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The need for high-energy batteries has driven the development of binder-free electrode architectures. However, the weak bonding between the electrode particles and the current collector cannot withstand the severe volume change of active materials upon battery cycling, which largely limit the large-scale application of such electrodes. Using tin nanoarrays electrochemically deposited on copper substrate as an example, here we demonstrate a strategy of strengthening the connection between electrode and current collector by thermally alloying tin and copper at their interface. The locally formed tin-copper alloys are electron-conductive and meanwhile electrochemically inactive, working as an ideal “glue” robustly bridging tin and copper to survive harsh cycling conditions in sodium ion batteries. The working mechanism of the alloy “glue” is further characterized through a combination of electrochemical impedance spectroscopy, atomic structural analysis and in situ X-ray diffraction, presenting itself as a promising strategy for engineering binder-free electrode with endurable performance., The authors here report a binder-free electrode based on tin nanoarrays deposited on copper substrate. It is found that the locally formed electrochemically inactive tin-copper alloys work as a glue that bridges tin and copper to survive harsh cycling conditions in sodium ion batteries.

There are five elements in group IVA of the periodic table, i.e., carbon (C), silicon (Si), germanium (Ge), tin (Sn) and lead (Pb), of which Si, Ge, and Sn can be used as alloying-type electrode materials for sodium-ion batteries. Pb is also capable of alloying with sodium, but it is generally ruled out as the cause of toxicity. In recent years, materials based on Si, Ge, and Sn have been intensively exploited as sodium anodes because of their abundant resource and large capacity with reasonable working voltages. However, successful deployment of these anode materials needs to overcome kinetic and thermodynamic issues related to poor electrochemical activity, particle pulverization associated with large volume swelling, and formation of unstable solid-electrolyte interphase. A diversity of material strategies has been employed to address these difficulties, mainly leveraging on the knowledge recently advanced for lithium anodes. This review highlights such issues and provides valuable insights for possible solutions, which serves as a guide and inspiration for future material innovation for rechargeable batteries.

In order to meet the requirements of alignment capability, gap tolerance and welding track control, dual-beam laser welding has been put forward to weld tailored blanks with different thicknesses. The arrangement mode and power ratio of dual-beam laser determine the heat transfer and temperature field distribution, and then influence the weld profile and weld quality. In this study, based on consideration of the temperature dependence of material physical properties, convection and radiation heat transfer, and material latent heat, the finite element model was developed. The model validated was conducted to compare with experimental results and it showed good agreement. The arrangement mode and power ratio of dual-beam laser welding were compared and optimized based on the consideration of the weld width on top surface and gap tolerance. Finally, the temperature field characteristics with the preferable process were analyzed in detail according to the numerical simulation. The calculated results indicated the weld width is mainly controlled by the laser irradiation on the thin plate, and dual-beam laser welding of tailored blanks has great advantages on improving heat transfer, weld profile and gap tolerance, which helps to reduce welding defects and enhance welding quality.

In the present study, aluminum alloy T-joints were welded using the laser stake-welding process. In order to improve the welding quality of the T-joints, an external electric current was used to aid the laser stake-welding process. The effects of the process parameters on the weld morphology, mechanical properties, and microstructure of the welded joints were analyzed and discussed in detail. The results indicate that the aided electric current should be no greater than a certain maximum value. Upon increasing the aided electric current, the weld width at the skin and stringer faying surface obviously increased, but there was an insignificant change in the penetration depth. Furthermore, the electric current and pressing force should be chosen to produce an expected weld width at the faying surface, whereas the laser power and welding speed should be primarily considered to obtain an optimal penetration depth. The tensile shear specimens failed across the faying surface or failed in the weld zone of the skin. The specimens that failed in the weld of the skin could resist a higher tensile shear load compared with specimens that failed across the faying surface. The microstructural observations and microhardness results demonstrated that the tensile shear load capacity of the aluminum alloy welded T-joint was mainly determined by the weld width at the faying surface.

Surface imprinted superparamagnetic nanoparticles (Fe3O4@MIP) for bisphenol A (BPA) have been prepared by a rapid and simple UV irradiation initiated suspension polymerization method. The obtained nanoparticles show high binding affinity for BPA and enable rapid and efficient extraction of BPA from water samples. By combination with liquid chromatography–mass spectrometry, the method allows sensitive and reliable quantification of BPA in tap water with a detection limit as low as 0.1 ng/L for a sample volume of 100 mL. The polymerization method may be further extended to the preparation of surface imprinted magnetic nanoparticles for other analytes of interest.

The sharp increase in the cost of lithium resource has driven the research on sodium-ion batteries (SIBs) as sodium shares a similar electrochemical property as lithium. Carbonaceous materials are important anodes for rechargeable batteries, but the prevailing graphite only shows a limited activity towards sodium storage. Herein, we demonstrate that carbon nanoflakes serve as an efficient anode material for SIBs, exhibiting a stable capacity of 148[Formula: see text]mAh[Formula: see text]g[Formula: see text] over 600 continuous cycles at 150[Formula: see text]mA[Formula: see text]g[Formula: see text] and an excellent rate capability of 120[Formula: see text]mAh[Formula: see text]g[Formula: see text] at 1500[Formula: see text]mA[Formula: see text]g[Formula: see text]. More importantly, sodium storage in carbon nanoflakes exhibits a pseudocapacitive behavior, possibly due to their larger interlayer spacing and less-ordered structure vs. crystallized carbon.

Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media., Synthetic cells are designed to mimic basic life processes, but it is challenging to prepare cells that can persist and operate at non-equilibrium conditions. Here, Yin et al. show complex dynamical behaviors of protocells made by exposing polylysine and single-stranded DNA droplets to an electric field.

In this chapter, recent achievements in the development of luminescent optical sensors based on nanoscale molecularly imprinted polymers were reviewed. The first part focused on introduction of the commonly used ways to convert the specific interactions between imprinted cavities and corresponding template into measurable luminescent signals. In the following parts, the MIP-based luminescent optical sensors are classified as fluorescent sensors, chemiluminescent sensors, colorimetric sensors, and other types of luminescent optical sensors. The principal analytical features and applications of these different types of MIP sensors that have been developed recently are all summarized and discussed. In the last part, some remaining challenges are briefly discussed for further development of the field.

In order to improve the properties of laser overlap welded T-joint, laser-additional current hybrid welding process is put forward. In this paper, the welding characteristics of laser-additional current hybrid welded aluminum and titanium alloy T-joint were conducted and compared. The weld width at faying surface increase, which results in tensile shear load increasing compared with those of laser welding for both aluminum and titanium alloy, but the effect of current on aluminum alloy is more obvious. The porosity defect within the laser-additional current hybrid welded joint sharply reduces compared with that within laser welding. The tensile shear load of aluminum alloy and titanium alloy hybrid welded joints respectively increase 21% and 15%. The effects of additional current on welding characteristics of aluminum alloy and titanium alloy are compared and analyzed.