▎ 摘　　要

The C2N monolayer, which is synthesized experimentally, has outstanding properties and is extensively used in catalysis and metal-ion batteries. Nevertheless, the deficiency of C2N monolayers and their impurity in experiments hinder their mechanistic investigation, thus limiting their further development. Also, the classical approach of one atom exploring the stable adsorption sites of metal ions in simulations does not yield successful results. In this work, the mechanisms of the C2N monolayer as an efficient anode material for magnesium ion battery (MIB) are studied by performing DFT calculations, and a new particle pair adsorption model is proposed. The maximum theoretical capacity of Mg ions is more than that of graphite and it reaches 419 mA h g(-1). At the microscale, the channels between C2N and Mg atoms are formed in order to allow electron transfer, which enhances the interactions between them. This is supported by Bader charge analysis and charge density difference. In a battery, due to the lower value diffusion barriers of Mg ions on the C2N monolayer, the charging and discharging processes are fast. In addition to the metallic characteristic of the complex of C2N monolayer/Mg ions, the C2N monolayer has the advantages of superior cycling stability and low average OCV (similar to 0.234 V). High-performance energy storage materials can be designed and innovated based on the insights provided by this research.