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"Vanadium-doped LiFePO4/Cused as a cathode for a lithium ion battery has been successfully synthesized.In this work, LiFePO4 was synthesized from LiOH, NH4H2PO4,and FeSO4.7H2O at a stoichiometric amount. Vanadium was added in theform of H4NO3V at concentration variations and 3 wt.%carbon black. The characterization includes thermal analysis, X-raydiffraction, electron microscopy, and electrical impedance spectroscopy. Thethermal analysis results showed that the LiFePO4 formationtemperature is 653.8?700.0°C. The X-raydiffraction results showed an olivine structure with an orthorhombic spacegroup, whereas the electron microscopy results showed that LiFePO4/Chas a round shape with an agglomerated microstructure. Electrical impedancetest results showed values of 158 Ω and 59 Ω for the as-synthesizedLiFePO4/C and the 5 wt.% vanadium-dopedLiFePO4/C, respectively. Cyclic performance test results at 1 Cshowed capacities of 24.0 mAh/g and 31.2 mAh/g for the as-synthesized LiFePO4/Cand the 5 wt.% vanadium-doped LiFePO4/C,respectively. Charge and discharge test results showed charge and dischargecapacities of 27.6 mAh/g and 40.2 mAh/g for the as-synthesized LiFePO4/Candthe5 wt.%vanadium-doped LiFePO4, respectively. This result is promisingin terms of increasing the performance of a lithium ion battery."

"Platinum is the most effective counter electrode for use in dye-sensitized solar cells (DSSC). However, as platinum is very expensive, its price impedes its broad use as a DSSC counter electrode. As an alternative, carbon has been used for this purpose. In this study, carbon has been successfully pyrolyzed from the precursors of table sugar and sucrose through a chemical process, i.e. the dehydration of the precursors with sulfate acid followed by a pyrolysis process, and used as Pt-less counter electrode in a DSSC device. The as-synthesized carbon was characterized using X-ray diffraction (XRD) to obtain crystal structure information and a scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX) was employed to carry out morphological and compositional examination. The material activity and performance of the counter electrode in the DSSC device were analyzed using a semiconductor parameter analyzer through current–voltage characteristic curves (I-V). The results show that the precursors of table sugar without the addition of a metal catalyst and with initial heat treatment at 300°C for 1 hour, and of sucrose with a catalyst could produce carbon with a particle size of around 600–900 nm. The I-V curve characteristic of the DSSC device assembled using carbon produced from sucrose as a counter electrode resulted in a power conversion efficiency (PCE) of only 0.041%, whereas the DSSC device assembled using carbon produced from table sugar as a counter electrode exhibited a good performance with a PCE of 3.239%, almost equivalent to that of platinum paste with a PCE of 4.024%. This result is promising in terms of using a cheap source of carbon for the Pt-less counter electrode."

"Vanadium-doped LiFePO4/C used as a cathode for a lithium ion battery has been successfully synthesized. In this work, LiFePO4 was synthesized from LiOH, NH4H2PO4, and FeSO4.7H2O at a stoichiometric amount. Vanadium was added in the form of H4NO3V at concentration variations and 3 wt.% carbon black. The characterization includes thermal analysis, X-ray diffraction, electron microscopy, and electrical impedance spectroscopy. The thermal analysis results showed that the LiFePO4 formation temperature is 653.8–700.0°C. The X-ray diffraction results showed an olivine structure with an orthorhombic space group, whereas the electron microscopy results showed that LiFePO4/C has a round shape with an agglomerated microstructure. Electrical impedance test results showed values of 158 ? and 59 ? for the as-synthesized LiFePO4/C and the 5 wt.% vanadium-doped LiFePO4/C, respectively. Cyclic performance test results at 1 C showed capacities of 24.0 mAh/g and 31.2 mAh/g for the as-synthesized LiFePO4/C and the 5 wt.% vanadium-doped LiFePO4/C, respectively. Charge and discharge test results showed charge and discharge capacities of 27.6 mAh/g and 40.2 mAh/g for the as-synthesized LiFePO4/C and the 5 wt.% vanadium-doped LiFePO4, respectively. This result is promising in terms of increasing the performance of a lithium ion battery."

"Faced with ever-shrinking reserves of fossil-based energy, in addition to the damaging impacts of the use of fossil-based energy sources, such as the greenhouse effect and global warming, efforts are needed to find energy alternatives. Currently under development as an alternative source of renewable energy, utilizing solar energy as its source, is a device incorporating the dye-sensitized solar cell (DSSC), which works using the simple photosynthetic-electrochemical principle at the molecular level. In this type of device, inorganic oxide semiconductors such as titanium dioxide (TiO2) offer great potential for the absorption of photon energy from the solar energy source, especially in the form of a TiO2 nanoparticle structure. In this study, a commercial TiO2 nanoparticle was used. The as-received TiO2 nanoparticle was characterized using X-ray diffraction (XRD) and a scanning electron microscope (SEM). For sensitizer, a natural dye extracted from mangosteen (Garcinia mangostana L.) pericarps was used. The extracted natural dye was characterized using Fourier transform infrared (FTIR) for the functional groups, whereas ultraviolet-visible (UV-Vis) was used to examine the absorption activity of the extracted natural dye. Performance of the DSSC was analyzed through a precision current versus potential difference (I-V) curve analyzer. The maximum power conversion efficiency (PCE) of the mangosteen natural dye was obtained using ethanol containing 20% distilled water as compared to commercial organic dye with a PCE of 4.02%. This result is convincing and promising for the next development."