CarbonâTungsten Disulfide Composite Bilayer Separator for High

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Letter

A carbon-tungsten disulfide composite bi-layer separator for high-performance lithium-sulfur batteries Shamshad Ali, Muhammad Waqas, Xiaopeng Jing, Ning Chen, Dongjiang Chen, Jie Xiong, and Weidong He ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b12682 • Publication Date (Web): 02 Nov 2018 Downloaded from http://pubs.acs.org on November 3, 2018

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ACS Applied Materials & Interfaces

A carbon-tungsten disulfide composite bi-layer separator for high-performance lithium-sulfur batteries Shamshad Alia,b, Muhammad Waqasa,c, Xiaopeng Jinga, Ning Chena, Dongjiang Chena, Jie Xiongb*, Weidong Hea,b* aSchool bState

of Physics, University of Electronic Science and Technology, Chengdu, Sichuan 611731, PR China. Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science

and Technology, Chengdu 611731, P.R. China. cDepartment of Electrical Engineering, Sukkur IBA University, Sukkur 65200, Pakistan. * Correspondence and request for materials should be addressed to [email protected] and [email protected]).

Abstract A bi-layer separator based on cost-effective carbon-tungsten disulfide composite and commercial separators is developed in this work. The C-WS2 separator reduces the shuttling effect and increases the cycle life of the battery owing to the excellent adsorption capability of polar WS2 to polysulfides. Furthermore, conductive carbon substantially enhances the ionic conductivity of (1 × 10-3 S cm-1). The cell with the CWS2 separator delivers an excellent discharge capacity of 996 mA h g-1 at 1 C and retained at 416 mA h g-1 after runs over 1000 cycles with a 0.045% capacity decay per cycle. The work provides insights into high-capacity lithium-sulfur batteries with costeffectiveness. KEYWORDS:

Lithium-sulfur

battery;

bi-layer

separator;

high-capacity;

effectiveness; carbon-tungsten disulfide composite; polysulfide adsorption;

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Significant research efforts have been focused on inexpensive and energy-efficient rechargeable batteries with long cycle life for potential applications in electric vehicles and smart grid systems. Lithium-sulfur (Li−S) batteries show great potentials in these applications owing to low cost, three to five-fold higher energy density as compared to Li-ion batteries and environment-friendliness1,2. The practical use of Li-S, however, has been impeded with a few serious issues. The poor conductivity of sulfur (5×10-28 S m-1) and its intermediate products lead to polarization, a large volumetric expansion (≈79 vol %) upon the formation of Li2S results in poor utilization of active material, and the dissolution of polysulfide discharge products in liquid electrolytes leads to shuttle effects3,4. To address these scientific problems, considerable efforts have been applied to the electrode, electrolyte, and separator design. Carbon-based host (hollow porous carbon5,6, graphene7–9,) improve the conductivity of sulfur in electrode and strategy with metal oxides10–12 and polar functional groups13–15 further increase the adsorption with LinSn species. Sulfur doped 3D graphene electrode structure16 and cobalt-nitrogen doped carbon structure17 enable high loading and suppress the shuttling effect. Generally, the separator is the significant part of the battery. Unfortunately, porous commercial separators are inefficient to block the polysulfides. Recently, modified separators with different materials, such as Super P18,19, CNTs20, PC21, graphene-oxide22, and graphene interlayers23, are introduced to reduce the shuttling effect. Zhang et al. introduce carbon nanofibers and MnO2 nanosheet composite into the separator, which improves electrochemical performances and efficiently suppresses polysulfide shuttling24. Separators with conductive frameworks have weak physical adsorption with Li2Sn due to


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nonpolar properties of carbon14, which lead to poor cycling performance. Zhang et al.25 suggested some materials with improved adsorption features which further improve the adsorption with carbon host. Here, we report a simple strategy by using a composite layer of conductive carbon, polar WS2 as polysulfide barrier, and PVDF-HFP as a binder with slurry coating method on Celgard separator at cathode side as shown in Figure S1a. The bi-layer C-WS2 separator significantly reduces the shuttling effect and results in high specific capacity. Tungsten disulfide is used for hydrodesulfurization in catalyst application to adsorb sulfur and sulfides26. When a C-WS2 polysulfide barrier is introduced to the lithiumsulfur batteries, polysulfides are confined to the cathode side and movement is inhibited to the anode side. Furthermore, with 70 wt% sulfur in cathode, cells with C-WS2 separator deliver ultra-high specific capacities of 916 mA h g-1 and 786 mA h g-1 at 2 C and 4 C, respectively. Besides, a low capacity decay of 0.045% per cycle after 1000 cycles at 1 C and 2 C, ensures the long life cycle of the Li-S battery. Figure S1b shows the photograph of C-WS2 separator coated with a thickness of 15µm towards the cathode. Figure S1c shows the good flexibility of the separator. The scanning electron microscopy (SEM) images of the C-WS2 separator, carbon coated separator, and Celgard separator are shown in Figures 1a-1d. The Celgard separator shows a highly porous structure and after coating two thin layers of carbon and tungsten disulfide composite, the Celgard separator is covered with interconnected nanoparticles, as shown in Figure 1a.



Figure 1. SEM images of (a) C-WS2 separator (surface), (b) C-WS2 separator (crosssection), (c) carbon-coated separator, and (d) Celgard separator. Cross section view of a bi-layer C-WS2 separator is shown in Figure 1b. BrunauerEmmett-Teller (BET) analyses present the pore size distribution of the separators. The N2 adsorption/desorption curves of the C-WS2 separator own type IV isotherms (Figures S2a-S2d). The total pore volume of the C-WS2 separator with dual coating is 0.108962 cm³/g, which effectively blocks the migrating polysulfides. Based on the measured weight of 5 coating separators, the estimated carbon coating with 0.395 mg cm-2 loading amount provides porous space for polysulfide dissolved in the electrolyte and 0.395 mg cm-2 loading amount of WS2 adsorbs these polysulfides at the cathode side. Figure 1c shows the SEM image of the conducting layer of carbon with the same mass loading as C- WS2 on Celgard separator. SEM images of C-WS2 and Celgard after cycling are shown in Figures S3a and S3b, showing that Celgard porosity is inhibited by polysulfide 4 ACS Paragon Plus Environment

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and diffusion of Li-ion is thus suppressed. C-WS2 interconnected particles capture polysulfide species inside the interspaces and efficiently facilitate the movement of Liion. Energy-dispersive X-ray spectroscopy (EDS) further confirms the elements on the surface of the C-WS2 separator before and after cycling. In Figures S4a and S4b, evenly distributed C, F, W, and S are seen, which is attributed to C-WS2 and PVDF-HFP binder. After cycling, the polysulfides are traped inside the C-WS2 matrix, as shown in Figure S4b. No agglomerates are seen and sulfur remains uniformly distributed during cycling. X-ray photoelectron spectroscopy (XPS) shows the chemical composition of the CWS2 separator. The main spectra of C-WS2 before and after cycling are shown in Figures S5a and S5b. The peak at 284.6 eV in the C1s spectrum is assigned to C-C single bond. In addition, two peaks at 287 eV and 290.8 eV are assigned to CF and CF2 of PVDF-HFP, as shown in Figures S5c and S5d. The W4f spectrum is shown in Figure 2a. The peaks at 33.1 eV and 35.2 eV are attributed to WS2 and a small peak at 38.6 eV is assigned to WO3. These values are consistent with the previous report15. As shown in Figure 2c, after cycling, two larger peaks at 35.9 eV and 38.2 eV appear, which are assigned to WO3 bondings with thiosulfate and thionate, probably generated from redox reaction of polysulfide and electrolyte during cycling.



Figure 2. XPS spectra of (a) W4f and (b) S2p before cycling, XPS spectra of (c) W4f and (d) S2p after cycling. Figure 2b shows the S2p spectrum before cycling. The doublet peaks at 162.8 eV and 163.9 eV are attributed to S2- in WS2. As shown in Figure 2d, after cycling two strong peaks at 167.3 eV and 169.2 eV appear, probably due to the bonding with polythionate and thiosulfate. The polythionate and thiosulfate act as mediator to bind polysulfide species and convert to lower-order polysulfides during discharge27. To evaluate the polysulfide adsorption performance of the C-WS2 separator, visual adsorption and UVvis spectroscopy tests are performed, as shown in Figures S6a-S6d. The C-WS2 separator shows the fast adsorption of polysulfides. The DFT simulation result shows that the adsorption binding energy between Li2S6 and WS2 is -0.40 eV, as shown in Figure S7. 6 ACS Paragon Plus Environment

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Ionic conductivities of the separators are shown in Figure S8a. The quantitative analysis reveals that ionic conductivities of the C-WS2 modified composite are (1 × 10-3 S cm-1), C-coated (9 × 10-4 S cm-1), and Celgard (5× 10-4 S cm-1) at 30 °C. Nyquist plots of the cell with C-WS2 soaked separator show lower values of bulk resistance, as shown in Figure S8b. Bulk resistances of C-coated and Celgard separators are higher than the CWS2, as shown in Figures S8c and S8d. Superior ionic conductivity is attributed to the sulfophilic sites of WS2 acting as Lewis base. Figures S8e and S8f show the stress-strain graph of C-coated and C-WS2 separators. The C-WS2 separator shows tensile strength of 70 MPa. Thermogravimetric analysis (TGA) further confirms the composition and weight loss of the separators. The C-WS2 separator shows the 50.5% of weight loss, as shown in Figure S9. The electrochemical impedance spectra (EIS) are shown in Figure 3a, with semicircles in higher frequency region attributed to the charge transfer resistance (Rct) and semicircles in middle-frequency region attributed to mass transfer resistance28. Before discharge, as shown in Figure 3a, charge transfer resistance and mass transfer resistance in C-WS2 are lower than those of carbon coated and Celgard separators. As shown in Figure S10a, after discharge two semicircles are observed in all separators due to the formation of polysulfides. The lower and depressed semicircles of charge transfer and mass transfer resistance in C-WS2 inhibit the formation of polysulfides. After the charge, reduced semicircle indicates electrolyte infiltration and reuse of dissolved sulfur, as shown in Figure S10b. These impedance results show that the C-WS2 conductive layer adsorbs the polysulfide, and the efficient transport of lithium ions and reuse of sulfur increase the capacity and cycle life of the Li-S battery. The values of charge transfer and 7 ACS Paragon Plus Environment


mass transfer resistances are shown in Table S1. Cv curves of different samples are shown in Figure 3b.

Figure 3. (a) Electrochemical impedance spectra before discharge using Celgard, Ccoated, and C-WS2 separators, (b) cyclic voltammogram curves for Li-S batteries with Celgard, C-coated, and C-WS2 separators with sulfur loading of 2.5 mg cm-2, and (c) specific discharge capacities of C-WS2 separator at 2 C (1.5 mg cm-2). Two reduction peaks and one oxidation peak are observed during the cathodic and anodic scan, respectively. The cathodic peak at 2.3 V confirms the conversion of sulfur into long-chain lithium polysulfides (Li2Sn, 4 ≤ n ≤ 8) and the peak at 2.0 V is assigned to the reduction of long-chain lithium polysulfides to short chain lithium sulfides (Li2S2/Li2S). The oxidation peak at 2.4 V is attributed to the oxidation of polysulfides to S8. The


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Celgard separator shows changed behavior due to the formation of polysulfide species. Figure 3c shows the long-term stability of the cell with C-WS2 separator, cycled at 2 C for 1000 cycles. An initial specific capacity of 916 mA h g-1 is observed, indicating good Li-ion transportation at a high rate. After 1000 cycles, the specific capacity of 430 mA h g-1 stabilizes with the capacity decay of 0.046% per cycle and an excellent Columbic efficiency of 98.5% is maintained. Figure S11 shows the cycling performances of cells with different C-to-WS2 ratios. Maximum capacity retention of 84% is realized with equal C-to-WS2 ratios. In addition, the thickness of separators impacts the important parameters of batteries, including the mechanical strength, impedance, energy, and power density29. The cycling performance of the Li-S battery, coated with different thicknesses of C-WS2 separators are shown in Figures S12a and S12b. The cell with 40 µm separator thickness owns high discharge capacity and stable cyclic performance.



Figure 4. (a) Specific discharge capacities of Li-S batteries with Celgard, C-coated, and C-WS2 separators at 1 C with sulfur loading of 1.5 mg cm-2 and (b) rate capabilities of LiS batteries with Celgard, C-coated, and C-WS2 separators with sulfur loading of 1.5 mg cm-2. The cycling performances of the Li-S battery based on Celgard, C-coated, and C-WS2 separators are further evaluated at 1 C (Figure 4a). The initial discharge capacity of the cell with Celgard separator is observed to be 300 mA h g-1 and drastically falls to 100 mA h g-1 after 500 cycles with a Columbic efficiency of 95 %. After the introduction of carbon coating layer, initial capacity is slightly improved from 800 to 319 mA h g-1 over 870 cycles. In contrast, the cell with C-WS2 separator delivers an initial capacity of 996 mA h g-1. The capacity is above 416 mA h g-1 after 1000 cycles with a Columbic efficiency of 98 % and a capacity fading of 0.045 % per cycle. The rate capabilities of the cells with C-WS2, C-coated, and Celgard separators are shown in Figure 4b. The rate 10 ACS Paragon Plus Environment

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capabilities decrease gradually as the current rates increase from 0.2 C to 4 C but the cell with C-WS2 separator exhibits excellent rate capability. C-WS2 delivers high discharge capacities of 1450 mA h g-1, 1141 mA h g-1, 996 mA h g-1, 896 mA h g-1, and 790 mA h g-1 at 0.2 C, 0.5 C, 1, 2 C, and 4 C, respectively. Moreover, the specific capacity of 1059 mA h g-1 is recovered after 30 cycles as different current rates turned back to 0.5 C and after 300 cycles a high specific capacity of 816 mA h g-1 is maintained. The higher capacity of C-WS2 is attributed to the higher ionic conductivity and adsorption properties of WS2 to polysulfide species. Figure S13a demonstrates the charge/discharge profiles of Li-S batteries with Celgard, C-coated, and C-WS2 separators at 1 C. Compared with the Celgard and C-coated separators, a higher discharge plateau of C-WS2 separator is observed at 2.3 V (conversion of S8 to soluble polysulfide) and a longer plateau at 2.0 V (conversion of polysulfide to solid Li2S2/Li2S) with corresponding charge plateaus at 2.17 V and 2.4 V (reduction of Li2S2/Li2S to soluble polysulfide and Sulfur).30 Furthermore, as shown in Figure S13b, for the cell with C-WS2 separator, a well-retained charge/discharge plateau is obtained even after cycled at a high current rate of 4 C, indicating stable reaction dynamics with the C-WS2 coating. The specific capacities of the batteries with the C-WS2 separators are further analyzed with higher sulfur loading, as shown in Figure S14. The cells with sulfur loadings of 2.5 mg cm-2, 3.5 mg cm-2, and 4.2 mg cm-2 deliver initial capacities of 743 mA h g-1, 650 mA h g-1, and 512 mA h g-1, respectively. After 200 cycles, capacities of 544 mA h g-1, 435 mA h g-1, and 305 mA h g1are

achieved.

In summary, a C-WS2 bi-layer composite separator has been prepared by a facile slurry coating method. Efficient C-WS2 polysulfide barrier enables the higher ionic 11 ACS Paragon Plus Environment


conductivity and reduces the interfacial resistance of the cell. When C-WS2 separator employed in Li-S cells, the sulfophilic sites inside C-WS2 polysulfide barrier efficiently trap polysulfides, enabling to high coulombic efficiency of 98.5%, and long cycle life. The initial capacity of 996 mAh g−1 is delivered with C-WS2 separator and maintained to above 416 mAh g−1 after 1000 cycles, with the capacity decay of 0.045% per cycle. Acknowledgments

The work was supported by the Fundamental Research Funds for the Chinese Central Universities (Grant No. ZYGX2015Z003) and the Science & Technology Support Funds of Sichuan Province (Grant No. 2016GZ0151).

Supporting Information

Experimental details, schematic illustration and photographs of the separators, N2 absorption-desorption isotherms, SEM images, EDS images, XPS images, visual adsorption test, DFT result, ionic conductivies, tensile strengt, TGA analysis, EIS spectras, cycling performences with different thicknesses, weight percentages and loadings, and summary of various parameters.

References: (1)

Ji, X.; Nazar, L. F. Advances in Li-S Batteries. J. Mater. Chem. 2010, 20 (44), 9821.

(2)

Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J. M. Li-O2 and Li-S Batteries with High Energy Storage. Nat. Mater. 2012, 11 (1), 19-29. 12 ACS Paragon Plus Environment

Page 12 of 16

Page 13 of 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(3)

Pang, Q.; Kundu, D.; Cuisinier, M.; Nazar, L. F. Surface-Enhanced Redox Chemistry of Polysulphides on a Metallic and Polar Host for Lithium-sulphur Batteries. Nat. Commun. 2014, 5, 4759.

(4)

Yin, Y. X.; Xin, S.; Guo, Y. G.; Wan, L. J. Lithium-sulfur Batteries: Electrochemistry, Materials, and Prospects. Angew. Chem., Int. Ed. 2013, 52 (50), 13186-13200.

(5)

Cheng, X. B.; Huang, J. Q.; Zhang, Q.; Peng, H. J.; Zhao, M. Q.; Wei, F. Aligned Carbon Nanotube/Sulfur Composite Cathodes with High Sulfur Content for Lithium-Sulfur Batteries. Nano Energy 2014, 4, 65-72.

(6)

Sun, Q.; He, B.; Zhang, X. Q.; Lu, A. H. Engineering of Hollow Core-Shell Interlinked Carbon Spheres for Highly Stable Lithium-Sulfur Batteries. ACS Nano 2015, 9 (8), 8504-8513.

(7)

Zhao, M. Q.; Zhang, Q.; Huang, J. Q.; Tian, G. L.; Nie, J. Q.; Peng, H. J.; Wei, F. Unstacked Double-Layer Templated Graphene for High-Rate Lithium-Sulphur Batteries. Nat. Commun. 2014, 5, 3410.

(8)

Zhou, G.; Paek, E.; Hwang, G. S.; Manthiram, A. Long-life Li/Polysulphide Batteries with High Sulphur Loading Enabled by Lightweight Three-Dimensional Nitrogen/Sulphur-Codoped Graphene Sponge. Nat. Commun. 2015, 6, 7760.

(9)

Qiu, Y.; Li, W.; Zhao, W.; Li, G.; Hou, Y.; Liu, M.; Zhou, L.; Ye, F.; Li, H.; Wei, Z.; et al. High-Rate, Ultralong Cycle-Life Lithium/Sulfur Batteries Enabled by Nitrogen-Doped Graphene. Nano Lett. 2014, 14 (8), 4821-4827.

(10)

Li, Z.; Zhang, J.; Lou, X. W. D. Hollow Carbon Nanofibers Filled with MnO2 Nanosheets as Efficient Sulfur Hosts for Lithium-Sulfur Batteries. Angew. Chem., Int. Ed. 2015, 54 (44), 12886-12890.

(11)

Liang, Z.; Zheng, G.; Li, W.; Seh, Z. W.; Yao, H.; Yan, K.; Kong, D.; Cui, Y. Sulfur Cathodes with Hydrogen Reduced Titanium Dioxide Inverse Opal Structure. ACS Nano 2014, 8 (5), 5249-5256.

(12)

Tao, X.; Wang, J.; Ying, Z.; Cai, Q.; Zheng, G.; Gan, Y.; Huang, H.; Xia, Y.; Liang, C.; Zhang, W.; et al. Strong Sulfur Binding with Conducting Magnéli-Phase TinO2n-1Nanomaterials for Improving Lithium-Sulfur Batteries. Nano Lett. 2014, 14 (9), 5288-5294.

(13)

Park, J.; Yu, B.; Park, J. S.; Choi, J. W.; Kim, C.; Sung, Y.; Goodenough, J. B. Tungsten Disulfide Catalysts Supported on a Carbon Cloth Interlayer for High Performance Li-S Battery. Adv. Energy Mater. 2017, 7 (11), 1602567.

(14)

Zheng, G.; Zhang, Q.; Cha, J. J.; Yang, Y.; Li, W.; Seh, Z. W.; Cui, Y. Amphiphilic Surface Modification of Hollow Carbon Nano fibers for Improved Cycle Life of Lithium Sulfur Batteries. Nano Lett. 2013, 13 (3), 1265-1270.

(15)

Lei, T.; Chen, W.; Huang, J.; Yan, C.; Sun, H.; Wang, C. Multi-Functional 13 ACS Paragon Plus Environment


Layered WS2 Nanosheets for Enhancing the Performance of Lithium-Sulfur Batteries. Adv. Energy Mater. 2016, 7 (4), 1601843. (16)

Li, N.; Gan, F.; Wang, P.; Chen, K.; Chen, S.; He, X. In Situ Synthesis of 3D Sulfur-Doped Graphene/Sulfur as a Cathode Material for Lithium-Sulfur Batteries. J. Alloys Compd. 2018, 754, 64-71.

(17)

Wang, P.; Zhang, Z.; Yan, X.; Xu, M.; Chen, Y.; Li, J.; Li, J.; Zhang, K.; Lai, Y. Pomegranate-Like Microclusters Organized by Ultrafine Co Nanoparticles@Nitrogen-Doped Carbon Subunits as Sulfur Hosts for Long-Life Lithium-Sulfur Batteries. J. Mater. Chem. A 2018, 6 (29), 14178-14187.

(18)

Yao, H.; Yan, K.; Li, W.; Zheng, G.; Kong, D.; Seh, Z. W.; Narasimhan, V. K.; Liang, Z.; Cui, Y. Improved Lithium-Sulfur Batteries with a Conductive Coating on the Separator to Prevent the Accumulation of Inactive S-related Species at the Cathode-Separator Interface. Energy Environ. Sci. 2014, 7 (10), 3381-3390.

(19)

Chung, S. H.; Manthiram, A. Bifunctional Separator with a Light-Weight CarbonCoating for Dynamically and Statically Stable Lithium-Sulfur Batteries. Adv. Funct. Mater. 2014, 24 (33), 5299-5306.

(20)

Chung, S. H.; Manthiram, A. High-Performance Li-S Batteries with an UltraLightweight MWCNT-Coated Separator. J. Phys. Chem. Lett. 2014, 5 (11), 19781983.

(21)

Su, Y. S.; Manthiram, A. Lithium-Sulphur Batteries with a Microporous Carbon paper as a Bifunctional Interlayer. Nat. Commun. 2012, 3, 1166.

(22)

Huang, J. Q.; Zhuang, T. Z.; Zhang, Q.; Peng, H. J.; Chen, C. M.; Wei, F. Permselective Graphene Oxide Membrane for Highly Stable and Anti-SelfDischarge Lithium-Sulfur Batteries. ACS Nano 2015, 9 (3), 3002-3011.

(23)

Li, F.; Zhou, G.; Pei, S.; Li, L.; Wang, D. W.; Wang, S.; Huang, K.; Yin, L. C.; Cheng, H. M. A Graphene-Pure-Sulfur Sandwich Structure for Ultrafast, LongLife Lithium-Sulfur Batteries. Adv. Mater. 2014, 26 (4), 625-631.

(24)

Lai, Y.; Wang, P.; Qin, F.; Xu, M.; Li, J.; Zhang, K.; Zhang, Z. A Carbon Nanofiber@Mesoporous δ-MnO2 Nanosheet-Coated Separator for HighPerformance Lithium-Sulfur Batteries. Energy Storage Materials 2017, 9 (932), 179-187.

(25)

Zhang, Q.; Wang, Y.; Seh, Z. W.; Fu, Z.; Zhang, R.; Cui, Y. Understanding the Anchoring Effect of Two-Dimensional Layered Materials for Lithium -Sulfur Batteries. Nano Lett. 2015, 15 (6), 3780-3786.

(26)

Fu, H. G.; Tuxen, A. K.; Moses, P. G.; Topsøe, H. Morphology and Atomic-Scale Structure of Single-Layer WS2 Nanoclusters. Phys. Chem. Chem. Phys. 2013, 15 (38), 15971-15980.

(27)

Liang, X.; Hart, C.; Pang, Q.; Garsuch, A.; Weiss, T.; Nazar, L. F. A Highly 14 ACS Paragon Plus Environment

Page 14 of 16

Page 15 of 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Efficient Polysulfide Mediator for Lithium-Sulfur Batteries. Nat. Commun. 2015, 6, 1-8. (28)

Yuan, L.; Qiu, X.; Chen, L.; Zhu, W. New Insight into the Discharge Process of Sulfur Cathode by Electrochemical Impedance Spectroscopy. J. Power Sources 2009, 189 (1), 127-132.

(29)

Ali, S.; Tan, C.; Waqas, M.; Lv, W.; Wei, Z.; Wu, S.; Boateng, B.; Liu, J.; Ahmed, J.; Xiong, J.; et al. Highly Efficient PVDF-HFP/Colloidal Alumina Composite Separator for High-Temperature Lithium-Ion Batteries. Adv. Mater. Interfaces 2018, 5 (5), 1-10.

(30)

Manthiram, A.; Fu, Y.; Chung, S.; Zu, C.; Su, Y. Rechargeable Lithium -Sulfur Batteries. Chem. Rev. 2014, 114 (23), 11751-11787.



Table of Contents

C-WS2 bi-layer composite separator is prepared with a facile slurry coating method. The C-WS2 separator reduces the shuttling effect owing to the excellent adsorption capability to polysulfides and improves the conductivity of the battery. The cells with CWS2 separator own high specific capacity, high Columbic efficiency and long cycle life.


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CarbonâTungsten Disulfide Composite Bilayer Separator for High

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