The recent development of individual mobility is characterized by a resource‐saving and environmentally friendly technology policy. Electromobility has the greatest potential to meet these demands. Due to the high volumetric power density at both the cell as well as the battery levels, pouch cells are addressed as a target cell format. As a separation of the electrodes is absolutely necessary for this cell design, the separation of the electrodes constitutes a basic operation of the pouch cell production. The established separation methods, such as die and laser cutting, are compared in this work with regard to their physical cutting‐edge quality. For reproducible evaluation, the occurring cutting‐edge characteristics are defined to clearly describe the quality of the separated electrode. Furthermore, the influence of the photonically and mechanically produced cutting edge on the electrochemical performance is presented. The results show that the delamination of the active materials and the bending of the collector and the metal spatter have the greatest influence on the electrochemical performance of the cell.
Laser cutting is a promising technology for the singulation of conventional and advanced electrodes for lithium-ion batteries. Even though the continuous development of laser sources, beam guiding, and handling systems enable industrial relevant high cycle times, there are still uncertainties regarding the influence of, for this process, typical cutting edge characteristics on the electrochemical performance. To investigate this issue, conventional anodes and cathodes were cut by a pulsed fiber laser with a central emission wavelength of 1059–1065 nm and a pulse duration of 240 ns. Based on investigations considering the pulse repetition frequency, cutting speed, and line energy, a cell setup of anodes and cathodes with different cutting edge characteristics were selected. The experiments on 9 Ah pouch cells demonstrated that the cutting edge of the cathode had a greater impact on the electrochemical performance than the cutting edge of the anode. Furthermore, the results pointed out that on the cathode side, the contamination through metal spatters, generated by the laser current collector interaction, had the largest impact on the electrochemical performance.
Industrially produced lignins are by-products of the pulp and paper industry and depending on the source and pulping technology they have deviating functional groups, solubility behavior and reactivity. In the present paper, kraft lignin was pretreated by mechanical milling and polyesterified with ε-caprolactone to create hydroxyl groups that are more easily available for further reactions. The products obtained were analysed by size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and functional group determination. The analytical data are presented as a function of reaction time, crosslinking reactions and the amount of ε-caprolactone input.
Inorganic solid electrolytes are the most important component for realizing all-solid-state batteries with lithium metal anodes and enable safe battery cells with high energy densities. Their synthesis and processing are the subject of current research, especially the NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP). Herein, the ability of sintering with electro-magnetic irradiation is investigated and correlated with different properties of prepared LATP pellets. First of all, an infrared camera records the temperature of the surface during the treatment. Second, the effect of the pulse fluence is investigated in terms of the topology and morphology of the pellets. Here, the arithmetic surface roughness Ra is the main parameter. Then, the depth of the radiation interaction in the pellet is measured. The focus of this paper is on the different pulse widths of the laser sources, and therefore, similar pulse and hatch overlap ensure equivalent areal energy input in both cases. As a summarized result, treatment with a shorter pulse width generates high peak pulse powers, resulting in higher temperatures, rougher surfaces and affecting deeper layers of the pellets compared to treatment with longer pulse width. On the contrary, excessive power leads to the ablation of the material up to destruction.
Monitoring the deformation within an adhesive joint during the curing cycle provides valuable information regarding the build-up of thermal strain and stress. Distributed fibre optic sensors are very useful for spatial continuous measurements of deformation or temperature. Integrated into a hybrid joint, the thermal curing process of the adhesive can be monitored. This detailed insight into the joint helps to understand the deformation and thereby also the resulting stress. Analysing the deformation process establishes the foundation to adapt techniques to reduce the thermally induced deformation and thereby the resulting stress.
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