Two-Dimensional Biphenylene-Based Carbon Allotrope Family with High Potassium Storage Ability

The development of new carbon materials with novel properties
and
excellent applications is essential and urgent in many fields, such
as potassium-ion batteries (PIBs). In this study, a family of 30 two-dimensional
biphenylene carbon allotropes (2D-BCAs) have been systematically extended
in theory. The energies of these allotropes are slightly higher than
that of graphene, which can be well described by a quantitative energy
equation. The 2D-BCAs show high synthesizability consistent with the
experimental biphenylene network via “HF-zipping” reactions.
The 2D-BCAs are metallic or semimetallic. Six representative 2D-BCAs
exhibit good lattice dynamical and thermal stability, excellent anisotropic
mechanical properties, and ORR catalytic activity. Moreover, the selected
2D-BCAs demonstrate ultrahigh theoretical potassium-storage capacities
of 1116–1489 mAh·g–1, low migration
barriers of 0.03–0.22 eV, and low open-circuit voltages of
1.10–0.02 V. The remarkable properties render 2D-BCAs as promising
anode materials in PIBs, electrocatalysts, and conductors in electronics
and iontronics.