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. © 2017 American Chemical Society.

Bimlesh Lochab

Chemistry

(SoNS) School of Natural Sciences

Ghosh A.

Shukla S.

Monisha M.

Kumar A.

Mitra S.

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Shiv Nadar University

ACS Energy Letters

Polybenzoxazines are evolving as a new class of phenolic resins with a tremendous amount of applications. The ease of structural designing, synthetic procedure, and polymerization reactions are attractive to affect their properties ensuing as an effective substitute for many existing polymers. The nonrenewable origin, toxicity, and increasing cost of petro-based raw materials are alarming issues. Therefore, the emergence of sustainable benzoxazines, especially based on naturally abundant, agro-waste origin cardanol is encouraging as it allows both solventless synthesis of monomers and processing to form highly thermally stable thermoset resins. The inherent functionalities in cardanol benzoxazine provide a platform for further structural modifications to advance their applications as adhesives, composites, and energy storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Macromolecular Chemistry and Physics

Cardanol Benzoxazines: A Versatile Monomer with Advancing Applications

An agro-waste origin cardanol benzoxazine monomer (Ca) has shown potential as a suitable sustainable linker to chemically bind petroleum industry generated waste, elemental sulphur (S) to form random copolymers poly(S-r-Ca). A series of random copolymers with varied weight percent of elemental sulphur (20–95\%) were synthesised via bulk polymerisation methodology. The Ca monomer offered several reaction sites to facilitate the formation of sulphur rich copolymers as supported by FT-IR, 1H NMR, Raman spectroscopy, XRD, DSC and TGA studies. The curing temperature of Ca was found to be lowered to reaction temperature i.e. 185 °C from 242 °C using elemental sulphur as co-reactant. Preliminary studies of random poly(S-r-Ca) copolymers with a very high sulphur loadings (&gt;80\% w/w) demonstrated inverse vulcanisation and suggest their utility as an efficient substitute to elemental sulphur as a cathode material in Li-S battery. © 2016 Elsevier Ltd

Polymer

Cardanol benzoxazines – A sustainable linker for elemental sulphur based copolymers via inverse vulcanisation

A sulfur-rich copolymer, poly(S-r-C-a) has been synthesized via a sustainable route, showing the utility of two major industrial wastes- elemental sulfur (petroleum waste) and cardanol (agro waste), to explore its potential as cathode material for Li-S batteries. The sulfur-rich copolymer exhibited a reduction in the active material dissolution into the electrolyte and a low self-discharge rate behavior during the rest time compared to an elemental sulfur cathode, indicating the chemical confinement of sulfur units. The presence of organosulfur moieties in copolymer suppress the irreversible deposition of end-discharge products on electrode surfaces and thus improve the electrochemical performances of Li-S batteries. This sulfur copolymer offered a reversible capacity of 892 mA h g-1 at 2nd cycle and maintained the capacity of 528 mA h g-1 after 50 cycles at 200 mA g-1. Reduced graphene oxide (rGO) prepared via a sustainable route was used as a conductive filler to extract the better electrochemical performances from this sulfur copolymer. Such sustainable origin batteries prepared via economically viable showed an improved specific capacity of ∼975 mA h g-1 after 100 cycles at 200 mA g-1 current rate with capacity fading of 0.15\% per cycle and maintained a stable performance over 500 cycles at 2000 mA g-1.

Fulltext

Scientific Reports

Sustainable Sulfur-rich Copolymer/Graphene Composite as Lithium-Sulfur Battery Cathode with Excellent Electrochemical Performance

A sulfur-rich copolymer is synthesized via a sustainable, eco-friendly approach using two major wastes namely, elemental sulfur (industrial waste) and cardanol (agro waste) and its application as cathode active material in Li−S battery. The presence of chemically bound sulfur (90 wt\%) utilising cardanol (10 wt\%) derivative in the copolymer (S90) showed a reduction in the active material dissolution into the electrolyte. In addition, the organic sulfur units get dispersed into the insoluble/insulating Li2S2/Li2S phase and thus found to suppress their irreversible deposition. Li−S battery based on S90/multi-walled carbon nanotubes (MWCNT) (10 wt\%) exhibited a reversible capacity of 1302 mAh g−1 at 2nd cycle, maintaining a high reversible capacity of 928 mAh g−1 after 70 cycles at a relatively constant coulombic efficiency over 99 \% at current rate of 200 mA g−1. At 1000 mA g−1 current rate, the composite cathode delivered a reversible capacity of 697 mAh g−1 at 2nd cycle and retained 75 \% of its initial capacity even after 180 cycles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

ChemistrySelect

Cardanol benzoxazine-Sulfur Copolymers for Li-S batteries: Symbiosis of Sustainability and Performance

Exploration of sustainable alternatives to chemicals derived from petro-based industries is the current challenge for maintaining the balance between the needs of a changing world while preserving nature. The major source for sustainable chemicals is either the natural existing plant sources or waste generated from agro-based industries. The utility of such resources will supplement new processed materials with different sets of properties and environmental friendliness due to their biodegradability and low toxicity during preparation, usage and disposal. Amongst other polymers used on a day-to-day basis, phenolic resins account for vast usage. Replacement of petro-based monomers such as phenol and its derivatives either partly or completely utilized for the synthesis of such resins is ongoing. Extraction of natural phenolic components from cashew nut shell liquid, lignin, tannin, palm oil, coconut shell tar or from agricultural and industrial waste, and their utilization as synthons for the preparation of bio-based polymers and properties obtained are reviewed in this paper. This review article is designed to acknowledge efforts of researchers towards the "3C" motto-not only trying to create but also adapting the principles to conserve and care for a sustainable environment. This review paper describes how extraction, separation and recovery of desired phenolic compounds have occurred recently; how substituted phenol compounds, unmodified and modified, act as monomers for polymerization; and how the presence of sustainable phenolic material affects the properties of polymers. There are about 600 references cited and still there is a lot to uncover in this research area. This journal is © the Partner Organisations 2014.