Pyrolyzed polyaniline–graphene nanosheets (PA–GNS) are examined as a lithium‐storage material. The PA–GNS composite is synthesized through heat treatment of polyaniline–graphite oxide precursors under a H2/Ar atmosphere at 850 °C. Scanning and transmission electron microscopies, X‐ray diffraction, Raman spectroscopy, and X‐ray photoelectron spectroscopy are employed to characterize the prepared PA–GNS composite in comparison with pristine graphene nanosheets (GNS). Galvanostatic charge/discharge experiments show that PA–GNS exhibits an improved rate and cycle capability at both 25 and 55 °C. It is also found from electrical resistivity tests and electrochemical impedance spectroscopy measurements that the PA–GNS composite demonstrates a higher vertical electronic conductivity and lower charge‐transfer resistance than GNS, and it is concluded that modifying GNS with pyrolyzed polyaniline is an effective way to enhance the rate capability and cyclability of GNS.
A gas flowmeter for measuring low flow rate has been widely used in the field of medical, health, environmental protection, energy industry, aerospace, etc. To against Covid-2019, the requirement on the low flow rate has been increasing dramatically. At present, the typical standard devices for calibrating low gas flowmeter mainly include standard bell provers of gas flow, standard piston provers of low gas flow and standard laminar of low gas flow. Different measuring principles are adopted among these typical standard devices. To ensure the consistency of these typical standard devices, a comparison test is performed. The standard devices used in the comparison are of the same accuracy grade, with an extended uncertainty of 0.2%(k=2). The piston-type gas flow calibrator of grade 1.0 is selected as the transfer standard, and three flow points with high flow rate, medium flow rate and low flow rate are selected for test. The consistency of measurement results is evaluated by normalized deviation En. The comparison results are acceptable which show that three typical standard devices are accurate and reliable.
Carbon-coated graphene was synthesized through pyrolysis of a polyaniline–graphite oxide (PANI–GO) precursor by annealing in an Ar and H2 atmosphere at various temperatures. X-ray diffraction, field-emission scanning and high-resolution transmission electron microscopies, X-ray photoelectron spectroscopy, Raman spectra, and thermogravimetric analysis were used to characterize the pyrolyzed PANI–GO at different temperatures. The PANI on the graphene at temperatures above 650 °C was completely converted into a nanocarbon film. Galvanostatic charge–discharge tests revealed that PANI–GO-800 exhibited improved rate and cycle capabilities over that of graphene due to the increased conductivity in the out-of-plane direction.
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