[PO-O2] Poster Session 2

[P2-81] Two-dimensional Na_xSiS as a promising anode material for rechargeable Sodium-based batteries: Ab initio material design.

Thi Dung Pham¹, ^○Van An Dinh^1,2, Kazunori Sato³, Yoji Shibutani^1,2 (1.Nanotechnology Program, Vietnam Japan University, Viet Nam, 2.Center for Atomic and Molecular Technology, Graduate School of Engineering, Osaka University, Japan, 3.Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, Japan)

The rapidly rising demand of energy storage system for electronic devices presents an imperative need to develop sodium-ion batteries with high energy density, high conductivity, and low barrier energy. In this work, we present the density functional study on properties of the two-dimensional (2D) Na_xSiS as a promising anode material for rechargeable sodium ion batteries (SIBs). Energetically stable structures of Na-adsorbed Silicene sulfide Na_xSiS were explored. It is found that silicene sulfide has an adsorption energy to sodium atom about of -0.4 eV, which is large enough to ensure a good stability for sodium inserting into SiS during sodiate process. The electronic structure and capacity of Na_xSiS were calculated. The electronic structure of pristine SiS monolayer and Na adsorbed layer shows the distinction of a semiconductor material. The fully sodiated phase of SiS is Na_0.5SiS corresponding to a highest theoretical capacity of 187.2 mAh/g per one side layer. The diffusion mechanism of Na ions was also investigated by using NEB method. Two possible elementary processes are explored: one is along a-and the other is along b-direction. Most importantly, Silicene sulfide shows a good sodium mobility with an energy barrier along two dimension is only 183 meV, which is much smaller than that in Li_xSiS (430meV), 2D TiS₂ (220meV), and 2D MoS₂ (280-680 meV). Our investigations also reveal that SiS exhibits the better electrochemical performance as an anode in the SIBs than in the LIBs. All these characteristics suggest that 2D SiS can expected to be a promising anode material for sodium batteries.