Lithium-sulfur batteries are a major focus of academic and industrial energy-storage research due to their high theoretical energy density and the use of low-cost materials. The high energy density results from the conversion mechanism that lithium-sulfur cells utilize. The sulfur cathode, being naturally abundant and environmentally friendly, makes lithium-sulfur batteries a potential next-generation energy-storage technology. The current state of the research indicates that lithium-sulfur cells are now at the point of transitioning from laboratory-scale devices to a more practical energy-storage application. Based on similar electrochemical conversion reactions, the low-cost sulfur cathode can be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum. These new "metal-sulfur" systems exhibit great potential in either lowering the production cost or producing high energy density. Inspired by the rapid development of lithium-sulfur batteries and the prospect of metal-sulfur cells, here, over 450 research articles are summarized to analyze the research progress and explore the electrochemical characteristics, cell-assembly parameters, cell-testing conditions, and materials design. In addition to highlighting the current research progress, the possible future areas of research which are needed to bring conversion-type lithium-sulfur and other metal-sulfur batteries into the market are also discussed.

Current Status and Future Prospects of Metal–Sulfur Batteries

Introduction Lithium-sulfur batteries are considered as a promising candidate for next-generation secondary batteries because of their high theoretical capacit y, safe operating voltage (2.15 V vs. Li/Li ), and low cost. Nevertheless, lithium-sulfur batteries suffer from capacity fading, which limits their widespread application, due to the insulating nature of sulfur and its reduced pro ducts and the dissolution of intermediate lithium polysul fides. To address these problems, carbon-based materials have been integrated with sulfur to enhance the conductivity and inhibit the polysulfide dissolutio n. Recently, graphene, a single-atom-thick carbon mate rial with superior electrical conductivity and mechanica l flexibility, has been successfully applied in lithi um-sulfur batteries. While graphene-sulfur composite cathodes  demonstrate promising electrochemical performance, their synthesis is usually complicated and challeng ing for large-scale application. On the other hand, the sol utionbased synthesis without heat treatment produces lar ge crystalline sulfur particles, resulting in low util ization of active materials and poor rate performance. Herein, we report hydroxylated graphene nanosheets as a substr ate to produce graphene-amorphous sulfur nanocomposites, exhibiting superior cyclability at high rates, by a facile in situ deposition method at room temperature.

Hydroxylated Graphene-Sulfur Nanocomposites for High-Rate Lithium-Sulfur Batteries

Ambient-temperature sodium-sulfur (Na-S) batteries are considered a promising energy storage system due to their high theoretical energy density and low costs. However, great challenges remain in achieving a high rechargeable capacity and long cycle life. Herein we report a stable quasi-solid-state Na-S battery enabled by a poly(S-pentaerythritol tetraacrylate (PETEA))-based cathode and a (PETEA-tris[2-(acryloyloxy)ethyl] isocyanurate (THEICTA))-based gel polymer electrolyte. The polymeric sulfur electrode strongly anchors sulfur through chemical binding and inhibits the shuttle effect. Meanwhile, the in situ formed polymer electrolyte with high ionic conductivity and enhanced safety successfully stabilizes the Na anode/electrolyte interface, and simultaneously immobilizes soluble Na polysulfides. The as-developed quasi-solid-state Na-S cells exhibit a high reversible capacity of 877 mA h g-1 at 0.1 C and an extended cycling stability.

https://opus.lib.uts.edu.au/bitstream/10453/128170/4/4CF85D1C-9895-4A4B-AC90-7BCECCCC98A3%20am.pdf

A Stable Quasi-Solid-State Sodium-Sulfur Battery.

Natural-sourced benzoxazine resins, homopolymers, blends and composites: A review of their synthesis, manufacturing and applications

Advances in sustainable thermosetting resins: From renewable feedstock to high performance and recyclability

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 Cou...

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

Polybenzoxazines (PBzs) are emerging as a highly promising and superior class of thermoset polymers for a variety of applications. However, it remains a significant challenge to substantially lower the ring-opening polymerization (ROP) temperature with an ease in processability. On the other hand, biomacromolecule chitosan (CS) is explored extensively, but its practical applications have been precluded by poor thermal and mechanical properties. Here, we developed a fully biobased copolymer of vanillin benzoxazine (V-fa) monomer with CS, which is effective in providing mutual benefits, effective lowering in ROP temperature of benzoxazine (70 °C), and an enhanced thermal stability of CS (by 85 °C, and with char yield of ∼32%). To understand this unusual lowering in ROP temperature, we investigated the structural interaction mechanism between solvated CS and V-fa using in situ NMR studies. The analysis of fully intercalated co-structure demonstrated that there is a strong preference for ROP over Schiff base ...

Sustainable Framework of Chitosan–Benzoxazine with Mutual Benefits: Low Curing Temperature and Improved Thermal and Mechanical Properties

Due to their outstanding and versatile properties, polybenzoxazines have quickly occupied a great niche of applications. Developing the ability to polymerize benzoxazine resin at lower temperatures than the current capability is essential in taking advantage of these exceptional properties and remains to be most challenging subject in the field. The current review is classified into several parts to achieve this goal. In this review, fundamentals on the synthesis and evolution of structure, which led to classification of PBz in different generations, are discussed. Classifications of PBzs are defined depending on building block as well as how structure is evolved and property obtained. Progress on the utility of biobased feedstocks from various bio-/waste-mass is also discussed and compared, wherever possible. The second part of review discusses the probable polymerization mechanism proposed for the ring-opening reactions. This is complementary to the third section, where the effect of catalysts/initiators has on triggering polymerization at low temperature is discussed extensively. The role of additional functionalities in influencing the temperature of polymerization is also discussed. There has been a shift in paradigm beyond the lowering of ring-opening polymerization (ROP) temperature and other areas of interest, such as adaptation of molecular functionality with simultaneous improvement of properties.

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers.

Halogen-free flame-retardant sulfur copolymers with stable Li–S battery performance

https://onlinelibrary.wiley.com/doi/pdf/10.1002/macp.201970005

Monisha Monisha

Papers

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

Sustainable Framework of Chitosan–Benzoxazine with Mutual Benefits: Low Curing Temperature and Improved Thermal and Mechanical Properties

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers.

Halogen-free flame-retardant sulfur copolymers with stable Li–S battery performance

Cardanol Benzoxazines: A Versatile Monomer with Advancing Applications