7660 Phys. Chem. Chem. Phys., 2011, 13, 7660–7665 This journal is c the Owner Societies 2011 Cite this: Phys. Chem. Chem. Phys., 2011, 13, 7660–7665 Sandwich-type functionalized graphene sheet-sulfur nanocomposite for rechargeable lithium batterieswz Yuliang Cao, ab Xiaolin Li, a Ilhan A. Aksay, c John Lemmon, a Zimin Nie, a Zhenguo Yang a and Jun Liu* a Received 10th November 2010, Accepted 8th March 2011 DOI: 10.1039/c0cp02477e A functionalized graphene sheet-sulfur (FGSS) nanocomposite was synthesized as the cathode material for lithium–sulfur batteries. The structure has a layer of functionalized graphene sheets/stacks (FGS) and a layer of sulfur nanoparticles creating a three-dimensional sandwich-type architecture. This unique FGSS nanoscale layered composite has a high loading (70 wt%) of active material (S), a high tap density of B0.92 g cm 3 , and a reversible capacity of B505 mAh g 1 (B464 mAh cm 3 ) at a current density of 1680 mA g 1 (1C). When coated with a thin layer of cation exchange Nafion film, the migration of dissolved polysulfide anions from the FGSS nanocomposite was effectively reduced, leading to a good cycling stability of 75% capacity retention over 100 cycles. This sandwich-structured composite conceptually provides a new strategy for designing electrodes in energy storage applications. Introduction Lithium–sulfur batteries have been studied as one of the most promising systems for the next generation high-energy rechargeable lithium batteries because of their high theoretical specific capacity (B1680 mAh g 1 ) and energy density (2600 Wh kg 1 ). 1–3 However, the poor electrical conductivity of elemental sulfur and the fast-capacity degradation from polysulfide dissolution into the electrolyte have greatly limited its practical applications. 4–7 Over the past several decades, extensive research has been carried out to address these problems. 8–25 Conductive polymers and carbon networks have been widely investigated to improve the conductivity of the composites containing sulfur. 8–14 Polymer modification, 9,16–17 alternative electrolytes, 18–21 and electrolyte additives 22–23 have been tested to mitigate the problem of polysulfides dissolving in electrolytes. 4,8,15 Recently, important progress was made by using sulfur and mesoporous carbon nanocomposites as the cathode for Li–S batteries. 9 A high reversible capacity of 1320 mAh g 1 and an 83% capacity retention over 20 cycles were achieved at a 0.1C discharge rate (168 mA g 1 ). 9 Progress was also made on sulfur-based batteries using a polymer/tin composite or silicon as anode materials. 24–25 In this study, we synthesized a functionalized graphene sheets-sulfur nanocomposite (FGSS), a sandwich-type archi- tecture containing functionalized graphene sheets/stacks (FGSs) 26,27 and a layer of sulfur nanoparticles. Furthermore, we here demonstrate the application of these nanoscale sandwich-structures as the cathode material for lithium–sulfur batteries. Graphene, with its excellent conductivity (electron mobility 200 000 cm 2 V 1 s 1 ) and a large surface area (2630 m 2 g 1 , calculated value), 28,29 has been widely studied in electrochemical energy storage devices, such as lithium ion batteries, to improve the conductivity and stability of the composite electrode. 30–33 Additionally, graphene is also a useful nanoscale building block for producing composite materials with polymer or metal oxide nanoparticles. 30–35 Very recently, sulfur was mixed with graphene that was prepared by solvothermal synthesis. The material indeed showed a higher conductivity and better capacity retention than pure sulfur. 36 However, the sulfur loading was extremely low (17 to 22 wt%) and the capacity decreased from >1100 mAh/g to B600 mAh/g at 0.03C within 40 cycles. Therefore, other methods to achieve higher sulfur loading and to protect the polysulfide from dissolution need to be developed. The FGSs for this work were prepared by a thermal expansion of graphite oxide that contains approximately 80 wt% single sheet graphene along with stacked graphene (graphene stacks). The carbon to oxygen ratio of the graphene material is about 14, which allows the FGSs to retain a good electrical conductivity. 26,27 The new sandwich-type structure allows a much higher sulfur loading and more uniform distribution of the sulfur nanoparticles in carbon, resulting in a much higher reversible capacity at fast charge/discharge rates. Further improvement a Pacific Northwest National Laboratory, Richland, WA 99352, USA. E-mail: [email protected]b Department of Chemistry, Wuhan University, Wuhan 430072, P. R. China c Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA w Electronic supplementary information (ESI) available. See DOI: 10.1039/c0cp02477e z This article was submitted following the 1st workshop on Energy Materials, organised by The Thomas Young Centre, and held on 7–9 September 2010 at University College London. PCCP Dynamic Article Links www.rsc.org/pccp PAPER Downloaded by Princeton University on 05 May 2011 Published on 30 March 2011 on http://pubs.rsc.org | doi:10.1039/C0CP02477E View Online
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7660 Phys. Chem. Chem. Phys., 2011, 13, 7660–7665 This journal is c the Owner Societies 2011
(FGSs)26,27 and a layer of sulfur nanoparticles. Furthermore,
we here demonstrate the application of these nanoscale
sandwich-structures as the cathode material for lithium–sulfur
batteries. Graphene, with its excellent conductivity (electron
mobility 200 000 cm2 V�1 s�1) and a large surface area
(2630 m2 g�1, calculated value),28,29 has been widely studied
in electrochemical energy storage devices, such as lithium ion
batteries, to improve the conductivity and stability of the
composite electrode.30–33 Additionally, graphene is also a
useful nanoscale building block for producing composite
materials with polymer or metal oxide nanoparticles.30–35 Very
recently, sulfur was mixed with graphene that was prepared by
solvothermal synthesis. The material indeed showed a higher
conductivity and better capacity retention than pure sulfur.36
However, the sulfur loading was extremely low (17 to 22 wt%)
and the capacity decreased from>1100 mAh/g toB600 mAh/g
at 0.03C within 40 cycles. Therefore, other methods to achieve
higher sulfur loading and to protect the polysulfide from
dissolution need to be developed.
The FGSs for this work were prepared by a thermal
expansion of graphite oxide that contains approximately
80 wt% single sheet graphene along with stacked graphene
(graphene stacks). The carbon to oxygen ratio of the graphene
material is about 14, which allows the FGSs to retain a good
electrical conductivity.26,27
The new sandwich-type structure allows a much higher
sulfur loading and more uniform distribution of the sulfur
nanoparticles in carbon, resulting in a much higher reversible
capacity at fast charge/discharge rates. Further improvement
a Pacific Northwest National Laboratory, Richland, WA 99352, USA.E-mail: [email protected]
bDepartment of Chemistry, Wuhan University, Wuhan 430072,P. R. China
cDepartment of Chemical and Biological Engineering,Princeton University, Princeton, NJ 08544, USAw Electronic supplementary information (ESI) available. See DOI:10.1039/c0cp02477ez This article was submitted following the 1st workshop on EnergyMaterials, organised by The Thomas Young Centre, and held on 7–9September 2010 at University College London.
This journal is c the Owner Societies 2011 Phys. Chem. Chem. Phys., 2011, 13, 7660–7665 7665
further before it becomes suitable for practical applications,
this research demonstrates a new approach to improve the
performance of Li–S batteries. Better graphene dispersion,
optimization of the interfacial reaction with sulfur, and better
coating materials to further improve the high rate capacity and
capacity retention properties are needed to build on the results
presented in this study.
Acknowledgements
The authors thank Dr B. Schwenzer for helpful suggestions.
This research is supported by the U.S. Department of Energy
(DOE), Office of Basic Energy Sciences, Division of Materials
Sciences and Engineering under Award KC020105-
FWP12152. Pacific Northwest National Laboratory (PNNL)
is a multiprogram national laboratory operated for DOE by
Battelle under Contract DE-AC05-76RL01830.
References
1 R. D. Rauh, K. M. Abraham, G. F. Pearson, J. K. Surprenant andS. B. Brummer, J. Electrochem. Soc., 1979, 126, 523.
2 J. Shim, K. A. Striebel and E. J. Cairns, J. Electrochem. Soc., 2002,149, A1321.
3 D. Peramunage and S. Licht, Science, 1993, 261, 1029.4 V. S. Kolosnitsyn and E. V. Karaseva, Russ. J. Electrochem., 2008,44, 506.
5 R. D. Rauh, F. S. Shuker, J. M. Marston and S. B. Brummer,J. Inorg. Nucl. Chem., 1977, 39, 1761.
6 S.-E. Cheon, K.-S. Ko, J.-H. Cho, S.-W. Kim, E.-Y. Chin andH.-T. Kim, J. Electrochem. Soc., 2003, 150, A800.
7 J. Wang, S. Y. Chew, Z. W. Zhao, S. Ashraf, D. Wexler, J. Chen,S. H. Ng, S. L. Chou and H. K. Liu, Carbon, 2008, 46, 229.
8 C. D. Liang, N. J. Dudney and J. Y. Howe, Chem. Mater., 2009,21, 4724.
9 X. L. Ji, K. T. Lee and L. F. Nazar, Nat. Mater., 2009, 8, 500.10 J. L. Wang, J. Yang, J. Y. Xie and N. X. Xu,Adv. Mater., 2002, 14,
963.11 M. M. Sun, S. C. Zhang, T. Jiang, L. Zhang and J. H. Yu,
Electrochem. Commun., 2008, 10, 1819.12 C. Lai, X. P. Gao, B. Zhang, T. Y. Yan and Z. Zhou, J. Phys.
Chem. C, 2009, 113, 4712.13 L. X. Yuan, H. P. Yuan, X. P. Qiu, L. Q. Chen and W. T. Zhu,
J. Power Sources, 2009, 189, 1141.14 F. Wu, S. X. Wu, R. J. Chen, J. Z. Chen and S. Chen, Electrochem.
Solid-State Lett., 2010, 13, A29.
15 S. E. Cheon, K. S. Ko, J. H. Cho, S. W. Kim, E. Y. Chin andH. T. Kim, J. Electrochem. Soc., 2003, 150, A796.
16 Y. J. Jung and S. Kim, Electrochem. Commun., 2007, 9, 249.17 S. E. Cheon, J. H. Cho, K. S. Ko, C.-W. Kwon, D.-R. Chang,
H.-T. Kim and S.-W. Kim, J. Electrochem. Soc., 2002, 149, A1437.18 L. X. Yuan, J. K. Feng, X. P. Ai, Y. L. Cao, S. L. Chen and
H. X. Yang, Electrochem. Commun., 2006, 8, 610.19 D. R. Chang, S. H. Lee, S. W. Kim and H. T. Kim, J. Power
Sources, 2002, 112, 452.20 B. Jin, J. U. Kim and H. B. Gu, J. Power Sources, 2003, 117, 148.21 J. H. Shin and E. J. Cairns, J. Power Sources, 2008, 177, 537.22 D. Aurbach, E. Pollak, R. Elazari, G. Salitra, C. S. Kelley and
J. Affinito, J. Electrochem. Soc., 2009, 156, A694.23 J. W. Choi, G. Cheruvally, D. S. Kim, J. H. Ahn, K. W. Kim and
H. J. Ahn, J. PowerSources, 2008, 183, 441.24 J. Hasosoun and B. Scrosati, Angew. Chem., Int. Ed., 2010, 49,
2371.25 Y. Yang, M. T. McDowell, A. Jackson, J. J. Cha, S. S. Hong and
Y. Cui, Nano Lett., 2010, 10, 1486.26 H. C. Schniepp, J. L. Li, M. J. McAllister, H. Sai, M.
Herrera-Alonso, D. H. Adamson, R. K. Prud’homme, R. Car,D. A. Saville and I. A. Aksay, J. Phys. Chem. B, 2006, 110, 8535.
27 M. J. McAllister, J. L. LiO, D. H. Adamson, H. C. Schniepp,A. A. Abdala, J. Liu, M. Herrera-Alonso, D. L. Milius, R. CarO,R. K. Prud’homme and I. A. Aksay, Chem. Mater., 2007, 19, 4396.
28 K. I. Bolotin, K. J. Sikes, Z. Jiang, M. Klima, G. Fudenberg,J. Hone, P. Kim and H. L. Stormer, Solid State Commun., 2008,146, 351.
29 M. D. Stoller, S. J. Park, Y. W. Zhu, J. H. An and R. S. Ruoff,Nano Lett., 2008, 8, 3498.
30 D. H. Wang, D. W. Choi, J. Li, Z. G. Yang, Z. M. Nie, R. Kou,D. H. Hu, C. M. Wang, L. V. Saraf, J. G. Zhang, I. A. Aksay andJ. Liu, ACS Nano, 2009, 3, 907.
31 D. H. Wang, R. Kou, D. Choi, Z. G. Yang, Z. M. Nie, J. Li,L. V. Saraf, D. H. Hu, J. G. Zhang, G. L. Graff, J. Liu, M. A. Popeand I. A. Aksay, ACS Nano, 2010, 4, 1587.
32 E. J. Yoo, J. Kim, E. Hosono, H. S. Zhou, T. Kudo and I. Honma,Nano Lett., 2008, 8, 2277.
33 S. M. Paek, E. J. Yoo and I. Honma, Nano Lett., 2009, 9, 72.34 T. Ramanathan, A. A. Abdala, S. Stankovich, D. A. Dikin,
M. Herrera-Alonso, R. D. Piner, D. H. Adamson,H. C. Schniepp, X. Chen, R. S. Ruoff, S. T. Nguyen,I. A. Aksay, R. K. Prud’Homme and L. C. Brinson, Nat. Nano-technol., 2008, 3, 327.
35 S. Stankovich, D. A. Dikin, G. H. B. Dommett, K. M. Kohlhaas,E. J. Zimney, E. A. Stach, R. D. Piner, S. T. Nguyen andR. S. Ruoff, Nature, 2006, 442, 282.
36 J.-Z. Wang, L. Lu, M. Choucair, J. A. Stride, X. Xu andH.-K. Liu, J. Power Sources, in press.
37 X. Wang, X. Zhou, K. Yao, J. Zhang and Z. Liu, Carbon, 2011, 49,133.