Novel two-dimensional K-Ge₂C₄ monolayer as an anode for Li-/Na-ion batteries with high theoretical capacity

Abstract

In this study, we utilized first-principles calculations to explore a two-dimensional (2D) multi-ring structure composed of carbon and germanium atoms and investigated its potential for Li/Na storage. This structure, consisting of 2 germanium atoms and 4 carbon atoms, is referred to as K-Ge₂C₄. Its stability, as well as mechanical, electronic, and energy storage-related properties, were also examined. he results show that the Young’s modulus and Poisson’s ratio confirm that K-Ge₂C₄ has a stable structure and good ductility. The high density of states near the Fermi level (0.831 state/eV/atom) indicates that the material exhibits superior conductivity. Furthermore, the density of states near the Fermi level increased to 1.473 and 2.001 state/eV/atom after Li and Na adsorption at the H₂ sites, suggesting high electronic transfer efficiency. The barriers to the diffusion potential for Li and Na are 0.223 and 0.121 eV, respectively, indicating excellent ionic diffusion capability in K-Ge₂C₄. Notably, the maximum storage capacity for Li and Na reaches as high as 975.49 mAhg⁻¹, demonstrating an exceptionally high energy storage density. These findings highlight K-Ge₂C₄ as a highly promising 2D anode material for LIBs/NIBs, offering new insights into the development of 2D anode battery materials.