Improved Cycling Performance of Lithium-Sulfur Cell Through

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C: Energy Conversion and Storage; Energy and Charge Transport

Improved Cycling Performance of LithiumSulfur Cell Through Supramolecular Interactions Shruti Suriyakumar, Kanagaraj Madasamy, Murugavel Kathiresan, Mohamed H. Alkordi, and Manuel Arul Stephan J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.8b08785 • Publication Date (Web): 22 Oct 2018 Downloaded from http://pubs.acs.org on October 23, 2018

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The Journal of Physical Chemistry

Improved Cycling Performance of Lithium-Sulfur Cell Through Supramolecular Interactions Shruti Suriyakumara, c Kanagaraj Madasamya, Murugavel Kathiresana, Mohamed H. Alkordi,*b and A. Manuel Stephan* a, c a

CSIR- Central Electrochemical Research Institute, Karaikudi 630 003, India

b

Center for Materials Science, Zewail City of Science and Technology, October Gardens, 6th of October, 12578 Giza, Egypt. c

Academy of Scientific and Innovative Research (AcSIR), CSIR-CECRI campus, Karaikudi 630 003, India *Corresponding authors Tel: +91 4565 241426 e-mail: [email protected] [email protected]

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Abstract The commercialization of lithium-sulfur batteries is plagued by the poor electronic conductivity of elemental sulfur, shuttling of polysulfide and poor interfacial properties of lithium metal anode with non-aqueous electrolytes. Although numerous attempts have been made to alleviate such challenges, trapping of polysulfides within sulfur composite cathode appears as an efficient way to improve the cycling performance of Li-S cells. In the present work, naphthyl viologen was successfully synthesized and incorporated in a sulfur cathode in order to enhance the electrochemical performance of Li-S cell. Charge-discharge studies revealed that the viologen-added Li-S cell delivered higher discharge capacity than the unladen one. The enhanced performance of viologen laden sulphur cathode was attributed to the electrostatic interaction between polysulfide and viologen which was further substantiated by UV-Vis spectroscopy.

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Introduction In the last two decades, miniaturization of electronic gadgets, propulsion of electric vehicles and the urgent need for large-scale storage of sustainable energy (load-levelling applications) have stimulated interest in the development of novel rechargeable batteries and supercapacitors.1,2 Despite the wide implementation of the state-of-the-art lithium-ion batteries to power portable electronic devices, certain drawbacks of currently deployed technology including high cost and poor safety remain as daunting challenges.3 Lithiumsulfur batteries demonstrate several appealing properties including high theoretical specific capacity (1672 mAh g-1) and energy density (2600 Wh kg-1), low cost, lower environmental footprint, and better safety, thus identifying lithium-sulfur batteries as ultimate power source for hybrid electric vehicles and large-scale storage.4 The manufacturers such as OXIS Energy, PolyPlus and Sion Power announced commercialization of rechargeable Li-S battery in a near future. OXIS Energy claim to launch 500Wh kg-1 Li-S cells by 2019. On the other hand, PloyPlus are introducing their proprietary glass-protected lithium-metal batteries featuring a solid-state lithium anode laminate that doubles the energy density of current rechargeable batteries. Sion Power uses Licerion lithium metal technology, which claims to deliver the highest combination of energy density and specific energy available. However their application in electronic devices and hybrid electric vehicles is yet to be realized. Unfortunately, the low electronic conductivity of elemental sulfur (2 x10-30 S cm-1 at 30 °C), formation

and

subsequent

shuttling

of

polysulfides,

hampered

the

wide-scale

commercialization of this system.5 As potential solution to the poor conductivity of elemental sulfur,novel

composites

encompassing

sulfur

through

wrapping

or

encapsulating

carbonaceous materials such as carbon nanotubes, graphene,etchas been reported.6 Elemental sulfur has a density of 2.03 g cm-3 while Li2S is 1.66 g cm-3 this in turn leads to the volume expansion of approximately 80%.7 This volume change leads to the pulverization of sulfur

3



particles and deteriorates the capacity of Li-S batteries eventually. Additionally, the parasitic process in which long polysulfide chains are converted in to short polysulfide chains, and vice versa has led to unfavourable shuttling processes. This phenomenon decreases the availability of active mass utilization and remarkably reduces the Coulombic efficiency.8 In order to address these challenges, rational design of electrode structure is essential. Trapping of polysulfides by the incorporation of solid additives within the composite sulfur cathode has been identified as an effective way. Attempts have also been made to confine the polysulfides within the composite cathode materials by the incorporation of inorganic materials such as NiFe2O4, MgAl2O4,9,10 metal-organic frameworks (MOFs),11,12 and sandwiching permselective membranes between sulfur composite cathode and lithium metal anode.13–15 Very recently, viologens find potential applications in the area of electrochemical energy conversion and storage devices such as lithium-ion and redox flow batteries.16–18 John Owen and his co-workers have illustrated the redox activity of ethyl viologen in lithium air batteries.19,20 So far, and to the best of our knowledge, no attempt has been made to confine polysulfides in Li-S batteries through supramolecular interactions. Therefore, in the present work, naphthyl viologen (NV) was synthesized and employed as a solid additive in the composite sulfur cathode in order to confine polysulfides. The electrochemical and chargedischarge studies of Li-S cells with and without viologen have been made systematically and are reported. EXPERIMENTAL SECTION Materials All starting materials and solvents were of highest grade used (Sigma-Aldrich, USA) or Alfa Aesar, USA) without further purification. All reactions were performed under dry conditions unless otherwise mentioned. Synthesis of compound NV.2Cl: 4


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4,4’-Bipyridine (1g, 6.40 mmol) and 1-chloromethyl naphthalene (4.52 g, 25.60 mmol) were dissolved in 15 ml dimethylformamide and the reaction mixture was stirred at 80 ○C for 48 h. The progress of the reaction was monitored by thin-layer chromatography. After completion of the reaction, the reaction mixture was diluted with acetone (200 mL), and the resulting precipitate was washed subsequently with acetone and dried to yield the NV.2Cl─ as a yellow solid as illustrated in Figure 1. In order to confirm the formation of the compound, 1H and 13

C NMR and DEPT analyses were carried out and the results are given as supplementary

information S1-S3.

Figure 1: Synthesis of NV.2Cl─. Li–S cell assembly and electrochemical characterizations NV-graphene- sulfur (NV-G-S) composite was obtained by simple mixing of elemental sulphur, NV and graphene in the weight ratio of 85:10:05 for 30 min. The resultant composite material was heated at 155 °C in an argon atmosphere for 90 min to impregnate sulfur into the graphene and NV mixture. In order to comprehend the role of NV, a composite cathode composed of graphene and sulfur (NV-free) was also prepared in a similar way with 85% sulfur content. The composite sulfur cathode for cycling studies were prepared by doctor blade-coating a slurry comprising 72 wt% of prepared sulfur composite, 12 wt% of poly(vinylidene fluoride) and 16 wt% of SuperP carbon dispersed in N-methyl-2-pyrrolidone on an aluminium foil, and was dried at 100 °C in an air oven. The cyclic voltammetry (CV) curves were recorded (Solartron, UK) at a scan rate of 0.1 mV s−1 between 3 and 1.6 V. The 2032-type coin cells were assembled with sulfur+graphene and sulfur+graphene+ viologens 5



electrodes with areal sulfur loading of 0.5 mg.cm-2 and 0.46 mg.cm-2 and lithium metal foil (Foote Minerals) with 0.25 mL electrolyte composed of 1 M LiN(CF3SO2)2 and 0.05M LiNO3 in a 1: 1 (v/v) mixtureof 1,3-dioxalane and dimethyl ether in an argon-filled glove box (M Braun, Germany). This amount was found to be optimal for charge–discharge studies. In addition, the sulfur to electrolyte ratio was also found to be 0.51 molL-1. Further, increase led to leakage of electrolyte after crimping and subsequently spoils the cell. Galvanostatic charge–discharge profiles were made between 3 V and 1.6 V by a computer-controlled battery testing unit (Arbin, USA) as reported earlier.21 The electrochemical impedance spectroscopy (EIS) measurements of Li-S cells were carried out (Biologic, France) before and after cycling between 50 m Hz and 1 MHz. The values of Rct, and Re were calculated by employing Electrochemical Z fit tool in Biologic software. The XPS analysis (Thermo Scientific Model: ESCA 250 Xi) for the NV viologen added cathode was made after 25 cycles between 100 and 600 eV. The spectra were referenced utilizing the C 1s line at 284.8 eV, TEM and SAED pattern of the composite cathode before and after cycling was obtained (Tecnai 20 G2 (FEI make)).

Results and Discussions In order to understand the redox reaction in the Li–S cells the cyclic voltammograms were performed at 0.1 mV s-1 at 25 oC. Figure 2 (a and b) illustrates the cyclic voltammograms of Li-S cells without and with viologen, respectively. It is clear from Figure 2a that in the redox pair, cathodic peak at 2.3 V and anodic peak that appeared at 2.38 V can be ascribed to the transformation of S8 molecules and Li2S8. The cathodic and anodic peaks observed at 2.04 and 2.3 V can be assigned to the transformation between soluble Li2Sn(4≤ n ≤ 8) and insoluble Li2S2 or Li2S. In the subsequent cycles, the oxidation peaks were shifted toward more positive potentials which is attributed to the polarization of electrode.22 Further cycling 6


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did not result in any discernible changes in the peak potential or peak area implying good reversibility and capacity retention of the system.23 Comparing the 5th cycle of CVs for the Li-S cell containing elemental S and graphene (viologen-free, Fig 2a), to the viologen added (Fig. 2b), it is apparent that the cell containing NV demonstrated less anodic shift of the oxidation peaks. This important observation can be ascribed to less polarization of the viologen-added electrode. This observation indicated that the added viologen plays a key role in preventing the shuttling of polysulfides during cycling. The 1st and 50th charge discharge profiles of Li-S cell with and without viologen are depicted in Figure 2 c and d respectively. The Li-S cell containing the viologen delivered an initial discharge capacity of 1150 mAh g−1 during its first cycle, appreciably more than the discharge capacity (820 mAh g−1) of the Li–S cell without viologen (Fig 2d). The viologenadded cathode delivered a specific discharge capacity of 1150 mAh g−1 which approached 85% of the theoretical specific capacity of sulfur with a corresponding Coulombic efficiency of 90% (Figure 2e). Also of importance that the viologen-added Li-S offered a stable cycling, i.e., a lesser capacity fade per cycle, when compared to the Li-S cell without viologen.

7



Figure 2. Cyclic voltammograms of Li-S cell (a) without viologen (b) with viologen. Charge-discharge profiles of Li-S cell (c) without viologen (d) with viologen. (e) Discharge capacity vs. cycle number of Li-S cell with and without viologen. 8


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Generally, elemental sulfur exhibits a rapid decrease in discharge capacity with a corresponding Coulombic efficiency of 75% and is attributed tothe low utilization and insulating nature of sulfur and volumeexpansion that arises due to the pulverization of sulfur and the high solubility of lithium polysulfides.24 In the present work, viologen-laden Li-S cell offers higher discharge capacity and Coulombic efficiency which is attributed to the confinement of polysulfides due its electrostatic interaction as demonstrated in the scheme 1. The polarization gap for the first cycle is 0.22 V and 0.28 V respectively for the Li-S cell with and without viologen at the first cycle. The polarization growth might be due to the formation of the passivation ﬁlm on the surface of lithium-metal anode, implying the dissolved long-chain Li2S4-8 could still pass through the blocking carbon layer gradually and migrate to the anode side in the subsequent cycles. In the present work, the difference in voltage hysteresis between the 1st and 50th cycle of the viologen-free and viologen-added cathode is 0.06 and 0.05 V respectively. The negligibly reduced voltage hysteresis indicates the improved stability of the viologen incorporated sulfur cathode.

9



Scheme 1. Graphical representation of the constructed composite cathode illustrating the potential electrostatic interaction(s) of NV and the sulfide species.

Figure 3. TEM image of (a-c) elemental sulfur+ graphene+ naphthyl viologen electrode (before cycling), (d-f) elemental sulfur+ graphene + naphthyl viologen electrode (after cycling). Table 1. ‘d’spacing and hkl values of SAED pattern obtained from Figure 3(c) Table 2. ‘d’spacing and hkl values of SAED pattern obtained from Figure 3(f) d (nm)

hkl

0.343

026

0.241

317

0.210

062

Table 1. ‘d’spacing and hkl values of SAED pattern obtained from Figure 3(c) d (nm)

hkl

0.338

111

0.205

220

0.121

420

10


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Table 2. ‘d’spacing and hkl values of SAED pattern obtained from Figure 3(f)

In order to validate the confinement of polysulfide by added viologen in the composite cathode transmission electron microscopic analysis (TEM) was employed. The cycled 2032type coin cell was dismantled very carefully in an argon-filled glove box without any contamination for TEM and XPS analyses. Figure 3 (a-c) depicts the TEM image and electron diffraction analysis of the slice obtained from the viologen – added sulfur composite electrode before cycling. The corresponding d and hkl values are presented as Table 1. As seen in the TEM image of the viologen–added sulfur electrode (Figure 3 a) the sulfur particles are more or less uniformly dispersed in the graphene layer. The magnified electron diffraction area shows (Figure 3 b and c) the interplanar distances of a face-centered orthorhombic alpha-S8 with h k l Miller indices which are in accordance with PDF no: 01089-2600. The TEM image and SAED pattern analysis of viologen-laden composite cathode after 50 cycles are displayed in Figure 3 (d-f). The corresponding values of interplanar distance ‘d’ and hkl which correspond to trapped Li2S are given as Table 2. According to Aurbach and his co-workers the cycled sulfur electrodes generally develop a typical granular structure in which the carbon particles are surrounded by sulfur compounds.25 The authors also demonstrated upon cycling the surface of elemental sulfur in the composite electrode are covered by layers of reduced particles such as Li2S and Li2S2 etc. which are insulating in nature. However these insulating particles do not prevent the sulfur from further reaction instead the cavities fromthe dissolved sulfur and flaws in the carbon structure facilitates for the mixture of sulfur and high oxidation state reduction products with both the solution phase as well as carbon matrix. This phenomenon helps the Li-S for a prolonged cycling synergistically. It is apparent from Figure 3 (d-f) and Table 2 that the intermediate

11



polysulfide species are trapped within the cathode due to the electrostatic interaction between the polysulfide and added viologen.

Figure 4. Post cycling XPS analysis of sulfur + graphene + naphthyl viologen cathode (a) N 1s, (b) S 2p, (c) Li 1s, and anode (d) N 1s, (e) S 2p, (f) Li 1s. The extent to which the composite sulfur cathode restricted polysulfide shuttling was probed by carrying out XPS analysis of cycled cathode and anode, spectra are depicted in Fig. 4 (a-c) and (d-f), respectively. The N1s detailed spectra of the cathode (Fig. 4a) can be deconstructed into two major components at 399.7 eV and 398.4 eV. The peak at higher binding energy can be ascribed to the nitrogen atoms of the electrolyte LiN(CF3SO2)226 while that observed at 398.4 can be ascribed to the NV in the diradical form, potentially formed due to strong interactions and charge transfer with formed sulfides.27 The decreased presence of aromatic nitrogen at the anode side is evident through inspecting the N1s peak at 398.4 eV (Fig. 4d), further

12


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supporting the argument for enhanced electrostatic interactions between the NV and polysulfides, hindering their diffusion across the cell and to the anode side. Figure 4 (b) demonstrates the detailed S2p spectrum from the cathode side with closely spaced spin-orbit components S 2p3/2 and S 2p1/2 separated by 1.16 eV with intensity ratio of 2 : 1.28 The S 2p peaks at 164.2 and 163.1 eV confirms the presence of elemental sulfur in cathode Fig. 4(b).29 Additionally, the existence of lithium polysulfides (Li2Sn, 8>n>4) is also observed from the broad peak around 160-162 eV which could be deconvoluted into two sharp peaks (161.3 and 160.1eV).28,30 While comparing it with the S2p spectrum obtained from the anode side (Fig. 4(e)), a dramatic decrease in the peak intensities (between 160 and 162

eV)

corresponding

to

Li2S2

or

Li2S

species,

clearly

indicates

hindered

diffusion/deposition of polysulfides on the anode side. In Fig. 4(b and e)the peaks recorded at 168.9 and 166.9 eV are attributed to various oxygenated (S–O) species on both cathode and anode surfaces.29,30 To further substantiate our claim, the S2p spectra of post cycled lithium metal anode from Li-S cell without viologen is provided as Figure S4. The intensity of the S2p peak between 160-162 eV is higher in the spectra of cell without viologen which indicates higher polysulfide shuttle and accumulation of polysulfides on the anode side of viologen free Li-S cell which obviously results in capacity fade.

The Li 1s spectra for the cathode (Fig. 4c) and anode (Fig. 4f) sides were also recorded. The Li 1s spectrum for the cathode can be deconvoluted into two main components at 55.1 and 53.7 eV. While the peak at 55.1 eV can be attributed to the Li2(CO3)/LiOH, the peak at 53.7 eV can be ascribed to Li2O.31 The strong peak at 54.8 eVin the Li 1s spectra of the anode Fig (4 (f)) shows a very intense characteristic peak of Li metal.28

UV-Vis analysis

13



In order to confirmthe interaction between polysulfide and viologen, the UV-Vis spectra of Li2S and NV.2Cl- (as a chloride salt) were recorded and shown in Figure 5. The addition of Li2S to NV.2Cl- solution resulted in immediate changes in the optical spectrum, appearance of new bands at 376 nm and 566 nm, indicating the interaction between the two species. The added Li2S concentration was increased from 1 equiv to 3 equiv. in few steps and the corresponding UV-Vis spectra were recorded. The initial solution was colourless and showed absorption only in the UV region, characteristic of the dication state of the NV. Increase in concentration of Li2S resulted in developing blue colour in the solution, indicating reduction of the viologen dication to monocation radical (blue colour), whose absorption was evident at 376 and 566 nm (visible region). Thus from the UV-Vis spectra, it is evident that Li2S has reduced the viologen dication to monocation radical. Such observation supports the hypothesis for electrostatic interactions between the formed polysulfides during the charge discharge process and the added-viologen molecules.

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Figure 5. UV-Vis titration of NV + Li2S. Electrochemical impedance spectroscopy (EIS) Electrochemical impedance spectroscopy (EIS) can be effectively employed to understand reactions of sulfur cathodes during charge–discharge process. According to Yuan and coworkers in the frequency domain of EIS, the role of charge transfer resistance, impedance of ion diffusion and the influence of Li2S film in terms of its formation, growth and dissolution can be understood.

32

Generally, the value of Rsis considered as Ohmic resistance which

arises due to the contribution from current collector, cell connections and electrolyte resistance.33 However, the value of Rs is mainly influenced by the electrolyte properties such as chemical composition or viscosity.34

15



Figure 6. EIS spectra of Li-S cells with and without viologen (a) before and (b) after cycling.

The Nyquist plots of Li-S cell before and after cycling are shown in Figure 6 (a) and (b) respectively. The corresponding equivalent circuits and the obtained values of Rs and Rct are also given as inset. Earlier report35 has clearly demonstrated that sulfur cathode without carbon content obviously shows higher charge transfer resistance Rct than the electrode coated/laden with carbon. The reduction in the value of Rct is attributed to enhanced electrical contact offered by added carbon and also decrease of active material loss due to the adsorption of polysulfide by coated carbon. In the present work, the value of Rs is 12 and 6 ohms for the Li-S cell without and with viologen respectively. The viologen added Li-S cell offers lower Rs value than the cell un-laden with viologen which is attributed to the prevention of polysulfide from dissolution by its electrostatic interaction with viologen as illustrated by UV-spectroscopic study.36,37 A similar trend in the values of Rct upon cycling is also observed which may be attributed to decrease of active material loss due to confinement of polysulfide attained through the interactions between added viologen and polysulfide.35,36,38 Thus the viologen-added Li-S cell offers better charge-discharge characteristics. 16


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Conclusions Naphtyl Viologen (NV) was successfully synthesized and incorporated in a composite sulfur cathode as a solid additive and was subjected to charge-discharge studies. The Li-S cell with viologen-added cathode delivered higher discharge capacity than the Li-S cell without viologen. The enhanced cycling performance of NV-added composite sulfur cathode was attributed to the electrostatic interactions between the Li2Sx and viologen as evidenced by UV-Visible spectroscopy. The XPS analysis of the cathode and anode sides clearly demonstrated restricted migration of the polysulfides to the anode side. Presence of Li2S in the cathode wasfurther confirmed by TEM analysis. Supramolecular designed interactions between the relatively bulky viologen and formed polysulfides has therefore contributed positively to enhance the Li-S cell characteristics through hindered sulfide shuttling, opening more doors for enhancement through effective utilization of the supramolecular interactions between the several components of the Li-S cell. ASSOCIATED CONTENT Supporting Information Synthesis of NV, NMR data and XPS data of post cycled Li-S anode. Acknowledgment The authors S.S. and A.M.S gratefully acknowledge the Department of Science and Technology (SERB), New Delhi [EMR/2014/000472] for the financial support. References (1)

Tarascon, J.-M.; Armand, M. Issues and Challenges Facing Rechargeable Lithium Batteries. In Materials for Sustainable Energy; Co-Published with Macmillan Publishers Ltd, UK, 2010; pp 171–179. 17



(2)

Yoo, H. D.; Markevich, E.; Salitra, G.; Sharon, D.; Aurbach, D. On the Challenge of Developing Advanced Technologies for Electrochemical Energy Storage and Conversion. Mater. Today 2014, 17, 110–121.

(3)

Whittingham, M. S. Lithium Batteries and Cathode Materials. Chem. Rev. 2004, 104, 4271–4301.

(4)

Ji, X.; Nazar, L. F. Advances in Li–S Batteries. J. Mater. Chem. 2010, 20, 9821–9826.

(5)

Mikhaylik, Y. V.; Akridge, J. R. Polysulfide Shuttle Study in the Li/S Battery System. J. Electrochem. Soc. 2004, 151, A1969–A1976.

(6)

Shim, J.; Striebel, K. A.; Cairns, E. J. The Lithium/Sulfur Rechargeable Cell Effects of Electrode Composition and Solvent on Cell Performance. J. Electrochem. Soc. 2002, 149, A1321.

(7)

Yang, Y.; Zheng, G.; Cui, Y. Nanostructured Sulfur Cathodes. Chem. Soc. Rev. 2013, 42, 3018–3032.

(8)

Bruce, P. G.; Scrosati, B.; Tarascon, J.-M. Nanomaterials for Rechargeable Lithium Batteries. Angew. Chem. 2008, 47, 2930–2946.

(9)

Fan, Q.; Liu, W.; Weng, Z.; Sun, Y.; Wang, H. Ternary Hybrid Material for HighPerformance Lithium–Sulfur Battery. J. Am. Chem. Soc. 2015, 137, 12946–12953.

(10)

Raja, M.; Bicy, K.; Suriyakumar, S.; Angulakshmi, N.; Thomas, S.; Stephan, A. M. High Performing Magnesium Aluminate-Coated Separator for Lithium Batteries. Ionics (Kiel). 2018, 24, 1–7.

(11)

Park, H.; Siegel, D. J. Tuning the Adsorption of Polysulfides in Lithium–Sulfur

18


Page 18 of 23

Page 19 of 23 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


Batteries with Metal–Organic Frameworks. Chem. Mater. 2017, 29, 4932–4939. (12)

Wang, Z.; Wang, B.; Yang, Y.; Cui, Y.; Wang, Z.; Chen, B.; Qian, G. Mixed-Metal– Organic Framework with Effective Lewis Acidic Sites for Sulfur Confinement in High-Performance Lithium–Sulfur Batteries. ACS Appl. Mater. Interfaces 2015, 7, 20999–21004.

(13)

Bai, S.; Zhu, K.; Wu, S.; Wang, Y.; Yi, J.; Ishida, M.; Zhou, H. A Long-Life Lithium– sulphur Battery by Integrating Zinc–organic Framework Based Separator. J. Mater. Chem. A 2016, 4, 16812–16817.

(14)

Suriyakumar, S.; Kanagaraj, M.; Kathiresan, M.; Angulakshmi, N.; Thomas, S.; Stephan, A. M. Metal-Organic Frameworks Based Membrane as a Permselective Separator for Lithium-Sulfur Batteries. Electrochim. Acta 2018, 265, 151–159.

(15)

Suriyakumar, S.; Stephan, A. M.; Angulakshmi, N.; Hassan, M. H.; Alkordi, M. H. Metal–organic Framework@SiO2 as Permselective Separator for Lithium–Sulfur Batteries. J. Mater. Chem. A 2018, 6, 14623-14632.

(16)

Wu, H.; Cao, Y.; Geng, L.; Wang, C. In Situ Formation of Stable Interfacial Coating for High Performance Lithium Metal Anodes. Chem. Mater. 2017, 29, 3572–3579.

(17)

Liu, T.; Wei, X.; Nie, Z.; Sprenkle, V.; Wang, W. A Total Organic Aqueous Redox Flow Battery Employing a Low Cost and Sustainable Methyl Viologen Anolyte and 4HO-TEMPO Catholyte. Adv. Energy Mater. 2016, 6, 1501449.

(18)

Beh, E. S.; De Porcellinis, D.; Gracia, R. L.; Xia, K. T.; Gordon, R. G.; Aziz, M. J. A Neutral PH Aqueous Organic–Organometallic Redox Flow Battery with Extremely High Capacity Retention. ACS Energy Lett. 2017, 2, 639–644.

19



(19)

Lacey, M. J.; Frith, J. T.; Owen, J. R. A Redox Shuttle to Facilitate Oxygen Reduction in the Lithium Air Battery. Electrochem. Commun. 2013, 26, 74–76.

(20)

Yang, L.; Frith, J. T.; Garcia-Araez, N.; Owen, J. R. A New Method to Prevent Degradation of Lithium–Oxygen Batteries: Reduction of Superoxide by Viologen. Chem. Commun. 2015, 51, 1705–1708.

(21)

Raja, M.; Angulakshmi, N.; Stephan, A. M. Sisal-Derived Activated Carbons for CostEffective Lithium–Sulfur Batteries. RSC Adv. 2016, 6, 13772–13779.

(22)

Wang, W. G.; Wang, X.; Tian, L. Y.; Wang, Y. L.; Ye, S. H. In Situ Sulfur Deposition Route to Obtain Sulfur-Carbon Composite Cathodes for Lithium-Sulfur Batteries. J. Mater. Chem. A 2014, 2, 4316–4323.

(23)

Li, G.-C.; Li, G.-R.; Ye, S.-H.; Gao, X.-P. A Polyaniline-Coated Sulfur/Carbon Composite with an Enhanced High-Rate Capability as a Cathode Material for Lithium/Sulfur Batteries. Adv. Energy Mater. 2012, 2, 1238–1245.

(24)

Jayaprakash, N.; Shen, J.; Moganty, S. S.; Corona, A.; Archer, L. A. Porous Hollow Carbon@Sulfur Composites for High-Power Lithium-Sulfur Batteries. Angew. Chem. 2011, 123, 6026–6030.

(25)

Elazari, R.; Salitra, G.; Talyosef, Y.; Grinblat, J.; Scordilis-Kelley, C.; Xiao, A.; Affinito, J.; Aurbach, D. Morphological and Structural Studies of Composite Sulfur Electrodes upon Cycling by HRTEM, AFM and Raman Spectroscopy. J. Electrochem. Soc. 2010, 157, A1131.

(26)

Ensling, D.; Stjerndahl, M.; Nytén, A.; Gustafsson, T.; Thomas, J. O. A Comparative XPS Surface Study of Li2 FeSiO4/C Cycled with LiTFSI- and LiPF6 -Based

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Page 20 of 23

Page 21 of 23 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


Electrolytes. J. Mater. Chem. 2009, 19, 82–88. (27)

Constantin, V.; Cao, L.; Sadaf, S.; Walder, L. Oligo-viologen/SWCNT Nanocomposites: Preparation and Characterization. Phys. Status Solidi B 2012, 249 (12), 2395–2398.

(28)

Kowalczyk, S. P.; Ley, L.; McFeely, F. R.; Pollak, R. A.; Shirley, D. A. X-Ray Photoemission from Sodium and Lithium. Phys. Rev. B 1973, 8, 3583–3585.

(29)

Diao, Y.; Xie, K.; Xiong, S.; Hong, X. Insights into Li-S Battery Cathode Capacity Fading Mechanisms : Irreversible Oxidation of Active Mass during Cycling. J. Electrochem. Soc. 2012, 159, 1816–1821.

(30)

Aurbach, D.; Pollak, E.; Elazari, R.; Salitra, G.; Kelley, C. S.; Affinito, J. On the Surface Chemical Aspects of Very High Energy Density, Rechargeable Li–Sulfur Batteries. J. Electrochem. Soc. 2009, 156, A694.

(31)

Naoi, K.; Mori, M.; Naruoka, Y.; Lamanna, W. M.; Atanasoski, R. The Surface Film Formed on a Lithium Metal Electrode in a New Imide Electrolyte, Lithium Bis(Perfluoroethylsulfonylimide) [LiN(C2F5SO2)2]. J. Electrochem. Soc. 1999, 146, 462–469.

(32)

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, 127–132.

(33)

Kolosnitsyn, V. S.; Kuzmina, E. V.; Karaseva, E. V.; Mochalov, S. E. A Study of the Electrochemical Processes in Lithium–sulphur Cells by Impedance Spectroscopy. J. Power Sources 2011, 196, 1478–1482.

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(34)

Cañas, N. A.; Wolf, S.; Wagner, N.; Friedrich, K. A. In-Situ X-Ray Diffraction Studies of Lithium–Sulfur Batteries. J. Power Sources 2013, 226, 313–319.

(35)

Choi, Y.-J.; Chung, Y.-D.; Baek, C.-Y.; Kim, K.-W.; Ahn, H.-J.; Ahn, J.-H. Effects of Carbon Coating on the Electrochemical Properties of Sulfur Cathode for Lithium/Sulfur Cell. J. Power Sources 2008, 184, 548–552.

(36)

Cañas, N. A.; Hirose, K.; Pascucci, B.; Wagner, N.; Friedrich, K. A.; Hiesgen, R. Investigations of Lithium–Sulfur Batteries Using Electrochemical Impedance Spectroscopy. Electrochim. Acta 2013, 97, 42–51.

(37)

Kolosnitsyn, V. S.; Kuz’mina, E. V.; Karaseva, E. V.; Mochalov, S. E. Impedance Spectroscopy Studies of Changes in the Properties of Lithium-Sulfur Cells in the Course of Cycling. Russ. J. Electrochem. 2011, 47, 793–798.

(38)

Barchasz, C.; Leprêtre, J.-C.; Alloin, F.; Patoux, S. New Insights into the Limiting Parameters of the Li/S Rechargeable Cell. J. Power Sources 2012, 199, 322–330.

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Improved Cycling Performance of Lithium-Sulfur Cell Through

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