NiX2(X = S, Se, and Te) Monolayers: Promising Anodes in Li/Na-Ion Batteries and Superconductors

Based on the density functional theory calculations, we report the stability, electron structure, and potential applications in single-layer (SL) NiX2(X = S, Se, and Te) that show high thermal, dynamical, and mechanical stability and possess ultralow isotropic Young’s modulus. Moreover, these NiS2, NiSe2, and NiTe2monolayers have high energy storage capacities of 874, 496, and 342 mA h g–1and low diffusion energy barriers of 0.23/0.24/0.27 and 0.12/0.13/0.12 eV when used as anodes in lithium-ion batteries and sodium-ion batteries, respectively. SL NiS2and NiSe2show semiconducting traits in their freestanding crystals. Specifically, the 2D NiTe2monolayer is determined to be an intrinsic superconductor with a transition temperature (Tc) of ∼2.24 K. The Tccan be improved to 5.48 K when subjected to an in-plane compressive strain of 6%. These results enrich the family of transition metal-based 2D materials with multifunctionality and facilitate further experimental efforts toward next-generation nanodevices.