C 5678 (697 mA h/g) 60 along the crystallographic a and b directions, respectively, without structural breakage, and the ideal strengths are as high as 30.13 and 34.85 N/m, respectively. More remarkably, the intrinsic metallicity is still maintained under the entire strain interval along the crystallographic a direction and under 9% strain along the crystallographic b direction.…”

“…H d -graphene is more stable than some previously reported 2D allotropes of carbon, as presented in Figure 1c. The calculated total energy of H dgraphene is −8.93 eV/atom, which is much lower than those of planar T-graphene (−8.73 eV/atom), 64 buckled T-graphene (−8.41 eV/atom), 64 net-τ (−8.89 eV/atom), 32 pentagraphene (−8.32 eV/atom), 13,41 C 5678 (−8.88 eV/atom), 60 C 568 (−8.83 eV/atom), 43 and a pentagon carbon network (−8.65 eV/ atom), 37 while being close to those of Θ-graphene (−8.98 eV/ atom) 38 and popgraphene (−8.97 eV/atom), 35 and slightly higher than that of Ψ-graphene (−9.07 eV/atom). 36 These results suggest that H d -graphene is a metastable carbon-based material.…”

“…With respect to graphene, these regions can provide many effective adsorption sites for metal ions, thereby enhancing the metal-ion adsorption and storage capacity of H d -graphene. 51,60 Total energy calculations were performed to investigate the thermodynamic stability of H d -graphene. H d -graphene is more stable than some previously reported 2D allotropes of carbon, as presented in Figure 1c.…”

“…To check thermodynamic stability, ab initio molecular dynamics (AIMD) simulations were performed with a 2 × 2 × 1 supercell in a canonical ensemble ( NVT ) at 300 and 1500 K for 5 ps. According to previous studies, ,,,, van der Waals (vdW) interactions can be omitted for the lattice optimization, mechanical property, and band structure calculations; thus, vdW corrections were only taken into account in the case of metal ion adsorption on H d -graphene. The DFT-D3 approach is adopted.…”

“…Remarkably, H d -graphene possesses low diffusion energy barriers of (0.21− 0.32)/(0.14−0.21)/(0.09−0.15) eV when used in LIBs/SIBs/ PIBs, respectively, and these values are much lower than those of recently proposed MIBs, such as xgraphene (0.44−0.49)/ (0.27−0.33)/(0.14−0.18) eV, 39 T-graphene (0.37−0.47)/ (0.35−0.41)/(0.25−0.29) eV, 40 Θ-graphene (0.45−0.48)/ 0.39/(0.22−0.37) eV, 38 and 2D pentadiamond C 558 (0.42− 0.49)/(0.25−0.31)/(0.10−0.15) eV for Li/Na/K ions, respectively. 42 As an anode of LIBs, the barrier of H d -graphene is more favorable than those of net-τ graphene (0.30−0.36), 32 popgraphene (0.37−0.55), 35 Ψ-graphene (0.27−0.31), 36 BC 3 -SW (0.33−0.61), 52 BC 3 -PR (0.34−0.61), 52 and C 5678 (0.29− 0.44), 60 meaning H d -graphene has faster charge−discharge rates when used as an anode in MIBs. All these results indicate that Li/Na/K ions are very mobile and can easily transfer on the basal plane of H d -graphene.…”