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Optimization of synthesis condition of water-resistant and thin titanium oxide layer-coated Ni-rich layered cathode materials and their cathode performance
摘要： In this study, in order to develop water-resistant LiNiaCobAl1?a?bO2 (a > 0.85, NCA) cathode materials which exhibit high-rate performance, the surface coating of NCA with titanium oxide (TiOx) was examined. The synthesis conditions for the TiOx-coated NCA cathode materials were investigated, by taking into account some essential factors in the surface coating of NCA by TiOx, with a view to improving the rate performance. We successfully prepared the TiOx-coated NCA cathode material, the rate performance of which is superior to that of the conventionally prepared NCA cathode materials, typically using a polyvinylidene difluoride (PVdF) binder and N-methyl-2-pyrrolidone (NMP) solvent. Their surface analysis suggested that the specific surface structure of TiOx layer coated on the NCA particle leads to both a water-resistant property and a high permeability of Li+ ions through it in the charging/discharging process.
关键词： Lithium ion secondary battery,Water-based hybrid polymer binder,TiOx coating layer,Water resistance,Ni-rich lithium transition metal oxide
更新于2025-09-23 15:21:21
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High quantum yield red-emission phosphor Li2Ge4O9:Mn4+ for WLEDs application
摘要： A series of high quantum yield Li2Ge4O9:Mn4+ phosphors are prepared by solid-state reaction method, and their structure has been determined by X-ray powder diffraction with Rietveld refinement. The excitation spectra of Li2Ge4O9:Mn4+ exhibits two excitation bands at 300–400 nm and 400–500 nm corresponding to 4A2→4T1 and 4A2→4T2 transition of Mn4+ ions respectively, and emission spectra from 625 to 750 nm with the strongest emission peak at 671 nm owing to the 4E→4A2 transition of Mn4+ ions. The optimal Mn4+ doping concentrations of Li2Ge4O9 host are determined to be 0.3 mol% and the optimum synthesis temperature is found 800°C. The Li2Ge4O9:Mn4+ phosphor demonstrated high quantum yield. The as-prepared phosphor shows excellent water-resistance and thermal stability property compared with commercial used K2SiF6:Mn4+ phosphor. Finally, a white LED with improved Ra (from 72.5 to 82) and reduced Tc (from 6530 K to 6107 K) was fabricated by using a 450 nm blue chip with Y3Al5O12:Ce3+ and the as-prepared Li2Ge4O9:0.003Mn4+ phosphor.
关键词： Mn4+,Quantum yield,Water-resistance property,UV and blue excited
更新于2025-09-19 17:13:59
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Resistive Water Sensors Based on PEDOT:PSS- <i>g</i> -PEGME Copolymer and Laser Treatment for Water Ingress Monitoring Systems
摘要： Water sensors are a type of level sensor that can be used in various applications requiring the sensing of water levels, such as in dams, nuclear power plants, water pipes, water tanks, and dehumidifiers. In particular, water sensors in water ingress monitoring systems (WIMS) protect lives and property from disasters caused by water leakage and flooding. Here, a resistive water sensor for WIMS that incorporates poly(3,4-ethylenedioxythinophene):poly(styrene sulfonate) (PEDOT:PSS) grafted with poly(ethylene glycol) methyl ether (PEGME) (PEDOT:PSS-g-PEGME copolymer) as high-conductivity electrodes and laser-treated PEDOT:PSS-g-PEGME copolymer as the low-conductivity resistive component is reported. The configuration of the water sensor is modeled as two parallel resistors (Rlaser treated PEDOT:PSS || Rwater) when water comes into contact with the sensor surface. The two-resistor configuration exhibits a better performance in comparison with single-resistor configurations comprising only PEDOT:PSS-g-PEGME copolymer or laser-treated PEDOT:PSS-g-PEMGE copolymer. Moreover, PEDOT:PSS-g-PEGME copolymer is applied to the sensor to improve the stability of PEDOT:PSS in water. We demonstrate that the sensor can detect the water level in real time with high sensitivity and accuracy, and thus has potential in applications for monitoring water-related hazards.
关键词： PEDOT:PSS,resistive water sensor,laser treatment,water resistance,water ingress monitoring systems
更新于2025-09-12 10:27:22
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Electrical Conductivity Modulation of Crosslinked Composite Nanofibers Based on PEO and PEDOT:PSS
摘要： The aim of this work is to investigate the development of nano?ber mats, based on intrinsically conductive polymers (ICPs), which show simultaneously a high electrical conductivity and mandatory insoluble water properties. In particular, the nano?bers, thanks to their properties such as high surface area, porosity, and their ability to o?er a preferential pathway for electron ?ow, play a crucial role to improve the essential characteristics ensured by ICPs. The nano?ber mats are obtained by electrospinning process, starting from a polymeric solution made of polyethylene oxide (PEO) and poly(styrene sulfonate) (PEDOT:PSS). PEO is selected not only as a dopant to increase the electrical/ionic conductivity, as deeply reported in the literature, but also to ensure the proper stability of the polymeric jet, to collect a dried nano?ber mat. Moreover, in the present work, two di?erent treatments are proposed in order to induce crosslinking between PEO chains and PEDOT:PSS, made insoluble into water which is the ?nal sample. The ?rst process is based on a heating treatment, conducted at 130°C under nitrogen atmosphere for 6 h, named the annealing treatment. The second treatment is provided by UV irradiation that is e?ective to induce a ?nal crosslinking, when a photoinitiator, such as benzophenone, is added. Furthermore, we demonstrate that both crosslinking treatments can be used to verify the preservation of nanostructures and their good electrical conductivity after water treatment (i.e., water resistance). In particular, we con?rm that the crosslinking method with UV irradiation results to being more e?ective than the standard annealing treatment. Indeed, we demonstrate that the processing time, required to obtain the ?nal crosslinked nano?ber mats with a high electrical conductance, results to being smaller than the one needed during the heating treatment.
关键词： PEO,PEDOT:PSS,intrinsically conductive polymers,electrical conductivity,nano?ber mats,water resistance,electrospinning,crosslinking
更新于2025-09-09 09:28:46
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Improvement of Electrical Conductivity and Chemical Durability in Fe <sub/>2</sub> O <sub/>3</sub> Doped V <sub/>2</sub> O <sub/>5</sub> –B <sub/>2</sub> O <sub/>3</sub> –P <sub/>2</sub> O <sub/>5</sub> Glasses
摘要： In this study, we veri?ed the relationship among the electrical conductivity, chemical durability, and structure of conductive vanadate glass in which Fe2+–Fe3+ and V4+–V5+ systems simultaneously coexist. We prepared samples of iron vanadium borophosphate glass with various compositions given by 78V2O5–15P2O5–7B2O3–xFe2O3 (1, 5, 7.5 and 10 mol%) and analyzed the electrical conductivity, chemical durability, FTIR spectra, thermal properties, density, and molar volume. The results indicated that the addition of Fe2O3 improved the electrical conductivity, chemical durability, and thermal properties. The following conclusions could be drawn: Fe2+–O–P bonds or Fe3+–O–P bonds were generated in the glass structure, and Fe3+ and Fe2+ ions were located at tetrahedral and octahedral sites. Furthermore, V O bonds were expected to be replaced with Fe–O–V and P–O–V bonds, which are stronger than double bonds, so that the complete glass structure was strong. The structural reinforcement of the glasses was additionally con?rmed based on thermal and chemical properties and electrical conductivity.
关键词： Water Resistance,Transition Metal Oxide,Vanadate Glass,Conductivity,Glass Structure
更新于2025-09-04 15:30:14