Structure and Conductivity of Na–P–S Superionic Conducting Glasses Studied by Neutron and X-ray Diffraction

All-solid-state sodium batteries with excellent safety have attracted much attention as one of candidates of post-lithium ion batteries because of great abundance and low cost of sodium. Recently, it was found that Na3PS4 glass-ceramic solid electrolyte synthesized by annealing of (Na2S)75(P2S5)25 glass has a conductivity in the order of 10 Scm at room temperature [1]. In this paper, we report results of structural analysis based on neutron and X-ray diffraction for (Na2S)x(P2S5)100-x superionic conducting glasses (x = 50, 60, 67, 70). Neutron and synchrotron X-ray diffraction experiments were carried out with the high intensity total diffractometer (NOVA) at the BL21 beam line of MLF in J-PARC and with a horizontal two-axis diffractometer at the BL04B2 beam line in SPring-8, respectively. Furthermore, reverse Monte Carlo (RMC) modeling based on neutron and X-ray structural factors, S(Q), was performed to derive three-dimensional atomic configurations of (Na2S)x(P2S5)100-x glasses. Figure 1 shows experimental S(Q)s and calculated S(Q)s by the RMC modeling for (Na2S)50(P2S5)50 glass. In the presentation, we will show results of an analysis focused on “void distribution” in the atomic configurations and discuss about conduction pathways of Na ions for the Na-P-S system.