Challenges and perspectives on high and intermediate-temperature sodium batteries

Energy storage systems are selected depending on factors such as storage capacity, available power, discharge time, self-discharge, efficiency, or durability. Additional parameters to be considered are safety, cost, feasibility, and environmental aspects. Sodium-based batteries (Na-S, NaNiCl₂) typically require operation temperatures of 300-350 ℃. The high operating temperatures substantially increase the operating costs and raise safety issues. This updated review describes the state-of-the-art materials for high-temperature sodium batteries and the trends towards the development and optimization of intermediate and low-temperature devices. Recent advances in inorganic solid electrolytes, glass-ceramic electrolytes, and polymer solid electrolytes are of immense importance in all-solid-state sodium batteries. Systems such as Na⁺ super ionic conductor (NASICON, Na_1+xZr₂P_3-xSi_xO₁₂ (0 ≤ x ≤ 3)), glass-ceramic 94Na₃PS₄·6Na₄SiS₄, and polyethylene oxide (PEO)-sodium triflate (NaCF₃SO₃) are also discussed. Room temperature ionic liquids (RTILs) are also included as novel electrolyte solvents. This update discusses the progress of on-going strategies to enhance the conductivity, optimize the electrolyte/electrode interface, and improve the cell design of emerging technologies. This work aims to cover the recent advances in electrode and electrolyte materials for sodium-sulfur and sodium-metal-halide (zeolite battery research Africa project (ZEBRA)) batteries for use at high and intermediate temperatures.