Two-dimensional PS2: a promising anode material for sodium-ion batteries and a potential superconductor

TL;DR

This study uses density functional theory to show that two-dimensional PS2 is a promising anode material for sodium-ion batteries due to its high capacity, good conductivity, and potential superconductivity at low temperatures.

Contribution

It introduces 2D PS2 as a novel anode material with unique electronic properties and potential superconductivity, expanding the applications of 2D disulfides.

Findings

High theoretical capacity of 1692 mAh/g

Low sodium diffusion barrier of 0.17 eV

Potential superconductivity at ~10 K

Abstract

Two dimensional materials as electrodes have shown unique advantages such as the infinite planar lengths, broad electrochemical window, and much exposed active sites. In this work, by means of density functional theory computations, we demonstrate that two dimensional PS2 with the 1T-Type structure as many two dimensional disulfides is a promising anode material for sodium ion batteries application. Different from many two dimensional disulfides (e.g. MoS2, TiS2, CrS2) compounds that are semiconducting, PS2 monolayer exhibits metallic character with considerable electronic states at the Fermi level, which can provide good electrical conductivity during the battery cycle and also suggest the potential superconductivity. Remarkably, PS2 monolayer has a considerably high theoretical capacity of 1692 mAh/g, a rather small sodium diffusion barrier of 0.17 eV, and a low average open circuit voltage of 0.18 V. These results suggest that PS2 monolayer can be utilized as a promising anode material for the application in sodium ion batteries with high power density and fast charge/discharge rates. In addition, estimated by first principle calculations, PS2 is found to be an intrinsic phonon-mediated superconductor with a relatively high critical superconducting temperature of about ~10 K.