- Email: [email protected]
Novel composite electrode material derived from hypercross-linked polymer of pyrene and polyaniline for symmetric supercapacitor
Materials Letters 257 (2019) 126732
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Novel composite electrode material derived from hypercross-linked polymer of pyrene and polyaniline for symmetric supercapacitor Hyun-Chul Jung, Rajangam Vinodh ⇑, Chandu V.V. Muralee Gopi, Moonsuk Yi, Hee-Je Kim ⇑ Department of Electrical and Computer Engineering, Pusan National University, Geumjeong-gu, Busan 46241, South Korea
a r t i c l e
i n f o
Article history: Received 13 August 2019 Received in revised form 5 September 2019 Accepted 22 September 2019 Available online 23 September 2019 Keywords: Pyrene Hypercross-linked polymer Polyaniline Symmetric supercapacitor Composite electrode
a b s t r a c t Herein, we report the fabrication of composite electrode (PyHCP-800/PANI) by two step method. Firstly, hypercross-linked polymer of pyrene (PyHCP) synthesized by a simple Friedel-Crafts alkylation method and subsequent carbonization at 800 °C to yield porous carbon of PyHCP (PyHCP-800). Secondly, polyaniline (PANI) was electrochemically grown on the surface of PyHCP-800. The synthesized PyHCP and PyHCP-800 was characterized by physicochemical characterization techniques. The composite shows excellent electrochemical behavior than pristine PyHCP-800 and PANI electrode. In three electrode system, PyHCP-800/PANI composite exhibits specific capacitance of 62.6 F g1 at 0.1 A g1. Also, the fabricated symmetric supercapacitor (SSC) device (PyHCP-800/PANI || PyHCP-800/PANI) delivers outstanding cycle life with 90.67% retention for 2000 cycles. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Supercapacitors (SCs) have gained much research consideration owing to its special characteristic properties of quick chargedischarge process, long cyclic stability, safe operation and good power output [1]. Up to date, various carbon based materials have been expansively explored due to the outstanding mechanical properties, excellent electrical conductivity, high surface area and good charge transfer capability. However, the low specific capacitance and energy density have extremely restricted their performances in practical applications. Recently, porous carbons derived from hypercross-linked polymers (HCPs) are considered to be one of the most alternative materials. Since, HCPs are microporous materials synthesized from cheap organic monomers that show good stability and potential for synthetic diversification. Permanent porosity in HCPs is a result of extensive cross-linking, which prevents the polymer chains from collapsing into a dense and no-porous state [2]. A new strategy for achieving high performance SCs and overcoming the poor resistance of porous carbon of PyHCP by electrochemically interweaving PyHCP-800 spheres with a conductive polymer, PANI. After electrochemical polymerization, the isolated carbon spheres are interconnected and linked up by the chains of PANI that act as bridges for electrons transportation between the external circuit and the internal surface of PyHCP-800. Herein, for the very first
time PyHCP-800@PANI based composite electrode was fabricated by a facile Friedel-Crafts alkylation followed by electrochemical polymerization technique. By using a 6 M KOH aqueous electrolyte in the 3-electrode system PyHCP-800@PANI electrode imposes a high specific capacitance of 62.6 F g1 at 0.1 A g1 current density. 2. Experimental 2.1. Synthesis of PyHCP and PyHCP-800 In a 250 mL round bottom flask, pyrene (4.9 mmol), paraformaldehyde (99 mmol) and 1, 2 dichloroethane (40 mL) were taken and stirred well at room temperature. Then ferric chloride (30.8 mmol) was slowly added into the above reaction mixture and the reaction was carried out for 24 h at 80 °C. After the completion of the reaction, the resultant brown colored precipitate was thoroughly washed several times with 1:1:1 ratio of water, HCl and ethanol mixture and dried in vacuum oven at 90 °C for overnight. The obtained material was pyrene based hypercrosslinked polymer and designated as PyHCP. PyHCP was subjected into carbonization at 800 °C for 6 h at argon atmosphere with the heating rate of 2 °C min1. The procured material was carbonized PyHCP and named as PyHCP-800. 2.2. Electrochemical polymerization of aniline onto PyHCP-800
⇑ Corresponding authors. E-mail addresses: [email protected] (R. Vinodh), [email protected] (H.-J. Kim). https://doi.org/10.1016/j.matlet.2019.126732 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
Nickel foam was used as the substrate material for the electrode fabrication. Pretreatment of nickel foam was given in Supporting
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H.-C. Jung et al. / Materials Letters 257 (2019) 126732
information section. In brief, PyHCP-800 was well mixed with polyvinylidene fluoride, acetylene black and N-methyl 2pyrrolidone in mortar and pestle to form a thick slurry. The obtained slurry was uniformly coat into the pretreated nickel foam with the help of brush (1 cm 1 cm) and dried in an oven at 80 °C for 12 h. The prepared electrode was subjected into electrochemical polymerization of aniline in 1 mM aniline + 0.5 M sulfuric acid at 50 mV s1 between the potential window of 0 and 1 V vs. Ag/ AgCl electrode for 20 cycles. The prepared composite electrode was named as PyHCP-800/PANI. The active mass of the working electrode was ~4 mg. The cyclic voltammogram (CV) was depicted in Fig. S1. The materials and physicochemical characterization techniques was given in Supporting information section. The electrochemical impedance spectroscopy (EIS) was examined ranging the frequency from 0.01 Hz to 0.1 kHz. The specific capacitance of the PyHCP-800/PANI (three electrode system) and PyHCP-800/ PANI || PyHCP-800/PANI (symmetric supercapacitor) was calculated by the following Eq. (1).
Cs ¼
I t m DV
ð1Þ
where Cs is the specific capacitance (F g1), I represents the specified current (A), m is the mass of the electrode materials (g), DV signifies the potential window range (E) and t denotes the discharge time (s).
3. Results and discussion FTIR spectrum of PyHCP was exhibited in Fig. 1(a). The hypercross-linked quinonoid of pyrene polymer showed a broad band around 3500 cm1 due to –OH stretch of water. The sharp intense peaks from 1700 to 1600 cm1 are associated with quinonoid skeleton. The peaks below 1000 cm1 are assigned C–H bending modes. XRD pattern was shown in Fig. 1(b). In PyHCP no obvious diffraction peak except 22°, whereas in PyHCP-800 shows two diffraction peaks at around 22° and 46° which corresponds to (0 0 2) and (1 0 0) plane respectively with little shift. It convincingly establishes the amorphous nature of the carbon based materials. Raman spectrum of PyHCP-800 was depicted in Fig. 1(c). It exhibits D band at 1380 cm1 and G band at 1520 cm1. The identified peaks were well match with other carbon materials. The ID/IG ratio was found to be 0.81. It suggests the prepared materials was amorphous in nature. Both the materials exhibit type IV sorption isotherm (Fig. 1(d)) and sharp increase at high relative pressure (p/p0 = 1.0) implies the existence of macropores. But PyHCP-800 did not coincide with the adsorption isotherm. It clearly illustrates the presence of hierarchical pores (meso- and nano-pores). The surface area of 450 and 827 m2 g1 are attained for PyHCP and PyHCP-800, respectively. Fig. 2 depicts SEM and TEM images of PyHCP and PyHCP-800. From the SEM images, both the materials showed spherical particles with uniform distribution and negligible amount of
Fig. 1. (a) FTIR spectrum, (b) XRD pattern, (c) Raman spectrum and (d) nitrogen sorption isotherms of synthesized materials.
H.-C. Jung et al. / Materials Letters 257 (2019) 126732
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Fig. 2. (a), (a1), (a2) and (b), (b1), (b2) represents the SEM images of PyHCP and PyHCP-800, respectively. (c), (c1), (c2) and (d), (d1), (d2) shows the TEM images of PyHCP and PyHCP-800, respectively. Inset of (c2) and (d2) depicts the SAED pattern of PyHCP and PyHCP-800, respectively.
agglomeration. The morphology of the samples didn’t change even pyrolysis at 800 °C. It clearly illustrates the stability of the HCPs. TEM images of PyHCP and PyHCP-800 also exhibits the same morphology with average size of each spheres around 120 nm. The low magnification TEM images and SAED pattern revealed porosity and amorphous nature of the materials, respectively. Fig. 3(a) shows the comparative CVs of PyHCP-800, PANI and PyHCP-800/PANI electrodes in 6 M KOH aqueous electrolyte at 50 mV s1. Among them, the composite electrode exhibits synergistic current–voltage response and in positive potential window of 0.1 to 0.6 V. The positive voltage window is a good sign for supercapacitor applications when compared to the negative potential window. Fig. 3(b) exhibits the EIS of PyHCP, PANI and PyHCP-800/PANI. Composite electrode possesses charge transfer resistance (Rct) along with straight line while the bare electrodes shows only straight line. It clearly signifies the composite electrode have improved conductivity, decreased ion movement obstruction and easier of electrochemical reaction [3]. Fig. 3(c) illustrates CVs
of PyHCP-800/PANI at different scan rate display quasi rectangular curves without any obvious redox peaks in the analyzed potential window, which clearly suggests a nearly ideal capacitance behavior. With increasing the scan rate, the peaks are slightly shifted to positive and negative potentials. It is mainly due to the capacitive diffusion control and mixture process including linear and capacitive diffusion [4]. The GCD curves of PyHCP-800/PANI (Fig. 3(d)) are almost symmetrical, suggesting high coulombic efficiency and good reversibility. The current density vs specific capacitance plot of PyHCP-800/PANI was shown in Fig. 3(e). The specific capacitances are 62.6, 48.5, 42.7, 34.78, 25.9 and 14.1 F g1 are 0.1, 0.2, 0.3, 0.5, 1.0 and 2.0 A g1, respectively. To access the feasibility of PyHCP-800/PANI, SSC device was fabricated. Fig. 4(a) shows the schematic illustration of the SSC device made-up of PyHCP-800/PANI on nickel mesh. Unlike PyHCP-800/PANI, SSC device no redox peaks observed and exhibits pseudocapacitance behavior within 0 to 1.5 V (Fig. 4(b)). The GCD curves of SSC at different current densities are shown
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H.-C. Jung et al. / Materials Letters 257 (2019) 126732
Fig. 3. Three electrode system in 6 M KOH electrolyte: (a) comparative CV curves at 50 mV s1, (b) comparative EIS spectra, (c) PyHCP-800/PANI at different scan rate, (d) PyHCP-800/PANI at different current density and (e) current density vs specific capacitance of PyHCP-800/PANI electrode.
in Fig. 4(c). Fig. 4(d) illustrates the Ragone plot of PyHCP-800 SSC device. The energy density reaches 3.72, 3.00, 0.97 and 0.57 Wh kg1 at the power density of 65.07, 129.79, 194.10 and 320.625 W kg1, respectively. The maximum specific capacitance was achieved for SSC device was 15.83 F g1 at 0.1 A g1. The current density versus specific capacitance plot was given in the inset of Fig. 4(d). For commercial application long cyclic stability is one of the key factors. The stability of the SSC device was tested over 2000 GCD cycles at 0.5 A g1. The materials retained 90.67%
of its initial specific capacitance after 2000 cycle (Fig. 4(e)). The SEM image was taken after 2000 cycles was depicted in the inset of Fig. 4(e). It clearly revealed even after 2000 cycles the electrode not damaged much. Fig. 4(f) shows the Nyquist plot of SSC device before and after 2000 GCD cycles. The SSC device displays almost similar resistance and charge transfer resistance before and after 2000 cycles. This is due to the large open surface area and good conductivity of the PyHCP-800/PANI, suggesting the excellent stability of the fabricated device.
H.-C. Jung et al. / Materials Letters 257 (2019) 126732
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Fig. 4. PyHCP-800/PANI || PyHCP-800/PANI device in 6 M KOH: (a) schematic illustration of SSC device, (b) different scan rate, (c) different current density, (d) Ragone plot, (e) cyclic stability test and (f) EIS spectra of before and after stability test. Inset of (d): Current density vs specific capacitance. Inset of (e): SEM image after the stability test.
4. Conclusions
Acknowledgements
In summary, we demonstrated a simple and efficient method to synthesize a novel composite electrode material from pyrene based HCP and PANI. The PyHCP-800/PANI composite electrode exhibited high specific capacitance of 62.6 F g1 at 0.1 A g1 in a 3-electrode system. The assembled device PyHCP-800/PANI || PyHCP-800/PANI possess maximum capacitance of 16.83 F g1 at 0.1 A g1 and 90.67% capacity retention after 2000 cycles. The corresponding energy density can reach 3.72 Wh kg1 with the power density of 65.07 W kg1.
The authors gratefully acknowledge the financial support from BK 21 PLUS, Creative Human Resource Development Program for IT Convergence, Pusan National University, Busan, South Korea. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.126732. References
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
[1] Y. Zhou, X. Zhou, C. Ge, W. Zhou, Y. Zhu, B. Xu, Mater. Lett. 246 (2019) 174–177. [2] J.M. Lee, M.E. Briggs, T. Hasell, A.I. Cooper, Adv. Mater. 28 (2016) 9804–9810. [3] J. Lü, Y. Zhang, Z. Lü, X. Huang, Z. Wang, X. Zhu, B. Wei, RSC Adv. 5 (2015) 5858– 5862. [4] X. Lang, X. Sun, Z. Liu, H. Nan, C. Li, X. Hu, H. Tian, Mater. Lett. 243 (2019) 34–37.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Novel composite electrode material derived from hypercross-linked polymer of pyrene and polyaniline for symmetric supercapacitor Hyun-Chul Jung, Rajangam Vinodh ⇑, Chandu V.V. Muralee Gopi, Moonsuk Yi, Hee-Je Kim ⇑ Department of Electrical and Computer Engineering, Pusan National University, Geumjeong-gu, Busan 46241, South Korea
a r t i c l e
i n f o
Article history: Received 13 August 2019 Received in revised form 5 September 2019 Accepted 22 September 2019 Available online 23 September 2019 Keywords: Pyrene Hypercross-linked polymer Polyaniline Symmetric supercapacitor Composite electrode
a b s t r a c t Herein, we report the fabrication of composite electrode (PyHCP-800/PANI) by two step method. Firstly, hypercross-linked polymer of pyrene (PyHCP) synthesized by a simple Friedel-Crafts alkylation method and subsequent carbonization at 800 °C to yield porous carbon of PyHCP (PyHCP-800). Secondly, polyaniline (PANI) was electrochemically grown on the surface of PyHCP-800. The synthesized PyHCP and PyHCP-800 was characterized by physicochemical characterization techniques. The composite shows excellent electrochemical behavior than pristine PyHCP-800 and PANI electrode. In three electrode system, PyHCP-800/PANI composite exhibits specific capacitance of 62.6 F g1 at 0.1 A g1. Also, the fabricated symmetric supercapacitor (SSC) device (PyHCP-800/PANI || PyHCP-800/PANI) delivers outstanding cycle life with 90.67% retention for 2000 cycles. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Supercapacitors (SCs) have gained much research consideration owing to its special characteristic properties of quick chargedischarge process, long cyclic stability, safe operation and good power output [1]. Up to date, various carbon based materials have been expansively explored due to the outstanding mechanical properties, excellent electrical conductivity, high surface area and good charge transfer capability. However, the low specific capacitance and energy density have extremely restricted their performances in practical applications. Recently, porous carbons derived from hypercross-linked polymers (HCPs) are considered to be one of the most alternative materials. Since, HCPs are microporous materials synthesized from cheap organic monomers that show good stability and potential for synthetic diversification. Permanent porosity in HCPs is a result of extensive cross-linking, which prevents the polymer chains from collapsing into a dense and no-porous state [2]. A new strategy for achieving high performance SCs and overcoming the poor resistance of porous carbon of PyHCP by electrochemically interweaving PyHCP-800 spheres with a conductive polymer, PANI. After electrochemical polymerization, the isolated carbon spheres are interconnected and linked up by the chains of PANI that act as bridges for electrons transportation between the external circuit and the internal surface of PyHCP-800. Herein, for the very first
time PyHCP-800@PANI based composite electrode was fabricated by a facile Friedel-Crafts alkylation followed by electrochemical polymerization technique. By using a 6 M KOH aqueous electrolyte in the 3-electrode system PyHCP-800@PANI electrode imposes a high specific capacitance of 62.6 F g1 at 0.1 A g1 current density. 2. Experimental 2.1. Synthesis of PyHCP and PyHCP-800 In a 250 mL round bottom flask, pyrene (4.9 mmol), paraformaldehyde (99 mmol) and 1, 2 dichloroethane (40 mL) were taken and stirred well at room temperature. Then ferric chloride (30.8 mmol) was slowly added into the above reaction mixture and the reaction was carried out for 24 h at 80 °C. After the completion of the reaction, the resultant brown colored precipitate was thoroughly washed several times with 1:1:1 ratio of water, HCl and ethanol mixture and dried in vacuum oven at 90 °C for overnight. The obtained material was pyrene based hypercrosslinked polymer and designated as PyHCP. PyHCP was subjected into carbonization at 800 °C for 6 h at argon atmosphere with the heating rate of 2 °C min1. The procured material was carbonized PyHCP and named as PyHCP-800. 2.2. Electrochemical polymerization of aniline onto PyHCP-800
⇑ Corresponding authors. E-mail addresses: [email protected] (R. Vinodh), [email protected] (H.-J. Kim). https://doi.org/10.1016/j.matlet.2019.126732 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
Nickel foam was used as the substrate material for the electrode fabrication. Pretreatment of nickel foam was given in Supporting
2
H.-C. Jung et al. / Materials Letters 257 (2019) 126732
information section. In brief, PyHCP-800 was well mixed with polyvinylidene fluoride, acetylene black and N-methyl 2pyrrolidone in mortar and pestle to form a thick slurry. The obtained slurry was uniformly coat into the pretreated nickel foam with the help of brush (1 cm 1 cm) and dried in an oven at 80 °C for 12 h. The prepared electrode was subjected into electrochemical polymerization of aniline in 1 mM aniline + 0.5 M sulfuric acid at 50 mV s1 between the potential window of 0 and 1 V vs. Ag/ AgCl electrode for 20 cycles. The prepared composite electrode was named as PyHCP-800/PANI. The active mass of the working electrode was ~4 mg. The cyclic voltammogram (CV) was depicted in Fig. S1. The materials and physicochemical characterization techniques was given in Supporting information section. The electrochemical impedance spectroscopy (EIS) was examined ranging the frequency from 0.01 Hz to 0.1 kHz. The specific capacitance of the PyHCP-800/PANI (three electrode system) and PyHCP-800/ PANI || PyHCP-800/PANI (symmetric supercapacitor) was calculated by the following Eq. (1).
Cs ¼
I t m DV
ð1Þ
where Cs is the specific capacitance (F g1), I represents the specified current (A), m is the mass of the electrode materials (g), DV signifies the potential window range (E) and t denotes the discharge time (s).
3. Results and discussion FTIR spectrum of PyHCP was exhibited in Fig. 1(a). The hypercross-linked quinonoid of pyrene polymer showed a broad band around 3500 cm1 due to –OH stretch of water. The sharp intense peaks from 1700 to 1600 cm1 are associated with quinonoid skeleton. The peaks below 1000 cm1 are assigned C–H bending modes. XRD pattern was shown in Fig. 1(b). In PyHCP no obvious diffraction peak except 22°, whereas in PyHCP-800 shows two diffraction peaks at around 22° and 46° which corresponds to (0 0 2) and (1 0 0) plane respectively with little shift. It convincingly establishes the amorphous nature of the carbon based materials. Raman spectrum of PyHCP-800 was depicted in Fig. 1(c). It exhibits D band at 1380 cm1 and G band at 1520 cm1. The identified peaks were well match with other carbon materials. The ID/IG ratio was found to be 0.81. It suggests the prepared materials was amorphous in nature. Both the materials exhibit type IV sorption isotherm (Fig. 1(d)) and sharp increase at high relative pressure (p/p0 = 1.0) implies the existence of macropores. But PyHCP-800 did not coincide with the adsorption isotherm. It clearly illustrates the presence of hierarchical pores (meso- and nano-pores). The surface area of 450 and 827 m2 g1 are attained for PyHCP and PyHCP-800, respectively. Fig. 2 depicts SEM and TEM images of PyHCP and PyHCP-800. From the SEM images, both the materials showed spherical particles with uniform distribution and negligible amount of
Fig. 1. (a) FTIR spectrum, (b) XRD pattern, (c) Raman spectrum and (d) nitrogen sorption isotherms of synthesized materials.
H.-C. Jung et al. / Materials Letters 257 (2019) 126732
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Fig. 2. (a), (a1), (a2) and (b), (b1), (b2) represents the SEM images of PyHCP and PyHCP-800, respectively. (c), (c1), (c2) and (d), (d1), (d2) shows the TEM images of PyHCP and PyHCP-800, respectively. Inset of (c2) and (d2) depicts the SAED pattern of PyHCP and PyHCP-800, respectively.
agglomeration. The morphology of the samples didn’t change even pyrolysis at 800 °C. It clearly illustrates the stability of the HCPs. TEM images of PyHCP and PyHCP-800 also exhibits the same morphology with average size of each spheres around 120 nm. The low magnification TEM images and SAED pattern revealed porosity and amorphous nature of the materials, respectively. Fig. 3(a) shows the comparative CVs of PyHCP-800, PANI and PyHCP-800/PANI electrodes in 6 M KOH aqueous electrolyte at 50 mV s1. Among them, the composite electrode exhibits synergistic current–voltage response and in positive potential window of 0.1 to 0.6 V. The positive voltage window is a good sign for supercapacitor applications when compared to the negative potential window. Fig. 3(b) exhibits the EIS of PyHCP, PANI and PyHCP-800/PANI. Composite electrode possesses charge transfer resistance (Rct) along with straight line while the bare electrodes shows only straight line. It clearly signifies the composite electrode have improved conductivity, decreased ion movement obstruction and easier of electrochemical reaction [3]. Fig. 3(c) illustrates CVs
of PyHCP-800/PANI at different scan rate display quasi rectangular curves without any obvious redox peaks in the analyzed potential window, which clearly suggests a nearly ideal capacitance behavior. With increasing the scan rate, the peaks are slightly shifted to positive and negative potentials. It is mainly due to the capacitive diffusion control and mixture process including linear and capacitive diffusion [4]. The GCD curves of PyHCP-800/PANI (Fig. 3(d)) are almost symmetrical, suggesting high coulombic efficiency and good reversibility. The current density vs specific capacitance plot of PyHCP-800/PANI was shown in Fig. 3(e). The specific capacitances are 62.6, 48.5, 42.7, 34.78, 25.9 and 14.1 F g1 are 0.1, 0.2, 0.3, 0.5, 1.0 and 2.0 A g1, respectively. To access the feasibility of PyHCP-800/PANI, SSC device was fabricated. Fig. 4(a) shows the schematic illustration of the SSC device made-up of PyHCP-800/PANI on nickel mesh. Unlike PyHCP-800/PANI, SSC device no redox peaks observed and exhibits pseudocapacitance behavior within 0 to 1.5 V (Fig. 4(b)). The GCD curves of SSC at different current densities are shown
4
H.-C. Jung et al. / Materials Letters 257 (2019) 126732
Fig. 3. Three electrode system in 6 M KOH electrolyte: (a) comparative CV curves at 50 mV s1, (b) comparative EIS spectra, (c) PyHCP-800/PANI at different scan rate, (d) PyHCP-800/PANI at different current density and (e) current density vs specific capacitance of PyHCP-800/PANI electrode.
in Fig. 4(c). Fig. 4(d) illustrates the Ragone plot of PyHCP-800 SSC device. The energy density reaches 3.72, 3.00, 0.97 and 0.57 Wh kg1 at the power density of 65.07, 129.79, 194.10 and 320.625 W kg1, respectively. The maximum specific capacitance was achieved for SSC device was 15.83 F g1 at 0.1 A g1. The current density versus specific capacitance plot was given in the inset of Fig. 4(d). For commercial application long cyclic stability is one of the key factors. The stability of the SSC device was tested over 2000 GCD cycles at 0.5 A g1. The materials retained 90.67%
of its initial specific capacitance after 2000 cycle (Fig. 4(e)). The SEM image was taken after 2000 cycles was depicted in the inset of Fig. 4(e). It clearly revealed even after 2000 cycles the electrode not damaged much. Fig. 4(f) shows the Nyquist plot of SSC device before and after 2000 GCD cycles. The SSC device displays almost similar resistance and charge transfer resistance before and after 2000 cycles. This is due to the large open surface area and good conductivity of the PyHCP-800/PANI, suggesting the excellent stability of the fabricated device.
H.-C. Jung et al. / Materials Letters 257 (2019) 126732
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Fig. 4. PyHCP-800/PANI || PyHCP-800/PANI device in 6 M KOH: (a) schematic illustration of SSC device, (b) different scan rate, (c) different current density, (d) Ragone plot, (e) cyclic stability test and (f) EIS spectra of before and after stability test. Inset of (d): Current density vs specific capacitance. Inset of (e): SEM image after the stability test.
4. Conclusions
Acknowledgements
In summary, we demonstrated a simple and efficient method to synthesize a novel composite electrode material from pyrene based HCP and PANI. The PyHCP-800/PANI composite electrode exhibited high specific capacitance of 62.6 F g1 at 0.1 A g1 in a 3-electrode system. The assembled device PyHCP-800/PANI || PyHCP-800/PANI possess maximum capacitance of 16.83 F g1 at 0.1 A g1 and 90.67% capacity retention after 2000 cycles. The corresponding energy density can reach 3.72 Wh kg1 with the power density of 65.07 W kg1.
The authors gratefully acknowledge the financial support from BK 21 PLUS, Creative Human Resource Development Program for IT Convergence, Pusan National University, Busan, South Korea. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.126732. References
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
[1] Y. Zhou, X. Zhou, C. Ge, W. Zhou, Y. Zhu, B. Xu, Mater. Lett. 246 (2019) 174–177. [2] J.M. Lee, M.E. Briggs, T. Hasell, A.I. Cooper, Adv. Mater. 28 (2016) 9804–9810. [3] J. Lü, Y. Zhang, Z. Lü, X. Huang, Z. Wang, X. Zhu, B. Wei, RSC Adv. 5 (2015) 5858– 5862. [4] X. Lang, X. Sun, Z. Liu, H. Nan, C. Li, X. Hu, H. Tian, Mater. Lett. 243 (2019) 34–37.