Twin graphene as an anode material for potassium-ion battery: A first principle study

Using density functional theory, we have investigated the usage of twin graphene as an anode material for potassium-ion batteries (KIBs). Twin graphene demonstrates excellent structural and cycling stability, with minimal changes in lattice parameters and negative cohesive energy during K charge/discharge cycles. Notably, the host material (twin graphene) offers multiple stable adsorption sites for potassium ions. We even observed that the pristine twin graphene, which is a semiconductor, consequently becomes metallic upon potassium adsorption. Twin graphene provides a high theoretical capacity of 495.84 mAh/g, along with low diffusion barrier of 0.290 V for K diffusion. Furthermore, the high electrical conductivity and low open-circuit voltage of the chosen host will definitely enhance its performance as a KIB material. The structural integrity of twin graphene is also retained with the adsorption of potassium ion, as checked through ab initio molecular dynamics simulation. These findings suggest that twin graphene may be considered as a promising anode material for KIBs.