Advanced Materials Research Vols. 724-725

Abstract: To enhance the electrochemical performance of LiFePO₄/C, Na and V have been co-doped in cathode material of the lithium ion batteries. A series of Na and V doped samples Li_0.97Na_0.03Fe_(1-x)V_xPO₄/C (x=0, 0.01, 0.03, 0.05) cathode materials are synthesized by solid state method. Results show that the Li_0.97Na_0.03Fe_0.97V_0.03PO₄/C exhibited the best electrochemical performances.

Abstract: Li₃V₂(PO₄)₃/C composite cathode material was synthesized by solid state method using LiOH•H₂O, NH₄H₂PO₄, NH₄VO₃ as raw materials, sucrose as carbon source, and two kinds of precursor’s treatment such as pre-sintering and hydrothermal methods. The effect of different precursor’s treatment methods on the electrochemical properties of the material was investigated. The results showed that the samples treated with hydrothermal process has smaller particle size and the initial discharge specific capacity of 119mAh/g, the capacity retention rate is 85% after 20 cycles. But the samples treated with pre-sintering (without hydrothermal process) has larger particle size and the initial discharge specific capacity 103.2mAh/g, the capacity retention rate is only 72% after 20 cycles. These results can be attributed to that the hydrothermally treated sample has smaller particle sizes, higher conductivity and shorter distances of lithium ion diffusion and electron mobility, thus the electrochemical performances are improved.

Abstract: Olivine structured LiFePO₄ are prepared by sol-gel method from FePO₄·H₂O nanocrystallites, which are synthesized via in situ polymerization restriction technique. These composites are fully characterized using XRD, SEM, and the electrochemical performances have been shown by the charge/discharge capacity, rate property and cycle performance. The synthesized LiFePO₄ samples show well-crystallized structures. Among those samples, the sample synthesized at 650°C presents the highest discharge capacity of 165.8 mAhg^-1 at 0.2 C. This compares with a theoretical discharge capacity of 170 mAhg^-1.

Abstract: Separator is one of the key components of primary batteries and affects the safety and life of the battery. In this study, separator was prepared based on the polyamide (PA) nonwoven with PA nanofiber. PA nonwoven was prepared meltblown method. The spinning conditions for meltblown were optimized to improve the mechanical strength and the electrolyte property, which play an important roll to determine the electrical performance of battery. It was revealed that the PA nanofiber in the PA separator contributed to the electrolyte absorption and electrolyte absorption speed as well. The electrical performance of battery having PA separator was also investigated.

Abstract: LiFePO₄/C(LFP/C) composite cathode material was synthesized by carbon thermal reduction route with the sucrose as reducing agent and characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Some parameters were optimized by means of determining the amount of sucrose and Li₂CO₃. The electrochemical performances were also tested through assembling batteries. The experimental results demonstrated that the proper theoretic coated carbon amount was 11.4% and 4.21% respectively, and the proper lithium usage is the normal stoichiometric proportion, namely, the lithium amount is not excess.

Abstract: Biodiesel from waste cooking oil offers sustainable alternative to diesel. This paper presents an experimental investigation of combustion of biodiesel derived from waste cooking oil to study the characteristics of biodiesel emissions compared to diesel. The combustion of neat biodiesel and biodiesel blended in different ratios with diesel was investigated using continuous combustion rig. The temperature of combustion gases, emissions of un-burnt HC and NO for different airflow rates were evaluated. Differences in the chemical composition between biodiesel and diesel result in different mechanisms of NO and HC formation. The results provide insight into combustion and emission from biodiesel. It was observed that the combustion gas temperature (CGT), adiabatic flame temperature, unburned hydrocarbon (HC) and carbon monoxide (CO) decrease, while nitrogen oxides (NOx) increases when the proportion of biodiesel is increased in the blend. Combustion of biodiesel blends for 2% excess O₂ shows the best compromise between the reduction in unburned HC and the lowest increase in NOx. It can be concluded that biodiesel made from waste cooking oil has potential to use as alternative to diesel fuel in internal combustion engine and has significant environmental benefits compare to diesel.

Abstract: Ni-Ce-Al layered double hydroxides (LDHs) with various Ni:Ce:Al molar ratios (3: 0.1:0.9, 3:0.2:0.8 and 3:0.5:0.5) were prepared by Co-precipitation. Ce can replace Al in a wide range of Ce/Al ratios to form Ni-Ce-Al-LDH with the unique layered structure of hydrotalcite. After the calcined at 600°C, LDHs samples were converted to mesoporous NiO-CeO₂ mixed oxides with a high surface area. The Ni-Ce-Al mixed oxide catalysts exhibit superior catalytic activity in oxidative dehydrogenation of propane and the excellent activities were attributed to mesoporous structure and the suppression of coke deposition.

Abstract: Sequential extraction of four coal oxidation residues (COR) from aqueous NaOCl solution with petroleum ether (PE), carbon disulfide (CS₂), acetone and methanol were investigated. The results suggest that methanol is an effective extraction solvent, giving the highest extraction yields for four COR. The extraction fractions were analyzed by GC/MS. It is found that no compounds, except for F₁ of HL and XL , F₂ of four COR, were detected. In total, 89 organic compounds were detected in F₁ of HL and XL, 23 organic compounds in F₂ from four COR. Most of which were arenes (As), normal alkanes (NAs) and oxygen-containing compounds (OCCs).

Abstract: In the process of oil vapor condensation, the phase and percentage content of each composition can be obtained by phase equilibrium calculation. On this basis, as the correction of ideal enthalpy and entropy, the residual enthalpy and entropy can be calculated by LKP equation and complementary function. Four kinds of oil vapor under different temperature were calculated by program written in VC++. The results are closed to that of Aspen software, so it can be taken as the basis of follow-up process simulation.

Abstract: Coker gas oil (CGO) is difficult to be cracked in the conventional FCC process, due to their high nitrogen content, especially the basic nitrogen compounds. To enhance the conversion of CGO, the high reaction temperature and catalyst to oil ratio processing scheme was performed in a pilot-scale riser FCC apparatus. To study the impact of (basic) nitrogen content, two kinds of CGO were tested. The results show that increasing the reaction temperature and CTO is an effective method for enhancing the conversion of CGO. The (basic) nitrogen content significantly influences the cracking behavior of CGO and the choose of optimal reaction conditions.