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

ABSTRACT

CONTEXT In recent years, undivided attention has been given to the unique properties of layered nitrogenated holey graphene (C2N) monolayers (C2NMLs), which have widespread applications (e.g., in catalysis and metal-ion batteries). Nevertheless, the scarcity and impurity of C2NMLs in experiments and the ineffective technique of adsorbing a single atom on the surface of C2NMLs 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 C2NML 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 C2NML 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 C2NML/K ions and because the diffusion barrier of K ions on the C2NML was low. Moreover, the C2NML 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 C2NML.