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Abstract

In this study, polyacrylonitrile (PAN) nanofiber yarns were obtained by twisting the nanofiber mat strips produced in the electrospinning device. On the drum collector, the nanofibers are produced in such a way that the diameter change can be controlled. Through stabilization and carbonization processes, PAN nanofiber yarns were converted to carbon nanofiber (CNF) yarns. The stabilization process stabilized the yarn structure, which was previously unstable, due to thermal treatments. The obtained CNF yarn had a diameter of approximately 360 μm and an average nanofiber diameter of 123 ± 20 nm. On a three-electrode system, the electrochemical performance of CNF yarn in 1 m H₂SO₄ electrolyte was determined using cyclic voltammetry and galvanostatic charge/discharge test methods. The specific capacitance of the CNF yarn electrode was determined to be 145 F/g at a current density of 0.2 A/g. Up to 500 charge/discharge cycles, the specific capacitance increased by approximately 20% and remained constant thereafter. Due to their superior properties such as high surface area, lightweight, and flexibility, CNF yarn electrodes can be used in a wide variety of electronic applications, including energy harvesting, energy storage (supercapacitors, batteries, etc.), and sensors.

Keywords

Carbon nanofiber yarn fiber supercapacitor electrospinning fiber-based energy storage flexible electrode

Introduction

Embedding electronic technologies in flexible and stretchable materials is a remarkable development that has sparked widespread interest in recent years and paved the way for wearable electronics and smart textile applications.¹ While electronic devices can be applied to textile surfaces by reducing them to two-dimensional structures, reducing them to one-dimensional fiber confers superior properties such as ultra-flexibility, tissue adaptability, and weavability on these structures.² This type of fiber electronics is used in a variety of applications, including energy harvesting,^3–10 energy storage,^11–17 and sensors.¹⁸

To ensure the widespread adoption of smart textile products, it is critical to address their energy requirements. Due to the disadvantages of conventional batteries, such as their high weight, short battery life, lengthy charging time, heavy metal content, and inability to be used in a variety of applications, researchers are concentrating their efforts on alternative energy storage technologies.^17,19–22 Supercapacitors are energy storage devices that can be used in place of batteries in a variety of applications by increasing their energy density, acting as a bridge between high-energy batteries and high-power capacitors.²² Supercapacitors have a number of advantages, including ability to be manufactured from flexible materials, environmental friendliness, light weight, long life, rapid charging/discharging, and high energy and power density.^23–33 Due to these superior properties, supercapacitors are the most promising candidate for energy-storing smart textiles.

Supercapacitors are divided into three categories according to the type of material used. These are electrical double-layer capacitors, pseudocapacitors, and hybrid supercapacitors. The most common type is electrical double-layer capacitors, and in such capacitors where carbon-based materials are used as electrodes, the charge is stored at the electrode/electrolyte interface by electrostatic interactions. For this reason, it is of great importance that the electrode material has a large surface area. For many years, activated carbon has been used as electrode material in supercapacitors due to its large surface area. In recent years, carbon-based alternative materials such as graphene, carbon nanotube, carbon nanofiber (CNF) with large surface area, and good electrical conductivity have been used in supercapacitors.²⁹

Fiber electrodes are the most critical component in the development of fiber-based supercapacitors. Numerous yarn supercapacitor studies have been published in the literature using electrode materials such as graphene yarn,^15,34–37 and carbon nanotube yarn.^38–42 Several studies have been conducted on the production of carbon nanofiber yarns as a substitute for these materials and on their use as supercapacitor electrodes.⁴³

Foroughi et al. deposited graphene flakes on the surface of multi-walled carbon nanotubes (MWNT) sheets and then twisted it to obtain highly conductive carbon nanotube/graphene hybrid yarns. The specific capacitance value of this hybrid yarn was measured as 111 F/g at a scanning speed of 2 mV/s, which shows that it has 425% higher electrochemical performance than the pristine MWCNT yarn.⁴⁴

Lu et al. obtained hybrid carbon nanotube/graphene yarn by using wet spinning method in their study and examined its properties. It has been observed that the obtained hybrid yarn has a specific capacitance value of approximately 60 F/g at a scanning rate of 10 mV/s.⁴⁵

Jia et al. fabricated aligned carbon nanofiber yarn by the solution blown method. The electrochemical performance of the obtained CNF yarn electrodes was investigated. CNF electrodes showed 70 F/g specific capacitance at 0.5 A/g current density.⁴⁶

In their study, Zhuang et al. succeeded in producing continuous carbon nanofiber yarn (CNFY) by solution blowing technique. The specific capacitance of CNFY electrodes was measured as 15.8 F/g at 2 A/g current density.⁴³

In the literature, there are studies on producing continuous nanofiber yarns using different mechanisms.^47–50 In some studies, the nanofiber is collected on a metal funnel, and then the material is twisted and winded into a bobbin.^{18,43,47,49,51–53} In this method, nanofiber yarn can be produced with a continuous system, but it has some disadvantages. There are breaks during production and also nanofiber diameter control becomes difficult. In our study, as an alternative to the nanofiber yarn production method used in the literature, nanofiber and yarn diameters can be controlled more easily and staple nanofiber yarns in meter sizes can be produced.

The optimal conditions for the polyacrylonitrile (PAN) nanofiber production and carbonization processes study were established in our previous researches,^54,55 and in this study, homogeneous PAN nanofiber mats collected on an aluminum drum capable of being rotated at various speeds were cut to a strip with specified width and twisted into yarn. Stabilizing and carbonizing the produced PAN nanofiber yarns resulted in the formation of flexible CNFY. Following that, the electrochemical properties of CNFY were characterized, as well as their suitability for use as supercapacitor electrodes.

Materials and method

Materials

Polyacrylonitrile (M_w = 150,000 g/mol) was purchased from J & K Scientific (Shanghai, China). N,N-dimethylformamide (DMF, ≥99 wt%), dimethyl sulfoxide (DMSO, ≥ 99.9 wt%), and sulfuric acid (H₂SO₄, 95–98%) were purchased from Acros Chemical (USA) and used without further purification. Unless otherwise specified, all aqueous solutions were prepared using deionized (DI) water.

Production of polyacrylonitrile nanofiber yarn

For nanofiber production, the Inovenso Nanospinner 24 electrospinning device was used in conjunction with the drum apparatus. To begin, a 1.5 cm wide and 300 cm long aluminum foil band was wound at an angle onto the aluminum drum, followed by electrospinning 10 mL of 7.5% PAN solution in DMF:DMSO (2:1) under previously optimized conditions (17.5 cm distance, 2 mL/h feed rate, 28 kV applied voltage).⁵⁴ At the end of production, the aluminum foil band was removed from the aluminum drum and the 300-cm-long band was cut to a width of 0.5 cm. Following that, a PAN nanofiber strip with a width of 0.5 cm and a length of 300 cm was removed from the aluminum band. The PAN nanofiber strip was fixed on one side and 333 turns per meter were applied. The schematic representation of the production of PAN nanofiber yarn is shown in Figure 1.

Figure 1.

Schematic illustration of polyacrylonitrile nanofiber yarn production.

Production of carbon nanofiber yarn

Our previous method^54,55 was followed and a new method was presented here to produce carbon nanofiber yarn. After obtained PAN nanofiber yarns wound around the glass beaker and fixed them at the ends, they were heated to 300°C at a heating rate of 10 ⁰C/min in an air environment and then, stabilized for 90 min at 300°C. Afterward, stabilized PAN nanofiber yarns were heated to 280°C at a rate of 10 C/min in an argon atmosphere and kept at 280°C for 60 min. When the twisting force is removed, the yarn structure is deformed. However, the PAN nanofiber yarn structure was stabilized after the thermal stabilization process. Following that, carbon nanofiber yarns were obtained by heating to 1000°C at a rate of 5°C/min and carbonizing for 3 h at 1000°C. Figure 2 illustrates the flexibility of carbon nanofiber yarns. Even after carbonization, it is possible to bend and twist flexible nanofiber yarns by moving them up and down (Supplementary Video S1-S2).

Figure 2.

Demonstration of the flexibility of the obtained carbon nanofiber yarn.

Materials characterization

The surface morphology of the samples was examined using a field emission scanning electron microscope (FE-SEM) (Zeiss-Gemini 300) equipped with a field emission electron gun operating at a voltage of 5 kV and working distances ranging from 5.4 to 8.6 mm. Nanofiber diameters were calculated using the ImageJ 1.51j8 program.

The electrochemical characterization of carbon nanofiber yarn electrodes

The electrochemical properties of CNF yarn electrodes were determined using a three-electrode configuration electrochemical workstation (CH-Instrument 608E). The reference electrode was an Ag/AgCl (1M KCl) electrode, and the counter electrode was a Pt wire. In 1 m H₂SO₄ as the electrolyte, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements were made. Each analysis excluded the first cycle of CV and GCD measurements. CV tests were conducted at scan rates ranging from 0.5 mV/s to 100 mV/s in the potential range of 0–1V. At 0.086 V and room temperature, EIS analyses were performed in the frequency range of 0.1 Hz–100 kHz.

The gravimetric capacitance was measured using equation (1)^56–62 and (2)^63,64 for CV and GCD, respectively

C_{s} = \frac{\int_{V_{a}}^{V_{b}} I (V) d V}{2 m v (V_{b} - V_{a})}

(1)

C_{s c} = \frac{i Δ t}{m Δ V}

(2)

where C_s and C_sc (F/g) are specific capacitances, m (g) is the mass of loaded active electrode materials, v (V/s) is the scan rate, ∆V (V) is the potential window, and V_a and V_b (V) are high and low potential limit, ∆t (s) is the time of discharge.

Results and discussions

Figure 3 shows SEM images of PAN nanofiber yarn, stabilized PAN nanofiber yarn, and carbon nanofiber yarn. Supplementary Figure S1 illustrates the average nanofiber diameters of nanofiber yarn.

Figure 3.

Scanning electron microscope images of (a) PAN nanofiber, (b) stabilized PAN nanofiber yarn, (c) carbon nanofiber yarn. PAN: Polyacrylonitrile.

While the diameter of the PAN nanofibers was 206 ± 35 nm, after stabilization and carbonization, the nanofiber diameter decreased to 155 ± 54 nm, and yarns with an average nanofiber diameter of 123 ± 20 nm were obtained. The carbon nanofiber yarn had a diameter of approximately 360 μm. As demonstrated by SEM images, the smooth nanofiber structure was preserved after twisting, winding and thermal processing. However, unlike the carbon nanofiber surfaces shown previously,^54,55 excessive breaks in the carbon nanofibers in nanofiber yarns were observed after twisting process.

Figure 4 shows Fourier-transform infrared spectroscopy (FT-IR) spectrum of PAN nanofiber, stabilized PAN nanofiber, and carbon nanofiber yarns. The very similar FT-IR spectrum was detailed discussed in our previous paper.⁵⁵ FT-IR analysis revealed that PAN nanofiber yarn was successfully stabilized, and carbonized to produced carbon nanofiber yarn.^55,65

Figure 4.

FT-IR spectrum of produced nanofiber yarns.

The CV curves of carbon nanofiber yarn electrodes in the 0–1V potential range at scanning rates ranging from 0.5 to 100 mV/s are shown in Figure 5(a). The scanning rate range of 0.5–5 mV/s is highlighted in Figure 5(b). The CV curves do not show any redox peaks, then which is evidence that the electrode behaves like a double-layer capacitor. On the other hand, while CV curves were close to rectangular shapes (quasi-rectangular shapes) at low scanning rate, they shifted to oval like shapes with increasing scanning rate.^66,67 This change in CV curve shape at high scanning rates is indicative of poor rate performance and higher internal resistance.⁶⁸

Figure 5.

Cyclic voltammetry curves for carbon nanofiber yarns (a) in the range of 0.5–100 mV/s scanning speed (b) in the range of 0.5–5 mV/s scanning rate.

Capacitance values were calculated using equation (1) from CV curves with a scanning rate of 0.5–100 mV/s are shown in Supplementary Figure S2. At scan rates of 0.5, 1, 2, 5, 10, 25, 50, and 100 mV/s, the specific capacitance was 80, 66, 59, 38, 29, 17, 11, and 5 F/g, respectively.

The GCD curves of the carbon nanofiber yarn electrode at current densities of 0.2–2 A/g are shown in Figure 6. Charge/discharge curves have been observed to have a nearly symmetrical shape. The values of specific capacitance calculated from the GCD curves using equation (2) are plotted in Supplementary Figure S3. Specific capacitance values of 145, 78, 53, 42, 30, and 21 F/g were calculated at current densities of 0.2, 0.3, 0.5, 1, 1.5, and 2 A/g, respectively.

Figure 6.

Galvanostatic charge/discharge curves at different current densities (a) in the range of 0.2–2 A/g current density, (b) in the range of 0.5–2 A/g current density.

In Figure 7(a), 1–10 GCD cycles are plotted. It exhibits similar charge/discharge curves throughout the cycle. The change in specific capacitance over 1000 charge/discharge cycles in the 0–1 V potential range at 1 A/g current density is depicted in Figure 7(b). The specific capacitance value of the carbon nanofiber yarn electrode increased by 20% until approximately 500 cycles, and this capacitance value was observed to be maintained thereafter. Ismar et al. observed an increase in the specific capacitance value following a charge/discharge cycle in a system containing 0.5 m H₂SO₄ electrolyte.²⁹ This increase is thought to be due to the gradual activation of the CNF yarn surface and improved electrolyte ion access to the pores following the charge/discharge cycle.^29,69

Figure 7.

Galvanostatic charge/discharge cycles at a current density of 1 A/g (a) 1–10 charge/discharge cycles, (b) Cyclic stability for 1000 charge/discharge cycles at 1 A/g current density.

The equivalent-series resistance (i.e., R_ESR) and the charge-transfer resistance (i.e., R_ct) of the CNF yarn electrode was determined by EIS and Figure 8 shows Nyquist plot of CNF yarn over the frequency range of 0.01 Hz–100 kHz at open circuit potential (0.456 V). In the Nyquist curve of ideal supercapacitors, a semi-circle in the high-frequency region and a vertical line in the low-frequency region are observed. In the high-frequency region of the above Nyquist curve, a semi-circle is observed, although it is very small. The value at which the semi-circle first intersect the Z^′ curve gives the R_ESR, while the diameter of the semi-circle gives the value R_ct.^70,71 Based on the Nyquist plot, R_ESR and R_ct was measured as 451.90 Ω and ∼9 Ω, respectively.

Figure 8.

Nyquist plots of the carbon nanofiber yarn electrode, the inset displays the zoom-in of Nyquist plots.

Conclusion

In this study, first PAN nanofiber yarns were obtained by twisting nanofiber strips with easily controllable diameters on the drum collector. Then, PAN nanofiber yarns were converted to carbon nanofiber yarns via stabilization and carbonization processes. After the stabilization process, it was observed that the unstable yarn structure became stable due to the thermal processes. The obtained CNF yarns had a yarn diameter of approximately 360 μm, and the average diameter of the nanofibers in the yarn was 123 ± 20 nm. Following that, the electrochemical performance of CNF yarns in 1 m H₂SO₄ electrolyte was determined using CV and GCD test methods on a three-electrode system. At a current density of 0.2 A/g, the specific capacitance of the CNF yarn electrode was determined to be 145 F/g. Additionally, the cyclic stability of the device was investigated over a period of 1000 charge/discharge cycles. The specific capacitance value increases by approximately 20% until 500 charge/discharge cycles, at which point it remains constant.

Supplemental Material

Supplemental Material - Flexible carbon nanofiber yarn electrodes for self-standing fiber supercapacitors

Supplementary Material for Flexible carbon nanofiber yarn electrodes for self-standing fiber supercapacitors by Yasin Altin and Ayse Celik Bedeloglu in Journal of Industrial Textiles.

Footnotes

Acknowledgements

Thanks to Prof. Dr Deniz Uzunsoy, Research Assistant Taha Yasin Eken and BTU-Metallurgy and Materials Engineering lab for their help on electrochemical workstation and tube furnace usage.

Author contributions

The manuscript was written through the contributions of all authors. All authors have approved the final version of the manuscript.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported as a PhD research project by Bursa Technical University Scientific Research Project (BAP) Unit, Project Number: 172D32.

ORCID iDs

Yasin Altin

Ayse Celik Bedeloglu

Supplemental Material

Supplemental material for this article is available online.

References

Wicaksono

Tucker

Sun

, et al. A tailored, electronic textile conformable suit for large-scale spatiotemporal physiological sensing in vivo. Npj Flex Electron 2020; 4: 1–13.

Xie

Zhang

, et al. The rise of fiber electronics. Angew Chem Int Ed Engl 2019; 58: 13643–13653.

Bedeloglu

Demir

Bozkurt

, et al. A photovoltaic fiber design for smart textiles. Text Res J 2010; 80: 1065–1074.

Celik Bedeloglu

Demir

Bozkurt

, et al. Photovoltaic properties of polymer based organic solar cells adapted for non-transparent substrates. Renew Energy 2010; 35: 2301–2306.

Bedeloglu

Koeppe

Demir

, et al. Development of energy generating photovoltaic textile structures for smart applications. Fibers Polym 2010; 11: 378–383.

Bedeloglu

Jimenez

Demir

, et al. Photovoltaic textile structure using polyaniline/carbon nanotube composite materials. J Text Inst 2011; 102: 857–862.

Borazan

. A study about lifetime of photovoltaic fibers. Sol Energy Mater Sol Cells 2019; 192: 52–56.

Borazan

Bedeloglu

Demir

. The effect of MWCNT-PEDOT:PSS layer in organic photovoltaic fiber device. Optoelectron Adv Mater Rapid Commun 2015; 9: 347–352.

Park

Kwon

Sung

, et al. Poling-free spinning process of manufacturing piezoelectric yarns for textile applications. Mater Des 2019; 179: 107889.

10.

Zhou

Zhang

Han

, et al. Woven structured triboelectric nanogenerator for wearable devices. ACS Appl Mater Interfaces 2014; 6(16): 14695–14701.

11.

Yang

Deng

Chen

, et al. A highly stretchable, fiber-shaped supercapacitor. Angew Chem Int Ed Engl 2013; 52: 13453–13457.

12.

Liu

Tao

, et al. Cable-type supercapacitors of three-dimensional cotton thread based multi-grade nanostructures for wearable energy storage. Adv Mater 2013; 25: 4925–4931.

13.

Kim

Ghosh

, et al. Coaxial fiber supercapacitor using all-carbon material electrodes. ACS Nano 2013; 7: 5940–5947.

14.

Jiang

Shang

Sun

, et al. Flexible and multi-form solid-state supercapacitors based on polyaniline/graphene oxide/CNT composite films and fibers. Diam Relat Mater 2019; 92: 198–207.

15.

Aboutalebi

Jalili

Esrafilzadeh

, et al. High-performance multifunctional graphene yarns: toward wearable all-carbon energy storage textiles. ACS Nano 2014; 8: 2456–2466.

16.

Park

Ambade

Noh

, et al. Porous graphene-carbon nanotube scaffolds for fiber supercapacitors. ACS Appl Mater Interfaces 2019; 11: 9011–9022.

17.

Liu

, et al. Wearable self-charging power textile based on flexible yarn supercapacitors and fabric nanogenerators. Adv Mater 2016; 28: 98–105.

18.

Yan

Wang

Y-Q

, et al. Carbon/graphene composite nanofiber yarns for highly sensitive strain sensors. Mater Des 2018; 143: 214–223.

19.

Fang

Hassan

SIS

Rahim

RBA

, et al. A review of techniques design acoustic energy harvesting. In: 2015 IEEE Student Conference on Research and Development (SCOReD 2015), Kuala Lumpur, Malaysia, 13–14 December 2015, pp. 37–42.

20.

Bakandritsos

Jakubec

Pykal

, et al. Covalently functionalized graphene as a supercapacitor electrode material. FlatChem 2019; 13: 25–33.

21.

Ren

Cong

. Review of electrical energy storage system for vehicular applications. Renew Sustain Energy Rev 2015; 41: 225–236.

22.

Zhao

Liu

Beirne

, et al. Recent development of fabricating flexible micro-supercapacitors for wearable devices. Adv Mater Technol 2018; 3: 1800028.

23.

Liu

Yan

, et al. Wearable energy-dense and power-dense supercapacitor yarns enabled by scalable graphene-metallic textile composite electrodes. Nat Commun 2015; 6: 7260.

24.

Fic

Platek

Piwek

, et al. Sustainable materials for electrochemical capacitors. Mater Today 2018; 21: 437–454.

25.

Jost

Dion

Gogotsi

. Textile energy storage in perspective. J Mater Chem A 2014; 2: 10776–10787.

26.

Winter

Brodd

. What are batteries, fuel cells, and supercapacitors? Chem Rev 2004; 104: 4245–4270.

27.

Simon

Gogotsi

Dunn

. Where do batteries end and supercapacitors begin? Science 2014; 343: 1210–1211.

28.

Zheng

Cai

, et al. Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors. ACS Appl Mater Interfaces 2015; 7: 3263–3271.

29.

Ismar

Karazehir

Ates

, et al. Electrospun carbon nanofiber web electrode: supercapacitor behavior in various electrolytes. J Appl Polym Sci 2018; 135: 1–10.

30.

Sun

Sills

, et al. A bamboo-inspired nanostructure design for flexible, foldable, and twistable energy storage devices. Nano Lett 2015; 15: 3899–3906.

31.

Dong

, et al. Flexible electrodes and supercapacitors for wearable energy storage: a review by category. J Mater Chem A 2016; 4: 4659–4685.

32.

Wang

, et al. Flexible solid-state supercapacitors: design, fabrication and applications. Energy Environ Sci 2014; 7: 2160–2181.

33.

Jost

Perez

McDonough

, et al. Carbon coated textiles for flexible energy storage. Energy Environ Sci 2011; 4: 5060–5067.

34.

Cheng

, et al. A fiber supercapacitor with high energy density based on hollow graphene/conducting polymer fiber electrode. Adv Mater 2016; 28: 3646–3652.

35.

Shan

Wang

, et al. Mordant inspired wet-spinning of graphene fibers for high performance flexible supercapacitors. J Mater Chem A 2019; 7: 6869–6876.

36.

Chen

Liu

Zhao

, et al. Graphene-based fibers for supercapacitor applications. Nanotechnology 2015; 27: 032001.

37.

Meng

Zhao

, et al. All-graphene core-sheath microfibers for all-solid-state, stretchable fibriform supercapacitors and wearable electronic textiles. Adv Mater 2013; 25: 2326–2331.

38.

Cao

, et al. Carbon nanotube fiber based stretchable wire-shaped supercapacitors. Adv Energy Mater 2014; 4: 1300759.

39.

Ren

Bai

Guan

, et al. Flexible and weaveable capacitor wire based on a carbon nanocomposite fiber. Adv Mater 2013; 25: 5965–5970.

40.

Choi

Park

Kim

, et al. Weavable asymmetric carbon nanotube yarn supercapacitor for electronic textiles. RSC Adv 2018; 8: 13112–13120.

41.

Jeong

Park

Lee

, et al. Electrodeposition of α-MnO2/γ-MnO2 on carbon nanotube for yarn supercapacitor. Sci Rep 2019; 9: 11271.

42.

Park

Lee

Kim

, et al. Highly loaded MXene/carbon nanotube yarn electrodes for improved asymmetric supercapacitor performance. MRS Commun 2019; 9: 114–121.

43.

Zhuang

Jia

Cheng

, et al. Solution blowing of continuous carbon nanofiber yarn and its electrochemical performance for supercapacitors. Chem Eng J 2014; 237: 308–311.

44.

Foroughi

Spinks

Antiohos

, et al. Highly conductive carbon nanotube-graphene hybrid yarn. Adv Funct Mater 2014; 24: 5859–5865.

45.

Foroughi

Wang

, et al. Superelastic hybrid CNT/graphene fibers for wearable energy storage. Adv Energy Mater 2018; 8: 1702047.

46.

Jia

Zhuang

Cheng

, et al. Solution blown aligned carbon nanofiber yarn as supercapacitor electrode. J Mater Sci Mater Electron 2013; 24: 4769–4773.

47.

Xie

Niu

Lin

. Continuous polyacrylonitrile nanofiber yarns: preparation and dry-drawing treatment for carbon nanofiber production. RSC Adv 2015; 5: 15147–15153.

48.

Zhou

Wang

, et al. Fabrication of superhydrophobic nanofiber fabric with hierarchical nanofiber structure. E-polymers 2017; 17: 249–254.

49.

Zhou

, et al. Continuous twisted nanofiber yarns fabricated by double conjugate electrospinning. Fibers Polym 2013; 14: 1857–1863.

50.

Yan

Pan

. High conductivity electrospun carbon/graphene composite nanofiber yarns. Polym Eng Sci 2018; 58: 903–912.

51.

Zhou

Wang

, et al. Carbon nanofiber yarns fabricated from co-electrospun nanofibers. Mater Des 2016; 95: 591–598.

52.

Demir

Acikabak

Ahan

. Development of carbon nanofiber yarns by electrospinning. In: IOP Conference Series: Materials Science and Engineering, Padang, Indonesia, 8–9 November 2018, p. 012027.

53.

Chawla

Naraghi

Davoudi

. Effect of twist and porosity on the electrical conductivity of carbon nanofiber yarns. Nanotechnology 2013; 24: 255708.

54.

Altin

Celik Bedeloglu

. Polyacrylonitrile/polyvinyl alcohol-based porous carbon nanofiber electrodes for supercapacitor applications. Int J Energy Res 2021; 45: 16497–16510.

55.

Altin

Bedeloglu

. Polyacrylonitrile nanofiber optimization as precursor of carbon nanofibers for supercapacitors. J Innov Sci Eng 2020; 4: 69–83.

56.

Yang

Mai

. Flexible solid-state electrochemical supercapacitors. Nano Energy 2014; 8: 274–290.

57.

Zhang

Gong

. Improvement in flexibility and volumetric performance for supercapacitor application and the effect of Ni-Fe ratio on electrode behaviour. J Mater Chem A 2015; 3: 7607–7615.

58.

Marcelina

Syakir

Wyantuti

, et al. Characteristic of thermally reduced graphene oxide as supercapacitors electrode materials. IOP Conf Ser Mater Sci Eng 2017; 196: 012034.

59.

Kim

, et al. Electrochemical supercapacitors for energy storage and conversion. In: Handbook of clean energy systems. Hoboken, NJ: Wiley, 2015, pp. 1–25.

60.

Nabi

Raza

Kamran

, et al. Role of cerium-doping in CoFe2O4 electrodes for high performance supercapacitors. J Energy Storage 2020; 29: 101452.

61.

Shaikh

Rabinal

. Rapid ambient growth of copper sulfide microstructures: binder free electrodes for supercapacitor. J Energy Storage 2020; 28: 101288.

62.

Liu

, et al. sp3-Defect and pore engineered carbon framework for high energy density supercapacitors. J Power Sources 2020; 464: 228203.

63.

Bhujel

Rai

Deka

, et al. Electrochemical, bonding network and electrical properties of reduced graphene oxide-Fe2O3 nanocomposite for supercapacitor electrodes applications. J Alloys Compd 2019; 792: 250–259.

64.

Agyemang

Tomboc

Kwofie

, et al. Electrospun carbon nanofiber-carbon nanotubes coated polyaniline composites with improved electrochemical properties for supercapacitors. Electrochim Acta 2018; 259: 1110–1119.

65.

Ismar

Sarac

. Oxidation of polyacrylonitrile nanofiber webs as a precursor for carbon nanofiber: aligned and non-aligned nanofibers. Polym Bull 2018; 75: 485–499.

66.

Mohammed

Chen

Zhu

. Low-cost, high-performance supercapacitor based on activated carbon electrode materials derived from baobab fruit shells. J Colloid Interface Sci 2019; 538: 308–319.

67.

Mahanta

Venkatesh

Sujatha

, et al. Imidazolium based ionic liquids as electrolytes for energy efficient electrical double layer capacitor: insights from molecular dynamics and electrochemical characterization. J Solut Chem 2019; 48: 1119–1134.

68.

Hao

Huang

, et al. Bio-templated fabrication of three-dimensional network activated carbons derived from mycelium pellets for supercapacitor applications. Sci Rep 2018; 8: 562.

69.

Zequine

Ranaweera

Wang

, et al. High per formance and flexible supercapacitors based on carbonized bamboo fibers for wide temperature applications. Sci Rep 2016; 6: 31704.

70.

Altin

Celik Bedeloglu

. Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate-coated carbon nanofiber electrodes via dip-coating method for supercapacitor applications. J Mater Sci Mater Electron 2021; 32: 28234–28244.

71.

Vicentini

Da Silva

Cecilio

EP,

Jr , et al. How to measure and calculate equivalent series resistance of electric double-layer capacitors. Molecules 2019; 24: 1452.

Supplementary Material

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