Composition Dependence of the Na+ Ion Conductivity in 0.5Na2S + 0.5[xGeS2 + (1 – x)PS5/2] Mixed Glass Former Glasses: A Structural Interpretation of a Negative Mixed Glass Former Effect

Structure and Properties of Na2S-SiS2-P2S5-NaPO3 Glassy Solid Electrolytes

In the development of sodium all-solid-state batteries (ASSBs), research efforts have focused on synthesizing highly conducting and electrochemically stable solid-state electrolytes. Glassy solid electrolytes (GSEs) have been considered very promising due to their tunable chemistry and resistance to dendrite growth. For these reasons, we focus here on the atomic-level structures and properties of GSEs in the compositional series (0.6-0.08y)Na2S + (0.4 + 0.08y)[(1 - y)[(1 - x)SiS2 + xPS5/2] + yNaPO3] (NaPSiSO). The mechanical moduli, glass transition temperatures, and temperature-dependent conductivity were determined and related to their short-range order structures that were determined using Raman, Fourier transform infrared, and 31P and 29Si magic angle spinning nuclear magnetic resonance spectroscopies. In addition, the conductivity activation energies were modeled using the Christensen-Martin-Anderson-Stuart model. These GSEs appear to be highly crystallization-resistant in the supercooled liquid region where no measurable crystallization below 450 °C could be observed in differential scanning calorimetry studies. Additionally, these GSEs were found to be highly conducting, with conductivities on the order of 10-5 (Ω cm)-1 at room temperature, and processable in the supercooled state without crystallization. For all these reasons, these NaPSiSO GSEs are considered to be highly competitive and easily processable candidate GSEs for enabling sodium ASSBs.

High-Sodium-Concentration Sodium Oxythioborosilicate Glass Synthesized via Ambient Pressure Method with Sodium Polysulfides

The practical utilization of all-solid-state sodium batteries necessitates the development of a mass synthesis process for high-alkali-content sulfide glass electrolytes, which are characterized by both high ionic conductivity and remarkable formability. Typically, vacuum sealing and quenching are conventional techniques employed during the manufacturing process. In this paper, we present a novel approach, a pioneering method for the production of sulfide glass electrolytes with high alkali concentrations, achieved through ambient-pressure heat treatment and a gradual cooling process. We enhance the glass-forming ability of Na3BS3 by incorporating a small quantity of SiO2. The ionic conductivity of the resulting Na3BS3·0.225SiO2 (molar ratio) glass exhibited 1.5 × 10-5 S cm-1 at 25 °C, surpassing that of Na3BS3 glass. An all-solid-state cell utilizing Na3BS3·0.225SiO2 glass is successfully operated as a secondary battery at 60 °C. Our findings suggest that sodium oxythioborosilicate glass with electrochemical properties identical to those of Na3BS3 can be prepared without the need for quenching. These results propel the advancement of research in the domain of mass production processes tailored for high-alkali-content sulfide glass.

Nuclear Magnetic Resonance Relaxation Pathways in Electrolytes for Energy Storage

Nuclear Magnetic Resonance (NMR) spin relaxation times have been an instrumental tool in deciphering the local environment of ionic species, the various interactions they engender and the effect of these interactions on their dynamics in conducting media. Of particular importance has been their application in studying the wide range of electrolytes for energy storage, on which this review is based. Here we highlight some of the research carried out on electrolytes in recent years using NMR relaxometry techniques. Specifically, we highlight studies on liquid electrolytes, such as ionic liquids and organic solvents; on semi-solid-state electrolytes, such as ionogels and polymer gels; and on solid electrolytes such as glasses, glass ceramics and polymers. Although this review focuses on a small selection of materials, we believe they demonstrate the breadth of application and the invaluable nature of NMR relaxometry.

NMR Investigations of Crystalline and Glassy Solid Electrolytes for Lithium Batteries: A Brief Review

The widespread use of energy storage for commercial products and services have led to great advancements in the field of lithium-based battery research. In particular, solid state lithium batteries show great promise for future commercial use, as solid electrolytes safely allow for the use of lithium-metal anodes, which can significantly increase the total energy density. Of the solid electrolytes, inorganic glass-ceramics and Li-based garnet electrolytes have received much attention in the past few years due to the high ionic conductivity achieved compared to polymer-based electrolytes. This review covers recent work on novel glassy and crystalline electrolyte materials, with a particular focus on the use of solid-state nuclear magnetic resonance spectroscopy for structural characterization and transport measurements.

Composition Dependence of the Glass-Transition Temperature and Molar Volume in Sodium Thiosilicophosphate Glasses: A Structural Interpretation Using a Real Solution Model

The glass-transition temperature, T_g, and molar volume, V̅, are two physical properties known to exhibit the mixed glass former effect (MGFE), a nonlinear nonadditive increase or decrease from a linear ideal mixing behavior, in ternary glass systems, where the two glass forming species are varied, whereas the glass modifier content remains constant across the system. In the next of our continuing studies of the MGFE in ternary glasses, the T_g and molar volumes of two ternary glass forming series, 0.5Na₂S + 0.5[ xSiS₂ + (1 - x)PS_5/2], the 0.50 NSP series, and 0.67Na₂S + 0.33[ xSiS₂ + (1 - x)PS_5/2], the 0.67 NSP series, have been determined across the full glass forming range in both series, 0 ≤ x ≤ 1. The 0.50 NSP glasses were found to have a strongly negative MGFE in the T_g and a weaker MGFE in the molar volume. The 0.67 NSP series of glasses exhibited weak negative and strong positive MGFEs in the T_g and molar volumes, respectively. Using the short-range order (SRO) structure model for each glass series that was previously developed, the number of bridging sulfurs (BS) and nonbridging sulfurs (NBS) was determined and analyzed for each of these two series of glasses. A clear linear correlation was observed between the T_g and both the fraction of BSs, BS/(BS + NBS), and the number of BS per glass former, BS/GF in both series. The molar volumes of both series of glasses were analyzed using both ideal and real solution models of mixing. The molar volumes of the glasses were best fit to the molar volumes of all of the individual molar volumes of the various SRO units. In the ideal solution model, the molar volumes of the SRO units were only fit to molar volumes of the end member glasses, x = 0 and 1. In the real solution model, the molar volumes were best fit to the full composition dependence of the molar volume of all of the glasses. In both cases, the same molar volumes for the SRO units were used to fit both sets of molar volumes of both glass series. It was found that the best-fit molar volumes of both the P and Si SRO units were essentially the same at the same number of NBS/GF. In this study, therefore, it was observed that the MGFE in the T_g of the glass was linearly correlated with the number of BS per glass former, BS/GF, whereas the MGFE in the molar volumes of the glasses was correlated with the number of NBS per glass former, NBS/GF.