Out-of-plane ion transport makes nitrogenated holey graphite a promising high-rate anode for both Li and Na ion batteries

Searching for suitable anodes with good performance is a key challenge for rechargeable Li- and Na-ion batteries (LIBs and NIBs). In this work, we adopt first-principles calculations and ab-initio molecular dynamics simulations to investigate the ion transport mechanism and potential of C2N stoichiometric nitrogenated holey graphite (C2N-NHG) as a promising anode material for LIBs and NIBs. Although the huge in-plane diffusion barriers for both Li and Na ions restrict the application of C2N-NHG monolayer as an effective anode, the Li and Na ions are found to exhibit facile out-of-plane ion transport in the most stable layered AD stacking C2N-NHG. The fully lithiated and sodiated cases of LiC2N and Na0.67C2N show reversible specific capacities up to 587 mA h g-1 and 353 mA h g-1, low chemical potentials of 0.12 V and 0.25 V, and small volume expansions of 7.16% and 13.54%, respectively. Meanwhile, the out-of-plane collective diffusion reduces the Li/Na collective migration barriers to 0.23 eV and 0.18 eV. These findings suggest that AD stacking C2N-NHG, with a metallic property after lithiation and sodiation process, high specific capacity, low open circuit voltage, small volume expansion, and low collective migration barriers, has potential to serve as a promising high-rate anode material for LIBs and NIBs with large energy density and power density. The calculations reveal the novel out-of-plane diffusion manner plays a crucial role for Li/Na ion transports in the holey layered materials.