Ni(OH)2 two dimension nanocomposites for high performance supercapacitors

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Contents lists available at ScienceDirect

Advanced Powder Technology journal homepage: www.elsevier.com/locate/apt

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Original Research Paper

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A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors

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Jie Tian, Qian San, Xianglu Yin, Wei Wu ⇑

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State Key Laboratory of Organic-Inorganic Composites and College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China

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a r t i c l e

i n f o

Article history: Received 18 July 2019 Received in revised form 17 September 2019 Accepted 19 September 2019 Available online xxxx Keywords: Ni(OH)2 composite Graphene/graphene oxide (G/GO) nanosheets Supercapacitor

a b s t r a c t A Ni(OH)2 composite with good electrochemical performances was prepared by a facile method. Ni(OH)2 was homogeneously grown on the hydrophilic graphene/graphene oxide (G/GO) nanosheets, which can be prepared in large scale in my lab. Then G/GO/Ni(OH)2 was reduced by L-Ascorbic acid to obtain G/RGO/ Ni(OH)2. Caused by the synergy effects among the components, the G/RGO/Ni(OH)2 electrode showed good electrochemical properties. The G/RGO/Ni(OH)2 electrode possessed a specific capacitance as high as 1510 F g 1 at 2 A g 1 and even 890 F g 1 at 40 A g 1. An asymmetric supercapacitor device consisting of G/RGO/Ni(OH)2 and reduced graphene oxide (RGO) was installed and displayed a high energy density of 44.9 W h kg 1 at the power energy density of 400.1 W kg 1. It was verified that the G/GO nanosheets are ideal supporting material in supercapacitor. Ó 2019 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved.

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1. Introduction

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Over the past decade, with the rapid consumption of fossil fuel and the increasingly serious environmental pollution, there has been a strong desire to explore new energy storage equipment [1–3]. Among available equipment of storing energy, supercapacitors have attracted wide attentions due to their excellent features [4–6]. Usually supercapacitors are divided into three categories: electrical double layer capacitors (EDLCs), pseudocapacitors, and hybrid capacitors. EDLCs, depending on physical adsorption and desorption of ions, have a low specific capacitance [7]. Pseudocapacitors, relying on the faradaic reactions of electrodes, possess high energy density and poor cycling stability [8,9]. To optimize the above two supercapacitor, researchers have designed hybrid supercapacitors combining EDLCs and pseudocapacitors [10]. Usually carbon materials (graphene, carbon nanofibers) are employed as electrode materials for EDLCs. Metal oxides or metal hydroxides (for MnO2, Ni(OH)2) and conducting polymers (such as polyaniline) are used as an electrode material for pseudocapacitors. Compared with EDLCs, pseudocapacitors possess ideal capacity. In recent years, transition-metal oxide or hydroxides materials for pseudocapacitor have attracted attentions of academia due to high theoretical capacity. In all of them, Ni(OH)2 stands out for its low cost and excellent theoretical capacity. In reported articles,

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⇑ Corresponding author.

low conductivity, low power performance and poor cycling stability limit practical applications of Ni(OH)2 [11–13]. Graphene, with remarkable characteristics (such as high electrical conductivity), has attracted worldwide attention since its advent. A lot of experiments show that graphene or graphene oxide is an ideal supporting matrix for active materials [14–16]. In situ reaction of nickel salts in graphene or graphene oxide suspension is a common synthetic route to prepare graphene/Ni(OH)2 composite. Wang [17] reported that Ni(OH)2 nanocrystals grown on graphene sheets by hydrothermal reaction at 180 °C for 10 h, which possessed a high specific capacitance. In this process, hydrophobic graphene was dispersed in organic solvent DMF which was toxic and environmentally unfriendly. And the time consumed by this process was long. Lee [18] used non-aqueous method to synthesize rGO/a-Ni (OH)2, which presented excellent electrochemical properties. Li [19] reported a green method to reduce graphene oxide with Ni powder and obtained Ni(OH)2/RGO composite. Graphene oxide, with rich oxygen-containing functional groups, is easy to couple with Ni(OH)2. However, reduced graphene oxide still remains high resistance, which is not best for energy storage applications. It is speculated that the uniform combination of graphene with high electrical conductivity and graphene oxide with rich oxygencontaining functional groups may improve the electrochemical properties of composites. However, it is difficult to obtain uniform composite nanosheets of graphene with high hydrophobicity and graphene oxide in green aqueous solution by simple mechanical mixing.

E-mail address: [email protected] (W. Wu). https://doi.org/10.1016/j.apt.2019.09.019 0921-8831/Ó 2019 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved.

Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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In this paper, G/GO nanosheets prepared by liquid-shearexfoliation using graphite oxide as an additive in our lab [20,21] were employed as a supporting substrate and Ni(OH)2 grew on G/GO nanosheets to obtain G/RGO/Ni(OH)2 composite. G/GO could be directly dispersed in aqueous solution without organic solvent, and the introduction of graphene increased the conductivity of G/ GO. The G/RGO/Ni(OH)2 exhibited a high specific capacitance and good cycling stability, which were superior to the RGO/Ni(OH)2 from pure graphene oxide. Finally, the asymmetric G/RGO/Ni (OH)2//RGO supercapacitor device was assembled, showing good

electrochemical properties. Those results indicate that G/GO is suitable for the preparation of composite materials for energy storage devices.

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2. Experiment

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2.1. Materials

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Graphite powder was bought from Fuchen Chemicals Reagents Company (Tianjin, China) and high purity graphite was derived

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Fig. 1. Schematic illustration of fabrication process of the G/RGO/Ni(OH)2.

Fig. 2. SEM images of G/RGO/Ni(OH)2 (3:1) (a), G/RGO/Ni(OH)2 (5:1) (b), and G/RGO/Ni(OH)2 (8:1) (c).

Fig. 3. XRD patterns of (a) G/RGO and Ni(OH)2, (b) G/RGO/Ni(OH)2 and RGO/Ni(OH)2.

Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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from Qingdao. Nickel sulfate (NiSO4
6H2O), L-Ascorbic acid (L-AC) and ammonia (NH3
H2O, 35 wt%) were obtained from Beijing Chemical Works. Nickel foam with a thickness of 1.0 mm was bought by Kunsan Teng Er Hui Technology Co., Ltd.

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2.2. Synthesis of materials

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Preparation process of G/GO were described in the supporting information. The 100 mL G/GO dispersion was obtained by adding G/GO powder (0.1 g) into deionized water. 0.5 g of NiSO4
6H2O was added into the G/GO aqueous dispersion and magnetic stirring for 0.5 h. 100 mL NH3
H2O solution (containing 2 mL 35 wt% NH3
H2O) was added to the above mixture drop by drop and maintained 2 h. Then 1 g of L-AC was added into 200 mL mixture and stirred to make it mix evenly. Finally, they were heated to 90 °C for 2 h. The obtained sample was collected and washed with deionized water several times. After freeze-drying, G/RGO/Ni(OH)2 was obtained. The whole process was shown in Fig. 1. According to the mass ratios (3:1, 5:1 and 8:1) of the NiSO4
6H2O to G/GO, the complexes were designated as G/RGO/Ni(OH)2 (3:1), G/RGO/Ni (OH)2 (5:1), and G/RGO/Ni(OH)2 (8:1), respectively.

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For comparison, G/GO was replaced by pure graphene oxide in equal amount. Using the same procedure, the final sample was RGO/Ni(OH)2. Ni(OH)2 nanoplates were synthesized by the same process without G/GO. G/RGO was prepared by reducing the G/GO dispersion by L-AC.

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2.3. Characterization

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X-ray diffraction (XRD) patterns were measured on Bruker D8A X-ray diffractometer from 10 to 90°. Raman spectra were performed on a Renishaw using a 514 nm laser beam. The elementary compositions of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) with ESCALAB 250 instrument (ThermoFisher, USA). Their morphological data were obtained from HR-TEM (H9500) and scanning microscopy (SEM, HITACHI S-4700).

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2.4. Electrode preparation

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According to a weight ratio of 80:10:10, the as-prepared materials, carbon black and Polyvinylidenefluoride (PVDF) were mixed and ground in an agate mortar. When grinding, N-methy-2-

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Fig. 4. SEM images of Ni(OH)2 (a and b), G/RGO/Ni(OH)2 (5:1) (c and d) and RGO/Ni(OH)2 (e and f).

Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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pyrrolidione was added drop by drop. Finally, a uniform paste was obtained. Then the slurry was coated on a piece of Ni foam and dried at 60 vacuum for 12 h. G/RGO/Ni(OH)2 and RGO were separately employed as the positive and negative electrodes to install an asymmetric supercapacitor device. Detailed electrochemical tests were displayed in the Supporting Information.

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3. Results and discussion

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In order to determine the optimum mass ratio, SEM and simple electrochemical properties of G/RGO/Ni(OH)2 (3:1, 5:1, 8:1) were tested. Compared with G/RGO/Ni(OH)2 (8:1), the Ni(OH)2 nanosheets on G/RGO (5:1) grow more uniformly (Fig. 2). Moreover, the existence of Ni(OH)2 will prevent restacking of G/RGO sheets to avoid the loss of a large amount of active sites. When the mass ratio of NiSO4
6H2O to G/GO is more than 5, the accumulation of Ni(OH)2 leads to the decrease of the surface area of the complex, which weakens the ion diffusion. The electrochemical properties of G/RGO/Ni(OH)2 (3:1, 5:1 8:1) are shown in Fig. S1. According to Eq. (1), the Cs of G/RGO/Ni(OH)2 (3:1, 5:1, 8:1) is 981.8, 1380, and 1401 F g 1, respectively. Capacitance retention of G/RGO/Ni(OH)2 (3:1, 5:1, 8:1) is separately 95%, 93.6%, and 82% at 2 A g 1 for 1000 continuous cycles. These results easily validate that G/RGO/Ni(OH)2 (5:1) has a great prospect for high performance supercapacitors. So G/RGO/Ni(OH)2 (5:1) is employed in subsequent experiments.

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The XRD patterns of G/RGO, Ni(OH)2, G/RGO/Ni(OH)2, and RGO/ Ni(OH)2 are given in Fig. 3. For G/RGO, the peak at 26.1° (0 0 2) reflection of the G/RGO sheet structure, indicating that graphene oxide is reduced by L-AC [22]. For the Ni(OH)2, all the diffraction peaks in XRD are consistent with standard cards of b-Ni(OH)2 (JCPDS:14-0117) [11]. The XRD patterns of composites are similar to that of Ni(OH)2 with the abroad diffraction line. For RGO/Ni (OH)2, the 002 peak is not prominent, which may be due to the low degree of reduction. Because of the introduction of graphene, there is obvious characteristic peak of graphene in G/RGO/Ni(OH)2. The Ni(OH)2 content in composites was calculated by TGA. As shown in Fig. S2, the weight loss below 100 is the evaporation of absorbed water [23]. The weight loss in range of 150–300 is attributed to the decomposition of the labile oxygen-containing groups from composites [24,25]. The weight loss in 300–500 is due to the combustion of the G/RGO or RGO and transition from Ni(OH)2 to NiO [26]. The remainder is NiO. The remaining weight of G/RGO/Ni(OH)2 and RGO/Ni(OH)2 are 47.8% and 30.3%, respectively. According to the formula (Ni(OH)2 ? NiO + H2O), the content of Ni(OH)2 is 56.1% and 30.6% in the G/RGO/Ni(OH)2 and RGO/Ni(OH)2, respectively. The morphologies of G/RGO/Ni(OH)2 and RGO/Ni(OH)2 were characterized by SEM and HR-TEM. From Fig. 4(a and b), the Ni (OH)2 prepared by this way is nanosheet. There are Ni(OH)2 nanosheets on G/RGO and RGO in Fig. 4(c and e) marked in red arrows. This indicates that G/GO and GO can serve as substrates to grow Ni(OH)2. The Ni(OH)2 are closely anchored on the surface of G/RGO and RGO, showing that Ni(OH)2 has a strong interaction

Fig. 5. HR-TEM images of G/RGO/Ni(OH)2 (5:1) (a and c) and RGO/Ni(OH)2 (b and d).

Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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with graphene nanosheets. It is conductive to accelerating electron transfer. Therefore, the electrochemical activity of electrode materials is improved. Meantime, the size of Ni(OH)2 in G/RGO/ Ni(OH)2 is obviously larger than that in RGO/ Ni(OH)2 from Fig. 5(a and b). Because GO surface has abundant functional groups and defects, the NiSO4 precursors coating on GO transform into small nanoparticles of Ni(OH)2 [17]. The lattice distance in Fig. 5(c and d) is 0.23 nm, which is the (1 0 1) plane of b-Ni(OH)2. The element mapping images are shown in Fig. S3. These results indicate that Ni (OH)2 has been successfully grown on G/RGO and RGO nanosheets.

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XPS was used to analyze chemical components of the composites. In Fig. 6a, it is the survey spectrum of the G/RGO/Ni(OH)2, including C, O, and Ni. The C 1s can be deconvoluted into three types of C bonds (Fig. 6b): C@C, C@O, and OAC@O [27]. In Fig. 6c the high-resolution spectrum of Ni 2p exhibits Ni 2p1/2 and Ni 2p2/3, which is located at 874.4 eV and 856.7 eV, respectively. The characteristics of the Ni(OH)2 phase with a spin-energy separation of 17.7 eV consistent with previous papers [22,28]. Fig. 6d shows the deconvolution of O 1s spectrum. The two peaks located at 531.6 eV and 533.3 eV are the Ni-OH, and CAOAC, respectively

Fig. 6. XPS spectra of G/RGO/Ni(OH)2: (a) survey spectra, (b) high-resolution C 1s spectrum, (c) high-resolution Ni 2p, and (d) high-resolution O 1s spectrum. (e) Raman spectra of the G/RGO, RGO/Ni(OH)2, and G/RGO/Ni(OH)2.

Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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[29]. The results of XPS prove that Ni(OH)2 has grown successfully on the G/GO. The Raman spectra of G/RGO, RGO/Ni(OH)2, and G/ RGO/Ni(OH)2 are shown in Fig. 6e. There is a weak peak around 451 cm 1 in the curves of RGO/Ni(OH)2 and G/RGO/Ni(OH)2, which is attributed to the symmetric Ni-OH stretching vibrational stretching mode in Ni(OH)2 [30]. This confirms the existence of Ni(OH)2 in RGO/Ni(OH)2 and G/RGO/Ni(OH)2. The G/RGO shows main peaks at 1350 cm 1 (D band) and 1596 cm 1 (G band). For RGO/Ni(OH)2 and G/RGO/Ni(OH)2, the peak for D band shifts to lower wavenumber (1342 cm 1) due to the charge transfer between graphene and Ni(OH)2. Generally, the intensity ratio of

D and G is used to assess the defects. The value is 1.08, 1.22, and 1.19 for G/RGO, RGO/Ni(OH)2, and G/RGO/Ni(OH)2, respectively. The slight increase suggests an increased disorder carbon structure in the RGO/Ni(OH)2 and G/RGO/Ni(OH)2, resulting from the loading of Ni(OH)2 on the surface of graphene sheets. To test the electrochemical properties of all materials, EIS, CV, GCD and stability of cycle in three-electrode system were performed. All EIS curves contain liner part and a semicircle (Fig. 7a). The diameter of a semicircle corresponds to the chargetransfer resistance (RCT), and the intercept on the real axis at the high frequency end is the electrolyte resistance (RESR). The results

Fig. 7. Electrochemical characterization of the G/RGO, Ni(OH)2, G/RGO/Ni(OH)2, RGO/Ni(OH)2: (a) EIS spectra of different samples (the insets show an enlarged highfrequency region of the plot), (b) CV curves of different samples at a scan rate of 10 mV s 1, (c) GCD curves of different samples at a current density of 2 A g 1, (d) the specific capacitance of different electrodes at different current densities, and (e) Cycling performance at a current density of 2 A g 1.

Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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J. Tian et al. / Advanced Powder Technology xxx (xxxx) xxx Table 1 The RESR and RCT values of theG/RGO, Ni(OH)2, G/RGO/Ni(OH)2, and RGO/ Ni(OH)2 electrodes. Samples

G/RGO

Ni(OH)2

G/RGO/Ni(OH)2

RGO/Ni(OH)2

RESR (O) RCT (O)

0.55 0.2

0.6 0.7

0.4 0.25

0.55 0.5

Fig. 8. (a) CV profiles of RGO at different scan rates from 5 to 50 mV s

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of RCT and RESR of all samples are shown in Table 1. All composites electrodes possess the smaller RCT than the Ni(OH)2 electrode, signifying a faster charge-transfer, which are attributed to the graphene sheets. It is obvious that G/RGO/Ni(OH)2 has the smallest RCT and RESR in all composites, which may be due to graphene in G/GO. The CV and GCD of G/RGO, Ni(OH)2, G/RGO/Ni(OH)2, and RGO/ Ni(OH)2 were measured with same methods. In Fig. 7b, the CV curves of composites show clearly a couple of distinct redox peaks, indicating the pseudocapacitance behavior typical. This is mainly due to the reversible reaction of Ni(OH)2 (Ni(OH)2 + OH M NiOOH + H2O + e ) [31,32]. In all CV curves, the G/RGO/Ni (OH)2 composite has the largest peak current density. Fig. S4a displays the typical CV curves of G/RGO/Ni(OH)2 at different scan rates. The peak current density increases with the increase of scan rate, and the shape has hardly changed. Meanwhile, the redox peaks shift to a more positive or negative potential due to the increase of internal diffusion resistance in electrode [33]. Fig. 7c shows the GCD curves at the potential 0–0.55 V. It found that the G/RGO/Ni(OH)2 composite has longer discharging time than those of the others materials, indicating that G/RGO/Ni(OH)2 composite has a higher specific capacitance (Cs). According to Eq. (1), the Cs of G/RGO, Ni(OH)2, G/RGO/Ni(OH)2, and RGO/Ni(OH)2, are 120, 780, 1510, and 1050 F g 1, respectively. Fig. S4b shows GCD curves of G/RGO/Ni(OH)2 at different current densities. The Cs are 1510, 1380, 1275, 1201, 1080, 998, 940, and 890 F g 1 at 2, 4, 6, 8, 10, 20, 30, and 40 A g 1, respectively. The performance curves of Ni (OH)2, G/RGO/Ni(OH)2, and RGO/Ni(OH)2 samples at various current densities are displayed in Fig. 7d. At any current density, the Cs of G/RGO/Ni(OH)2 is higher than that of other samples. Apart from these, electrochemical stability of all samples were measured. Capacitance retention of G/RGO, Ni(OH)2, G/RGO/Ni (OH)2, and RGO/Ni(OH)2 is separately 97%, 64%, 93.6%, and 83.5% at 2 A g 1 for 1000 continuous cycles (Fig. 7e). These results easily validate that G/RGO/Ni(OH)2 has a great prospect for high performance supercapacitors. To calculate the mass ratio of positive material to negative material, CV and GCD curves of RGO were performed in three-

and (b) GCD curves of RGO at different current densities from 1 to 10 A g

1

.

electrode system. Fig. 8a shows the CV curves of RGO at high scan rates. The similar rectangular shapes imply good electric double layer capacitance behavior of RGO. The Cs of the RGO from GCD (Fig. 8b) is 260 F g 1 at 1 A g 1. The two-electrode asymmetric supercapacitor was installed by using the G/RGO/Ni(OH)2 composite as a positive electrode and RGO as a negative electrode (Fig. 9a). Fig. 9b displays the CV curves of G/RGO/Ni(OH)2 and RGO at 10 mV s 1 in three-electrode system. The G/RGO/Ni(OH)2 electrode is measured in a range 0–0.65 V, while RGO is measured in 1.0 to 0 V. The CV curves of asymmetric supercapacitor device in the range of 5–100 mV s 1 almost maintain the same shapes in Fig. 9c, indicating the good reversibility of materials. Fig. 9d exhibits the GCD curves at diverse current densities. According to Eq. (3), the Cs are 126.4, 86.72, 63.44, 52.03, and 49.5 F g 1 at 0.5, 1, 2, 3, and 5 A g 1, respectively. The energy density and the power density are calculated from the GCD curves using Eqs. (4) and (5). Depending on the GCD curves, the Ragone plots of the asymmetric supercapacitor device are completed and are shown in Fig. 9e. The G/RGO/Ni(OH)2//RGO device possesses an energy density of 44.9 W h kg 1 at 400.1 W kg 1 and maintains 15.6 W h kg 1 even when the power density increases to 4087 W kg 1. Fig. 9f is the cycling stability of asymmetric supercapacitor device at 1.0 A g 1. After 5000 cycles, capacitance still has an initial 82%, which indicates that the device has a good electrochemical stability. The electrochemical performances are superior to the asymmetric supercapacitors from some reported Ni(OH)2 materials. The detailed data are shown in Table 2.

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4. Conclusion

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G/RGO/Ni(OH)2 composite as a promising material for supercapaitor with good electrochemical properties was prepared by a facile method. G/GO, which was low cost, green, and easy to be scaled up, was as a supporting matrix. Due to the lightly oxidized and electrically conducting graphene sheets, G/GO nanosheets prepared by our lab were benefit to the growth of large size Ni(OH)2. And the introduction of graphene in G/GO increased the electrical conductivity of composite, which would accelerate the diffusion

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Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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Fig. 9. Electrochemical performance of the G/RGO/Ni(OH)2//RGO asymmetric supercapacitor: (a) schematic of the assembled structure of an asymmetric supercapacitor based on G/RGO/Ni(OH)2 as the positive electrode material and RGO as the negative material, (b) CV curves comparison of RGO and G/RGO/Ni(OH)2 at 10 mV s 1, (c) CV curves at different scan rates from 5 to 100 mV s 1, (d) GCD curves with a cell voltage of 1.6 V at current densities varying from 0.5 to 10 A g 1, (e) Ragone plot, (f) cycling performance measured at a current density of 1 A g 1 for 5000 cycles.

Table 2 Comparison of the electrochemical performance of some electrode materials and the present work. Electrode materials

Electrode materials Synthesis method

Specific Capacitance of positive electrode

Energy density (W h kg 1)

Power density (W kg 1)

Capacitance retention (cycles)

Reference

Ni(OH)2/NG//AC 3D a-Ni(OH)2//AC NiCo2O4/rGO//AC NieCo binary hydroxides//CG NiCoeOH/ultraphene//AC NiCo2S4//AC Ni(OH)2@GCA//GCA G/RGO/Ni(OH)2//RGO

Hydrothermal \ Situ transformation Solvothermal Electrophoresis deposition hydrothermal Chemical bath deposition Situ reaction

896 F g 1 at 0.5 A g 1 563.1C g 1 at 1 A g 1 1222 F g 1 at 0.5 A g 1 1030 F g 1 at 3 A g 1 889.35 F g 1 at 20 mV s 744 F g 1 at 1 A g 1 1208 F g 1 at 1 A g 1 1510 F g 1 at 2 A g 1

28.7 14.9 23.3 26.3 23.4 25.5 30 44.9

360 140 320 320 930 330 820 400.1

74.3% (5000th) 79% (10000th) 83% (2500th) \ 56% (3000th) 85.6 (4000th) 88% (2000th) 82% (5000th)

[34] [35] [36] [37] [38] [39] [40] This work

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Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019

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and migration of ions between the interfacial electrolyte and electrodes during the charge/discharge process. So the electrochemical properties of G/RGO/Ni(OH)2 were superior to that of RGO/Ni (OH)2. The G/RGO/Ni(OH)2//RGO supercapacitor device showed good energy density and power density. This paper also indicates that G/GO possesses a potential as a substrate material for energy storage applications.

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Acknowledgments

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This work was supported by the National Natural Science Foundation of China (No. 21676023).

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Appendix A. Supplementary material

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Supplementary data to this article can be found online at https://doi.org/10.1016/j.apt.2019.09.019.

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Please cite this article as: J. Tian, Q. San, X. Yin et al., A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors, Advanced Powder Technology, https://doi.org/10.1016/j.apt.2019.09.019