Fig. 1

(a) Number of publications for Na-S batterie (based on the data from the Web of Science, on April, 2022, using the following keywords “Na-S battery”), (b) Theoretical electrochemical performance of different alkali metal-based secondary batteries"

Fig. 2

(a) Schematic diagram of principle of the redox reaction of sulfur cathode for the RT Na-S battery, (b) Con?guration of a RT Na-S battery with an interlayer between the cathodeand the separator[12]"

Fig. 3

(a) CV[18], (b) discharge curve of Na-S batteries with 1.5 mol/L NaClO4+0.3 mol/L NaNO3 in TEGDME electrolyte[19], (c) CV Curves[18], (d) Discharge-charge pro?les of a S cathode under a carbonate ester electrolyte at various current densities[15]"

Fig. 4

(a) Preparation process of the cZIF-8/S composite, (b) TEM image of the individual cZIF-8 particles, (c) Discharge pro?le at different rate[35], (d) The synthesis process of the HPCM/S composite, (e) Schematic illustrations of the preparation process of NSCA, (f) Cycling performance and Coulombic efficiency s of HPCM/S composite electrode at 0.7 C"

Fig. 5

(a) Schematic synthesis process of the materials steps using sucrose, (b) Transmission electron microscope (TEM) image exhibiting the morphology of micropores inside carbon spheres[37], (c) Fabrication process and schematics of structures of Zn-MOF, MOF-C/S, MOF-C/PDAc, and MOF-C/S/PDAc composites, (d) Schematic illustration of preparation process of the microporous carbon a with small S molecules[39] (e) Graphical Illustration of the Preparation of S/KCPs"

Fig. 6

(a) Binding energies of sodium sul?de, short-chain sodium polysul?des, and sulfur allotropes to various nitrogen-containing groups within a carbon framework, (b) Cycle performance of the MPC 800-S composite cathode at 0.5 C[56], (c) The typical TEM images of covalent S-C, (d) Diagram of the covalent S-C reaction mechanism, (e) Rate performance[54]"

Fig. 7

(a) Schematic diagram of the modi?ed separator to inhibit polysul?de shuttle effect in Na-S batteries[61], (b) Architecture of Nafion membrane and schematic illustration of the ionic-selectivity of the Nafion membrane by ionic interactions at the hydrophilic pores of the membrane[65], (c) Schematic diagram of the S/C composite and the S@HCS/MoS2 electrode with modified glass fiber during the discharge process[66], (d) Schematic illustration of the Al2O3-Nafion separator blocking polysulfide shuttling[67]"

Fig. 8

Advantages and disadvantages of RT Na-S batteries with different electrolyte systems"

Fig. 9

(a) Plausible mechanism for EC and EMC decomposition by polysulfide, (b) Voltage-capacity profile of a microporous-mesoporous carbon (MMC)/S2-4 cathode and Na anode in carbonate electrolyte[40], (c) S in the pores of the cathode host, (d) S on the surface of the cathode host[14]"

Fig. 10

(a) Crystal structures of the representative NASICON (Na3Zr2Si2PO12) with rhombohedral and monoclinic phase[81], (b) XRD pattern of the PIN material and a PIN-coated Na3Zr2Si2PO12 pellet, (c) SEM image of the surface of a PIN-coated Na3Zr2Si2PO12 pellet, (d) Specific discharge capacities and Coulombic ef?ciencies versus cycling number of a Na ∥ PIN-Na3Zr2Si2PO12 ∥ CNF/S cell and a Na ∥ Celgard ∥ CNF/S cell at a cycling rate of C/5[61]"