Battery research depends upon up-to-date information on the cell characteristics found in current electric vehicles, which is exacerbated by the deployment of novel formats and architectures. This necessitates open access to cell characterization data. Therefore, this study examines the architecture and performance of first-generation Tesla 4680 cells in detail, both by electrical characterization and thermal investigations at cell-level and by disassembling one cell down to the material level including a three-electrode analysis. The cell teardown reveals the complex cell architecture with electrode disks of hexagonal symmetry as well as an electrode winding consisting of a double-sided and homogeneously coated cathode and anode, two separators and no mandrel. A solvent-free anode fabrication and coating process can be derived. Energy-dispersive X-ray spectroscopy as well as differential voltage, incremental capacity and three-electrode analysis confirm a NMC811 cathode and a pure graphite anode without silicon. On cell-level, energy densities of 622.4 Wh/L and 232.5 Wh/kg were determined while characteristic state-of-charge dependencies regarding resistance and impedance behavior are revealed using hybrid pulse power characterization and electrochemical impedance spectroscopy. A comparatively high surface temperature of ∼70 °C is observed when charging at 2C without active cooling. All measurement data of this characterization study are provided as open source.
2 September 2024 in Journal of the Electrochemical Society
Considering the growing need for extensive energy storage solutions in smart grid technologies and affordable options for entry-level electric vehicles, sodium-ion batteries offer a promising alternative. They use raw materials that are cheaper, less toxic, and more abundant than those used in lithium-ion batteries, making them especially suitable for large-scale applications. This study comprehensively investigated four commercially available sodium-ion batteries to examine their structural and electrochemical characteristics. The cells were dissected, and the electrode dimensions, the areal mass loadings, and the material compositions were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and attenuated total reflection Fourier-transform infrared spectroscopy. Electrical characterization, including electrochemical impedance spectroscopy, C-rate testing up to 6 C under different ambient temperatures, along with cyclic aging studies, provided insights into the cells’ performance and degradation mechanisms. The findings highlighted variations in electrode coatings, particle sizes, and cathode materials among the cells, which were then correlated with their electrical behavior. This emphasized the challenges in maintaining sodium-ion battery performance, especially at low temperatures. This study was designed to establish a comprehensive knowledge base for both academic and industrial research in sodium-ion battery technology.
Polyoxymethylene dimethyl ethers (OME) are promising substitutes for fossil diesel fuel. Besides the possibility of closing the carbon cycle, OME also feature soot-free combustion. Although this has been demonstrated sufficiently, nanoparticle emission in OME exhaust is mainly unknown. Many studies provide information about the particle size distribution (PSD) in the exhaust of OME-fueled diesel engines, but lack a distinction between solid particles and particles of a volatile nature. This distinction is necessary in order to evaluate the potential of OME regarding Euro VI and the Euro VII exhaust gas legislation being discussed. This study investigates the PSD of fossil diesel and the OME exhaust of a heavy-duty engine with and without removal of the volatile fraction via a catalytic stripper, by means of a purpose-built sampling system based on proposals from the Particle Measurement Programme (PMP). The experiments showed that most of the nuclei mode investigated in OME operation is of a volatile nature and that the solid particle number (PN) emission is below that of Euro VI diesel operation. Moreover, the results indicate that a state-of-the-art aftertreatment system removes most of the particle emission, regardless of whether it is volatile or solid. Selective catalytic reduction using aqueous urea dosing increases solid particle emission, especially in the sub-23 nm range. However, a PMP-conformant measurement of PN23 and PN10 during WHSC and WHTC runs demonstrated that the PN emission of an OME-fueled engine falls below the average immission level of urban and regional background in Germany.
One of the major challenges of battery cell manufacturing is the reduction of production costs. Production defects and manufacturing inaccuracies, combined with high value streams, cause cost-intensive scrap rates. Conventional batch tracing is insufficient to detect rejects at an early stage, since the quality-critical intermediate products are not considered in a differentiated manner. To address this deficiency, tracking and tracing approaches in battery cell production are becoming increasingly popular. To obtain sufficient resolutions of the production data, the allocation of process and product data must be performed at the electrode sheet level. An interface is required for this, which can be realized by marking the individual electrodes. This paper investigates the integration of two well-known marking technologies: laser and ink marking. Integrating these marking technologies requires the consideration of physical boundary conditions in the process chain. For this purpose, the necessary investigations are presented in a structured manner to ensure that the marking does not have a negative influence on the process chain and vice versa. A pilot production line is used as an example to demonstrate the necessary tests for the integration of laser or ink markings.
The production of lithium‐ion batteries consists of a long and complex process chain. The individual process steps influence each other, resulting in unknown cause‐and‐effect interactions. As a result, production fluctuations cause variations in the final battery cell properties, which, coupled with high material costs, lead to costly scrap. Sensor and machine data provide important information during production about the manufacturing and condition of intermediate products. However, a challenge exists, in that these valuable production data cannot be precisely assigned to the corresponding intermediate products, and consequently, the cause of the production fluctuation cannot be explained. In this article, a method for tracking and tracing single‐electrode sections from coating to formation is described. Using the example of areal mass loading, it shows that all production data for the electrode production can be assigned automatically to the individual electrode sheets. In addition, all production data for cell assembly and cell finalization can be assigned to each cell stack and thus to the electrodes used. The monitored electrode areal mass loading of individual electrode sheets enables the identification of deviating electrode sections and a cell‐specific calculation of the final capacity from manufactured battery cells.