Shuttle Effect Of Polysulfides Research Articles

Single-Atom Cobalt Catalyst with Boron and Nitrogen Codoped Graphene (Co-BN-G) Enables Adsorption and Catalytic Conversion of Polysulfides for High-Performance Lithium-Sulfur Batteries.

In lithium-sulfur batteries, the shuttling effect and sluggish redox conversion of soluble polysulfides lead to unsatisfactory sulfur utilization and capacity retention. In this research, we used a one-pot hydrothermal method to prepare graphene with single-atom Co and B, N codoped as a sulfur host in Li-S batteries, thereby suppressing the shuttling effect and facilitating the redox conversion of lithium polysulfides (LiPSs). A series of characterizations demonstrated that dual doping of B and N introduces more lattice defects and structural deformations in graphene oxide, thus enhancing its adsorption of polysulfides. Simultaneously, single-atom cobalt can also polarize adsorption and accelerate the conversion reaction of LiPSs. The Li-S cell with the as-prepared Co-BN-G sulfur host materials exhibited an excellent capacity of 1034 mAh g-1 at 0.5 C and satisfactory cycle performance (retention of 69% over 500 cycles). Even at a rate of 2 C, a discharge capacity of 851 mAh g-1 is achieved. The results show that the Co-BN-G configuration efficiently captures LiPSs and enhances their rate conversion kinetics in redox reactions, demonstrating significant practical potential.

A 3D network-structured gel polymer electrolyte with soluble starch for enhanced quasi-solid-state lithium-sulfur batteries

The polysulfide shuttling effect and safety concerns associated with liquid electrolytes impede the commercialization of lithium-sulfur (Li-S) batteries. We report a novel gel polymer electrolyte (GPE) denoted as "PTPHS" prepared via facile ultraviolet polymerization of pentaerythritol tetrakis (3-mercaptopropionate) (PETT) and pentaerythritol tetraacrylate (PETEA) with poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the polymer matrix. Soluble starch (SST) is incorporated as an interacting filler to construct a 3D network structure with intermolecular hydrogen bonds. This unique architecture not only ensures high ionic conductivity and mechanical robustness but also effectively mitigates the polysulfide shuttling effect, thereby improving cycling stability. The PTPHS-based Li-S cell exhibits stable cycling over 150 cycles at 0.2 C with 87.6 % capacity retention. This strategy provides insights into material development and structural design of GPEs for high-performance quasi-solid-state Li-S batteries.

Multimodal X-Ray Measurements for Sulfur and Sulfide Related Electrochemical Energy Storage

Sulfur and sulfide are very promising candidates for electrochemical energy storage in electric vehicles and grid-scale storage due to their high theoretical capacity, low cost, and abundance. Although tremendous efforts have been devoted to sulfur and sulfide related batteries in recent years, they are still facing several challenges that need to be addressed before they can be widely adopted. Challenges including polysulfide shuttling effect in metal-sulfur batteries and electrochemical/interphase stabilities in sulfide solid-state electrolytes hindered their practical applications. Various techniques and strategies have been developed to address the above-mentioned challenges. However, revealing a next-level understanding of sulfur species interactions and speciation, using multimodal X-ray measurements to study the interaction temporally and spatially is still lacking. Here, we employed multimodal X-ray measurements including in situ sulfur K-edgeX-ray absorption spectroscopy, X-ray diffraction, and transmission X-ray microscopy to reveal electronic structure, crystal structure, morphology of sulfur species during battery cycling. Specifically, using operando sulfur K-edge X-ray absorption and X-ray diffraction, we obtained real-time and chemical information of sulfur species occurring at the sulfur cathode during lithium-sulfur battery operation. In the case of sulfide solid-state electrolytes, we explored the capacity loss mechanism in LiNi0.8Mn0.1Co0.1O2 cathodes when using argyrodite Li6PS5Cl sulfide solid electrolytes. Nickel K-edge X-ray absorption spectroscopy and transmission X-ray microscopy showed the cracking formation and heterogeneity in oxidation states for LiNi0.8Mn0.1Co0.1O2 cathodes using Li6PS5Cl solid-state electrolytes. In summary, we elucidated the dynamic changes in sulfur and provide insights on designing next-generation sulfur and sulfide related batteries.

Nickel-doped CNTs composite as cathode by sulfur vapor deposition for high-performance all-solid-state lithium‑sulfur batteries

Shuttle effect of polysulfide in the cathode and the safety issues arising from dendrite formation at Li metal anode are the main challenges of traditional liquid lithium‑sulfur batteries. In order to solve the shuttle effect and prevent short circuit, the all-solid-state lithium‑sulfur battery (ASSLSB) is proposed. However, the huge volume expansion of sulfur and the improvement of sulfur conversion efficiency during charge and discharge, which could lead to the limitation of electrochemical performance. Herein, a homogeneous Ni-doped carbon-nanotubes (H-Ni-SVD@CNT) composite cathode of ASSLSB is prepared by sulfur vapor deposition to confine sulfur and promote the conversion of sulfur and Li2S. In this work, SVD-5-S@CNT composite cathode demonstrates high reversible discharge capacity of 1001.1 mAh g−1 after 127 cycles and capacity retention rate of 78.6 % at the rate of 0.1C and 60 °C. Moreover, H-Ni-SVD@CNT composite cathode exhibits superior electrochemical performance, displaying the discharge specific capacity of 1519.3 mAh g−1 at 0.1C and 60 °C. Meanwhile, the discharge specific capacity of H-Ni-SVD@CNT composite cathode is 1060.9 mAh g−1 at room temperature. The synergistic effect of physical confinement and chemical catalysis improves the electrochemical performance of the all-solid-state lithium‑sulfur battery. This work proposes a new strategy for the cathode structure design of the all-solid-state lithium‑sulfur 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).

The Role of Transition Metal Versus Coordination Mode in Single-Atom Catalyst for Electrocatalytic Sulfur Reduction Reaction.

Electrocatalytic sulfur reduction reaction (SRR) is emerging as an effective strategy to combat the polysulfide shuttling effect, which remains a critical factor impeding the practical application of the Li-S battery. Single-atom catalyst (SAC), one of the most studied catalytic materials, has shown considerable potential in addressing the polysulfide shuttling effect in a Li-S battery. However, the role played by transition metal vs coordination mode in electrocatalytic SRR is trial-and-error, and the general understanding that guides the synthesis of the specific SAC with desired property remains elusive. Herein, we use first-principles calculations and machine learning to screen a comprehensive data set of graphene-based SACs with different transition metals, heteroatom doping, and coordination modes. The results reveal that the type of transition metal plays the decisive role in SAC for electrocatalytic SRR, rather than the coordination mode. Specifically, the 3d transition metals exhibit admirable electrocatalytic SRR activity for all of the coordination modes. Compared with the reported N3C1 and N4 coordinated graphene-based SACs covering 3d, 4d, and 5d transition metals, the proposed para-MnO2C2 and para-FeN2C2 possess significant advantages on the electrocatalytic SRR, including a considerably low overpotential down to 1 mV and reduced Li2S decomposition energy barrier, both suggesting an accelerated conversion process among the polysulfides. This study may clarify some understanding of the role played by transition metal vs coordination mode for SAC materials with specific structure and desired catalytic properties toward electrocatalytic SRR and beyond.

High-Entropy Alloy Electrocatalysts Bidirectionally Promote Lithium Polysulfide Conversions for Long-Cycle-Life Lithium-Sulfur Batteries.

High-entropy alloys (HEAs) have attracted considerable attention, owing to their exceptional characteristics and high configurational entropy. Recent findings demonstrated that incorporating HEAs into sulfur cathodes can alleviate the shuttling effect of lithium polysulfides (LiPSs) and accelerate their redox reactions. Herein, we synthesized nano Pt0.25Cu0.25Fe0.15Co0.15Ni0.2 HEAs on hollow carbons (HCs; denoted as HEA/HC) by a facile pyrolysis strategy. The HEA/HC nanostructures were further integrated into hypha carbon nanobelts (HCNBs). The solid-solution phase formed by the uniform mixture of the five metal elements, i.e., Pt0.25Cu0.25Fe0.15Co0.15Ni0.2 HEAs, gave rise to a strong interaction between neighboring atoms in different metals, resulting in their adsorption energy transformation across a wide, multipeak, and nearly continuous spectrum. Meanwhile, the HEAs exhibited numerous active sites on their surface, which is beneficial to catalyzing the cascade conversion of LiPSs. Combining density functional theory (DFT) calculations with detailed experimental investigations, the prepared HEAs bidirectionally catalyze the cascade reactions of LiPSs and boost their conversion reaction rates. S/HEA@HC/HCNB cathodes achieved a low 0.034% decay rate for 2000 cycles at 1.0 C. Notably, the S/HEA@HC/HCNB cathode delivered a high initial areal capacity of 10.2 mAh cm-2 with a sulfur loading of 9 mg cm-2 at 0.1 C. The assembled pouch cell exhibited a capacity of 1077.9 mAh g-1 at the first discharge at 0.1 C. The capacity declined to 71.3% after 43 cycles at 0.1 C. In this work, we propose to utilize HEAs as catalysts not only to improve the cycling stability of lithium-sulfur batteries, but also to promote HEAs in energy storage applications.

Flower-like covalent organic frameworks as host materials for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have emerged as a promising alternative energy storage system due to their high energy density and cost-effectiveness. However, practical applications of Li-S batteries are hindered by challenges such as the shuttle effect and sluggish redox kinetics. In this study, a three-dimensional (3D) flower-like diaminoanthraquinone (DAAQ)-covalent organic framework (COF) was developed, featuring nanorod-like petals and enriched with abundant N and O adsorption sites, serving as a host material for the sulfur cathode of Li-S batteries. Through a process of sulfur melting-diffusion, the resulting DAAQ-COF@S cathode material demonstrated a stable 3D cross-linked morphology with a hierarchical pore structure, maximizing the exposure of N/O adsorptive sites and facilitating rapid ion diffusion. This effectively inhibited the shuttling effect of lithium polysulfides (LiPSs) and enhanced rate performance. Consequently, DAAQ-COF@S cathodes exhibited a high initial discharge capacity of 1182.0 mAh g−1 at 0.1 C, with a capacity retention rate of 79.6% after 500 cycles at 2 C. Even at a high current density of 4 C, they maintained a high capacity of 616.8 mAh g−1, surpassing the majority of previously reported COF-based host materials for Li-S batteries. This work underscores the significance of COF micromorphology and advances the development of high-performance cathodes for Li-S batteries.

Configuring single-layer MXene nanosheet onto natural wood fiber via C–Ti–C covalent bonds for high-stability Li-S batteries

Lithium-sulfur batteries (LSBs) are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and cost-effectiveness. However, the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of LSBs. Herein, in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber (MX/PCWF) composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas diffusion. The unique architecture, wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls, ensures rapid polysulfide conversion and continuous electron transfer for redox reactions. The C–Ti–C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides, effectively suppressing the shuttle effect. An impressive capacity of 1301.1 mA h g−1 at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host, as evidenced by the capacity maintenance of 722.6 mA h g−1 after 500 cycles. Notably, the MX/PCWF/S cathode can still deliver a high capacity of 886.8 mA h g−1 at a high S loading of 5.6 mg cm−2. The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.

Establishing reaction networks in the 16-electron sulfur reduction reaction.

The sulfur reduction reaction (SRR) plays a central role in high-capacity lithium sulfur (Li-S) batteries. The SRR involves an intricate, 16-electron conversion process featuring multiple lithium polysulfide intermediates and reaction branches1-3. Establishing the complex reaction network is essential for rational tailoring of the SRR for improved Li-S batteries, but represents a daunting challenge4-6. Herein we systematically investigate the electrocatalytic SRR to decipher its network using the nitrogen, sulfur, dual-doped holey graphene framework as a model electrode to understand the role of electrocatalysts in acceleration of conversion kinetics. Combining cyclic voltammetry, in situ Raman spectroscopy and density functional theory calculations, we identify and directly profile the key intermediates (S8, Li2S8, Li2S6, Li2S4 and Li2S) at varying potentials and elucidate their conversion pathways. Li2S4 and Li2S6 were predominantly observed, in which Li2S4 represents the key electrochemical intermediate dictating the overall SRR kinetics. Li2S6, generated (consumed) through a comproportionation (disproportionation) reaction, does not directly participate in electrochemical reactions but significantly contributes to the polysulfide shuttling process. We found that the nitrogen, sulfur dual-doped holey graphene framework catalyst could help accelerate polysulfide conversion kinetics, leading to faster depletion of soluble lithium polysulfides at higher potential and hence mitigating the polysulfide shuttling effect and boosting output potential. These results highlight the electrocatalytic approach as a promising strategy for tackling the fundamental challenges regarding Li-S batteries.

Enhancing the electrochemical properties of a lithium-sulfur battery using a modified separator with a phase-inversion layer.

The commercial application of lithium-sulfur (Li-S) batteries is limited by the inherent defects of poor conductivity of sulfur and the shuttling effect of polysulfides. To overcome these limitations, a modified layer comprising a porous network PVDF-PMMA skeleton and Ketjen black (KB) carbon nanoparticles was coated on the polyethylene (PE) separator using the phase inversion method. The PVDF-PMMA-KB (PPK) composite layer with a structure abundant in mesopores can effectively limit the shuttling effect of polysulfides via a physical barrier and adsorption. Moreover, the utilization of active substances substantially increased as the KB carbon nanoparticles could provide additional reaction sites for activating inactive polysulfides and depositing lithium sulfide. The electrochemical properties of the Li-S battery were considerably enhanced using the modified separator with a PPK layer, which was reflected in the higher rate capability and longer cycling life. The cell with a modified separator delivered a specific capacity of 723 mA h g-1 at 1 C, and the capacity retention reached 73.3% after 400 cycles with a low decay rate of 0.223% per cycle. This work provides a novel preparation method for a modified layer on the separator and promotes the large-scale application of Li-S batteries.

Alleviating the Polysulfide Shuttle Effect by Optimization of 3D Flower-Shaped Vanadium Dioxide for Lithium-Sulfur Batteries

With the rapid development of portable devices and Energy Storage Systems (ESS), secondary batteries with high energy density and high capacity are in great demand. Among various candidates, Lithium-sulfur (Li-S) batteries have been considered for next-generation energy devices given their high theoretical capacity (1675 mAh g<sup>-1</sup>) and energy density (2500 Wh kg<sup>-1</sup>). However, the commercialization of Li-S batteries faces challenges due to sulfur’s low electrical conductivity and the shuttle effect, caused by the dissolution of lithium polysulfide intermediates in the electrolyte during the charge-discharge process. Herein, to resolve these problems, we report the fabrication of a vanadium dioxide (VO<sub>2</sub>) composite via a simple hydrothermal method and optimize the structure of VO<sub>2</sub> for constructing an effective Multi-Walled Carbon Nano Tube (MWCNT) and 3D flower-shaped VO<sub>2</sub> (MWCNT@VO<sub>2</sub>) binary sulfur host by a simple melt diffusion method. In particular, the polar VO<sub>2</sub> composite not only physically absorbs the soluble lithium polysulfides but also has strong chemical bonds with a higher affinity for lithium polysulfides, which act as a catalyst, enhancing electrochemical reversibility. Additionally, MWCNT improves sulfur’s poor electrical conductivity and buffers volume expansion during cycling. The designed S-MWCNT@VO<sub>2</sub> electrode also exhibits better capacity retention and cycling performance than a bare S-MWCNT electrode as a lithium polysulfide reservoir.

A Detailed Discourse on the Epistemology of Lithium‐Sulfur Batteries

AbstractThe architecture of lithium‐sulfur (Li‐S) batteries can hold five times more charge capacity compared to Li‐ion batteries. This review emphasizes the recent research findings on the desired loading of sulfur, the electrolyte‐to‐sulfur ratio, and a detailed view of the polysulfide shuttling effect. Problems with electrolyte stability are also discussed as well as the potential remedies they provided in various systems, as Li‐S batteries have great potential to surmount these critical issues by understanding the mechanism. Future scopes of Li‐S batteries can be progressively attained by optimizing the pore structure, designing highly conductive and strong sulfur confinement systems, and thereby pairing with anode materials to explore the possibility of innovative components for commercializing Li‐S batteries.

Heterostructures Regulating Lithium Polysulfides for Advanced Lithium-Sulfur Batteries.

Sluggish reaction kinetics and severe shuttling effect of lithium polysulfides seriously hinder the development of lithium-sulfur batteries. Heterostructures, due to unique properties, have congenital advantages that are difficult to be achieved by single-component materials in regulating lithium polysulfides by efficient catalysis and strong adsorption to solve the problems of poor reaction kinetics and serious shuttling effect of lithium-sulfur batteries. In this review, the principles of heterostructures expediting lithium polysulfides conversion and anchoring lithium polysulfides are detailedly analyzed, and the application of heterostructures as sulfur host, interlayer, and separator modifier to improve the performance of lithium-sulfur batteries is systematically reviewed. Finally, the problems that need to be solved in the future study and application of heterostructures in lithium-sulfur batteries are prospected. This review will provide a valuable reference for the development of heterostructures in advanced lithium-sulfur batteries.

Modification of interlayers with YCl3 for the suppression of shuttle effects in lithium-sulfur batteries

To reinforce the electrochemical properties of next-generation lithium-sulfur batteries (LSBs), modified interlayers emerge as a promising approach to suppress the polysulfide shuttling effect and improve cycle stability. This work presents a straightforward approach to produce a YCl3-doped carbonized cellulose paper (YCl3-CCP) as an interlayer, which has been demonstrated to significantly suppress the shuttle effect in LSBs. The synergistic effect of graphite and Y2O3 of the interlayer of YCl3-CCP can capture lithium polysulfides through strong absorption, thereby improving both cycle stability and coulombic efficiency. Herein, our results indicate that LSBs with interlayers of YCl3-CCP achieve a discharge capacity of 903 m Ah g−1 at 2 C, with a capacity retention of 77.3% over 500 cycles and an average capacity fading rate of 0.045% per cycle. Overall, this work provides a promising strategy for addressing the polysulfide shuttling effect in LSBs and opens up new avenues for further research in this area.

Sulfur-doped hollow C@CoP nanosphere modified separator for enhancing polysulfides anchoring and conversion in Li–S batteries

Lithium-sulfur (Li–S) battery with high theoretical energy density is recognized as a promising energy storage device, while its commercial applications are still hampered by the severe shuttling effect and sluggish kinetics of lithium polysulfides (LiPSs). Heteroatoms doping, which can adjust the electronic configuration and regulate the adsorption and catalytic properties, is realized as an effective strategy to solve the above problems. Herein, sulfur-doped CoP nanoparticles embedded in hollow carbon microspheres (C@S–CoP) is designed and employed as the modification material for separator. The introduction of sulfur atom into CoP leads to enhanced chemisorption for LiPSs and favorable conversion kinetics of sulfur species. In addition, the hollow porous structure of C@S–CoP is beneficial to the penetration of electrolyte and the alleviation of the sulfur species expansion during cycles. Theoretical calculation is further utilized to elucidate the enhanced mechanisms of S–CoP in Li–S chemistry at molecular level. The cell with C@S–CoP-separator delivers a superior rate performance of 761 mAh g−1 at 5C and excellent cyclability over 400 cycles at 2C with a low-capacity decay rate of 0.060%. This work furnishes a feasible strategy to boost the electrochemical performance and promotes the development of functional separators for highly efficient Li–S battery.

Rational construction of rich coordination-unsaturated Zr-BTB electrocatalyst towards advanced lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries show great potential to achieve high-density energy storage, but their commercial application is severely hindered by the notorious shuttling effect of lithium polysulfides (LiPS) and their sluggish conversion kinetics. Herein, we develop a Quasi Zr-based metal–organic frameworks with the tritopic carboxylate ligand 1,3,5-tris(4-carboxyphenyl)benzene (BTB) microflowers with cross-linked CNTs (Q-Zr-BTB@CNTs). The deficiency of Zr-O coordination at the Zr6 node is realized via a control of the deligandation behavior, which subtly modulates the local environment and electronic structure towards enhanced chemical affinity to polysulfides. Meanwhile, the interweave of the ultrathin Q-Zr-BTB nanosheets and CNTs establishes a porous and conductive network for fast charge transfer as well as a vast exposure of active interfaces. As a result, such a combination of defect engineering and architecture construction imposes strong sulfur adsorption and catalyzation, endowing the S/Q-Zr-BTB@CNTs cathode with a high initial capacity (1130 mAh g−1 at 0.2 C) and an excellent cycling stability (500 cycles at 1 C with 0.05% decay per cycle), as well as a decent electrochemical performance even under a high sulfur loading up to 12.7 mg cm−2. This study provides a novel strategy of designing unsaturated coordination centers to boost sulfur catalysis for high-performance lithium sulfur batteries.

Engineering single-atom catalysts as multifunctional polysulfide and lithium regulators toward kinetically accelerated and durable lithium-sulfur batteries

Developing electrocatalyst to ameliorate the shuttling effect of lithium polysulfides (LiPSs), sluggish sulfur redox reaction kinetics and the rampant dendrite growth is of paramount importance for lithium-sulfur (Li-S) batteries. Yet still, the utilization of the most mainstream traditional metal electrocatalytic nanoparticles is far below expectation. Herein, we engineer an exclusive single-atom catalyst with planar Co-N4 coupling of nitrogen-doped graphene mesh (SA-Co/NGM) to achieve exceptional atom utilization efficiency for catalytic conversion of LiPSs. High surface area and ultra-thin two-dimensional texture can not only accommodate high concentration monodispersed lithiophilic atomic Co sites, but also guarantee homogenize high-flux Li ion transport, alleviating the formation of Li-dendrites. Critically, the maximized exposure of Co-N4 as a regulator in sulfur electrochemistry can conspicuously suppress the shuttle effect and accelerate bidirectional sulfur redox kinetics via electron delocalization, as demonstrated by a judicious combination of electro-kinetic analysis, in situ spectroscopy and density functional theory (DFT) computations. As expected, the batteries based on a SA-Co/NGM modified separator achieve an ultrahigh rate capability, exceptionally long cycle life and a distinguished favorable areal capacity under high sulfur loading. This work provides a rational design of single-atom catalysts for kinetics-boosted electrocatalysis towards long-lasting Li-S batteries.

Nitrogen-doped hollow carbon@tin disulfide as a bipolar dynamic host for lithium-sulfur batteries with enhanced kinetics and cyclability

Lithium-sulfur batteries (LSBs) are promising next-generation electrochemical energy storage systems owing to high theoretical specific capacity (1675 mAh/g) and low cost. However, the shuttling effect of soluble polysulfides with slow conversion kinetics has deferred their commercial applications. The feasible design and synthesis of composite cathode hosts offer a promise solution to improving their electrochemical performances. In this work, tin disulfide (SnS2) nanosheets were anchored on nitrogen-doped hollow carbon with mesoporous shells, forming a bipolar dynamic host (“SnS2@NHCS”). It can efficiently confine the polysulfides and promote their conversion during (dis)charge. The as-assembled LSBs delivered a high capacity, superior rate and cyclability. This work presents a new view on the exploration of novel composite electrode materials for various rechargeable batteries with emerging applications.

Cobalt-loaded three-dimensional ordered Ta/N-doped TiO2 framework as conductive multi-functional host for lithium-sulfur battery

The low electrical conductivity of sulfur and severe shuttling effect of lithium polysulfides (LiPSs) have hindered the practical application of lithium-sulfur (Li-S) batteries. In this work, a conductive Ta/N co-doped TiO2 framework featured with three-dimensional ordered macroporous (3DOM) structure embedded with ZIF-67 derived Co-anchored N-doped carbon (Co-NC) is synthesized as efficient sulfur host material in Li-S batteries. The 3DOM Ta/N-TiO2 backbone has good structural stability, which benefits the electrolyte penetration and sulfur accommodation. Meanwhile, the Ta/N co-doping not only improves the conductivity of TiO2, but also strengthens the adsorption of LiPSs. In addition, the embedded Co-NC increases the active site of 3DOM skeleton towards LiPSs conversion, facilitates the diffusion of Li+ ion, and at the same time provides additional microspores for sulfur confinement. Attributed to these features, the sulfur electrode based on 3DOM Ta/N-TiO2@Co-NC achieves excellent electrochemical performance. The S/3DOM Ta/N-TiO2@Co-NC cell maintains a discharge capacity of 789.2 mAh g−1 after 500 cycles at 1C with a low decay rate of 0.06 % per cycle. Additionally, an initial area capacity of 5.67 mAh cm−2 is obtained under areal sulfur loading of 6.55 mg cm−2. This multistage porous sulfur cathode design has the potential to expedite the development of feasible Li-S battery.