Preparation and characterization of superionic conducting Li7P3S11 crystal from glassy liquids

Abstract

Superionic Li+ ion conducting Li 7 P 3 S 11 crystal was prepared by crystallization of the 70Li 2 S·30P 2 S 5 (mol %) glass and melt. In the case of crystallization of the 70Li 2 S·30P 2 S 5 glass, the crystallized electrolyte heated at 360°C for 1 h showed a conductivity of 4.1 © 10 ¹3 S cm ¹1 at room temperature. In the case of crystallization from the 70Li 2 S·30P 2 S 5 melt, a single phase of the Li 7 P 3 S 11 crystal was obtained by crystallization of the melt at 700°C for 48 h and then quenching in ice water. The crystallized electrolyte showed the conductivity of 2.9 © 10 ¹3 S cm ¹1 at room temperature. The precipitated crystal depended on the heat treatment temperature, holding time, and cooling rate. In both crystallization processes from the glass and melt, the Li 7 P 3 S 11 crystal was precipitated as a primary phase from supercooled liquids and thus the superionic conducting Li 7 P 3 S 11 crystal is a high temperature phase at the composition 70Li 2 S·30P 2 S 5 .

Compliant Yet Brittle Mechanical Behavior of Li2S–P2S5 Lithium‐Ion‐Conducting Solid Electrolyte

“…Direct observation by transmission electron microscopy and related methods is challenged by the extreme moisture sensitivity of these materials. However, as discussed below, the ionic conductivity of the present material is comparable to those reported previously for other LPS considered to be amorphous; specifically, the conductivity was reported to be somewhat lower for amorphous than for crystalline LPS, [24] and thus our samples are assumed to be similarly disordered.…”

“…This magnitude is consistent with other reports in the literature for amorphous LPS. [24] Figure 3b shows that the conductivity was unchanged by annealing. To summarize the variation in mechanical properties that would typically be present in an all-solid-state lithium battery, we illustrate in Figure 4 a simplified battery "stack" consisting of a Li X CoO 2 cathode, LPS electrolyte, and Li metal anode, along with the corresponding E, H, and K Ic .…”

“…[10,23] To confirm the structure and conductivity of the sample, we ground the LPS to a powder form and conducted X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) measurements. Figure 3a shows the XRD pattern of the melt-quenched LPS sample (after grinding to powder), the same material after annealing for stress-relief, and the pattern reported by Minami et al [24] for "glassy" LPS powder obtained via the same melt-quench process. We observed broad peaks for the present samples indicating a high degree of disorder; the extent of short-range order or possibly nanocrystalline content requires more detailed study, such as by pair-distribution function analysis.…”

“…The sample was not immersed within oil during such experiments due to instrument constraints. However, the surfaces of samples removed from mineral oil baths immediately before testing retained an oil surface film and thus remained stable for [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] minutes as required for these experiments. Beyond such durations, visible oxidation reaction products were apparent in some surface regions.…”

Structure and Ionic Conductivity of Li2S–P2S5 Glass Electrolytes Simulated with First-Principles Molecular Dynamics

“…Sulfide SEs are classified into three categories based on their structural characteristics: crystalline, amorphous (glass), and partially crystalline (glass-ceramic), all of which are known to be fast ionic conductors. Among the crystalline SEs, metastable Li 7 P 3 S 11 (Yamane et al, 2007;Minami et al, 2010) and nanoporous β-Li 3 PS 4 (Liu et al, 2013) have high conductivities, 3 × 10 −3 and 1.6 × 10 −4 S/cm, respectively. Much research has been conducted since the first report that the glass and glass-ceramic phases are fast ionic conductors (Zhang and Kennedy, 1990).…”