How the electrochemical reversibility of a battery-type material affects the charge balance and performances of asymmetric supercapacitors

Hsu, Chih-Hung; Hu, Chi‐Chang; Wu, Tzu−Ho; Chen, Jia-Cing; Rajkumar, Muniyandi

doi:10.1016/j.electacta.2014.09.041

Cited by 49 publications

(29 citation statements)

References 36 publications

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“…These unique electrochemicalf eatures of rGO-PMo 12 and rGO-PW 12 hybrid electrodes motivated us to pair them in an asymmetric cell, which is expected to offer high capacitance (due to the dual charge storagem echanism in the hybridm aterials) with an increased operating voltage and, consequently,h igh energy density.I n this context, an asymmetricS Cw as fabricated using the rGO-PMo 12 (positive electrode) and rGO-PW 12 (negative electrode) in 1 m H 2 SO 4 .N ote that the charges stored in both electrodes need to be balanced to take advantage of full voltage window, which can be achieved by balancing mass of the material. [24] The rGO-PMo 12 -to-rGO-PW 12 mass ratio was calculated using Equation (3): [25] where C is the specific capacitance and DE is the potential range for positive (+ +)a nd negative (À)e lectrodes. The calculated mass ratio is 1.7:1 for rGO-PMo 12 k rGO-PW 12 ;t hus, for at otal mass loading of 3.1 mg (both electrodes), am ass loading of 2.1 and 1.21 mg for rGO-PMo 12 and rGO-PW 12 ,r espectively,w as used.…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

et al. 2017

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Nanofabrication using a "bottom-up" approach of hybrid electrode materials into a well-defined architecture is essential for next-generation miniaturized energy storage devices. This paper describes the design and fabrication of reduced graphene oxide (rGO)/polyoxometalate (POM)-based hybrid electrode materials and their successful exploitation for asymmetric supercapacitors. First, redox active nanoclusters of POMs [phosphomolybdic acid (PMo ) and phosphotungstic acid (PW )] were uniformly decorated on the surface of rGO nanosheets to take full advantage of both charge-storing mechanisms (faradaic from POMs and electric double layer from rGO). The as-synthesized rGO-PMo and rGO-PW hybrid electrodes exhibited impressive electrochemical performances with specific capacitances of 299 (269 mF cm ) and 370 F g (369 mF cm ) in 1 m H SO as electrolyte at 5 mA cm . An asymmetric supercapacitor was then fabricated using rGO-PMo as the positive and rGO-PW as the negative electrode. This rGO-PMo ∥rGO-PW asymmetric cell could be successfully cycled in a wide voltage window up to 1.6 V and hence exhibited an excellent energy density of 39 Wh kg (1.3 mWh cm ) at a power density of 658 W kg (23 mW cm ).

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Section: Resultsmentioning

confidence: 99%

Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

et al. 2017

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“…However, this meant that an optimized mass balance was only achieved at one specific charge/discharge rate, because the correlation between capacity and specific current differed significantly between the "battery-type" anode and double-layer capacitor cathode. 41…”

Section: Physical Characterization-powder X-ray Diffraction (Pxrd)mentioning

confidence: 99%

High Power Sodium-Ion Batteries and Hybrid Electrochemical Capacitors Using Mo or Nb-Doped Nano-Titania Anodes

Bauer

Roberts

Patnaik

et al. 2018

J. Electrochem. Soc.

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Nano-sized anatase (TiO 2) and doped anatase (Mo 0.1 Ti 0.9 O 2 and Nb 0.25 Ti 0.75 O 2) materials (ca. 5 nm) were synthesized using continuous hydrothermal flow synthesis and evaluated as negative electrodes in Na-ion batteries and hybrid capacitors. Na-ion halfcells (vs. Na metal counter electrodes) for the Mo-doped titania (Mo 0.1 Ti 0.9 O 2) and Nb-doped titania (Nb 0.25 Ti 0.75 O 2) electrodes both showed significantly higher specific discharge capacities than undoped anatase (ca. 75 mAh g −1 compared to only 30 mAh g −1 for undoped TiO 2 at 1 A g −1). This improved performance was attributed to higher pseudocapacitive contributions to charge storage, as well as improved sodium ion diffusion and lower charge transfer resistance. Na-ion hybrid electrochemical capacitors (Na-HECs) were made from the electrodes with activated carbon positive electrodes. As expected, Na-HECs using doped titania showed superior performance to the undoped anatase, with power densities up to 10.5 kW kg −1 or energy densities of over 60 Wh kg −1 (based on the weight of active material in both anode and cathode). The Mo 0.1 Ti 0.9 O 2 /AC Na-ion hybrid capacitor also showed excellent specific capacitance retention of ca. 75% over 3000 cycles at 5 mA cm −2 (1 A g −1).

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“…This problem is not only related to energy shortages, but also to energy sources to minimize the environmental impact [1] . In this context, supercapacitors have played an outstanding role in research energy groups, with new promising approaches to produce renewable energy sources besides reducing environmental problems.…”

Section: Introductionmentioning

confidence: 99%

“…However, there are distinctions between them with respect to charge storage mechanisms. In the case of supercapacitors there are two possible mechanisms for energy storage: (1) firstly, by the accumulation of charge on the surfaces of the active material, where this process occurs by the electrostatic charge accommodation at the electrical double-layer, through the adsorption of the electrolyte ions on the surfaces of electrically stimulated carbon-based materials; (2) secondly, by the fast and reversible redox or Faradaic reactions during the oxidation/reduction process, where the devices are called as pseudocapacitors, whose electrodes are made up by transition metal-oxides, hydroxides, and/or conducting polymers oxides or conducting polymers, [2][3][4][5][6] . Recently, supercapacitors have played an increasingly important role in applications such as the auxiliary power source in combination with battery electric and hybrid vehicles [6] , because they exhibit power densities which are about ten times higher than those of batteries, showing excellent cycling stability even after hundreds of thousands of charge/discharge cycles.…”

Section: Introductionmentioning

confidence: 99%

Influence of the polymeric coating thickness on the electrochemical performance of Carbon Fiber/PAni composites

et al. 2015

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SbstractCarbon fiber/polyaniline composites (CF/PAni) were synthesized at three different deposition time of 30, 60 and 90 min by oxidative polymerization. The composite materials were morphologically and physically characterized by scanning electron microscopy and by Raman spectroscopy, respectively. Their electrochemical responses were analyzed by cyclic voltammetry, by galvanostatic test, and by electrochemical impedance spectroscopy. The influence of the PAni layer thickness deposited on carbon fibers for the composite formation as well as for their electrochemical properties was discussed. The CF/PAni-30 showed a nanometric thickness with more homogeneous morphology compared to those formed in deposition times of 60 and 90 min. It also showed, from the electrochemical impedance spectroscopy measurements, the lowest charge transfer resistance value associated to the its highest value for the double-layer capacitance of 180 Fg -1 making it a very strong candidate as a supercapacitor electrode.

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How the electrochemical reversibility of a battery-type material affects the charge balance and performances of asymmetric supercapacitors

Cited by 49 publications

References 36 publications

Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

High Power Sodium-Ion Batteries and Hybrid Electrochemical Capacitors Using Mo or Nb-Doped Nano-Titania Anodes

Influence of the polymeric coating thickness on the electrochemical performance of Carbon Fiber/PAni composites

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