An electrochemically stable homogeneous glassy electrolyte formed at room temperature for all-solid-state sodium batteries

Abstract

All-solid-state sodium batteries (ASSSBs) are promising candidates for grid-scale energy storage. However, there are no commercialized ASSSBs yet, in part due to the lack of a low-cost, simple-to-fabricate solid electrolyte (SE) with electrochemical stability towards Na metal. In this work, we report a family of oxysulfide glass SEs (Na3PS4−xOx, where 0 < x ≤ 0.60) that not only exhibit the highest critical current density among all Na-ion conducting sulfide-based SEs, but also enable high-performance ambient-temperature sodium-sulfur batteries. By forming bridging oxygen units, the Na3PS4−xOx SEs undergo pressure-induced sintering at room temperature, resulting in a fully homogeneous glass structure with robust mechanical properties. Furthermore, the self-passivating solid electrolyte interphase at the Na|SE interface is critical for interface stabilization and reversible Na plating and stripping. The new structural and compositional design strategies presented here provide a new paradigm in the development of safe, low-cost, energy-dense, and long-lifetime ASSSBs.

NaPON Doping of Na4P2S7 Glass and Its Effects on the Structure and Properties of Mixed Oxy-Sulfide-Nitride Phosphate Glass

“…For example, in recent work in our group, we have shown how additions of O in the solid electrolyte (SE) Na 3 PS 4-x O x can not only create a SE that is stable in contact with metallic Na anodes, that the homogeneous structure of this SE produced by pressing also makes it resistant to Na metal dendrite penetration up to 1 mA/cm 2 current densities. 16 Similarly, Cengiz et al have shown that adding a source of oxygen, such as P 2 O 5 , to their Li 2 S−P 2 S 5 glass system improved the materials ability to suppress lithium metal (LM) dendrite formation and growth and thus improved the materials cycle life in a solid state lithium battery (SSLB). 26 Finally, it has long been known through the exhaustive work of Bates and Dudney et al that the incorporation of nitrogen into thin sputtered films of LiPON has also shown to advantageously improve the performance of GSEs, particularly the conductivity and electrochemical stability in contact with LM.…”

“…SSSBs, on the other hand, can be made from earth abundant low-cost materials, such as sodium and sulfur, and are much safer due their use of a solid-state inorganic electrolyte (SSIE). , In fact, sodium batteries (SBs) have already proven useful as grid-scale energy storage candidates through the application of oxide-based NASICON in ZEBRA batteries. − However, their required high-operating temperatures of ∼300 °C to keep the NiCl 2 catholyte in the molten state creates a high energy penalty and a corrosive environment, which needs to be closely controlled . Sulfide-based Na 2 S–P 2 S 5 glasses and glass-ceramic materials, which have a conductivity of ∼10 –4 Ω-cm –1 at room temperature, have also been fabricated into SSSBs, but their pure sulfide chemistry and grain boundaries for the glass-ceramics create poor electrochemical stability and poor resistance to dendrite penetration, respectively. − …”

“…The continuous amorphous structure and high elastic modulus of glass make it a promising material for SSSBs because it can be resistant to dendrite formation. , Further, it has been shown that the addition of oxygen to a sulfide glass is beneficial for the stability and cyclability of glassy solid electrolytes (GSEs). For example, in recent work in our group, we have shown how additions of O in the solid electrolyte (SE) Na 3 PS 4‑x O x can not only create a SE that is stable in contact with metallic Na anodes, that the homogeneous structure of this SE produced by pressing also makes it resistant to Na metal dendrite penetration up to 1 mA/cm 2 current densities . Similarly, Cengiz et al have shown that adding a source of oxygen, such as P 2 O 5 , to their Li 2 S–P 2 S 5 glass system improved the materials ability to suppress lithium metal (LM) dendrite formation and growth and thus improved the materials cycle life in a solid state lithium battery (SSLB) .…”

NaAlCl4: New Halide Solid Electrolyte for 3 V Stable Cost-Effective All-Solid-State Na-Ion Batteries

“…Li-ion batteries (LIBs) have expanded into application areas such as large-scale energy storage systems (ESSs) that could stabilize the power grid. , However, the price of Li rose more than 10-fold over the past decade (from 6.06 USD kg –1 in 2012 to 75 USD kg –1 in 2022 for Li 2 CO 3 ) . In addition, the uneven distribution of Li mines has caused political and economic issues. − Moreover, there are safety concerns about LIBs, as seen from frequent fire accidents associated with the use of flammable organic liquid electrolytes. − These factors have impeded the widespread use of LIBs for ESSs. ,, Solidifying electrolytes with nonflammable inorganic Na + superionic conductors could improve safety and reduce cost, making all-solid-state Na-ion or Na batteries (ASNBs) promising for use as ESSs. ,− …”

Scaling Relations for Ionic and Thermal Transport in the Na+ Ionic Conductor Na3PS4

“…Solid Na + ion conductors have attracted significant interest in recent years, because of their possible application as electrolytes in Na + solid-state batteries. − One of the most investigated Na + solid-electrolyte classes is the Na 3 PS 4 material family, because of its relatively high ionic conductivity paired with its structural simplicity and compositional variety, making it a suitable model system for sodium-ion conductors. − Upon substitution and doping, room-temperature ionic conductivities ranging from 0.018 mS cm –1 (Na 3 PS 4 ) , to 0.3 mS cm –1 (Na 3 SbSe 4 ) and up to 40 mS cm –1 (W-doped Na 3 SbS 4 ) , have been achieved. As a consequence of its high ionic conductivity, these materials are currently considered as ionic conductors in solid-state battery applications. − In part, the fast ionic transport has been explained by largely anharmonic phonon dynamics, ,, and other considerations about atomic vibrations . However, a deeper investigation and understanding of the thermal transport properties, which are fundamentally linked to the lattice dynamics of a material, , are missing.…”