Investigating the electrochemical properties of SnO monolayer in sodium-ion batteries

The increasing energy crises have driven the world toward the exploration of clean and renewable energy sources. The selection of electrodes is a fundamental step in sodium (Na)-ion batteries (SIBs) to achieve extraordinary performance. Two-dimensional (2D) materials are strong candidates as electrode materials for SIBs owing to their enormous surface area, high thermal and electrical conductivities, and plenty of accumulation sites for adsorption of Na atoms. In this study, we investigate the electrochemical performance of two-dimensional tin mono-oxide (SnO) monolayers as an anodic material for SIBs using first-principles calculations. The electronic band structure, adsorption process, diffusion mechanism, and storage capacity of Na atoms in the SnO monolayer are examined. Our simulations disclose the semiconducting nature of the SnO monolayer, which becomes metallic after adsorption of a minor amount of Na atoms. This metallic behavior provides good electrical conductivity and mobility with low diffusion energy (0.15 eV) for the migration of Na on the SnO monolayer, indicating a rapid charge–discharge process. Furthermore, the determined specific capacity of the Na-loaded SnO monolayer is 398 mAh g⁻¹ with low average open circuit voltage of 0.60 V. The above encouraging results show that the SnO monolayer is a promising anode for rechargeable SIBs.