A novel PPESK fibrous membrane separator based on electrospinning technique for lithium-ion battery
In order to improve the low porosity, poor thermal stability and insufficient electrolyte wettability of commercial polyolefin separator, the novel PPESK fibrous membrane separator has been fabricated via electrospinning for the use of lithium-ion batteries. By the use of high-speed collection drum, the tensile strength of the electrospinning oriented PPESK fiber membranes increase significantly and reaches 18.9 MPa. Hot oven testing shows that oriented PPESK fiber membranes are thermally size stable at a high temperature of 220 °C. The oriented PPESK fiber membrane exhibits high level of porosity (83%) and excellent electrolyte uptake (720%). Moreover, the ionic conductivity increases to 1.85 mS cm -1 compared with the 0.41mS cm -1 of commercial Celgard 2400 separator. In addition, the lithium-ion battery assembled with electrospinning oriented PPESK fiber membrane shows high capacity retention, stable cycle performance and excellent rate capability. Therefore, the electrospinning oriented PPESK fiber membrane is likely to be a promising candidate of high-power lithium-ion battery owing to its comprehensive outstanding characteristics.
RSC Advances
Optical sensing of palladium ions has attracted considerable attention due to their serious environmental and health problems. Water resources, soil, dust and natural ora have been contaminated by increased palladium emissions which are caused by a wide spectrum of applications such as the electrical and electronic industries, catalytic converters, dental appliances, fuel cells and jewellery. In addition, it is also exploited as catalyst in many cross-coupling reactions such as Buchwald– Hartwig, Heck, Sonogashira and Suzuki–Miyura, leading to the formation of difficult bonds for the synthesis of complex molecules involving many clinical drugs. Fruitful use of Pdcatalysed reactions in pharmaceutical industry increases the risk of Pd-contamination in active pharmaceutical ingredients because a high level of residual palladium is oen found in nal products, despite rigorous purication steps and thus, it can cause harm to human body. Traditional methods like atomic absorption spectroscopy (AAS), solid-phase microextraction high performance liquid chromatography (SPME-HPLC), inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray uorescence, etc., can be applied for the detection of palladium ions, however they all suffer from complicated sample preparation procedures, expensive experimental setup and the requirement for highly-trained individuals. Therefore, development of analytical techniques with selective and sensitive detection of palladium ions is urgently needed in a high-throughput fashion. As a new insights into the optical sensing systems, chemiluminescence based ones would be promising due to their superior advantages such as operational simplicity, cost effectiveness, rapid and high sensitivity of the target, free from interferences caused by light scattering and
Preparation and characterization of thin-film zeolite–PDMS composite membranes☆
Abstract Thin-film zeolite filled PDMS composite membranes, as thin as 3μm, have been prepared. Two criteria are essential for the successful preparation of these membranes: (a) application of ultrafine silicalite crystallites (0.2–0.5 μm) and (b) prepolymerization of the suspension comprising silicalite, two-component polydimethylsiloxane (PDMS) polymer, and isooctane. The separation properties of the composite membrane were characterized by pervaporation and gas permeation. High flux and high selectivity were observed in the pervaporation of aqueous ethanol solution. Composite membranes, having a silicalite to PDMS ratio (ws/wp) of 3.3, give a selectivity of 34 for separating ethanol from water, while the flux remains 150 g/m2-hr, at 22°C. The composite membranes also show improved performance in gas permeation, e.g. for separating O2 from N2. Optimization experiments provide suitable conditions and compositions for the preparation of the membranes. Employing PDMS concentrations in the 3.5–4.0 wt.% range and silicalite to PDMS ratios from 1.5 to 3.3, highly-selective composite membranes can be fabricated with high reproducibility.