Two-dimensional 1T-PS2 as a promising anode material for sodium-ion batteries with ultra-high capacity, low average voltage and appropriate mobility

Abstract

As electrodes, two-dimensional materials show special advantages including the infinite planar lengths, broad electrochemical window, large surface–volume ratio, and much exposed active sites. In theory, the two-dimensional materials consist of the elements with high electronegativity may absorb more Na atoms, resulting in a high battery storage capacity. Based on the above idea, we selected the two dimensional metallic PS2 with 1T-Type structure as an anode material, and explored its potential applications as an electrode material for Na-ion battery through first-principle calculations. As we expected, when two dimensional PS2 is used as an anode in Na-ion battery, it can adsorb maximum three layers of sodium atoms on both sides of the monolayer, resulting in a maximum theoretical capacity of 1692 mAh/g. Furthermore, it also possesses a rather small sodium diffusion barrier of 0.17 eV, a low average open-circuit voltage of 0.18 V, and a relatively small lattice changes within 13% during the intercalation of Na. These results suggested that the two dimensional PS2 is a potentially excellent Na-ion battery anode. Our idea of designing two-dimensional anode materials with high storage capacity may provide some references for designing the next generation anode materials of metal-ion batteries.