Sulfur Host Research Articles

Facile construction of porous carbon fibers from coal pitch for Li-S batteries

Coal pitch, an important by-product in the coal coking industry with a high output, is a low-cost and high-carbon yield precursor for the manufacturing of high-value carbon materials. Herein, N/O co-doped carbon fiber (CFCP), fabricated by electrospinning using pre-oxidized coal pitch as the precursor, was employed as the sulfur host for Li-S batteries. The presence of more pyrrolic N and graphic N in CFCP than carbon fiber made from polyacrylonitrile benefits the adsorption of lithium polysulfide and the battery’s life. Sulphur-CFCP cathode (S@CFCP) exhibited excellent specific capacity and cyclability, with a specific capacity of 701.1 mAh/g and a low capacity decay rate of 0.088% per cycle over 200 cycles at 2.0 C, respectively. The high ion diffusion rate, low charge transfer resistance, and effective conversion of lithium polysulfides enable the high electrochemical performance of S@CFCP.

High-Entropy Metal Nitride Embedded in Concave Porous Carbon Enabling Polysulfide Conversion in Lithium-Sulfur Batteries.

The practical implementation of lithium-sulfur batteries is severely hindered by the rapid capacity fading due to the solubility of the intermediate lithium polysulfides (LiPSs) and the sluggish redox kinetics. Herein, high-entropy metal nitride nanocrystals (HEMN) embedded within nitrogen-doped concave porous carbon (N-CPC) polyhedra are rationally designed as a sulfur host via a facile zeolitic imidazolate framework (ZIF)-driven adsorption-nitridation process toward this challenge. The configuration of high-entropy with incorporated metal manganese (Mn) and chromium (Cr)will optimize the d-band center of active sites with more electrons occupied in antibonding orbitals, thus promoting the adsorption and catalytic conversion of LiPSs. While the concave porous carbon not only accommodates the volume change upon the cycling processes but also physically confines and exposes active sites for accelerated sulfur redox reactions. As a result, the resultant HEMN/N-CPC composites-based sulfur cathode can deliver a high specific capacity of 1274 mAh g-1 at 0.2C and a low capacity decay rate of 0.044% after 1000 cycles at 1C. Moreover, upon sulfur loading of 5.0mg cm-2, the areal capacity of 5.0mAhcm-2 can still be achieved. The present work may provide a new avenue for the design of high-performance cathodes in Li-S batteries.

In-situ chemical state transition of Ni nano-metal catalytic site promotes the reaction kinetics of lithium-sulfur battery

Researchers have extensively explored the implementation of metal-based catalysts to address the slow conversion kinetics of lithium polysulfides (LiPSs) in lithium-sulfur (Li-S) batteries. However, the elucidation of foundational aspects, such as the in-situ transformation processes of monometallic catalysts within the Li-S battery reaction milieu, as well as the chemical states of resultant catalytic active centers, remains elusive. In this study, a flexible material (CBC/Ni) was prepared, consisting of a carbonized bacterial cellulose framework uniformly loaded with nickel nanoparticles, serving as a sulfur host. Through in-situ XRD and in-situ Raman studies, it was demonstrated that the nanoscale Ni catalyst in the S@CBC/Ni electrode undergoes an interaction with LiPSs during the operation of Li-S batteries, transforming into the chemical state of NiS2 and subsequently acting as a new active center to promote the conversion of LiPSs in the subsequent cycling process. Due to these advantageous characteristics, the S@CBC/Ni cathode delivers a high-rate capacity of 798.7 mAh/g at 2C, with an average capacity decay rate of only 0.064% over 500 cycles. This work provides a theoretical reference for the in-situ chemical transformation and functionality of nanoscale metal catalysts in the Li-S system.

Atomically dispersed Co/Mn immobilized on O, N dual doped hollow carbon spheres as sulfur host for lithium sulfur batteries

The regulation of the chemical coordination environment in the electrocatalyst can effectively suppress the shuttle effect of sulfur species in lithium-sulfur batteries. However, the mechanism of the atomically dispersed dual metal atom with the coordination of various heteroatoms used as the sulfur cathode catalyst and trapper remains unknown. This study introduces, for the first time, atomically dispersed Co and Mn in-situ immobilized on O, N dual-doped hollow carbon spheres (SACoMn/C-(N, O)) as sulfur host. Experiments combined with density functional theory calculations reveal that the synergy between Co-(N, O) and Mn-(N, O) sites enhances the nucleation/deposition and decomposition capabilities of Li2S. This enhancement is attributed to the anchoring-coupling-conversion behavior of sulfur species on the SACoMn/C-(N, O) surface, which effectively restrains the shuttle effect and facilitates the conversion kinetics. Moreover, the cooperation of dual metal atoms with O, N non-metal atoms embedded in the carbon network structure accelerates electric transport and ion diffusion kinetics. The cathode demonstrates a high initial specific capacity of 890 mAh·g−1 at 1 C and show exceptional long-term cycling durability, with a low capacity degradation of 0.037 % per cycle after 1700 cycles. This research may offer novel insights into the design of dual metal atom-decorated, functionalized carbon materials to improve the conversion reaction in sulfur cathodes.

Marine waste derived carbon materials for use as sulfur hosts for Lithium-Sulfur batteries

Lithium–sulfur batteries are a promising alternative to lithium-ion batteries as they can potentially offer significantly increased capacities and energy densities. The ever-increasing global battery market demonstrates that there will be an ongoing demand for cost effective battery electrode materials. Materials derived from waste products can simultaneously address two of the greatest challenges of today, i.e., waste management and the requirement to develop sustainable materials. In this study, we detail the carbonisation of gelatin from blue shark and chitin from prawns, both of which are currently considered as waste biproducts of the seafood industry. The chemical and physical properties of the resulting carbons are compared through a correlation of results from structural characterisation techniques, including electron imaging, X-ray diffraction, Raman spectroscopy and nitrogen gas adsorption. We investigated the application of the resulting carbons as sulfur-hosting electrode materials for use in lithium–sulfur batteries. Through comprehensive electrochemical characterisation, we demonstrate that value added porous carbons, derived from marine waste are promising electrode materials for lithium–sulfur batteries. Both samples demonstrated impressive capacity retention when galvanostatically cycled at a rate of C/5 for 500 cycles. This study highlights the importance of looking towards waste products as sustainable feeds for battery material production.

Dynamically regulated redox shuttling and nucleation of lithium polysulfides through the built-in ferroelectric field

Sulfur is highly desired for energy storage devices by virtue of its high theoretical specific capacity and natural abundance. Yet the lithium-sulfur battery becomes practically unstable due to the migration of lithium polysulfides (LiPSs), which is the major challenge for its widespread application. Here, we demonstrate that the polysulfide redox shuttling can be kinetically buffered, which relies on a rational design of ferroelectric/carbon interfaces in a silica-based host structure. In situ TEM observation shows that a robust sulfur host is constructed by spatially embedding ferroelectric BaTiO3 nanodots within both the shell and bulk of a yolk-shell microsphere. During the electrochemical cycling process, the as-prepared composite material functions as a LiPSs pocket. It facilitates the reversible LiPSs conversion, giving rise to long-term stabilization of lithium-sulfur battery. This is due to the synergetic effect of the built-in polarization electric field and abundant LiPSs nucleation sites at internal ferroelectric/carbon interfaces. Furthermore, we show that the nucleation and growth of Li2Sn can be regulated by the designed polarization electric field in the yolk-shell structure. This study further highlights the potential of physical field towards high-performance lithium-slfur batteries.

Tube‐in‐Tube Structure Design and In‐situ Growth of Fe3C for Efficient Reaction Kinetics in Lithium‐Sulfur Batteries

AbstractTo improve the sulfur reaction kinetics and inhibit the notorious shuttle effects, a tube‐in‐tube structure decorated by carbon nanotubes (CNT) and Fe3C nanoparticles (TIT/Fe3C‐CNT) is designed as sulfur host for lithium‐sulfur batteries (LSBs) in this work. The construction of tube‐in‐tube structure increases the active sites and the specific surface area of the material. Additionally, Fe3C nanoparticles can effectively adsorb the soluble lithium polysulfides and promote their catalytic conversion, thus greatly alleviating the shuttle effects. As a result of these advantages, the TIT/Fe3C‐CNT‐based cathode exhibits a high reversible capacity of 841 mAh g−1 after 200 cycles with a low decay of 0.056 % per cycle at 0.5 C. This work provides a promising and reasonable approach to the rational design of sulfur host for LSBs.

Partially oxidized Ti3–yNbyC2Tx MXene nanosheets as efficient sulfur hosts and separator modification for Li–S batteries

Partially oxidized Ti3–yNbyC2Tx MXene nanosheets as efficient sulfur hosts and separator modification for Li–S batteries

Impeding polysulfide diffusion strategies in lithium-sulfur batteries using 3D porous carbon nanosheets integrated by cathode and functional separator

Lithium-sulfur(Li-S) batteries show high theoretical capacity and energy density compared to lithium-ion batteries(LIBs), which are one of the candidates for next-generation energy storage systems. However, rapid capacity fading caused by polysulfide shuttling effects remains critical issue for the commercial development in the Li-S batteries. Therefore, we aimed to derive 3D porous carbon nanosheets(C900) through the simple carbonization of organic salts as base materials for application as both sulfur host and functional separator. C900 had 3D vertically aligned and hierarchical carbon nanosheet structure with a high specific surface area and large pore volume, which was benefits for sulfur hosts because of the efficient electrolyte diffusion pathways and high mass loading of sulfur. Furthermore, nitrogen doped C900(NC900) can be improved chemical reactions with lithium polysulfides. Subsequently, an integrated electrode composed of a cathode with C900 and functional separator with NC900, respectively, was found to be highly efficient in restraining the shuttle effect via multimodal capturing effects. Consequently, all-integrated electrode composed of S-C900 and NC900@PP delivered a high initial specific capacity of 1453mAh·g-1 at 0.1C and achieved cycle stability with 64% capacity retention after 300cycles at 0.5C. This work suggests a potential carbon material design for bi-functional materials in a high-performance Li-S batteries.

Fe3O4-doped mesoporous carbon cathode with a plumber’s nightmare structure for high-performance Li-S batteries

Shuttling of lithium polysulfides and slow redox kinetics seriously limit the rate and cycling performance of lithium-sulfur batteries. In this study, Fe3O4-dopped carbon cubosomes with a plumber’s nightmare structure (SP-Fe3O4-C) are prepared as sulfur hosts to construct cathodes with high rate capability and long cycling life for Li-S batteries. Their three-dimensional continuous mesochannels and carbon frameworks, along with the uniformly distributed Fe3O4 particles, enable smooth mass/electron transport, strong polysulfides capture capability, and fast catalytic conversion of the sulfur species. Impressively, the SP-Fe3O4-C cathode exhibits top-level comprehensive performance, with high specific capacity (1303.4 mAh g−1 at 0.2 C), high rate capability (691.8 mAh gFe3O41 at 5 C), and long cycling life (over 1200 cycles). This study demonstrates a unique structure for high-performance Li-S batteries and opens a distinctive avenue for developing multifunctional electrode materials for next-generation energy storage devices.

Hollow Defect-Rich Nanofibers as Sulfur Hosts for Lithium-Sulfur Batteries.

The slow redox kinetics of lithium-sulfur batteries severely limit their application, and sulfur utilization can be effectively enhanced by designing different cathode sulfur host materials. Herein, we report the hollow porous nanofiber LaNi0.6Co0.4O3 as a bidirectional host material for lithium-sulfur batteries. After Co is substituted into LaNiO3, oxygen vacancies are generated to enhance the material conductivity and enrich the active sites of the material, and the electrochemical reaction rate can be further accelerated by the synergistic catalytic ability of Ni and Co elements in the B-site of the active site of LaNi0.6Co0.4O3. As illustrated by the kinetic test results, LaNi0.6Co0.4O3 effectively accelerated the interconversion of lithium polysulfides, and the nucleation of Li2S and the dissolution rate of Li2S were significantly enhanced, indicating that LaNi0.6Co0.4O3 accelerated the redox kinetics of the lithium-sulfur battery during the charging and discharging process. In the electrochemical performance test, the initial discharge specific capacity of S/LaNi0.6Co0.4O3 was 1140.4 mAh g-1 at 0.1 C, and it was able to release a discharge specific capacity of 584.2 mAh g-1 at a rate of 5 C. It also showed excellent cycling ability in the long cycle test, with a single-cycle capacity degradation rate of only 0.08%. Even under the harsh conditions of high loaded sulfur and low electrolyte dosage, S/LaNi0.6Co0.4O3 still delivers excellent specific capacity and excellent cycling capability. Therefore, this study provides an idea for the future development of bidirectional high-activity electrocatalysts for lithium-sulfur batteries.

Iron, cobalt co-embedded in situ graphitized xerogel-derived carbon as sulfur host for ultrahigh rate and high-performance lithium-sulfur batteries

Lithium‑sulfur battery (LSB) is an enticing technology because of its high specific capacity, potential energy density, and natural abundance of sulfur in the earth's crust. However, some notorious issues need to mitigate before commercialization. Here we report a novel and scalable iron, cobalt co-embedded resorcinol formaldehyde derived carbon framework as sulfur host for high-performance LSB. To further increase the specific surface area and porosity of carbon, polyvinyl alcohol (PVA) is used as a sacrificial polymer. One pot synthesis method is used for preparing the Fe, Co co-embedded PVA incorporated RF xerogel-derived carbon (FC-PRFC) framework. The first-principles calculations suggest the advantage of bimetallic doping in enhancing the binding energy and reducing the energy gap of the carbon host for polysulfide anchoring. The porous structure and higher specific area of FC-PRFC enable high sulfur loading in the composite and show excellent rate performance and cyclability, as suggested by detailed electrochemical analysis. Moreover, the FC-PRFC cathode host with a high areal sulfur loading of 4.2 mg cm−2 delivers a high initial discharge capacity of 1283 mAh g−1 at 0.1C. During long-cycling at a high current rate of 4C, it retains a capacity of 372 mAh g−1 after 400 charge-discharge cycles with a capacity retention of 73 %. This scalable, innovative, low-cost fabrication technique has the potential to pave the way for developing an outstanding xerogel-derived carbon framework for high-performance LSBs for commercial applications.

A Sustainable and Cost-Effective Nitrogen-Doped Three-Dimensional Porous Carbon for High-Performance Lithium-Sulfur Batteries.

Affordable clean energy is one of the major sustainable development goals that can transform our world. At present, researchers are working to develop cheap electrode materials to develop energy storage devices, the Lithium-sulfur (Li-S) battery is considered a promising energy storage device owing to its excellent theoretical specific capacity and energy density. Herein, utilizing the ramie degumming waste liquid as raw materials, after freeze-drying and high-temperature calcination, a sustainable and cost-effective three-dimensional (3D) porous nitrogen-doped ramie carbon (N-RC) was synthesized. The N-RC calcined at 800 °C (N-RC-800) shows a superior high specific surface area of 1491.85 m2 ⋅ g-1 and a notable high pore volume of 0.90 cm3 ⋅ g-1. When employed as a sulfur host, the S@N-RC-800 cathode illustrates excellent initial discharge capacity (1120.6 mAh ⋅ g-1) and maintains a reversible capacity of 625.4 mAh ⋅ g-1 after 500 cycles at 1 C. Simultaneously, the S@N-RC-800 cathode also shows excellent coulombic efficiency and ideal rate performance. Such exceptional electrochemical performance of S@N-RC-800 can be primarily attributable to N-RC's high specific surface area, high porosity, and abundant polar functional groups. This green and low-cost synthesis strategy offers a new avenue for harnessing the potential of waste biomass in the context of clean energy storage.

Accelerating the Rate-Determining Steps of Sulfur Conversion Reaction for Lithium-Sulfur Batteries Working at an Ultrawide Temperature Range.

Wide operation temperature is the crucial objective for an energy storage system that can be applied under harsh environmental conditions. For lithium-sulfur batteries, the "shuttle effect" of polysulfide intermediates will aggravate with the temperature increasing, while the reaction kinetics decreases sharply as the temperature decreasing. In particular, sulfur reaction mechanism at low temperatures seems to be quite different from that at room temperature. Here, through in situ Raman and electrochemical impedance spectroscopy studies, the newly emerged platform at cryogenic temperature corresponds to the reduction process of Li2S8 to Li2S4, which will be another rate-determining step of sulfur conversion reaction, in addition to the solid-phase conversion process of Li2S4 to Li2S2/Li2S at low temperatures. Porous bismuth vanadate (BiVO4) spheres are designed as sulfur host material, which achieve the rapid snap-transfer-catalytic process by shortening lithium-ion transport pathway and accelerating the targeted rate-determining steps. Such promoting effect greatly inhibits severe "shuttle effect" at high temperatures and simultaneously improves sulfur conversion efficiency in the cryogenic environment. The cell with the porous BiVO4 spheres as the host exhibits excellent rate capability and cycle performance under wide working temperatures.

Nitrogen-doped hollow carbon sphere composite Mn3O4 as an advanced host for lithium-sulfur battery

As the most promising advanced energy storage system, lithium-sulfur batteries (LSBs) are highly favored by the researchers because of their advantages of high energy density (2500 W h kg−1), low cost and non-pollution. However, the low conductivity, volume expansion of sulfur, and shuttle effect are still the great hindrance to the practical application of LSBs. Herein, the above problems can be addressed through the following strategies: (1) Hollow carbon microspheres with high specific surface area were constructed as sulfur hosts to increase sulfur loading while also being able to enhance the physical adsorption of polysulfides; (2) the loading of Mn3O4 particles on the basis of hollow carbon microspheres facilitates the capture and adsorption of polysulfides; (3) the hollow carbon sphere structure as a conductive network can provide more pathways for rapid electrical/ionic transport and also accelerate electrolyte wetting. Moreover, the thinner shell of hollow carbon microsphere is conducive to ion diffusion and speed up the reaction rate. Thus, the NHCS/Mn3O4/S composites exhibit a high discharge specific capacity of 1010.3 mAh g−1 at first and still maintained a reversible capacity of 269.2 mAh g−1 after 500 cycles. This work presents a facile sustainable and efficient synergistic strategy for the development of advanced LSBs.

CoN//Co9S8 co-embedded in reduced graphene oxide as catalyst for catalytic conversion of polysulfides

Lithium-sulfur (Li–S) batteries with high theoretical specific capacity of 1675 mAh g−1 and energy density of 2600 Wh kg−1 are considered as a promising candidate for energy conversion and storage devices in future. However, some critical dilemmas such as low real energy density, high solubility of ether-based electrolytes and slow redox kinetics of long-chain polysulfides remain unsettled hindering their development. Here we design and propose a high-performance sulfur host material constructed by growing CoN/Co9S8 nanoparticles enclosed in reduced graphene oxide (RGO) and Co9S8 modified separator to enhance the electrochemical performance of Li–S batteries. The results of first principal calculations confirm that the calculated adsorption energies of Li2S8, Li2S6, Li2S4 and Li2S2 on the Co9S8 (111) surface are lower than that of the CoN (111) surface, indicating that the Co9S8 has stronger adsorbing effect with polysulfides. Furthermore, the catalytic effect in Li2S6 symmetric batteries and the nucleation of the Li2S tests display that the CoN/Co9S8@RGO has a fast conversion reaction kinetics and catalytic effect of polysulfides, thereby inhibiting the leakage of the polysulfides. Consequently, the S@CoN/Co9S8@RGO cathode with Co9S8 layer represents a high discharge capacity of 1367.7 mAh g−1 at 0.1C and a prolonged lifespan over 700 cycles at 1 C with an extremely low decay rate of 0.06 % per cycle and high cycling stability.

Coupling interfacial effect in heterogeneous RuP2-RuP for accelerating sulfur reduction reaction of lithium sulfur batteries

The cathodic host for practical lithium sulfur (Li–S) batteries needs to meet numerous requirements, such as outstanding electron conductivity, desirable lithium polysulfide (LiPSs) adsorption ability, and efficient catalytic effect towards the redox of sulfur. Given the above considerations, an N, P, S tri-doped 3D interconnected porous carbon embedded with heterogeneous ruthenium phosphides (RuP2-RuP@NPSC) was constructed to serve as a sulfur host for high-performance and practical Li–S battery. Strong interfacial coupling effect in the RuP2-RuP heterojunctions endowed the active sites with favorable LiPSs adsorption ability and boosted sulfur reduction reaction. The density functional theory calculation suggested that the electronic tuning of the constructed heterojunction interface could enhance the electron transport and LiPSs adsorption ability. The higher current response of symmetric cells, larger Li2S deposition and dissolution capacity of RuP2-RuP@NPSC in comparison to other counterparts of RuP@NPSC, RuP2@NPSC, and NPSC further verified the great catalytic capability of RuP2-RuP heterojunctions. As a result, corresponding cells with RuP2-RuP@NPSC/S electrodes delivered an impressive reversible capacity of 565 mAh g−1 at 6 C, and an ultralow capacity decay rate of 0.019 % per cycle after 1000 cycles was achieved at the current of 2 C. The commercial level high sulfur loading pouch cells further confirmed the feasibility and practicability of RuP2-RuP@NPSC/S based Li–S battery

Synergistic Effect of In2O3/NC-Co3O4 Interface on Enhancing the Redox Conversion of Polysulfides for High-Performance Li-S Cathode Materials at Low Temperatures.

Lithium-sulfur (Li-S) batteries are considered as a promising energy storage technology due to their high energy density; however, the shuttling effect and sluggish redox kinetics of lithium polysulfides (LiPSs) severely deteriorate the electrochemical performance of Li-S batteries. Herein, we report a novel configuration wherein In2O3 and Co3O4 are incorporated into N-doped porous carbon as a sulfur host material (In2O3@NC-Co3O4) using metal-organic framework-based materials to synergistically tune the catalytic abilities of different metal oxides for different reaction stages of LiPSs, achieving a rapid redox conversion of LiPSs. In particular, the introduction of N-doped carbon improved the electron transport of the materials. The polar interface of In2O3 and Co3O4 anchors both long- and short-chain LiPSs and catalyzes long-chain and short-chain LiPSs, respectively, even at low temperatures. Consequently, the Li-S battery with In2O3@NC-Co3O4 cathode materials delivered an excellent discharge capacity of 1042.4 mAh g-1 at 1 C and a high capacity retention of 85.1% after 500 cycles. Impressively, the In2O3@NC-Co3O4 cathode displays superior performances at high current density and low temperature due to the enhanced redox kinetics, delivering 756 mAh g-1 at 2 C (room temperature) and 755 mAh g-1 at 0.1 C (-20 °C).

Carbonaceous Sulfur Host for Cathodes in Room-Temperature Metal–Sulfur Batteries

Carbonaceous Sulfur Host for Cathodes in Room-Temperature Metal–Sulfur Batteries

Entropy‐Driven Highly Chaotic MXene‐Based Heterostructures as an Efficient Sulfur Redox Electrocatalysts for Li‐S Battery

AbstractBoth the sluggish sulfur redox reaction (SRR) kinetics and lithium polysulfides (LiPSs) shuttle effect limit the practical application of Li‐S batteries. Designing heterostructure sulfur hosts has emerged as an effective way to address these two issues with one material. However, the principles of heterostructures reinforced Li‐S batteries remain inadequately understood. Here, it is demonstrated for the first time that increasing the entropy of heterostructure can promote its SRR catalytic activity and alleviate the LiPSs shuttling. By a simple solution‐based strategy, a highly chaotic MXene‐based heterostructure (HCMH, TiS2/TiN/TiO2/Ti3C2Tx) is fabricated. The smart integration of “high entropy”, heterostructure, and MXene endow the HCMH catalyst with significantly improved performance, demonstrated by a much smaller Tafel slope of 62.9 mV dec−1 and a higher electron transfer number of 7.10, compared with the moderately chaotic MXene‐based heterostructure (MCMH, TiO2/TiN/Ti3C2Tx) and MXene. DFT theoretical calculations reveal that introducing new phases lowers the Gibbs energy barriers of both rate‐limiting Li2S2/Li2S reduction and Li2S decomposition. Upon the addition of only 5 wt.% HCMH to the sulfur cathode, both the reversible capacity and rate capability of Li‐S cells are greatly improved, which further highlights the importance of the high entropy “cocktail effect” in the design of SRR electrocatalysts in the future.