Exploring the role of 2D-C2N monolayers in potassium ion batteries

Context In recent years, undivided attention has been given to the unique properties of layered nitrogenated holey graphene (C 2 N) monolayers (C 2 NMLs), which have widespread applications (e.g., in catalysis and metal-ion batteries). Nevertheless, the scarcity and impurity of C 2 NMLs in experiments and the ineffective technique of adsorbing a single atom on the surface of C 2 NMLs have significantly limited their investigation and thus their development. Within this research study, we proposed a novel model, i.e., atom pair adsorption, to inspect the potential use of a C 2 NML anode material for KIBs through first-principles (DFT) computations. The maximum theoretical capacity of K ions reached 2397 mA h g −1 , which was greater in contrast with that of graphite. The results of Bader charge analysis and charge density difference revealed the creation of channels between K atoms and the C 2 NML for electron transport, which increased the interactions between them. The fast process of charge and discharge in the battery was due to the metallicity of the complex of C 2 NML/K ions and because the diffusion barrier of K ions on the C 2 NML was low. Moreover, the C 2 NML has the advantages of great cycling stability and low open-circuit voltage (approximately 0.423 V). The current work can provide useful insights into the design of energy storage materials with high efficiency. Methods In this research, we used B3LYP-D3 functional and 6–31 + G* basis with GAMESS program to calculate adsorption energy, open-circuit voltage, and maximum theoretical capacity of K ions on the C 2 NML.