Sulfur Copolymer: A New Cathode Structure for Room-Temperature Sodium–Sulfur Batteries

Abstract

High-energy electrochemical storage containing earth abundant materials could be a choice for future battery development. Recent research reports indicated the possibility of room-temperature sodium-ion–sulfur chemistry for large storage including smart grids. Here, we report a room-temperature sodium–sulfur battery cathode that will address the native downsides of a sodium–sulfur battery, such as polysulfide shuttling and low electrical conductivity of elemental sulfur. In this Letter, we use a sustainable route which ensures a large sulfur confinement (i.e., ∼90 wt %) in the cathode structure. The sulfur-embedded polymer is realized via thermal ring-opening polymerization of benzoxazine in the presence of elemental sulfur (CS90) and later composite with reduced graphene oxide (rGO). The resulting CS90 allows a homogeneous distribution of sulfur due to in situ formation of the polymer backbone and allows maximum utilization of sulfur. This unique electrode structure bestows CS90–rGO with an excellent Coulombic efficiency (99%) and healthy cycle life.

Improving the Stability of an RT‐NaS Battery via In Situ Electrochemical Formation of Protective SEI on a Sulfur–Carbon Composite Cathode

“…Among the EESs using sodium, the high temperature sodium-sulfur battery (HT-NaS battery) is best known and operates at 300-350 °C with a molten electrode and a ß″-alumina solid electrolyte. [8,9] In recent years, a room-temperature sodium sulfur battery (RT-NaS battery) that uses liquid organic electrolytes has attracted great interest due to the abundance of sulfur, low operating temperature, and high theoretical capacity (1672 mAh g −1 ). [6] However, the HT-NaS battery has limited capacity, with one third of the theoretical capacity due to solid phase products (Na 2 S 2 ) with a high melting point (T m = 470 °C) formed during the discharge process.…”

Schwefel‐basierte Elektroden mit Mehrelektronenreaktionen für Raumtemperatur‐Natriumionenspeicherung

“…[74] Abbildung 5h zeigt als S-äquivalente Kathoden einsetzbare eindimensionale S-reiche amorphe MoS 3 -Ketten. Ghoshs Gruppe entwickelte eine Schwefel-Kopolymerkathode,u md ie intrinsischen Nachteile von RT-NaS-Batterien (Shuttle-Phänomen und die niedrige Leitfähigkeit von elementarem Schwefel) zu beheben.…”

“…Mit Genehmigung aus Lit [58]. C opyright 2017, American Chemical Society.g )Postulierte chemische Struktur von CS900 und Herstellung aus einem Ca-Monomer mit elementarem S. Mit Genehmigung aus Lit [74]. C opyright 2014, AmericanC hemical Society;C opyright2 015, Wiley-VCH.…”

Cardanol Benzoxazines: A Versatile Monomer with Advancing Applications

“…to improve the electronic/ionic conductivity. The utility of C‐a‐based sulfur copolymer is also explored in Na‐S battery, Figure a …”

“…The presence of phenolicOH, long alkylene chain, and free ortho ‐ and para ‐ positions in cardanol provides reaction sites for chemical modification to form green synthons suitable in various applications . In general, cardanol and its derivatives are attractive and explored as curing agents, coatings, surfactants, antioxidants, plasticizers, adhesives, and more recently in energy storage applications …”