Advanced Lithium Sulfur Batteries Research Articles

An Effective Polysulfide Trapping Strategy for the Development of a Scalable, High Energy Density Lithium-Sulfur Battery

Rechargeable lithium-sulfur (Li-S) batteries represent an attractive, “beyond Li-ion”, battery technology because they offer a high specific energy of 2,500 Wh/kg at the material level1 and 550 Wh/kg at the cell level.2 However, Li-S batteries face substantial technical challenges that have thus far prevented the realization of the battery’s tremendous performance potentials.3 One of the major technical challenges is low practical specific capacity and fast performance degradation due to the formation, migration, and shuttling of intermediate lithium polysulfides (PSs). Several strategies have been used to trap the PS species either chemically or physically; however, they either incur increased cost due to the use of expensive catalysts4 or suffer from the reduced battery specific energy due to added inactive weights from the cell design.5,6 We will present a novel strategy to address the PS-shuttle issue using a nanolayer polymer modified high surface area carbon (NPC) as a new type of PS-trapping material.7 When thin films of NPC were coated on sulfur electrodes (NPC-S), we found that our NPC-S based Li-S battery demonstrated a high discharge specific capacity (~1,600 mAh/g) that is nearing sulfur’s theoretical specific capacity. Our molecular dynamics simulation suggests such an excellent performance is attributed to NPC’s strong PS trapping capability via dipole-dipole interactions. We will show that, using a sustainable starting material, our approach is low-cost and economically scalable for the advanced Li-S battery technology. References Zhang, S. S., Journal of Power Sources 2013, 231, 153-162.Manthiram, A.; Fu, Y.; Su, Y.-S., Accounts of Chemical Research 2013, 46 (5), 1125-1134.Chen, Z. X.; Zhao, M.; Hou, L. P.; Zhang, X. Q.; Li, B. Q.; Huang, J. Q., Advanced Materials 2022, 2201555.Hamal, D.; Awadallah, O.; El-Zahab, B., Catalysis in Lithium-Sulfur Cathodes for Improved Performance and Stability. In 242nd The Electrochemical Society Meeting, Atlanta, GA, USA, 2022.Chung, S.-H.; Han, P.; Singhal, R.; Kalra, V.; Manthiram, A., Advanced Energy Materials 2015, 5 (18).Singhal, R.; Chung, S.-H.; Manthiram, A.; Kalra, V., Journal of Materials Chemistry A 2015, 3 (8), 4530-4538.Hasan, W.; Hyynh, K.; Razzaq, A.; Smdani, G.; Shende, R.; Paudel, T.; Xing, W., "Scalable, High Energy Density Lithium-Sulfur Batteries". In NASA Battery Workshop, November 15-17, 2022 , Huntsville, AL, USA, 2022. Acknowledgment This work was supported by the Larry and Linda Pearson Endowed Chair at the Department of Mechanical Engineering, South Dakoda School of Mines and Technology and by the South Dakota Governor’s Research Center for Electrochemical Energy Storage. Figure 1

Honeycomb-like porous carbon embedded ferrous sulfide nanoparticles as bifunctional separator modifier by forming sulfur bonds with polysulfides in advanced lithium-sulfur batteries

To develop practical and outstanding lithium-sulfur (Li-S) batteries, it is advisable to adsorb soluble polysulfides and catalyze insoluble Li2S2/Li2S. Herein, a ferrous sulfide decorated honeycomb-like porous carbon (FeS/HMPC) was synthesized by sulfuration strategy to act as a separator modifier in Li-S batteries. Owing to the positive migration of the Fe d-band center, the binding of FeS to polysulfides is dominated by the S bond (Fe-SLiPSs), which makes FeS have strong adsorption capacity for various types of polysulfides. Moreover, FeS shows the minimum energy path for the migration of typical polysulfide Li2S. In other words, it has the smallest diffusion barrier. Hence, the FeS/HMPC-PP not only realizes the efficient suppression of the shuttle effect but also catalyzes the redox reaction of polysulfides. Benefiting from the above advantages, the FeS/HMPC-PP based cells exhibit a high initial capacity of 1673 mAh g−1 at 0.2 C and a reversible capacity of 686.7 mAh g−1 at 3 C after 500 cycles. Moreover, the cell with a high sulfur loading of 2.4mg cm−2 demonstrates an ultra-low-capacity decay of 0.007% per cycle at 0.2 C. This work provides novel insights and promising candidates to act as a functional separator for Li-S batteries with long life and high-rate electrochemical performance.

Preparation of CoO-CoP-CNT heterogeneous materials for advanced lithium-sulfur battery cathode electrode

A one-dimensional linear material (CoO-CoP-CNT) was successfully prepared and studied as a sulfur-loaded material for the cathode. This heterostructure material exhibits a high specific surface area (115.29 m2 g−1) and rich active sites, which effectively suppress the volume expansion of sulfur and enhance the catalysis and adsorption of LiPS. As a result, it mitigates the shuttle effect of LiPS and improves the electrochemical performance of the battery. The initial discharge capacity of the battery employing the sulfur carrier was measured at 979.9 mAh g−1 at 0.2 C, and it demonstrated a capacity of 367.9 mAh g−1 after 200 cycles of charging and discharging. At 2 C, the initial discharge capacity of S/CoO-CoP-CNT reached 743.7 mAh g−1, with a capacity retention rate of 42.0% after 500 cycles. These findings indicate that the battery with S/CoO-CoP-CNT positive electrode exhibits superior electrochemical performance.

Multi-functions of amino thiophenol additives for shielding lithium metal anode in advanced Li-S battery

Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for the next generation of battery systems due to their high specific capacity and energy density. However, some barriers impede the application of Li-S batteries, such as the “shuttle effects” of lithium polysulfides (LPS), the poor electrical conductivity of sulfur, and lithium dendrite formation on lithium metal electrodes. Herein, we investigated a series of amino thiophenol as electrolyte additives: 2-amino thiophenol (2-ATP), 3-amino thiophenol (3-ATP), and 4-amino thiophenol (4-ATP); as well as p-phenylenediamine (PPD). These additives react with Li to form a stable and uniform solid electrolyte interphase (SEI) to protect the Li anode and minimize the interaction of Li with soluble LPS. Initial specific capacity at 0.1C and reversible specific capacity after 100 cycles are 1420 and 1043 mAh/g, 1429 and 982 mAh/g, 1148 and 871 mAh/g, 1317 and 791 mAh/g for 4-ATP, 3-ATP, 2-ATP, and PPD, respectively. Long-term cycling testing of Li-S cells was conducted at 0.2C and the cell with 4-ATP additives deliver an initial specific capacity of 1159 mAh/g and capacity retention of 77% after 300 cycles. The morphology and composition of the after-cycled SEI layers were examined by SEM and XPS. The findings suggest amino thiophenols (ATPs) form stable and smooth closed-packed SEI layers, that ameliorate lithium dendrite problems and LPS reactions with Li metal. 4-ATP is found to exhibit the best electrochemical performance followed by 3-ATP, 2-ATP, and PPD, which are in good agreement with the surface morphology. In addition, the amine group can assist the reaction between the thiol group and S8 on the cathode and modify the redox pathway of polysulfide.

Surface Engineering in Covalent Organic Polymers for High-Performance Li-S Batteries.

Lithium-sulfur (Li-S) batteries are promising energy storage technology due to their tempting high theoretical capacity and energy density. Nevertheless, the wastage of active materials that originates from the shuttling effect of polysulfides still hinders advancement of Li-S batteries. The effective design of cathode materials is extremely pivotal to solve this thorny problem. Herein, Surface engineering in covalent organic polymers (COPs) has been performed to investigate the influence of pore wall polarity on the performance of COP-based cathodes used for Li-S batteries. With the assistance of experimental investigation and theoretical calculations, performance improvement by increasing pore surface polarity and a synergy effect of the polarized functionalities, along with nano-confinement effect of the COPs, are disclosed, to which the improved performance of Li-S batteries including outstanding Coulombic efficiency (99.0%) and extremely low capacity decay (0.08% over 425 cycles at 1.0 C) is attributed. This work not only enlightens the designable synthesis and applications of covalent polymers as polar sulfur hosts with high utilization of active materials, but also provides a feasible guide for the design of effective cathode materials for future advanced Li-S batteries.

Cathode Kinetics Evaluation in Lean-Electrolyte Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries afford great promise on achieving practical high energy density beyond lithium-ion batteries. Lean-electrolyte conditions constitute the prerequisite for achieving high-energy-density Li-S batteries but inevitably deteriorates battery performances, especially the sulfur cathode kinetics. Herein, the polarizations of the sulfur cathode are systematically decoupled to identify the key kinetic limiting factor in lean-electrolyte Li-S batteries. Concretely, an electrochemical impedance spectroscopy combined galvanostatic intermittent titration technique method is developed to decouple the cathodic polarizations into activation, concentration, and ohmic parts. Therein, activation polarization during lithium sulfide nucleation emerges as the dominant polarization as the electrolyte-to-sulfur ratio (E/S ratio) decreases, and the sluggish interfacial charge transfer kinetics is identified as the main reason for degraded cell performances under lean-electrolyte conditions. Accordingly, a lithium bis(fluorosulfonyl)imide electrolyte is proposed to decrease activation polarization, and Li-S batteries adopting this electrolyte provide a discharge capacity of 985 mAh g-1 under a low E/S ratio of 4 μL mg-1 at 0.2 C. This work identifies the key kinetic limiting factor of lean-electrolyte Li-S batteries and provides guidance on designing rational promotion strategies to achieve advanced Li-S batteries.

Bidirectional Catalyst with Robust Lithiophilicity and Sulfiphilicity for Advanced Lithium–Sulfur Battery

AbstractThe application of lithium–sulfur batteries (LSBs) is immensely impeded by notorious shuttle effect, sluggish redox kinetics, and irregular Li2S deposition, which result in large polarization and rapid capacity decay. To obtain the LSBs with high energy density and fast reaction kinetics, herein, a heterostructure composed by nitrogen‐deficient graphitic carbon nitride (ND‐g‐C3N4) and MgNCN is fabricated via a magnesiothermic denitriding technology. Lithophilic C3N4 with abundant nitrogen‐deficient acts as a conductive framework, together with the sulfiphilic MgNCN, lithium‐polysulfides (LiPSs) can be effectively captured followed by a regulated Li2S nucleation. Furthermore, the oxidation conversion kinetics can be accelerated as well. As expected, the LSBs with catalytic MgNCN/ND‐g‐C3N4 as the interlayer exhibit remarkable electrochemical performance with a discharge capacity of 650 mAh g−1 at 4 C. Meanwhile, a low capacity decay of 0.008% per cycle can be reached at 1 C after 400 cycles. Even with a high areal sulfur loading of 5.1 mg cm−2, outstanding capacity retention can be achieved at 0.5 C (64.18%) and 1 C (90.46%). The presented strategy unlocks a new way for the LSBs design with highly efficient catalyst.

CoFe2O4@rGO as a Separator Coating for Advanced Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are hindered by the undesired shuttle effect and sluggish electrochemical conversion kinetics. Herein, a well‐designed CoFe2O4@reduced graphene oxide (CFO@rGO) composite is used to modify the separator to develop a multifunctional polysulfide barrier. Density functional theory (DFT) calculations confirm that highly electronegative oxygen ions in CFO tend to bond with transition metal (TM) ions at octahedral (Oh) sites, which induces the formation of FeS and CoS bonds between CFO and polysulfides. This indicates that CFO can effectively anchor polysulfides. Furthermore, the low Li2S decomposition energy barrier and Li+ diffusion energy barrier reveal that CFO can accelerate the redox reaction kinetics of sulfur species. Electronic structure calculations speculate that the low‐energy barrier can be attributed to the electron‐hopping phenomenon between TM ions of different valence states at Oh sites. Benefiting from these advantages, a CFO@rGO/PP separator demonstrates satisfactory cycling performance (0.087% capacity decay rate at 2C with 500 cycles) and superb rate performance (686 mAh g−1 at 5C). This work provides a valuable reference for future research on spinel‐type materials as electrocatalysts for Li–S batteries.

Enhancing Sulfur Redox Conversion of Active Iron Sites by Modulation of Electronic Density for Advanced Lithium-Sulfur Battery.

Despite lithium-sulfur (Li-S) batteries possessing ultrahigh energy density as great promising energy storage devices, the suppressing shuttle effect and improving sulfur redox reaction (SROR) are vital for their practical application. Developing high-activity electrocatalysts for enhancing the SROR kinetics is a major challenge for the application of Li-S batteries. Herein, single-molecule iron phthalocyanine species are anchored on the N and P dual-doped porous carbon nanosheets (Fe-NPPC) via axial Fe-N coordination to optimize the electronic structure of active centers. The Fe-NPPC can promote the catalytic conversion of polysulfides by modulation of the electronic density in active moieties, endowing the Li-S battery with a high reversible capacity of 1023 mAh g-1 at 1 C as well as an ultralow capacity decay of 0.035% per cycle over 1500 cycles. Even with a high sulfur loading of 7.1mg cm-2 , the Li-S battery delivers a high areal capacity of 4.8 mAh cm-2 after 150 cycles at 0.2 C. With further increasing the sulfur loading to 9.2mg cm-2 , an excellent areal capacity of up to 9.3 mAh cm-2 is obtained at 0.1 C.

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.

Nickel-embedded hierarchically-porous carbon microspheres as a multifunctional separator modifier for achieving advanced lithium-sulfur batteries

Lithium-sulfur batteries (LSBs), one of the most promising electrochemical energy storage systems, are in the spotlight due to their high theoretical energy density, alongside environmental friendliness and low cost of sulfur. Several unforgiving issues, however, hamper their commercial applications, such as the notorious shuttle effect of intermediary polysulfides and retarded redox kinetics, growth of dendritic Li, among other things. The crux of sorting out the problems above is designing a versatile material with good electrical conductivity, catalytic activity, together with abilities in suppression of polysulfide shuttling and Li dendrite growth. In this work, a composite of Ni nanoparticles embedded in the gradient-porous carbon microspheres (Ni/PCMS), acting like a miniature reactor, was fabricated as a separator modification material. Adequate electron conductivity can be guaranteed by the carbon substrate and the inlays of Ni nanoparticles. The physical/chemical adsorption and high Li+ transference number of Ni/PCMS assure suppressed shuttle effect and Li dendrite growth, respectively. Catalytic activity is fulfilled with the exposed Ni active sites. As a consequence, the batteries based on Ni/PCMS-modified separators achieve a high initial discharge capacity of 1426.7 mAh g−1 at 0.1 C and a low capacity fading rate of 0.078% per cycle over 800 cycles at 1 C. Even under a high sulfur mass loading of ∼ 3.0 mg cm−2, the battery still displays a superior rate performance of 555.6 mAh g−1 at 0.5 C. This work provides a thought for the rational design of a wide range of separator modifiers for high-performance Li-S batteries.

A two-in-one design realized by metal-organic framework nanosheets for dendrite-free and durable lithium-sulfur batteries

The overgrowth of dendrites and polysulfide shuttle are the most critical bottlenecks preventing the extensive application of lithium-sulfur (Li-S) batteries. In this work, we report a two-in-one design of a self-supporting anode and a modified separator based on metal-organic framework (MOF) Co-1,4-benzenedicarboxylate (Co-BDC) nanosheets for these challenges. On one aspect, the MOF-derivative Co-N-C nanosheets arrays supported on carbon cloth, which are obtained by the ammonia treatment of Co-MOF nanosheets, provide sufficient Li nucleation sites for avoiding dendrite growth and internal space for buffering the volume change during Li plating/stripping. On the other aspect, the MOF functionalized polypropylene separator effectively restrains the polysulfide shuttle through its adsorption and electrocatalytic effects towards polysulfide. As a result, the batteries with this MOF-based anode and separator exhibit an initial capacity of 630 mAh g−1 and an extraordinary cycle performance with an extremely low decay of 0.024 % over 1000 cycles at 5 C. Moreover, remarkable cycling stability and rate capability under enhanced sulfur loadings with reduced electrolyte content are also achieved. This study provides fresh insights into the material design for advanced Li-S batteries.

Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries

Commercial application of lithium-sulfur (Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray’s carbon nanostructure (N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray’s law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result, the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray’s law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

Functional Interlayer with Highly Dispersed Co1–XS Embedded in N-Doped Carbon Spheres as Trapping-Catalyst Nanoreactors for Advanced Lithium–Sulfur Batteries

Shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPSs) have become the bottleneck in lithium–sulfur (Li-S) batteries. Herein, hierarchically porous nitrogen-doped carbon spheres with highly dispersed Co1–XS nanoparticles (CoXS-NC) as a trapping-catalyst interlayer for high-performance Li-S batteries is proposed. The nitrogen-doped hierarchically porous carbon spheres generate high specific surface area and large pore volume which provide adequate sites for the adsorption of LiPSs and facilitate the good dispersion of Co1–XS nanoparticles. Nitrogen doping and Co1–XS modification improve the polarity, which promotes the adsorption and rapid conversion of LiPSs. The exceptional properties of the CoXS-NC interlayer are confirmed with an exceeding low delay rate of 0.031% per cycle after 1000 cycles at 0.5 C and an outstanding retention rate of 78.7% over 300 cycles at 2 C. Even employed with high sulfur loading of 6 mg cm–2, it also delivers a high initial areal capacity of 5.74 mAh cm–2 at 0.1 C with capacity retention of 4.58 mAh cm–2 after 100 cycles. This research opens up possibilities for the construction of multifunctional interlayers for use in commercial Li-S batteries.

Fabrication of tantalum carbide cathode by ball milling processes for advanced lithium–sulfur batteries

Fabrication of tantalum carbide cathode by ball milling processes for advanced lithium–sulfur batteries

Application of Inorganic Quantum Dots in Advanced Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have emerged as one of the most attractive alternatives for post-lithium-ion battery energy storage systems, owing to their ultrahigh theoretical energy density. However, the large-scale application of Li-S batteries remains enormously problematic because of the poor cycling life and safety problems, induced by the low conductivity , severe shuttling effect, poor reaction kinetics, and lithium dendrite formation. In recent studies, catalytic techniques are reported to promote the commercial application of Li-S batteries. Compared with the conventional catalytic sites on host materials, quantum dots (QDs) with ultrafine particle size (<10nm) can provide large accessible surface area and strong polarity to restrict the shuttling effect, excellent catalytic effect to enhance the kinetics of redox reactions, as well as abundant lithiophilic nucleation sites to regulate Li deposition. In this review, the intrinsic hurdles of S conversion and Li stripping/plating reactions are first summarized. More importantly, a comprehensive overview is provided of inorganic QDs, in improving the efficiency and stability of Li-S batteries, with the strategies including composition optimization, defect and morphological engineering, design of heterostructures, and so forth. Finally, the prospects and challenges of QDs in Li-S batteries are discussed.

High graphitized N-doping porous carbon combined with bifunctional separator for the synergistic adsorption/conversion of polysulfides in Li–S batteries

Inferior conductivity of sulfur and inevitable shuttle effect of polysulfides are major obstacle of commercial application for Li–S batteries. Balancing the relation between adsorption effect and polysulfides synchronous conversion on the surfaces of metal oxides is crucial. Herein, a combination strategy with graphitized porous carbon and bifunctional separator is proposed for the multiple suppression of shuttle effect by the synergistic adsorption and synchronous conversion of polysulfides. Silk cocoon derived in-situ N-doping porous carbon and nano-TiO2/Super P decorated bifunctional separator are prepared by simultaneous activation/carbonization and surface coating approach, respectively. The unique lamellar porous carbon and nano-TiO2 effectively encapsulate active sulfur and immobilize polysulfides by the physical/chemical synergetic adsorption. The density functional theory calculations effectively testify that TiO2 with exposed (101) plane shows high chemical affinity toward polysulfides. Especially the as-prepared porous carbon shows an ultrahigh degree of graphitization that enhances the electronic conductivity. The TiO2/Super P-coated conductive bifunctional separator not only accelerates the electron transmission but also synchronously facilitates the redox conversion of polysulfides adsorbed on the TiO2 surface. Benefiting from the above structure merits, the optimized battery delivers high initial discharge capacity of 1311 mAh g−1 at 0.2C and good cycling stability with a low capacity decay of 0.037% per cycle at 1.0C as well as excellent rate capacity of 977 mAh g−1 at 2.0C. Even with 4.2 mg cm−2, the discharge capacity of 697 mAh g−1 is still retained after 70 cycles at 0.1C. This combination strategy exploits a novel way for the design and preparation of advanced lithium-sulfur batteries.

Donor-Acceptor Conjugated Microporous Polymer toward Enhanced Redox Kinetics in Lithium-Sulfur Batteries.

Conjugated microporous polymers (CMPs) with porous structure and rich polar units are favorable for high-performance lithium-sulfur (Li-S) batteries. However, understanding the role of building blocks in polysulfide catalytic conversion is still limited. In this work, two triazine-based CMPs are constructed by electron-accepting triazine with electron-donating triphenylbenzene (CMP-B) or electron-accepting triphenyltriazine (CMP-T), which can grow on a conductive carbon nanotube (CNT) to serve as separator modifiers for Li-S batteries. CMP-B@CNT features faster ion transportation than the counterpart of CMP-T@CNT. More importantly, compared with acceptor-acceptor (A-A) CMP-T, donor-acceptor (D-A) CMP-B possesses a higher degree of conjugation and a narrower band gap, which are conducive to the electron transfer along the polymer skeleton, thus accelerating the sulfur redox kinetics. Consequently, the CMP-B@CNT functional separator endows Li-S cells with an outstanding initial capacity of 1371 mAh g-1 at 0.1 C and favorable cycling stability with a capacity degradation rate of 0.048% per cycle at 1 C for 800 cycles. This work provides insight into the rational design of efficient catalysts for advanced Li-S batteries.

Tubular NiCo2S4 hierarchical architectures as sulfur hosts for advanced rechargeable lithium sulfur batteries

Tubular nickel and cobalt bimetal sulfides NiCo2S4 hierarchical architectures were fabricated by a facile solvothermal method and investigated electrochemically as sulfur hosts for lithium sulfur batteries compared to bare sulfur. The results indicated that the single/double-walled tubular NiCo2S4 could be tuned to assemble the hierarchical architectures consisting of the nanoparticles, their electrochemical performances as sulfur hosts for lithium sulfur batteries are exhibited differently with respect to the host morphology and even compared to those of bare sulfur as well. Comparatively, the double-walled tubular NiCo2S4 hierarchical architecture as sulfur host for lithium sulfur batteries delivers a higher initial specific capacity of as high as 1078.9 mAh g−1, and exhibits better cyclability and rate capability, which might be ascribed to even dispersion of sulfur over the electrically conductive double-walled tubular NiCo2S4 hierarchical architecture, thus facilitating the full utilization of sulfur and the fast redox reaction kinetics of lithium polysulfides. In a word, bimetal sulfide NiCo2S4 are promising as sulfur host for the industrial implementation of lithium sulfur batteries, dependent of its optimization on morphology and structure.

Coordinating Interface Polymerization with Micelle Mediated Assembly Towards Two-Dimensional Mesoporous Carbon/CoNi for Advanced Lithium-Sulfur Battery.

Lithium-sulfur battery has attracted significant attention by virtues of their high theoretical energy density, natural abundance, and environmental friendliness. However, the notorious shuttle effect of polysulfides intermediates severely hinders its practical application. Herein, a novel 2D mesoporous N-doped carbon nanosheet with confined bimetallic CoNi nanoparticles sandwiched graphene (mNC-CoNi@rGO) is successfully fabricated through a coordinating interface polymerization and micelle mediated co-assembly strategy. mNC-CoNi@rGO serves as a robust host material that endows lithium-sulfur batteries with a high reversible capacity of 1115 mAh g-1 at 0.2 C after 100 cycles, superior rate capability, and excellent cycling stability with 679.2 mAh g-1 capacity retention over 700 cycles at 1 C. With sulfur contents of up to 5.0mg cm-2 , the area capacity remains to be 5.1 mAh cm-2 after 100 cycles at 0.2 C. The remarkable performance is further resolved via a series of experimental characterizations combined with density functional theory calculations. These results reveal that the ordered mesoporous N-doped carbon-encapsulated graphene framework acts as the ion/electron transport highway with excellent electrical conductivity, while bimetallic CoNi nanoparticles enhance the polysulfides adsorption and catalytic conversion that simultaneously accelerate the multiphase sulfur/polysulfides/sulfides conversion and inhibit the polysulfides shuttle.