Theoretical investigation of NbB as an electrode material for Li/Na-ion batteries

Abstract The utilization of MBenes as electrode materials for lithium/sodium-ion batteries (LIBs/NIBs) has emerged as a prominent research area. The potential application of two-dimensional niobium boride (NbB) in LIBs/NIBs was explored through first-principles calculations. The results indicate that the monolayer of NbB exhibits exceptional dynamic stability, thermodynamic stability and electrical conductivity. The migration path of Li/Na on the NbB surface was determined, revealing diffusion barriers as low as 0.034 and 0.017 eV respectively, indicating the exceptional mobility and reversibility exhibited by NbB. The theoretical capacities of Li and Na on NbB are 258 and 323 mAh/g, respectively. The open circuit voltage (OCV) varies within the range of 0.58 to 0.71 V and 0.05 to 0.81 V for Li/Na concentrations. Meanwhile, the investigation into the influence of various functional groups of NbB on the adsorption properties of Li/Na atoms reveals that both NbBO and NbBS surfaces retain their maximum capacity for Li/Na adsorption, whereas the NbBSe surface fails to achieve complete layer adsorption of Li/Na atoms. The introduction of the S functional groups not only maintains the ultra-low diffusion barrier (0.09 eV) of Na ions but also results in a significant decrease in the average OCV of Li/Na adsorption, which is approximately 0.37 and 0.14 V, respectively. The electrochemical properties of NbB in LIBs/NIBs are exceptional, positioning it as a promising electrode material within the MBenes family.