Papers by Keyword: Energy Storage Materials

Abstract: The composite nanofibers of PVDF/BiFeO₃ (PVDF/BF) signify a notable advancement in the domain of piezoelectric nanogenerators (PENGs), providing a high surface area alongside enhanced physicochemical properties for energy harvesting and storage applications. These nanofibers were synthesized through the electrospinning technique, which enables the creation of porous fibers by the dissolution of polymers in volatile solvents. This study investigates the crystalline and chemical structures of PVDF/BF nanofibers with modified formulations. X-ray diffraction (XRD) analysis has confirmed the presence of a rhombohedral (R3c) phase, characteristic of both BiFeO₃ and the PVDF phase. The measured fiber diameters for pure PVDF and PVDF/BF composites varied from approximately 400 nm to 950 nm. Fourier-transform infrared (FTIR) spectroscopy has identified absorption bands at 410–555 cm^-1, which correspond to the functional groups of BiFeO₃, as well as at 612–1430 cm^-1 for PVDF. Moreover, Raman spectroscopy has validated molecular vibrational shifts for BiFeO₃ (4A1+9E) and PVDF within the range of 2973–2977 cm^-1. The incorporation of BiFeO₃ within the PVDF/BF nanofibers enhances the formation of the electroactive β-phase, thereby potentially improving their electrical properties.

Abstract: This study investigated the application of phase change material and fins into photovoltaic panel. The experimental design was divided into 2 cases: conventional photovoltaic and photovoltaic with phase change material and fins. The thermal performance and electrical efficiency was tested under the solar radiation simulator between 500 and 1000 W/m². The insolation intensity was tested by an incident-light photometer. The power of the nine halogen lamps was controlled by a simple voltage control device. It was found that temperature of normal PV module is constant after the tested time of 20 minutes. The temperatures of PV module with phase change material and fins were lower than a normal PV module throughout the testing duration. Approximately 2-6% of photovoltaic module temperatures have decreased and this have improved the electrical efficiency of about 1-4%. This indicated the use of phase change material and fins is able to decrease the photovoltaic module temperature and thus increase the efficiency of photovoltaic module cooling.

Abstract: In the present study, Li-B-H films contained LiBH₄ and Li₂B₁₂H₁₂ were fabricated under different hydrogen pressures (20, 70 Pa) at ambient temperature by pulsed laser deposition (PLD). The corrosion behaviors of the films were studied over a time of 1-24 h in the air at ambient temperature. Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to analyze the formed oxidation film. The results indicated that an oxidation film with obvious cracks and holes were formed, which was composed by Li₂B₄O₇ and Li₂CO₃. The films were mainly reacted with H₂O and CO₂, so the oxidation of Li-B-H could be prevented by avoiding exposed to air.

Abstract: The compound Dy₂Si₂O₇ exists in two polymorphs, the low temperature triclinic phase (type B) and a high temperature orthorhombic phase (type E).The dc and ac electrical conductivities of E-Dy₂Si₂O₇ are measured in the temperature range 290-510 K and frequency range 1 kHz to 1 MHz . The dc electrical transport data are analyzed according to Motts variable-range hopping model. The disorder parameter (T_o) and density of states at fermi level are obtained. The ac conductivity σ_ac (ω) is obtained through the dielectric parameters. The ac conductivity can be expressed as σ_ac (ω) =B ω ^s , where s is slope and it decreases with increase in temperature. The conduction mechanism in the compound is discussed in low and high temperature regions in the light of theoretical models.

Abstract: Paraffin and modified inorganic porous materials composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of inorganic materials. In composite materials, paraffin was used as phase change material (PCM) for thermal energy storage, and γ-Al2O3 acted as supporting material, ethanol was solvent. A series of characterization were conducted to analyse and test the performance of the composite materials, and differential scanning calorimeter (DSC) results showed that the PCM-3 composite has the melting latent heat of 115.9 kJ/kg with melting temperature of 63.0°C. Due to the capillary and surface tension forces between paraffin and γ-Al2O3, the leakage of melted paraffin from the composites can be prevented. Several kinds of paraffin mixtures were also studied by adsorbing into the supporting materials, so that the composite energy storage materials with different phase change temperature can be used in the building wall to storage thermal of different regions. In a word, the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly.