Structural Analysis for Lithium Ion Conduction in Li-P-S Solid Electrolyte

Introduction and Result

 Batteries are used to power electric and hybrid electric vehicles, and to store a wind and solar energy in smart grids. The research and development of electrical vehicles has been an important subject. All solid batteries and solid electrolyte are key technologies for electric powered vehicles. Thus, drastic improvement in the performance of the rechargeable batteries is strongly needed. We focused on Thio-LISICON as Li₂S-P₂S₅ glass system. This system was already reported that has similar local structure and differential lithium ion conductivities [1-2]. We think that lithium ion conduction is influenced array of local structure as total glass structure. However, it is not clearly.

 In this study, we researched the local structure of (Li₂S)_x(P₂S₅)_100-x glasses (x = 67, 70 and 75)_.  We model the atomic and electronic structure of the glasses by density functional theory and reverse Monte Carlo simulations using synchrotron X-ray diffraction, Time of flight type neutron diffraction and Raman spectroscopy data. To obtain a reliable structural model, it is worth noting that local structure information from Raman spectroscopy are included in our study. The agreement with experimental X-ray and neutron structure factors is excellent as shown in Figure 1. Intriguingly, although a characteristic difference has been reported, pair correlation functions as Li-Li is similar. Since Pair correlation function as Li-P is reflected coordination state for lithium and P_xS_ypolyhedron as shown in Figure 2, such coordination state would influence the lithium ion conduction as an electrochemical characteristic of the glass solid electrolyte. For structure detail, we will make a presentation on the day.

 In summary, we succeeded in the modeling the glass structure and discussion lithium diffusion mechanism in glass solid electrolyte.

Acknowledgment:

This work was partially supported by the RISING project of the New Energy and Industrial Technology Development Organization (NEDO).

 

References:

[1] Y. Onodera, et al. Journal of the Physical Society of Japan 81 (2012) 044802.

[2] K. Mori, et al. Chemical Physics Letters 584 (2013) 113–118