Table 2. Comparison of representative liquid electrolyte systems for room-temperature Na–S batteries^a.

Electrolyte class	Electrolyte composition	Cathode	Ionic conductivity	The S content; S loading	Electrolyte/sulfur (E/S) ratio	Potential window; initial capacity; retention; long-term cycling	CE: first cycle; subsequent	Note	Ref.
Ether electrolyte	1 M NaCF3SO3 in TEGDME	S/C composite	n.r.	45%; 0.31 mg cm−2	6.25 µL mg−1 (cathode side), 12.5 µL mg−1 (total cell)	1–3 V vs. (Na/Na+); 1070 mAh g−1 of sulfur at 1/128C; A 73% retention over 37 cycles at RT.	∼84.6%; nearly 100%	Molar concentration of sulfur in the cell relative to the solubility limit of each specific polysulfide species	48
Ether electrolyte	1 M NaClO4 in TEGDME	SPAN	n.r.	∼46.3%; n.r.	n.r.	0.7–2.8 V vs. (Na/Na+); ∼1420 mAh g−1; ∼800 mAh g−1 over 5 cycles, with a 56.3% retention; 10 cycles	n.r.	Short-chain sulfur confinement makes carbonate chemistry viable by avoiding soluble long-chain NaPS pathways	56
Ether electrolyte with carbonate additives	1 M NaClO4 in TEGDME with PC					0.7–2.8 V vs. (Na/Na+); ∼720 mAh g−1; ∼390 mAh g−1 over 2 cycles, with a 41.7% retention; 10 cycles	∼58.3%; n.r.
	1 M NaClO4 in TEGDME with DMC					0.7–2.8 V vs. (Na/Na+); ∼1200 mAh g−1; ∼300 mAh g−1 over 2 cycles, with a 32.5% retention; 10 cycles	∼36.7%; n.r.
Ether electrolyte	1 M NaClO4 with 10% FEC in DOL : DME (1 : 1)	S@sPAN (active component 42.06 wt%, theoretical capacity −704 mAh g−1)	n.r.	42.02%; n.r.	n.r.	0.7–2.8 V vs. (Na/Na+); 1035 mAh g−1 at 0.1 A g−1; degradation 0.064%/cycle; 470 mAh g−1 at 1.0 A g−1 over 500 cycles	∼65–70%; ∼99–100%	Solvent effects depend on strongly sulfur chemistry and cathode architecture. Tellurium acts as a eutectic accelerator to increase electron conductivity and accelerate the diffusion of sodium ions	57
	1 M NaClO4 with 10% FEC in DOL : DME (1 : 1)	Te0.04S0.96@pPAN (active component 47.77 wt%, theoretical capacity −714 mAh g−1)	n.r.	40.97%; n.r.	n.r.	0.7–2.8 V vs. (Na/Na+); 1111 mAh g−1 at 0.1 A g−1; 601 mAh g−1 at 6 A g−1; degradation 0.031%/cycle; 894 mAh g−1 at 1.0 A g−1 over 500 cycles	∼66%; ∼100%
Carbonate electrolyte	1 M NaClO4 in a mixture of EC and DMC (1 : 1, v/v) with 10% FEC	S@sPAN (active component 42.06 wt%, theoretical capacity −704 mAh g−1)	n.r.	42.02%; n.r.	n.r.	0.7–2.8 V vs. (Na/Na+); 234 at 6 A g−1; degradation 0.09%/cycle; 736 mAh g−1 at 0.5 A g−1 over 300 cycles	∼65–66%; ∼99–100%
	1 M NaClO4 in a mixture of EC and DMC (1 : 1, v/v) with 10% FEC)	Te0.04S0.96@pPAN (active component 47.77 wt%, theoretical capacity −714 mAh g−1)	n.r.	40.97%; n.r.	n.r.	0.7–2.8 V vs. (Na/Na+); 1816 mAh g−1 at 0.1 A g−1, 629 mAh g−1 at 6 A g−1; degradation 0.015%/cycle; 970 mAh g−1 at 0.5 A g−1 over 600 cycles	∼68%; ∼100%
Carbonate electrolytes	2 M NaTFSI in PC : FEC (1 : 1) + 10 mM InI3	S@MPCF	1.95 × 10−3 S cm−1, 25 °C	n.r.; ∼0.36 mg cm−2 (standard), from ∼0.35 to ∼4.64 mg cm−2 (highest)	∼50 µL mg−1	0.8–3 V vs. (Na/Na+); 1170 mAh g−1 at 0.1C; 77% over 200 cycles; 581 mAh g−1 over 500 cycles	79.1% (0.1C), 71.9% (0.5C), 61.6% (1C); 98.5–100.4%	Concentrated carbonate/FEC suppresses NaPS dissolution; InI3 simultaneously assists Na protection and sulfur conversion	58
	1 M Na[B(hfip)4] in EC : DMC (1 : 1) + 13 wt% FEC	Sulfurated PAN (SPAN), sulfur content 38.18%wt.±0.17wt%	6.135 · 10−3 S cm−1, RT	n.r.; ∼0.6 mg S/electrode	∼200 µL mg−1	0.2–3 V vs. (Na/Na+); 2441 mAh g−1 at 0.2C; 78.8%; 1072 mAh g−1 over 1000 cycles at 3C	High/stable: lower efficiency at the first cycle; 100%	Weakly coordinating anion gives high conductivity and enables SPAN cycling in carbonate electrolyte	59
	1 M NaTFSI in FDMA and MTFE (antisolvent) in a 1 : 1 ratio with 1 wt%	S@C	4.3 × 10−3 S cm−1, 25 °C	60%	n.r.	0.5–2.8 V vs. (Na/Na+); 1114 mAh g−1 at 0.1C; 65% retention at 0.1C over 200 cycles; 491 mAh g−1 at 0.3C, 419 mAh g−1 at 0.5C, 369 mAh g−1 at 1.0C over 300 cycles	66.3; 99.5%	Fluorinated solvent/antisolvent combination suppresses polysulfide dissolution and stabilizes both electrode interfaces	54
Organic carbonate electrolyte	1 M NaTFSI in pure FEC	Molten sulfur inside biomass microporous carbon (S@MRP composite)	n.r.	∼40 wt%; 0.65–1.2 mg cm−2	n.r.	0.1–3.0 V vs. (Na/Na+); ∼960–970 mAh g−1 at 0.1C; degradation 0.12% per cycle; 807 mAh g−1 at 0.1C over 200 cycles	n.r.; >99.5%	EC as the sole solvent triggers a unique two-step cathode-electrolyte interphase (CEI) formation to enable an efficient solid–solid conversion process of S	28
High-concentration electrolyte	2 M NaFSI in DMP/TFTFE (vol. ratio 5 : 3)	SPAN	∼0.15–0.16 mS cm−1, 20 °C	46%; n.r.	13.5 µL mg−1	0.8–2.8 V vs. (Na/Na+); 530 mAh g−1 at 0.5C; degradation 0.077% per cycle; 530 mAh g−1 at 0.5C over 600 cycles	n.r.; ∼100% under both high (45 °C) and low (10 °C) temperatures	The asymmetric DMP inner solvent and low-solvating TFTFE outer diluent form robust, highly protective CEI and SEI layers, suppressing the NaPS shuttle effect and Na dendrite growth	60
Localized high-concentration electrolyte	DME: NaFSI: TTE in a 1 : 1.2 : 1 molar ratio	Ketjenblack (KB) carbon as the S host	1.98 × 10−3 S cm−1, n.r.	n.r.; ∼3.0 mg cm−2 (for pouch cells)	4.5 µL mg−1	0.8–2.8 V vs. (Na/Na+); 922 mAh g−1 at 0.1C (coin cell) and 1028 mAh g−1 at C/20 (pouch cell); degradation 0.10%/cycle; high over 300 cycles	∼5% capacity goes to forming a solid-electrolyte interphase (SEI) on the cathode; 100% over 300 cycles	Altered solvation creates inorganic-rich interfaces, suppresses NaPS shuttle, and enables dendrite-free Na cycling	61
	6 M NaFSI in DME diluted with BTFE, 1 : 1.5 molar ratio	SPAN	n.r.	46.21 wt%; 3.0 mg cm−2 (coin cell), 2.0 mg cm−2 (pouch cell)	n.r.	0.5–3.0 V vs. (Na/Na+); 1365 mAh g−1 (coin cell) and 1100 mAh g−1 (pouch cell); 94.5% retention over 300 cycles (coin cell) and 80.7% retention over 300 cycles (pouch cell)	n.r.	Highly aggregated Na+–FSI− solvation and minimal free DME stabilize Na and suppress soluble NaPS formation	62

^an.r. is for “not reported”.