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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    • "Owing to its ultra-large specific surface area, high carrier mobility and extraordinary lithium ion/atom storage capacity, graphene sheet has been considered as one of the most promising anode materials for lithium ion battery (LIB) [1] [2] [3] [4] [5] [6] [7]. However , there are two problems remained to be overcome using bare graphene sheets as anode materials [2]. "
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    ABSTRACT: Nanoporous graphene sheets were generated through a simple thermal annealing procedure using composites of ferrocene nanoparticles and graphene oxide sheets as precursors in a large scale. The morphology, composition, and formation mechanism of the as-obtained nanoporous graphene sheets were studied complementarily with scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, and other spectroscopy techniques. We found that the density of nanopores on the graphene sheet was determined by the surface distribution of oxygen-containing groups on the original graphene oxide sheets. The coin cells using nanoporous graphene sheets as anode materials showed higher specific lithium ion storage capacity, better discharge/charge rate capability and higher cycling stability when compared to the coin cells with graphene or chemically reduced graphene sheets as anodes.
    Carbon 04/2015; 84(1):469-478. DOI:10.1016/j.carbon.2014.12.039 · 6.20 Impact Factor
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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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    Electrochimica Acta 09/2014; 152. DOI:10.1016/j.electacta.2014.09.061 · 4.50 Impact Factor
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