Atomic Manipulation on 2D Sumanene for Precise Fermi Level Positioning in Ultrafast High-Capacity Alkali Metal...

A sumanene monolayer, with a Kagome-like lattice and two flat bands and two Dirac cones in the band structures, can be atomically assembled by C₂₁ clusters. In this paper, first-principles simulations indicate surface charge doping can purposely shift the Fermi level between Dirac cones and flat bands. Interestingly, Li/Na/K atoms can be well distributed in bowl-like structures, transforming the semiconducting sumanene monolayer into a semimetal by shifting the Fermi energy exactly to the Dirac cone. As a natural hosting platform, sumanene shows a high theoretical storage capacity (1115.7 mAh/g for Na/K). Additionally, the moderate adsorption and very low diffusion barrier (≤0.24 eV) imply a suitable open-circuit voltage and ultrafast charge. Besides, the naturally curved and flexural configuration of sumanene effectively releases the lattice expansion during charging and discharging. Therefore, doped sumanene is a compelling anode material for alkali-metal batteries with high capacity, ultrafast charge, and high structural stability.