Sulfur-rich Copolymer Research Articles

A sulfur-rich copolymer hybrid cathode for anchoring polysulfides and accelerating redox reaction in lithium sulfur batteries

In lithium-sulfur batteries (LSBs), sulfur-rich copolymers have attracted wide attention due to the reduced dissolution of active material and alleviated self-discharge problem through the efficient chemical interaction between polysulfide and carbon. Herein, we present an effective strategy to encapsulate sulfur-rich copolymer into NiCo2S4 encapsulated hierarchical porous N/O dual-doped graphitic carbon nanocages (GCNs), named S-DIB@NiCo2S4@PDA@rGO-GCNs. The host NiCo2S4@PDA@rGO-GCNs matrix can not only provide the “lithiophilic”-rich polar sites and tight anchored LiPSnon the N/O dual-doped GCNs surface, and “sulfphilic” NiCo2S4 electrocatalyst for accelerated sulfur electrochemistry, but also offer abundant hierarchical pores for accommodating sulfur and cushioning its volume expansion. Both of the experimental and theoretical analyses reveal the S-DIB@NiCo2S4@PDA@rGO-GCNs possesses the strong chemisorptions and catalytic ability with the synergetic mechanism, suppressing the self-discharge problem. As a proof-of-concept study, the assembled LSBs cells show excellent discharge capacities of 486 and 324 mA h g−1 at 5C and 10C after 1000 cycles, respectively. The corresponding capacity loss rate is as low as 0.032 % and 0.030 % per cycle, respectively. Thanks to the exceptional lithiophilic and sulfiphilic characteristic, the LSBs pouch cell also demonstrates high cycling stability. The proposed hierarchical encapsulation strategy with synergetic chemisorptions and catalytic ability shows great potential for developing advanced electrodes for next-generation high-performance rechargeable batteries.

Self-Healing and Recyclable Vulcanized Polyisoprene Based on a Sulfur-Rich Copolymer Cross-Linking Agent Derived from Inverse Vulcanization

Self-Healing and Recyclable Vulcanized Polyisoprene Based on a Sulfur-Rich Copolymer Cross-Linking Agent Derived from Inverse Vulcanization

Closed-loop chemically recyclable covalent adaptive networks derived from elementary sulfur.

The development of sulfur-rich polymers derived from elementary sulfur provides an innovative approach to industrial waste valorization. Despite significant advancements in polymerization techniques and promising applications beyond traditional polymers, polysulfide networks are still primarily stabilized by diene crosslinkers, forming robust C-S bonds that hinder the degradation of sulfur-based polymers. In this study, the anionic ring-opening copolymerization of chemically homologous S8 and cyclic disulfides was explored to yield robust sulfur-rich copolymers with high molecular weight. The incorporation of polysulfide segments not only efficiently activated the crosslinked networks for excellent reprocessability and mechanical adaptability but also endowed the resulting copolymer with high optical transparency in the near-infrared region. More importantly, the dynamic disulfide crosslinking sites promoted the chemical closed-loop recyclability of the polysulfide networks via reversible S-S cleavage. This innovative inverse vulcanization strategy utilizing dynamic disulfide crosslinkers offers a promising pathway for the advanced applications and upcycling of high-performance sulfur-rich polymers.

The exploration of the inverse vulcanization mechanism of tung oil by controlling the oxygen and moisture presence during reactions

Inverse vulcanization is a cost-effective method for producing high sulfur-content copolymers by combining elemental sulfur with organic monomers, which has rapidly gained popularity due to its simplicity of synthesis and wide range of applications. Although numerous examples of sulfur-rich copolymers have been synthesized at different reaction rates and temperatures using various monomers, the precise reaction mechanism remains unclear. In this paper, we used tung oil containing conjugated triene as a monomer to synthesize sulfur-rich copolymers under six different reaction conditions and investigate the effects of oxygen and moisture. Our study, which employed DSC, XRD, 1H NMR, and XPS characterization methods, revealed that oxygen accelerated the reaction rate and decreased the free sulfur content of the products, while moisture shortened the gel times but increased the free sulfur content. These findings confirm that reverse vulcanization involves two simultaneous mechanisms: the free radical mechanism and the anion mechanism. With regard to the radical mechanism, we discuss the source, ease, and reactivity of radicals and show that the creation of radicals depends on the second monomer rather than sulfur. Tung oil not only acts as a comonomer in the reaction but also plays an initiating role in promoting the dissociation of sulfur chains to generate free radicals for addition of non-conjugated double bonds. The effect of the anion mechanism exceeds that of the radical mechanism once certain factors are stimulated, such as the presence of metal ions and sulfide ions. Understanding the detailed mechanisms involved in inverse vulcanization is essential for selecting optimal monomers, which can enhance not only the synthesis process but also the properties of sulfur-rich materials.

A semi-immobilized sulfur-rich copolymer backbone with conciliatory polymer skeleton and conductive substrates for high-performance Li-S batteries

Sulfur-rich polymers have gained a great deal of attention as the next-generation active materials in lithium-sulfur (Li-S) batteries due to their low cost, environmental compatibility, naturally sulfur uniform dispersion, and distinctive structure covalently bonding with sulfur atoms. However, the poor electrical conductivity and undesirable additional shuttle effect still hinder the commercial application of sulfur-rich polymers. Herein, we report a flexible semi-immobilization strategy to prepare allyl-terminated hyperbranched poly(ethyleneimine)-functionalized reduced graphene oxide (A-PEI-EGO) as sulfur-rich copolymer backbone. The semi-immobilization strategy can effectively reconcile the demand for polymer skeleton and conductive substrates through forming quaternary ammonium groups and reducing oxygen-containing functional groups, resulting in enhanced skeleton adsorption capacity and substrate electronic conductivity, respectively. Furthermore, the stable covalent bonding connection based on polymer molecules (A-PEI) not only completely prevents the additional shuttle effect of lithiation organic molecules and even sulfur-rich oligomers, but provides more inverse vulcanization active sites. As a result, the as-prepared A-PEI-EGO-S cathodes display an initial discharge capacity of 1338 mA h g−1 at a rate of 0.1 C and an outstanding cycling stability of 0.046% capacity decay per cycle over 600 cycles. Even under 6.2 mg cm−2 S-loaded and sparing electrolyte of 6 µL mg−1, the A-PEI-EGO-S cathode can also achieve a superior cycling performance of 98% capacity retention after 60 cycles, confirming its application potential.

Effect of Sulfur Chain Length on the Electrochemical Performance of Sulfur-Rich Copolymers in Li-S Batteries

Lithium-Sulfur battery is considered to be a promising next-generation candidate because of its high theoretical capacity of ~1675 mAh/g compared to current commercial batteries. However, there are challenges related to the long-term cycling of these batteries, originating from the formation of soluble lithium polysulfides species and their subsequent shuttling. Recently, we synthesized a sulfur-rich copolymer/ carbon nanofiber cathode material for Li-S batteries. The formation of a C-S bond in these sulfur-rich copolymers results in formation of organo-lithium polysulfides (OPs) instead of lithium polysulfides (PS). The copolymer is synthesized using inverse vulcanization reaction, where sulfur powder reacts with a monomer, here 1,3-di-isopropenyl benzene (DIB), at high temperatures. In this study, we varied the DIB monomer concentration, and three samples with different sulfur/DIB wt% were synthesized. We characterized these three different samples using XRD, DSC, and FTIR. The XRD results show that the sulfur-rich copolymer transitions from a crystalline material to a completely amorphous composite. Moreover, FTIR results show a redshift in the C-S peak of the sulfur-rich copolymer with increasing the monomer wt%. These results confirm that the molecular structure of the sulfur-rich copolymer is changed as a result of changing S/DIB wt ratio in the synthesis of sulfur-rich copolymers. We believe that by increasing the monomer to sulfur ratio in such copolymers, the sulfur chain length becomes shorter. Figure 1 shows the cyclic voltammetry (CV) obtained using these three different cathodes. As can be seen from this figure, two reduction peaks at ~2.3 and ~2 V represent the formation of higher and lower order Ps and OPs. However, with further increase in DIB concentration, the first reduction peak at ~2.3V disappears. We hypothesize that the disappearance of the first reduction peak can be attributed to the existence of a short sulfur chain length. To investigate the hypothesis, an in situ cell consisted of two different cathodes, one cathode with a low (sample 1) and another with a high DIB wt% (sample 2), were built on the FTIR to simultaneously collect IR spectra and CVs. The FTIR results show a redshift from 695 cm-1 to 705 cm-1 in the C-S bond for sample 1 with higher sulfur chain length (lower monomer wt%). This shift is attributed to the formation of organopolysulfides. Moreover, as the cell was discharged, multiple peaks between the lithium polysulfide region (510 to 480 cm-1) appeared, which confirms the formation of high and low order lithium polysulfides. On the other hand, when sample 2 with lower sulfur chain length (high monomer wt%) was tested, the C-S peak shifted from 704 cm-1 to 706 cm-1 only. The smaller C-S peak shift in sample 2 compared to sample 1 confirms the existence of short-chain polysulfides. Moreover, there was no lithium polysulfide peaks observed in the polysulfide region for sample 2, which confirms that the formation of loose lithium polysulfide is avoided. Figure 1

Bifunctional polyvinylpyrrolidone generates sulfur-rich copolymer and acts as “residence” of polysulfide for advanced lithium-sulfur battery

Sulfur-rich copolymer is considered as a promising cathode in lithium-sulfur battery due to its superior chemical confinement for polysulfides on the molecular level, but the sulfur-rich copolymer with low cost and physiological inert is reported rarely. Here, a novel sulfur-polyvinylpyrrolidone (PVPS) copolymer is synthesized by one-step thermal polymerization. The break and recombination of CO lead to the formation of PVPS, which is proved by various characterizations. Due to the strong chemical confinement of C–S bond, the excellent polysulfides adsorption ability of PVP with abundant polar bonds (such as C–O and C–N) and the improved charge transfer of PVPS, 20PVPS combining with PVP-modified separator as “residence” of polysulfides delivers the high reversible capacity of 1079 and 729 mAh g−1 at 0.1 and 2 C and a slow capacity fading rate of 0.093% over 500 cycles at 1 C. These findings provide a reference for the synthesis of low-cost, biocompatible and high-performance sulfur-rich copolymer in lithium-sulfur battery.

In Situ FTIR Study on Organo-Polysulfide Evolution in CNF/Sulfur-Copolymer Cathodes for Li-S Batteries: Effect of Sulfur Chain Length on the Electrochemical Performance

Lithium-Sulfur batteries offer five times more energy density compared to conventional Li-ion batteries. However, there are challenges related to long term cycling of these batteries. Recently, we synthesized a sulfur-rich copolymer/ carbon nanofiber cathode material for Li-S batteries. The formation of a C-S bond in these sulfur-rich copolymers results in the formation of organo-lithium polysulfides (OPs), instead of lithium polysulfides (PS). In the present work, we demonstrate in situ FTIR spectroscopy as a tool to investigate the C-S bond and lithium polysulfide evolution in sulfur-rich copolymer-based Li-S batteries. The copolymer is synthesized using inverse vulcanization reaction, where sulfur powder reacts with a monomer, here 1,3-diisopropenylbenzene (DIB), at high temperatures. In this study, we varied the DIB monomer concentration and three samples with differen sulfur/DIB wt% were synthesized. Figure 1 shows the cyclic voltammetry (CV) obtained using the three different cathodes. As it can be seen from this fugure two reduction peaks at ~2.3 and 2 V represent the formation of higher and lower order Ps and OPs. However, with further increase in DIB concentration, the first reduction peak at ~2.3V disappears. We hypothesize that the disappearance of the first reduction peak can be attributed to the existence of short sulfur chain length. To investigate the hypothesis, an in situ cell consisted of two different cathodes, one cathode with a low (sample 1) and another with a high DIB wt% (sample 2), were built on the FTIR to simultaneously collect IR spectra and CVs. Our results show that the C-S bond located at ~695 cm-1 in sample 1 shifts to higher wavenumbers (~705cm-1) as we discharge the cell. The shift to higher wavenumbers shows that the formation of OPs, strengthens the C-S bonds which originates from having Li, with lower electronegativity (0.98 VS. 2.58), instead of S. However, when we tested the sample 2 cell, the C-S cyclic shift, happens between ~704 to ~706 cm-1, only. The smaller C-S peak shift in sample 2 compared to sample 1 is attributed to the existence of the short chain length sulfur. Figure 1

Synergistic effect of sulfur-rich copolymer/S8 and carbon host porosity in Li-S batteries

In this work, we investigate the possible role of host material porosity in performance of Li-S batteries, when sulfur-rich copolymer is used as an active ingredient in the cathode. We synthesized a freestanding cathode material using electrospun carbon nanofibers (CNFs) and poly(sulfur-random-1,3-diisopropenylbenzene)/SDIB (with some residual unreacted sulfur) and used it without adding any binders or current collectors. To study the effect of porosity of CNFs, two different porous samples, microporous (miCNF) and mesoporous (meCNF), were designed. When miCNF was used as a host material, the capacity stabilized to 577 mAh/g within 50 cycles and remained stable up to 600 cycles with a small capacity decay rate of 0.046% per cycle along with an excellent coulombic efficiency of >98% throughout the 600 cycles. On the other hand, SDIB-meCNF cathodes delivered a stable capacity of ~600 mAh/g with negligible decay. However, the stability only lasted for 145 cycles. Despite the positive effect of C-S bond formed in SDIB active material, we hypothesize that the porosity of the cathode host still plays a significant role not only due to residual unreacted S8 in the original cathode, but also due to additional loose soluble -Sn- chains that emerge from S-S bond breakage in C-S-Sn-S-C (SDIB) over the course of cycling. Moreover, using the effective capacity calculation, we compared the discharge capacity of our cathode to other works on sulfur rich copolymers at C/2 and C/5 rates. The effective capacity analysis clearly manifests the advantages of using current-collector and binder-free electrospun CNFs as a host matrix for SDIB.

Conductive Sulfur-Rich Copolymer Composites as Lithium–Sulfur Battery Electrodes with Fast Kinetics and a High Cycle Stability

Lithium–sulfur batteries are attracting significant attention due to their high specific capacity, reaching 1672 mAh g–1, but their practical applications are hindered by the inherent insulation of...

Electrospun Nanofiber-Based Cathodes for Lithium-Sulfur Batteries

Lithium-Sulfur is a next generation battery chemistry that offers a theoretical capacity of 1,675 mAh/g, an order of magnitude higher than that of the currently used Li-ion battery cathodes. However, a serious challenge that has plagued the development of this technology is the dissolution and shuttle of intermediate polysulfides (Li2Sx, x=4-8) in the electrolyte resulting in loss of active material and rapid capacity fade during cycling. I will present two projects from my group both centred around Li-S batteries. In the first part of my talk, I will discuss our work on stabilization of titanium monoxide (TiO) nanoparticles in carbon nanofibers (CNF) through electrospinning and carbothermal processes and their unique bi-functionality – high conductivity and ability to bind polysulfides via Lewis acid-base interactions–as sulfur hosts. The developed 3-D TiO/CNF architecture with the inherent inter-fiber macropores of nanofiber mats provides a much higher surface area (~427 m2 g-1) and overcomes the challenges associated with the use of highly dense powdered Ti-based suboxides/monoxide materials, thereby allowing for high active sulfur loading among other benefits. The developed TiO/CNF-S cathodes exhibit high initial discharge capacities of ~1080 mAh g-1, ~975 mAh g-1, and ~791 mAh g-1 at 0.1C, 0.2C, and 0.5C rates, respectively with long-term cycling. Furthermore, free-standing TiO/CNF-S cathodes developed with rapid sulfur melt infiltration (~5 sec) eradicate the need of inactive elements viz. binders, additional current collectors (Al-foil) and additives. Using postmortem XPS and Raman analysis, this study reveals the presence of strong Lewis acid-base interaction between TiO (3d2) and Sx 2- through the coordinate covalent Ti-S bond formation. In the second part, I will discuss our work on in-situ infrared spectroelectrochemistry to understand redox mechanisms – a critical step for rational design of cathode systems for Li-S batteries. Specifically, I will discuss the use of sulfur-rich copolymers as active cathode materials and demonstrate in-situ FTIR with attenuated total reflection (ATR) to monitor polysulfide (PS) speciation (S x 2-, 2 ≤ x ≤ 8) and polymeric signature evolution while simultaneously discharging/charging a full battery coin cell.

A Highly Crosslinked and Conductive Sulfur-Rich Copolymer with Grafted Polyaniline for Stable Cycling Lithium–Sulfur Batteries

Lithium–sulfur batteries offer promisingly high energy density, but suffer from low lithium ion diffusion and lithium polysulfide shuttling, resulting in capacity loss. Herein, we present a novel sulfur-rich copolymer combination Poly(S-r-DIB)-g-PANI (SBPA) to address these chronic issues. Two organic compounds 1,3-diisopropylbenzene and p-aminostyrene are sequentially grafted to sulfur forming multiple crosslinking carbon-sulfur bonds; the amino group of p-aminostyrene then provides a site for aniline polymerization. The combination of the copolymer graftings create a novel structure of highly crosslinked copolymer chains with covalently grafted polyaniline. As cathode material for lithium–sulfur batteries, the sulfur has high specific capacity, impressive cycling stability, and good rate capability, i.e. 1089 mAh g−1 at 0.1 C after 160 cycles (∼84% retention) and 612 mAh g−1 after 450 cycles at 0.5 C (∼73% retention). Compared to controls of sulfur/polyaniline mixtures or to non-aniline-reacted sulfur-copolymer, the polyaniline crosslinked copolymer has superior capacity retention and rate capability due to the unique combination of crosslinked sulfur and grafted polyaniline.

Trapping of Polysulfides with Sulfur-Rich Poly Ionic Liquid Cathode Materials for Ultralong-Life Lithium-Sulfur Batteries.

Sulfur-rich polymers synthesized by inverse vulcanization are promising cathodes for Li-S batteries and can suppress the shuttle effect to improve the cycling properties of Li-S batteries. However, developing a sulfur-rich copolymer with new chemical functionality to enhance performance of Li-S batteries remains a huge challenge. In this report, a sulfur-rich polymer cathode containing ionic liquid segments named poly(sulfur-co-1-vinyl-3-allylimidazolium bromide) [poly(S-co-DVIMBr)] was obtained by the inverse vulcanization of S8 with DVIMBr and used as cathode for the first time. This sulfur-rich poly ionic liquid cathode showed effective suppression of the shuttle effect through joint effects of the stable chemical bonding of C-S and strong cation absorption for lithium polysulfides, which was confirmed by DFT calculations. In particular, the Li-S cell with poly(S-co-DVIMBr) cathode delivered high capacity retention of 90.22 % even over 900 cycles. Developing sulfur-rich poly ionic liquids may provide a new strategy of introducing the functional groups with cations into the cathode materials for suppressing the shuttle effect and improving the performance of Li-S batteries.

Inverse vulcanized sulfur–cycloalkene copolymers: Effect of ring size and unsaturation on thermal properties

Herein, we study the influence of ring size and number of carbon-carbon double bonds of cycloalkene on structure property relation of inverse vulcanized sulfur copolymers. Reaction kinetics was monitored by XRD and the copolymer structure was confirmed by 1H NMR and FTIR spectroscopy. DSC and TGA indicate the significant increase in Tg and thermal stability of the copolymer with increase in ring size and number of double bonds density; respectively. Thermal conductivity of the copolymers (0.083 W/mK at 50 °C) was also considerably reduced compared to the pristine sulfur, which make these copolymer suitable for thermal insulation applications. Moreover, these sulfur-rich copolymers can also be used as potential cathode materials in lithium-sulfur batteries.

Freestanding CNF/Sulfur-Copolymer Cathodes for Li-S Batteries: Effect of Host Porosity on Battery Performance

Lithium-sulfur batteries have been considered as the next generation energy storage devices due to their high energy density of ~2600 Wh/kg. However, the challenge of developing Li-S with long-term cycling stability still exists due to shuttling of intermediate polysulfides. Recently, a class of sulfur-rich copolymers has shown several advantages compared to their sulfur counterpart owing to the (a) presence of C-S bond, which can chemically bind lithium polysulfides and suppress shuttle effect, and (b) enhanced Li+ transport and electronic conductivity due to conjugated structure. However, the use of such active material is in its nascent stage and the role (if any) of the conductive host material porosity in enhancing the polysulfide suppressing functionality of such chemically-bound active material is unclear. In our work, we use freestanding, binder and current collector-free electrospun nanofibers as a platform to understand the role of host porosity in sulfur-rich copolymer-based Li-S batteries. The sulfur rich copolymer (SDIB) was synthesized using 1,3-diisopropenylbenzene (DIB) and sulfur (S) in a weight ratio of 20:80 (SDIB20) at 185 °C. To study the effect of porosity of CNFs on the cycling and capacity of polymerized sulfur based Li-S cells, two different porous samples were designed using PAN: Nafion weight ratio as 4:6 (mi-CNF) and 3:7 (me-CNF) followed by carbonization. The BET results showed that mi-CNF exhibited slightly higher micropore volume (0.315 cm3/g vs. 0.271 cm3/g) and substantially lower mesopore volume (0.192 cm3/g vs. 0.502 cm3/g) and size (<4.5 nm vs. <7 nm) than me-CNF. A heat-press assisted ultra-rapid melt diffusion technique (2 minutes) developed in our group was used to incorporate SDIB20 into mi-CNFs and me-CNFs. The as-prepared free-standing SDIB/CNF cathodes with final sulfur loading of 1.1-1.3 mg/cm2 (45-50 wt%) ­were used in Li-S cells. When mi-CNF was used as a host material, the capacity was stabilized to 577 mAh/g within 50 cycles and remained stable up to 600 cycles with a small capacity decay rate of 0.046% per cycle along with coulombic efficiency >98% (Figure 1a). On the other hand, SDIB/me-CNF cathodes delivered a stable capacity of ~600 mAh/g with negligible decay. However, the stability only lasted for 145 cycles (figure 1a inset). Additionally, the control/reference cell with sulfur as the active material (mi-CNF as host) showed a rapid decay in capacity in less than 100 cycles (Figure 1a) suggesting a clear advantage of sulfur-rich copolymers as active material (over pure loose sulfur) due to the presence of C-S bond leading to chemically bound insoluble polysulfides. We hypothesize that porosity of the cathode host still plays a significant role as loose soluble -Sn- chains start to gradually emerge from S-S bond breakage in C-S-Sn-S-C over the course of cycling. This slow polysulfide formation rate in SDIB/mi-CNF results in effective polysulfide adsorption by micropores in SDIB/mi-CNF cathodes leading to substantial enhancement of cycling stability. We believe that as the pore size and volume increase in me-CNFs, the electrolyte accessibility enhances, which results in relatively higher capacity. However, this also potentially leads to easier escape of polysulfides and early capacity fade in SDIB/me-CNFs based Li-S cells. We calculated the effective capacity of our SDIB/me-CNF cathode and compared it to other works on sulfur rich copolymers in powdered nanostructure (Fig. 1b) at C/2 (presented in red) and C/5 rates (presented in black). To calculate the effective capacity, the discharge capacity of sulfur after 100 cycles is adjusted based on the total weight of the electrode (i.e., current collector, binder, sulfur and conductive material). The effective capacity analysis clearly manifests the advantages of using current-collector and binder-free electrospun CNFs as a host matrix for SDIB. Figure 1

Squalene-derived sulfur-rich copolymer@ 3D graphene-carbon nanotube network cathode for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with high theoretical energy density and low cost are considered a promising energy storage system. However, great challenges still remain in achieving high sulfur loading and long cycle life. Herein we report a well-designed sulfur-rich copolymer@ 3D graphene-carbon nanotubes (G-CNT) network cathode for high-performance Li-S batteries. The sulfur-rich copolymer (87.29% sulfur) synthesised by inverse vulcanization between two eco-friendly sources, sulfur and squalene, can greatly suppress the dissolution of sulfur and polusulfides due to the chemical confinement from the crosslinking of polysulfur chains with the squalene molecules. The interlinked Sp2 G-CNT network can not only further enhance the polysulfide entrapment capability, but also provide the composite with an 3D electrical conductive path as well as an eminent mechanical resilience towards the huge volume change of sulfur. The as-developed cathode can deliver a high specific capacity of 1265 mAh g−1 at 0.2C with excellent rate performance and cycling stability (782 mAh g−1 at after 300 cycles at 1C).

Rapid Mercury(II) Removal by Electrospun Sulfur Copolymers.

Electrospinning was performed with a blend of commercially available poly(methyl methacrylate) (PMMA) and a sulfur-rich copolymer based on poly(sulfur-statistical-diisopropenylbenzene), which was synthesized via inverse vulcanization. The polysulfide backbone of sulfur-containing polymers is known to bind mercury from aqueous solutions and can be utilized for recycling water. Increasing the surface area by electrospinning can maximize the effect of binding mercury regarding the rate and maximum uptake. These fibers showed a mercury decrease of more than 98% after a few seconds and a maximum uptake of 440 mg of mercury per gram of electrospun fibers. These polymeric fibers represent a new class of efficient water filtering systems that show one of the highest and fastest mercury uptakes for electrospun fibers reported.

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

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.

Inverse Vulcanization of Elemental Sulfur to Prepare Polymeric Electrode Materials for Li-S Batteries.

Sulfur-rich copolymers based on poly(sulfur-random-1,3-diisopropenylbenzene) (poly(S-r-DIB)) were synthesized via inverse vulcanization to create cathode materials for lithium-sulfur battery applications. These materials exhibit enhanced capacity retention (1005 mAh/g at 100 cycles) and battery lifetimes over 500 cycles at a C/10 rate. These poly(S-r-DIB) copolymers represent a new class of polymeric electrode materials that exhibit one of the highest charge capacities reported, particularly after extended charge-discharge cycling in Li-S batteries.

Sulfur-rich copolymers of sulfur with 5-vinylbicyclo[2.2.1]hept-2-ene and tricyclo[5.2.1.0 2.6]deca-3,8-diene as prospective cathode materials for lithium cells

Catalytic copolymerization of sulfur with 5-vinylbicyclo[2.2.1]hept-2-ene or tricyclo[5.2.1.0 2.6 ]deca-3,8-diene (sulfur:diene ratio=20:1) at 170 v °C in bulk or decalin in the presence of 1,4-diazabicyclo[2.2.2]octane or N,N,N,N-tetramethylethylenediamine in combination with CoCl 2 - 6H 2 O or Cu(acac) 2 occurs at two dienic double bonds to form partially cross-linked copolymers stable up to 200 v °C (DSC/TGA). Preliminary evaluation of the specific discharge capacity of cathodes made using the above copolymers in model lithium button cells gives 670-970 and 300-330 v mA - h - g m 1 in the 1st and 50th cycles, respectively.