Organic liquid electrolytes in sodium-based batteries: Actualities and perspectives

With the increasing demand for large-scale energy storage batteries, sodium-ion batteries have garnered considerable attention due to their abundant resources, low cost, excellent low-temperature performance and rate capability. To compete with or complement lithium-ion battery technology, a thorough understanding of the chemical properties and accompanying phenomena of sodium-ion batteries is crucial. The electrolyte serves as the connection between the highly polarized cathode and anode materials and governs the interface chemistry and overall performance of the battery, including the electrochemical window, energy density, rate capability, safety, and lifespan. Currently, mature anhydrous organic liquid electrolytes are employed in production, offering superior overall battery performance compared to alternative electrolytes such as solid or aqueous electrolytes. Consequently, achieving desirable electrochemical performance and high safety of sodium-ion batteries necessitates a comprehensive evaluation of the electrolyte and electrode/electrolyte interfaces. This review analyzes the advantages and existing challenges of organic liquid electrolytes in sodium-based battery from the perspectives of working and failure mechanism, summarizes the research progress in solvents, sodium salts and additives. We also examine the future development trends and demands of organic liquid of electrolytes, highlight emerging opportunities for the advancement of advanced sodium-based battery.