Overview and perspectives of solid electrolytes for sodium batteries

Abstract

Quoting the abundance and cost of sodium reserve and robustly safe and high-energy solid electrolytes, sodium solid-state batteries (SSBs) exhibit huge promise for future energy storage applications compared to battery systems using organic liquid electrolytes and Li counterparts. However, the progress and application are still in infancy, experiencing numerous challenges for sodium SSBs due to inherent properties, interface complications, and fabrication. These are recently receiving unprecedented research attention by understanding and steadily resolving the issues associated with sodium SSBs. In this review, the governing bulk and interfacial issues and dynamics, background research correlations from Li counterparts, and strategies to address them are investigated for various ceramic-, polymer-, and ceramic-polymer composite based solid electrolytes. Particular attention is devoted to issues with ceramic electrolytes (such as interfacial stability, brittleness, porosity, and grain-grain boundary resistance) and polymer electrolytes (like dendrite formation, passivation layer, electrochemical instability, and ionic conductivity), and finally, robustness in overall performance and a few drawbacks (such as filler agglomeration, interface dynamics, and crack propagation) on the composited state-of-the-art ceramicpolymer electrolytes are highlighted. To end with, crucial inferences and future research perspectives are condensed on the development of enhanced solid electrolytes for sodium SSBs overcoming the shortcomings illustrated for different electrolytes.

Sodium Polymer Electrolytes: A Review

“…The first type includes SPEs, in which only sodium salts (NaPF 6 , NaBF 4 , NaClO 4 , etc.) are dissolved in polymer matrices [36,37]. The second type is represented by gel PEs (GPEs), which more stably combine solid and liquid phases.…”

Length-Scale-Dependent Ion Dynamics in Ca-Doped Na3PS4

“…Besides Na-ion batteries with liquid electrolytes, ,, we have witnessed an increasing demand for solid or even ceramic Na-ion conductors − as they might pave the way toward safe, nonflammable all-solid-state Na-battery systems. − Only few groups of solid electrolytes have been considered so far for the use in Na-ion batteries, such as β″-alumina, NASICON-type (Na superionic conductor) materials, − and the sodium variants of the well-known Li + conductor LGPS (Li 10 GeP 2 S 12 ), which are based on Na 11 Sn 2 PS 12 . In particular, among these promising ionic conductors, we also find Na 3 PS 4 , first reported in 1992 to have an ionic conductivity of approximately 4.2 × 10 –6 S cm –1 at ambient temperature .…”