High and intermediate temperature sodium–sulfur batteries for energy storage: development, challenges and perspectives

Abstract

In view of the burgeoning demand for energy storage stemming largely from the growing renewable energy sector, the prospects of high (>300 C), intermediate (100-200 C) and room temperature (25-60 C) battery systems are encouraging. Metal sulfur batteries are an attractive choice since the sulfur cathode is

Challenges of today for Na-based batteries of the future: From materials to cell metrics

“…Although this technology has been developed over the years to yield a commercial product (NGK Insulators) for stationary storage, its market competitiveness is yet to be demonstrated. The high operating temperature leads to technological challenges and limits the discharge capacity (Table 1), which is why Na/S batteries operating at room temperature or intermediate temperatures are being reconsidered [239,[307][308][309]. Further research in this field has been motivated by the potentially promising performance: the formal reduction of sulphur to form Na 2 S corresponds to a capacity of 687 mAh.g − 1 (or 1672 mAh.g − 1 without accounting for the mass of sodium).…”

Remedies for Polysulfide Dissolution in Room‐Temperature Sodium–Sulfur Batteries

“…For instance, at high temperature (HT) of 300–350 °C, a two‐phase liquid of immiscible S and Na 2 S 5 is present; but Na 2 S 2 or Na 2 S cannot exist in the liquid state due to their high melting points at 470 and 1168 °C, respectively. Accordingly, there are three types of NaS batteries with different operating temperature regions, including HT (270–350 °C), intermediate temperature (IT, 130–180 °C), and room temperature (RT), which have been developed with different cell configurations . As illustrated in Figure b, HT‐NaS and IT‐NaS batteries are typically constructed in a tubular design by using metal cases, which contain central molten Na as the cathode, which is confined in a beta‐alumina solid electrolyte (BASE) tube with a molten S cathode surrounding the tube due to the high operation temperature .…”

“…With a relatively lower operation temperature, the IT‐NaS batteries show inferior S utilization and reversible capacity due to the lower ionic conductivity of BASE, but they are likely to deliver higher capacity and energy density in the future, if Na 2 S 2 or Na 2 S could be further formed reversibly with a special cell configuration . For the typical HT‐NaS and IT‐NaS batteries, with active Na (melting point, T m = 98 °C) and S ( T m = 119 °C) in the liquid state in this temperature range, Na ions can migrate through the BASE to react with S, leading to the formation of Na 2 S x ( x = 5–3) during the discharge process, which will lead, in turn, to a relatively low theoretical gravimetric capacity of 557 mA h g −1 and specific energy density of 760 W h kg −1 . The high operation temperature was found to be the culprit, under which both molten S and polysulfides are highly corrosive toward sealing components with a high risk of short‐circuits, thus causing serious safety concerns, increasing energy loss, and high additional costs associated with cell packing for thermal‐corrosion resistance.…”

Large Planar Na-β″-Al2O3 Solid Electrolytes for Next Generation Na-Batteries

“…Sodium batteries have received increased interest in recent years principally for stationary energy storage, where load leveling is required to offset the intermittent nature of renewable energy sources (solar, wind, hydroelectric) and thus improve their implementation [1][2][3]. Na-β"-Al 2 O 3 has high sodium-ion conductivity at elevated temperatures (0.20 S cm −1 at 300 • C) and is commercially utilized as the solid electrolyte in both sodium-sulfur (NaS) and sodium-nickel-chloride (NaNiCl) batteries [4][5][6].…”