Few-layer graphene via electrochemically cathodic exfoliation for micro-supercapacitors

ZHOU Feng1 TIAN Lijun2 GAO Lei2 WU Zhongshuai1

(1.Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China 116023)
(2.Great Scientific Research Institute, Datong Coal Mine Group Co., Ltd., Datong, Shanxi, China 037003)

【Abstract】The use of graphite as a raw material for efficient, green, and low-cost preparation of few-layer graphene is of great significance for the large-scale production and application of graphene. However, the efficient exfoliation of graphite to graphene without use of strong oxidants and acids is still a great challenge. Herein, we developed a green and scalable aqueous-based electrochemical cathodic exfoliation approach, in which graphite as a negative electrode can be electrochemically charged and expanded in an electrolyte of 6 mol·L−1 potassium hydroxide (KOH under high current density and exfoliated efficiently into few-layer graphene sheets with the aid of sonication. The obtained few-layer graphene has low oxygen content [1.27% (mass)], few defects (ID/IG < 0.035), a plate size of 5–10 μm, high conductivity of >200 S·cm−1, and good solution additivity. Moreover, such electrochemically exfoliated graphene (EG) nanosheets are readily used to produce highly solution-processable ink (1 mg·mL−1) in ethanol without the need of any surfactants, allowing for the production of large-area EG microelectrodes for EG based micro-supercapacitors (EG-MSCs). Furthermore, the as-fabricated aqueous EG-MSCs show ultrahigh scan rate of 100 000 mV·s−1 and short time constant of only 24 ms. More importantly, using ionic liquids-based electrolyte of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide with bis(trifluoromethanesulfonyl)imide lithium sal (EMIMTFSI/LiTFSI), EG-MSCs can work at a high voltage of 4.0 V, and show high volumetric energy density of 113 mW·h·cm−3, outperforming the most reported MSCs (< 50 mW·h·cm−3).

【Keywords】 electrochemical; cathode exfoliation; graphene; graphite; micro-supercapacitors;


【Funds】 National Natural Science Foundation of China (51872283, 21805273) Graphene Applied Technology Research Program, Datong Coal Mine Group Co., Ltd. National Key R&D Program of China (2016YFA0200200) Program of Dalian National Laboratory For Clean Energy, CAS (DNL180310, DNL180308, DNL201912, DNL201915) DICP (DICP ZZBS201708, DICP ZZB201802) PhD Start-Up Foundation of Liaoning Province (2019-BS-246)

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    [1] Novoselov K S, Geim A K, Morozov S V, et al. Electric field effect in atomically thin carbon films [J]. Science, 2004, 306 (5696): 666–669.

    [2] Sutter P W, Flege J I, Sutter E A, Epitaxial graphene on ruthenium [J]. Nat. Mater., 2008, 7 (5): 406–411.

    [3] Berger C, Song Z, Li X, et al. Electronic confinement and coherence in patterned epitaxial graphene [J]. Science, 2006, 312 (5777): 1191–1196.

    [4] Reina A, Jia X, Ho J, et al. Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition [J]. Nano Lett., 2009, 9 (1): 30–35.

    [5] Bae S, Kim H K, Lee Y B, et al. Roll-to-roll production of 30-inch graphene films for transparent electrodes [J]. Nat. Nanotechnol., 2010, 5 (8): 574–578.

    [6] Park S, Ruoff R S. Chemical methods for the production of graphenes [J]. Nat. Nanotechnol., 2009, 4 (4): 217–224.

    [7] Cote L J, Kim F, Huang J. Langmuir–Blodgett assembly of graphite oxide single layers [J]. J. Am. Chem. Soc., 2009, 131 (3): 1043–1049.

    [8] Li D, Muller M B, Gilje S, et al. Processable aqueous dispersions of graphene nanosheets [J]. Nat. Nanotechnol., 2008, 3 (2): 101–105.

    [9] Gao W, Alemany L B, Ci L, et al. New insights into the structure and reduction of graphite oxide [J]. Nat. Chem., 2009, 1 (5): 403–408.

    [10] Chen C M, Yang Q H, Yang Y G, et al. Self-assembled freestanding graphite oxide membrane [J]. Adv. Mater., 2009, 21 (29): 3007–3011.

    [11] Li X, Wang H, Robinson J T, et al. Simultaneous nitrogen doping and reduction of graphene oxide [J]. J. Am. Chem. Soc., 2009, 131 (43): 15939–15944.

    [12] Wei Y, Sun Z Y. Liquid-phase exfoliation of graphite for mass production of pristine few-layer graphene [J]. Current Opinion in Colloid and Interface Science, 2015, 20 (5): 311–321.

    [13] Hernandez Y, Nicolosi V, Lotya M, et al. High-yield production of graphene by liquid-phase exfoliation of graphite [J]. Nat. Nanotechnol., 2008, 3 (9): 563–568.

    [14] Blake P, Brimicombe P D, Nai R R, et al. Graphene-based liquid crystal device [J]. Nano Lett., 2008, 8 (6): 1704–1708.

    [15] De S, King P J, Lotya M, et al. Flexible, transparent, conducting films of randomly stacked graphene from surfactant-stabilized, oxide-free graphene dispersions [J]. Small, 2010, 6 (3): 458–464.

    [16] Biswas S, Drzal L T. A novel approach to create a highly ordered monolayer film of graphene nanosheets at the liquid–liquid interface [J]. Nano Lett., 2009, 9 (1): 167–172.

    [17] Gu W T, Zhang W, Li X M, et al. Graphene sheets from worm-like exfoliated graphite [J]. J. Mater. Chem., 2009, 19 (21): 3367–3369.

    [18] Su C Y, Lu A Y, Xu Y P, et al. High-quality thin graphene films from fast electrochemical exfoliation [J]. ACS Nano, 2011, 5 (3): 2332–2339.

    [19] Liu J, Yang H, Zhen S G, et al. A green approach to the synthesis of high-quality graphene oxide flakes via electrochemical exfoliation of pencil core [J]. RSC Adv., 2013, 3 (29): 11745–11750.

    [20] Parvez K, Wu Z S, Li R, et al. Exfoliation of graphite into graphene in aqueous solutions of inorganic salts [J]. J. Am. Chem. Soc., 2014, 136 (16): 6083–6091.

    [21] Wang G X, Wang B, Park J, et al. Highly efficient and large scale synthesis of graphene by electrolytic exfoliation [J]. Carbon, 2009, 47 (14): 3242–3246.

    [22] Lu J, Yang J X, Wang J Z, et al. One-pot synthesis of fluorescent carbon nanoribbons, nanoparticles, and graphene by the exfoliation of graphite in ionic liquids [J]. ACS Nano, 2009, 3 (8): 2367–2375.

    [23] Wang J, Yin H S, Meng X M, et al. Preparation of the mixture of graphene nanosheets and carbon nanospheres with high desorptivity by electrolyzing graphite rod and its application in hydroquinone detection [J]. J. Electronal. Chem., 2011, 662 (2): 317–321.

    [24] Singh V V, Gupta G, Batra A, et al. Greener electrochemical synthesis of high quality graphene nanosheets directly from pencil and its SPR sensing application [J]. Adv. Funct. Mater., 2012, 22 (11): 2352–2362.

    [25] Zhong Y L, Swager T M. Enhanced electrochemical expansion of graphite for in situ electrochemical functionalization [J]. J. Am. Chem. Soc., 2012, 134 (43): 17896–17899.

    [26] Zhou F, Huang H B, Xiao C X, et al. Electrochemically scalable production of fluorine modified graphene for flexible and high energy ionogel-based micro-supercapacitors [J]. J. Am. Chem. Soc., 2018, 140 (26): 8198–8205.

    [27] Wang J, Manga K K, Bao Q, et al. High-yield synthesis of few layer graphene flakes through electrochemical expansion of graphite in propylene carbonate electorlyte [J]. J. Am. Chem. Soc., 2011, 133 (23): 8888–8891.

    [28] Liu N, Luo F, Wu H, et al. One-step ionic liquids-assisted electrochemical synthesis of ionic-liquids-functionalized graphene sheets directly from graphite [J]. Adv. Funct. Mater., 2008, 18 (10): 1518–1525.

    [29] Zhou M, Tang J, Cheng Q, et al. Few-layer graphene obtained by electrochemical exfoliation of graphite cathode [J]. Chem. Phys. Lett., 2013, 572: 61–65.

    [30] Suo L M, Borodin O, Gao T, et al. “Water-in-salt” electrolyte enables high-voltage aqueous lithium-ion chemistries [J]. Science, 2015, 350 (6263): 938–943.

    [31] Zhou F, Liu S M, Yang B Q, et al. Highly selective electrocatalytic reduction of carbon dioxide to carbon monoxide on silver electrode with aqueous ionic liquids [J]. Electrochem. Commun., 2014, 46: 103–106.

    [32] Xiao H, Wu Z-S, Chen L, et al. One-step device fabrication of phosphorene and graphene interdigital micro-supercapacitors with high energy density [J]. ACS Nano, 2017, 11 (7): 7284–7292.

    [33] Wu Z-K, Lin Z, Li L, et al. Flexible micro-supercapacitor based on in-situ assembled graphene on metal template at room temperature [J]. Nano Energy, 2014, 10: 222–228.

    [34] Watanabe M, Thomas M L, Zhang S G, et al. Application of ionic liquids to energy storage and conversion materials and devices [J]. Chem. Rev., 2017, 117 (10): 7190–7239.

    [35] El-Kady M F, Strong V, Dubin S, et al. Laser scribing of high-performance and flexible graphene-based electrochemical capacitors [J]. Science, 2012, 335 (6074): 1326–1330.

    [36] Wu Z-S, Parvez K, Feng X, et al. Graphene-based in-plane micro-supercapacitors with high power and energy densities [J]. Nat. Commun., 2013, 4: 2487–2494.

    [37] Heon M, Lofland S, Applegate J, et al. Continuous carbide-derived carbon films with high volumetric capacitance [J]. Energy Environ. Sci., 2011, 4 (1): 135–138.

    [38] Ghosh A, Viet T L, Bae J J, et al. TLM-PSD model for optimization of energy and power density of vertically aligned carbon nanotube supercapacitor [J]. Sci. Rep., 2013, 3: 2939.

    [39] Pech D, Brunet M, Durou H, et al. Ultrahigh-power micrometre-sized supercapacitors based on onion-like carbon [J]. Nat. Nanotechnol., 2010, 5 (9): 651–654.

This Article


CN: 11-1946/TQ

Vol 71, No. 06, Pages 2724-2734+2920

June 2020


Article Outline


  • Introduction
  • 1 Analysis of exfoliation mechanism
  • 2 Experimental section
  • 3 Results and discussion
  • 4 Conclusion
  • References