The Fabrication of Porous Si with Interconnected Micro-Sized Dendrites and Tunable Morphology through the Dealloying of a Laser Remelted Al–Si Alloy

Coral-like porous Si was fabricated through the dealloying of a laser remelted as-cast AlSi12 alloy(Al-12 wt % Si). The porous Si was composed of interconnected micro-sized Si dendrites and micro/nanopores, and compared to flaky Si, which is fabricated by direct dealloying of the as-cast AlSi12 alloy. The structure of the porous Si was attributed to the dendritic solidification microstructure formed during the laser remelting process. The micropore size of the porous Si decreased from 4.2 μm to 1.6 µm with the increase in laser scanning velocity, indicating that the morphology of porous Si could be easily altered by simply controlling the laser remelting parameters. The coral-like porous Si provided enough space, making it promising for high-performance Si-based composite anode materials in lithium-ion batteries. The proposed hybrid method provides a straightforward way of tuning the porous structure in the dealloyed material

Laser pressure welding of Al-Li alloy 2198: effect of welding parameters on fusion zone characteristics associated with mechanical properties

Al-Li alloy 2198 exhibits good combination of toughness and strength but its application is strongly limited by the poor weldability due to the formation of porosities during fusion-welding. This is the first study proposing and verifying a new approach to produce defect-free laser welds of poorly fusion-weldable Al-Li alloy 2198 with applied external pressure, i.e., feasibility of laser pressure welding to Al-Li alloy 2198 was examined. The microstructures associated with tensile shear behavior of laser pressure welded Al-Li alloy 2198 obtained at various welding parameters were analyzed. The results showed that formation of the welding defect in the weld could be successfully suppressed by applying laser pressure welding, even without shielding gas. Three microstructural zones, including the chill zone, the columnar zone and the equiaxed zone were observed in the fusion zone. Size of fusion zone and area fraction of porosities generally increased with increasing roller pressure and welding heat-input, and they dominantly affected the tensile shear behavior, including the peak load and the failure mode, of the weld

Effect of Laser-Textured Cu Foil with Deep Ablation on Si Anode Performance in Li-Ion Batteries

Si is a highly promising anode material due to its superior theoretical capacity of up to 3579 mAh/g. However, it is worth noting that Si anodes experience significant volume expansion (>300%) during charging and discharging. Due to the weak adhesion between the anode coating and the smooth Cu foil current collector, the volume-expanded Si anode easily peels off, thus damaging anode cycling performance. In the present study, a femtosecond laser with a wavelength of 515 nm is used to texture Cu foils with a hierarchical microstructure and nanostructure. The peeling and cracking phenomenon in the Si anode are successfully reduced, demonstrating that volume expansion is effectively mitigated, which is attributed to the high specific surface area of the nanostructure and the protection of the deep-ablated microgrooves. Moreover, the hierarchical structure reduces interfacial resistance to promote electron transfer. The Si anode achieves improved cycling stability and rate capability, and the influence of structural features on the aforementioned performance is studied. The Si anode on the 20 μm-thick Cu current collector with a groove density of 75% and a depth of 15 μm exhibits a capacity of 1182 mAh/g after 300 cycles at 1 C and shows a high-rate capacity of 684 mAh/g at 3 C

Microstructure and mechanical properties of laser beam-welded AA2060 Al-Li alloy

Laser beam welding of a newly developed AA2060 aluminum–lithium (Al-Li) alloy was performed with AlSi12 filler wire. The fusion zone (FZ) consisted of dendritic solidification structure with the LiAlSi and CuAl2 phases and a small quantity of Mg2Si phase at the dendritic and grain boundaries, reducing the precipitation ability in the interior of grains. The microhardness was decreased in the FZ, being 90–120 HV0.1, compared to the based material (BM), being 152 HV0.1, and the variation was consistent with local strength across the joint. The joint transverse tensile strength was 416 MPa and the elongation was 1.2%. The presence of grain boundary phases caused the fracture mode varied from a low–energy intergranular fracture in the FZ to a high–energy transgranular fracture in the BM. The formation of LiAlSi phases in the weld metal, resulting from the addition of Si, helped increase the tensile strength of the joints. The AA2060 Al-Li alloy is considered weldable due to the over 80% tensile strength of BM in laser beam welding, which readily meets most applications

Data for: One-Step Fiber Laser Fabrication of Mesoporous and Compact TiO2 Layers for Enhanced Performance of Dye-Sensitized Solar Cells

Data includes Laser processing video recorded by thermal camera, electrochemical impedance spectra, I-V curves, raman spectra for compact and mesoporous TiO2 layers, laser confocal microscopy images, XRD spectra for compact and mesoporous TiO2 layers