S−functionalized Nb2N MXenes as novel anode materials for metal ion batteries: a first-principles study

Abstract Introducing functional groups can efficiently play an electrochemical role in two-dimensional (2D) transition metal nitrides as MXene-based electrode materials beyond graphene. Herein, the suitability of sulfur−functionalized Nb 2 N (Nb 2 NS 2 ) MXenes as battery anode materials was investigated through first-principles calculations for lithium ion batteries (LIBs), sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs) and aluminum ion batteries (AIBs). The results show that Nb 2 NS 2 MXenes can exhibit metallic conductivity and improve mechanical strength. Additionally, five metal ions are adsorbed on Nb 2 NS 2 MXenes with negative adsorption energies and low lattice change rates, which is favorable for electrode applications in energy storage. More importantly, Nb 2 NS 2 MXenes have theoretical storage capacities superior to some typical 2D anode materials, where they are 609.18 mA (h g) −1 for LIBs, SIBs and PIBs, while they are 1218.37 mA (h g) −1 and 1827.55 mA (h g) −1 for MIBs and AIBs. The extraordinary electrochemical activities and performances of the Nb 2 NS 2 MXenes are confirmed by the relatively low open circuit voltages and diffusion barriers. This work can offer a theoretical foundation for designing excellent MXene-based electrode materials.