First principles study of two-dimensional penta-germagraphene as good anode material for potassium ion batteries

Due to plenty of potassium in the Earth's crust, potentially high energy density, high conductivity and fast ionic diffusion, potassium ion batteries (PIBs) are expected as promising and competitive alternatives to lithium-ion batteries (LIBs). However, in order to obtain high-performance potassium ion batteries, it is crucial to find suitable anode materials. Herein, from first principles methods based on DFT, we have investigated the possibility of a new two-dimensional material, penta-germagraphene (denoted as P-Ge₂C₄) obtained by doping Ge atoms in penta-graphene, as anode materials for PIBs. The theoretical specific capacity is 554.8 mA h g⁻¹. The intercalation potentials between 0.1 and 0.65 V are suitable for use in batteries. The metallic electronic structures of P-Ge₂C₄ adsorbed K-ions and relatively small of diffusion energy barriers ensure good rate performance. The results show that two-Dimensional P-Ge₂C₄ can be applied as an anode material for PIBs with good performance.