Advanced intermediate-temperature Na–S battery

Abstract

In this study, we reported an intermediate-temperature ($150 C) sodium-sulfur (Na-S) battery. With a relatively low operating temperature, this novel battery could reduce the cost and safety issues associated with the conventional high-temperature (300-350 C) Na-S battery. A dense b 00 -Al 2 O 3 solid membrane and tetraglyme were utilized as the electrolyte separator and catholyte solvent in this battery. Solubility tests indicated that a cathode mixture of Na 2 S 4 and S exhibited extremely high solubility in tetraglyme (e.g., >4.1 M for Na 2 S 4 + 4 S). CV scans of Na 2 S 4 in tetraglyme revealed two pairs of redox couples with peaks at around 2.22 and 1.75 V, corresponding to the redox reactions of polysulfide species. The discharge/charge profiles of the Na-S battery showed a slope region and a plateau, indicating multiple steps and cell reactions. In situ Raman measurements during battery operation suggested that polysulfide species were formed in the sequence of Na

Liquid-metal electrode to enable ultra-low temperature sodium–beta alumina batteries for renewable energy storage

“…Previously, we reported an intermediate-temperature (that is, 150°C) Na-S battery that uses pure sodium as the anode, BASE as the electrolyte separator and tetraglyme as the catholyte solvent 32 . The cell showed significant improvement in cycle life over state-of-the-art low-or roomtemperature Na-S batteries because of the dense ceramic membrane 32,33 . Figure 4 compares the performance of Na-S cells with Na-Cs alloy and pure sodium anodes.…”

“…Excess anhydrous NaCl (Alfa Aesar, 99.99%) was then added into the melt and heated at the same temperature overnight. For the Na-S battery, tetraglyme containing 1 mol NaI was selected as the catholyte as before 32 .…”

“…Molten catholyte of NaAlCl 4 or NaCl-saturated AlCl 3 -[MEI]Cl was infiltrated into the cathode. For the Na-S battery, the catholyte of NaI-containing tetraglyme was heated to 150°C and a mixture of S and Na 2 S 4 (molar ratio of 4:1) was dissolved into the solution 32 . The solution was poured into the cathode chamber and a carbon felt was inserted into the chamber as a current collector.…”

“…Single cells were fabricated as described previously 24,32,36,37 . BASE discs with a diameter of 26 mm were glass-sealed to a-Al 2 O 3 rings with an active cell area of B3 cm 2 .…”

“…BASE discs were prepared using a vapour phase process as described previously 7,24,32,36,37 . a-Al 2 O 3 (Almatis, 499.8%), yttria-stabilized zirconia (YSZ) (8YSZ, UCM Advanced Ceramics), dispersant (Phospholan PS-236, Akzo Nobel), solvent (methyl ethyl ketone/ethanol), plasticizer (benzyl butyl phthalate, Aldrich), and binder (Butvar B-79) were thoroughly mixed to make a slurry.…”