Li-Air Rechargeable Battery Based on Metal-free Graphene Nanosheet Catalysts

Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, Japan.
ACS Nano (Impact Factor: 12.88). 03/2011; 5(4):3020-6. DOI: 10.1021/nn200084u
Source: PubMed


Metal-free graphene nanosheets (GNSs) were examined for use as air electrodes in a Li-air battery with a hybrid electrolyte. At 0.5 mA cm(-1), the GNSs showed a high discharge voltage that was near that of the 20 wt % Pt/carbon black. This was ascribed to the presence of sp(3) bonding associated with edge and defect sites in GNSs. Moreover, heat-treated GNSs not only provided a similar catalytic activity in reducing oxygen in the air, but also showed a much more-stable cycling performance than GNSs when used in a rechargeable Li-air battery. This improvement resulted from removal of adsorbed functional groups and from crystallization of the GNS surface into a graphitic structure on heat treatment.

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    • "Several different types of related rGO have been tested as the Li–air battery cathode material, such as ''normal'' rGO [17] [18], doped rGO [20] [21], and metal containing rGO [22] [23] [24] [25]. rGO cathodes have been tested for both the aprotic [17] [18] and hybrid [26] Li–air battery systems with promising results. Even though rGO has been investigated [19] [27] [28], the difference of the functional groups in the graphene oxide (GO) and their relation with the functional groups in rGO has not been explored in detail. "
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    ABSTRACT: Reduced graphene oxide (rGO) has shown great promise as an air-cathode for Li–air batteries with high capacity. In this article we demonstrate how the oxidation time of graphene oxide (GO) affects the ratio of different functional groups and how trends of these in GO are extended to chemically and thermally reduced GO. We investigate how differences in functional groups and synthesis may affect the performance of Li–O2 batteries. The oxidation timescale of the GO was varied between 30 min and 3 days before reduction. Powder X-ray diffraction, micro-Raman, FE-SEM, BET analysis, and XPS were used to characterize the GO’s and rGO’s. Selected samples of GO and rGO were analyzed by solid state 13C MAS NMR. These methods highlighted the difference between the two types of rGO’s, and XPS indicated how the chemical trends in GO are extended to rGO. A comparison between XPS and 13C MAS NMR showed that both techniques can enhance the structural understanding of rGO. Different rGO cathodes were tested in Li–O2 batteries which revealed a difference in overpotentials and discharge capacities for the different rGO’s. We report the highest Li–O2 battery discharge capacity recorded of approximately 60,000 mAh/gcarbon achieved with a thermally reduced GO cathode.
    Carbon 01/2015; 85:233-244. DOI:10.1016/j.carbon.2014.12.104 · 6.20 Impact Factor
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    • "(10 3 $10 4 S m À1 ), large specific surface area (calculated theoretical value 2630 m 2 g À1 ) and good thermal conductivity ($5000 W m À1 K À1 ) [2] [3] "
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    ABSTRACT: In this work, we present a new type of three-dimensional (3D) nanohybrid electrode based on microscopic graphene foam loaded nickel − cobalt hydroxides nanoflakes (NixCo2x(OH)6x/graphene foam) synthesized by one-step electrochemical method. This method allows for better structural integration of different electrode component and improves the electrochemical properties in terms of capacitive performance and electrocatalytic activity. When used as binder-free electrode for supercapacitor, the 3D NixCo2x(OH)6x/graphene foam exhibits a high specific capacitance of 703.6 mF cm−2 at a current density of 10 mA cm−2 and a good rate capability of 83.8% at 100 mA cm−2, and the specific capacitance retention remains 97.5% after 1000 cycles. Furthermore, for electrochemical biosensor application, the NixCo2x(OH)6x/graphene nanohybrid electrode exhibits high selectivity, reproducibility and stability towards the nonenzymatic detection of hydrogen peroxide. These enable it as a multifunctional electrode material for wide spectrum of electrochemical application.
    Electrochimica Acta 09/2014; 152. DOI:10.1016/j.electacta.2014.09.061 · 4.50 Impact Factor
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    • "Fig. 5c depicts the discharge specific capacity vs. W D ; it is obviously that the capacity increases as the amount of disordered carbon phase decreases in the carbon black. This finding is interesting because in our previous study about graphene nanosheets, the electrode made of nitrogen doped graphene nanosheets which have more defects delivered higher discharge capacity than pristine sample [12] [13] [15]. In this study, we believe that the different behavior comes from the nature of the carbon black and graphene nanosheets. "
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    ABSTRACT: Carbon materials have been widely used as cathodes in lithium oxygen batteries but the detailed influence of the structure of these materials on their performance is not very clear yet. In this study, the same starting pristine commercial carbon black (N330) was treated under different atmospheres and the resultant carbons were employed as cathode materials for lithium oxygen batteries. It was demonstrated that the porosity and surface topology of these carbons tremendously changed as their treating time increased. The parameters that influenced the battery performance were identified. It was found that the main factor determining the battery performance is the specific surface area of the carbon mesopores, while nitrogen- or oxygen-bearing functionalities, introduced in these carbons during their heat-treatment or by contact with air after their pyrolysis, had little or no influence on the battery performance. (C) 2013 Elsevier Ltd. All rights reserved.
    Carbon 11/2013; 64:170-177. DOI:10.1016/j.carbon.2013.07.049 · 6.20 Impact Factor
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