Recently, aluminum ion batteries (AIBs) have attracted great attention across the globe by virtue of their massive gravimetric and volumetric capacities in addition to their high abundance. Though carbon derivatives are excellent cathodes for AIBs, there is much room for further development. In this study, flexuous graphite (FG) was synthesized by a simple thermal shock treatment, and for the first time, an Al/FG battery was applied as a cathode for AIBs to reveal the real-time intercalation of AlCl 4 − into FG with high flexibility by using in-situ scanning electron microscope (SEM) measurements exclusively. Similarly, in-situ X-ray diffraction (XRD) and in-situ Raman techniques have been used to understand the anomalous electrochemical behavior of FG. It was found that FG adopts a unique integrated intercalation−adsorption mechanism where it follows an intercalation mechanism potential above 1.5 V and an adsorption mechanism potential below 1.5 V. This unique integrated intercalation−adsorption mechanism allows FG to exhibit superior properties, like high capacity (≥140 mAh/g), remarkable long-term stability (over 8000 cycles), excellent rate retention (93 mAh/g at 7.5 A/ g), and extremely rapid charging and slow discharging.
When ammonia is added in methane to form carbon films using thermal chemical vapor deposition, effects of the ammonia/methane ratio on the deposition rate and microstructures of carbon films are investigated. Meanwhile, effects of the deposition temperature, working pressure, and residence time on the deposition rate are also considered. Experimental results indicate that as the ammonia/methane rate increases, the deposition rate of carbon films decreases, and also, the ordered degree, nano-crystallite size, and sp2 carbon atoms of carbon films increase. Nevertheless, if the deposition temperature, working pressure, and residence time increase, the deposition rate of carbon films increases. The relationship between the deposition rate and deposition process parameters is formulated. The deposition process is controlled by the process to create mono-carbon and bi-carbon species in carbon films. Moreover, one mono-nitrogen will suppress about three mono-carbons to form carbon films. Few nitrogen and hydrogen atoms are incorporated into carbon films. The activation energy (507 kJ/mole) of carbon deposition is related to the activation energies of methane and ammonia dissociation. If the working pressure is smaller than a threshold value (30 kPa) or the residence time is shorter than a threshold value (1.5 s), no film is formed
When ethylene/ammonia (C2H4/NH3) mixtures are used to deposit carbon films by thermal chemical vapor deposition (CVD), effects of C2H4/(C2H4+NH3) ratios on the deposition rate and microstructures of carbon films are investigated. Experimental results reveal that the deposition rate of carbon films increases with the C2H4/(C2H4+NH3) ratio, and also, raises with the residence time, deposition temperature, and working pressure. The kinetics of this thermal CVD process is discussed. The deposition rate of carbon films is proportional to the C2H4/(C2H4+NH3) ratio with a power of first order, which is resulted from the adsorption of remaining precursor gas C2H4 on the silica glass plate substrate. Few nitrogen and hydrogen atoms are incorporated into carbon films. The activation energy (=152 kJ/mole) of carbon deposition is related to the activation energy of C2H4 dissociation. The crystallinity, degree of ordering, and nano-crystallite size of carbon films decrease with increasing the C2H4/(C2H4+NH3) ratio, while the fraction of sp3 carbon sites of carbon films increase. Finally, the results of thermal CVD carbon deposition using C2H4/NH3 mixtures are compared with those using CH4/NH3, C2H2/NH3, and C2H4/N2 mixtures
When propane/nitrogen (C3H8/N2) mixtures are used to deposit carbon films by thermal chemical vapor deposition (CVD), effects of C3H8/(C3H8+N2) ratios on the deposition rate and microstructures of carbon films are investigated. Experimental results show that as the C3H8/(C3H8+N2) ratio increases from 20 to 100%, the deposition rate increases from 23.7 to 127 nm/min. Alternatively, if the residence time, deposition temperature, and working pressure raise, the deposition rate of carbon films also increases. The kinetics of this thermal CVD process is discussed. The activation energy obtained in this work is 234 kJ/mole. Furthermore, this CVD reaction is controlled by a process of about first order, which is resulted from the adsorption of main product gases, acetylene (C2H2) and ethylene (C2H4), on the silica glass plate substrate. Few nitrogen and hydrogen atoms are incorporated into carbon films. The crystallinity, ordering degree, and nano-crystallite size of carbon films decrease with increasing the C3H8/(C3H8+N2) ratio. Meanwhile, as the C3H8/(C3H8+N2) ratio increases from 20 to 100%, the sp2/(sp2+sp3) ratio of carbon films decreases from 92 to 61%. Finally, the results of thermal CVD carbon deposition using C3H8/N2 mixtures are compared with those using methane/nitrogen (CH4/N2), C2H2/N2, and C2H4/N2 mixtures
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