Evaluating the Potential of Planar Checkerboard Lattice Cu2N Monolayer As Anode Material for Lithium and Sodium-Ion Batteries Using First-Principles Methods

We present first-principles insights into the electrical and electrochemical properties of Cu2N, a newly synthesized two-dimensional material that features a planar, checkerboard lattice structure [Hu et al., Nano Lett. 2023, 23 (12), 5610-5616]. We evaluate the suitability of monolayer Cu2N as an anode material for Li and Na-ion batteries by examining its storage capacity, diffusion barrier, open-circuit voltage (OCV), volume expansion, and the impact of defects on its electrochemical performance. The monolayer Cu2N demonstrates a storage capacity of 379.88 mAh.g(-1) for both Li and Na, comparable to that of commercial graphite for Li (372 mAh.g(-1)) and significantly higher for Na (less than 35 mAh.g(-1)). The migration barriers for Li and Na are found to be 0.1 eV and 0.01 eV, respectively, substantially lower than those theoretically reported for commercial anodes TiO2 (0.4-1.0 eV) and graphite (similar to 0.4 eV), which imply that monolayer Cu2N demonstrates excellent charge/discharge capabilities. Moreover, the volume growth of monolayer Cu2N is 4.14 % with maximal Li adsorption, which is 2.4 times less than graphite. The analysis of vacancy defects reveals a significant enhancement in the binding energies of Li and Na atoms, accompanied by minimal changes in diffusion barriers. Since monolayer Cu2N has already been successfully synthesized, these findings would pave the way for large-scale experimental fabrication of monolayer Cu2N as a battery anode.