Limits...
Electrodeposition of porous graphene networks on nickel foams as supercapacitor electrodes with high capacitance and remarkable cyclic stability.

Yang S, Deng B, Ge R, Zhang L, Wang H, Zhang Z, Zhu W, Wang G - Nanoscale Res Lett (2014)

Bottom Line: The electrodeposition process was accomplished by electrochemical reduction of graphene oxide (GO) in its aqueous suspension.The resultant binder-free PG/NF electrodes exhibited excellent double-layer capacitive performance with a high rate capability and a high specific capacitance of 183.2 mF cm(-2) at the current density of 1 mA cm(-2).Moreover, the specific capacitance maintains nearly 100% over 10,000 charge-discharge cycles, demonstrating a remarkable cyclic stability of these porous supercapacitor electrodes. 82.47.Uv (Electrochemical capacitors); 82.45.Fk (Electrodes electrochemistry); 81.05.Rm (Fabrication of porous materials).

View Article: PubMed Central - PubMed

Affiliation: Hefei National Laboratory for Physical Sciences at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, People's Republic of China, shorlin@mail.ustc.edu.cn.

ABSTRACT

Unlabelled: We describe a facile, low-cost, and green method to fabricate porous graphene networks/nickel foam (PG/NF) electrodes by electrochemical deposition of graphene sheets on nickel foams (NFs) for the application of supercapacitor electrodes. The electrodeposition process was accomplished by electrochemical reduction of graphene oxide (GO) in its aqueous suspension. The resultant binder-free PG/NF electrodes exhibited excellent double-layer capacitive performance with a high rate capability and a high specific capacitance of 183.2 mF cm(-2) at the current density of 1 mA cm(-2). Moreover, the specific capacitance maintains nearly 100% over 10,000 charge-discharge cycles, demonstrating a remarkable cyclic stability of these porous supercapacitor electrodes.

Pacs: 82.47.Uv (Electrochemical capacitors); 82.45.Fk (Electrodes electrochemistry); 81.05.Rm (Fabrication of porous materials).

No MeSH data available.


Electrochemical measurements of the PG/NF deposited at the potential of -1.2 V with different deposition times. (A) Cyclic voltammetry curves at the scan rate of 100 mV s-1 and (B) plots of specific capacitances versus scan rate. (C) Galvanostatic charge-discharge curves and (D) plot of specific capacitances at current density of 10 mA cm-2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4493843&req=5

Fig4: Electrochemical measurements of the PG/NF deposited at the potential of -1.2 V with different deposition times. (A) Cyclic voltammetry curves at the scan rate of 100 mV s-1 and (B) plots of specific capacitances versus scan rate. (C) Galvanostatic charge-discharge curves and (D) plot of specific capacitances at current density of 10 mA cm-2.

Mentions: The electrochemical tests of the PG/NFs deposited under the potential of -1.2 V with deposition times of 300, 400, 500, 600, and 700 s were shown in Figure 4. Considering the incompatibility between the weight of the deposited graphene materials (1.0 ~ 2.0 mg) and the NF supports (60 ~ 70 mg), the specific capacitance of the PG/NFs in area units were used as measurements instead of the mass-specific capacitance. Figure 4A compares the CV curves of these PG/NF electrodes at the potential scan rate of 100 mV s-1. All CV curves are in a nearly perfect rectangular shape, indicating pure electric double-layer capacitances and rapid charge propagations at the electrode/electrolyte interfaces [26]. Figure 4B displays the comparison of the specific capacitances of these electrodes versus scan rate from 10 to 1,000 mV s-1. These specific capacitances decrease with the increase of scan rate, probably due to an increase of ion diffusion-related resistance [39]. It is obvious that the specific capacitances of the PG/NF electrodes do not always increase with the deposition time. They increase with deposition time from 300 to 500 s because of larger surface area generated by larger amounts of graphene materials deposited. However, the specific capacitances began to decrease with the deposition time of 600 s and continued to reduce for longer deposition. This phenomenon can be explained by that the covering of the pores of the NFs by excessive graphene materials as shown in Figure 2D(I) and E(I), impeding ion dispersion into the pores of the PG/NF electrodes and thereby decreasing the accessible surface area. This can be verified by the specific surface area measured by methylene blue adsorption to be 0.913, 1.026, 1.268, 1.122, and 1.010 m2 cm-2 for PG/NF electrodes fabricated with the deposition time of 300, 400, 500, 600, and 700 s, respectively.Figure 4


Electrodeposition of porous graphene networks on nickel foams as supercapacitor electrodes with high capacitance and remarkable cyclic stability.

Yang S, Deng B, Ge R, Zhang L, Wang H, Zhang Z, Zhu W, Wang G - Nanoscale Res Lett (2014)

Electrochemical measurements of the PG/NF deposited at the potential of -1.2 V with different deposition times. (A) Cyclic voltammetry curves at the scan rate of 100 mV s-1 and (B) plots of specific capacitances versus scan rate. (C) Galvanostatic charge-discharge curves and (D) plot of specific capacitances at current density of 10 mA cm-2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493843&req=5

Fig4: Electrochemical measurements of the PG/NF deposited at the potential of -1.2 V with different deposition times. (A) Cyclic voltammetry curves at the scan rate of 100 mV s-1 and (B) plots of specific capacitances versus scan rate. (C) Galvanostatic charge-discharge curves and (D) plot of specific capacitances at current density of 10 mA cm-2.
Mentions: The electrochemical tests of the PG/NFs deposited under the potential of -1.2 V with deposition times of 300, 400, 500, 600, and 700 s were shown in Figure 4. Considering the incompatibility between the weight of the deposited graphene materials (1.0 ~ 2.0 mg) and the NF supports (60 ~ 70 mg), the specific capacitance of the PG/NFs in area units were used as measurements instead of the mass-specific capacitance. Figure 4A compares the CV curves of these PG/NF electrodes at the potential scan rate of 100 mV s-1. All CV curves are in a nearly perfect rectangular shape, indicating pure electric double-layer capacitances and rapid charge propagations at the electrode/electrolyte interfaces [26]. Figure 4B displays the comparison of the specific capacitances of these electrodes versus scan rate from 10 to 1,000 mV s-1. These specific capacitances decrease with the increase of scan rate, probably due to an increase of ion diffusion-related resistance [39]. It is obvious that the specific capacitances of the PG/NF electrodes do not always increase with the deposition time. They increase with deposition time from 300 to 500 s because of larger surface area generated by larger amounts of graphene materials deposited. However, the specific capacitances began to decrease with the deposition time of 600 s and continued to reduce for longer deposition. This phenomenon can be explained by that the covering of the pores of the NFs by excessive graphene materials as shown in Figure 2D(I) and E(I), impeding ion dispersion into the pores of the PG/NF electrodes and thereby decreasing the accessible surface area. This can be verified by the specific surface area measured by methylene blue adsorption to be 0.913, 1.026, 1.268, 1.122, and 1.010 m2 cm-2 for PG/NF electrodes fabricated with the deposition time of 300, 400, 500, 600, and 700 s, respectively.Figure 4

Bottom Line: The electrodeposition process was accomplished by electrochemical reduction of graphene oxide (GO) in its aqueous suspension.The resultant binder-free PG/NF electrodes exhibited excellent double-layer capacitive performance with a high rate capability and a high specific capacitance of 183.2 mF cm(-2) at the current density of 1 mA cm(-2).Moreover, the specific capacitance maintains nearly 100% over 10,000 charge-discharge cycles, demonstrating a remarkable cyclic stability of these porous supercapacitor electrodes. 82.47.Uv (Electrochemical capacitors); 82.45.Fk (Electrodes electrochemistry); 81.05.Rm (Fabrication of porous materials).

View Article: PubMed Central - PubMed

Affiliation: Hefei National Laboratory for Physical Sciences at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, People's Republic of China, shorlin@mail.ustc.edu.cn.

ABSTRACT

Unlabelled: We describe a facile, low-cost, and green method to fabricate porous graphene networks/nickel foam (PG/NF) electrodes by electrochemical deposition of graphene sheets on nickel foams (NFs) for the application of supercapacitor electrodes. The electrodeposition process was accomplished by electrochemical reduction of graphene oxide (GO) in its aqueous suspension. The resultant binder-free PG/NF electrodes exhibited excellent double-layer capacitive performance with a high rate capability and a high specific capacitance of 183.2 mF cm(-2) at the current density of 1 mA cm(-2). Moreover, the specific capacitance maintains nearly 100% over 10,000 charge-discharge cycles, demonstrating a remarkable cyclic stability of these porous supercapacitor electrodes.

Pacs: 82.47.Uv (Electrochemical capacitors); 82.45.Fk (Electrodes electrochemistry); 81.05.Rm (Fabrication of porous materials).

No MeSH data available.