Van Tu Nguyen

For modern UAVs, the power source is usually a Li-ion polymer battery. Using modern physicochemical analysis methods such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), differential thermogravimetry (TGA), specific surface area (BET) and infrared spectroscopy (FT-IR), we determined the chemical composition of some of the main materials in Li-ion polymer batteries used for drones. We used the method of determining the corresponding size, voltage, and internal resistance to determine some of the main technical indicators of this type of battery. The analysis results show that the Li-ion polymer battery used for UAV has a cubic shape, dimensions of 281×72×5.2 mm (LxWxH), voltage of 3.78 V, internal resistance of 0.456 mΩ, positive electrode material is LiNi0.6Co0.2Mn0.2O2 coated on Al foil, negative electrode material is graphite coated on Cu foil, separator is polyethylene, binder is polyvinylidene fluoride (PVDF), positive electrode side leaf is Al, negative electrode side leaf is Cu. The analysis results also show that both negative and positive electrodes are made of fine, micrometer-sized, uniform powdered materials.

Leachate in landfills becomes difficult to treat due to its complex and widely variable composition, containing a large amount of organic, inorganic substances and heavy metals. When it seeps into the ground, leachate pollutes groundwater, and if discharged into surface water, it will harm the aquatic environment in the corresponding area. Therefore, it is extremely necessary to treat leachate before discharging it into the environment to prevent this negative impact. In this study, a lab-scale A2O (Anaerobic–Anoxic–Oxic) system integrated with a Moving Bed Biological Reactor (MBBR) was established. We evaluated key water quality indicators of wastewater pretreated by internal electrolysis, the effluent from the A2O–MBBR system, and the combined treatment process. The wastewater was taken from Nam Son landfill, Soc Son, Hanoi, in Viet Nam. COD, BOD5, NH4+-N, and pH of the input leachate wastewater were 2140 mg/L, 250 mg/L, 895 mg/L, and 8 ± 0.5, respectively. The conditions of internal electrolysis were as follows: 120 minutes of reaction time, pH =4, 4.0 g/L Fe/Cu dosage and 100 mg/L PAM dosage. Following the internal electrolysis pretreatment, the removal efficiencies of COD, BOD₅, and NH₄⁺–N reached 49.0%, 4.8%, and 11.2%, respectively. After 24 hours of operation, the integrated treatment process exhibited markedly enhanced performance, achieving removal rates of 85.0% for COD, 85.2% for BOD₅, 94.1% for total nitrogen, 98.0% for total phosphorus, and 96.7% for NH₄⁺–N. These results demonstrate the high synergistic efficiency of the combined internal electrolysis–A₂O–MBBR system. Furthermore, all post-treatment parameters complied with the Vietnamese standard QCVN 40:2011/BTNMT (Column B2) for leachate wastewater, confirming its effectiveness and environmental suitability.

The choice of precursor and simple synthesis techniques have decisive roles in the viable production and commercialization of carbon products. The intense demand for developing high-purity carbon nanomaterials through inexpensive techniques has promoted the usage of fossil derivatives as a feasible source of carbon. In this study, Vietnamese-coal-derived porous carbon (PC) was used to fabricate coal-derived porous carbon nanomaterials (CDPCs) using the modified Hummers method. The resulting porous carbon nanomaterials achieved a nanoscale structure with an average pore size ranging from 3 to 10 nm. The findings indicate that CDPC exhibits well-developed micropores and mesopores. The presence of macropores and mesopores not only facilitates the complete immersion of the material in the electrolyte but also effectively shortens the ion diffusion pathways. CDPC boasts a high carbon content, constituting 80.88% by weight. Electrochemical impedance spectroscopy (EIS) Nyquist plot of electrodes made from CDPC showed good conductivity value with low charge-transfer resistance. This electrode worked well and stably with capacitance retention of 74.7% after 1000 cycles. The CDPC specific capacitance reached 236 F/g under a current density of 0.1 A using the constant current discharge method and then decreased as the current density increased. Based on the results of the electrochemical properties of the materials, the energy storage capacity of the CDPC material was good and stable. This investigation presents an eco-friendly methodology for the judicious utilization of coal in energy storage applications, specifically as electrodes for supercapacitors and anodes for Li-ion batteries.

In this paper, ZnO nanorods were synthesized by the hydrothermal method and used as anodes for zinc-silver batteries. The Tafel and EIS curve analysis results show that ZnO nanorods have better anti-corrosion and charge transport properties than ZnO powders. At 0.1 C discharge conditions, the ZnO electrode exhibits more stable cycle efficiency than the powder electrode; after 25 cycles, the capacity is higher by 95%. The superior electrochemical performance is due to the ZnO nanorods having the ability to conduct electrons and increase the surface area. Therefore, the possible growth mechanism of ZnO nanorods has been investigated.