Publications Search Results

Now showing 1 - 10 of 152
  • Publication
    Measurement resolution limits of local thermal inhomogenities on lithium-ion pouch cells
    ( 2022)
    Engeser, J.
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    Colak, C.
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    Ruf, J.
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    Heuer, A.
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    Figgemeier, E.
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    Pitta Bauermann, L.
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    Vetter, M.
  • Publication
    Non-Contacting Interferometric Distance Measurements of Pouch Cells During Cycling
    ( 2022)
    Engeser, J.
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    Berg, S.
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    Laufen, H.
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    Ruf, J.
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    Bruch, M.
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    Heuer, A.
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    Figgemeier, E.
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    Bauermann, L.
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    Vetter, M.
  • Publication
    The role of batteries in meeting the PV terawatt challenge
    ( 2021)
    Peters, I.M.
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    Breyer, C.
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    Jaffer, S.A.
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    Kurtz, S.
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    Reindl, T.
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    Sinton, R.
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    Vetter, M.
    What role have batteries to play in the transition toward terawatt levels of photovoltaics? In this perspective, we attempt to answer this question by looking at technical, economic, and ecological features of PV-battery systems. We argue that the window of opportunity for batteries lies in the capacities of a few kWh/kWP, the exact amount depending on various factors including battery cost, degradation rate, location, load profile, diversification of renewable energy sources, and interconnections. Using a simple PV plus battery model, we illustrate that such storage capacities efficiently reduce fluctuations in electricity generation, enabling higher PV adoption rates at competitive costs, and with a carbon footprint that is at least five times lower than that of the current energy mixes. Using sensible capacities, batteries are a powerful companion for solar energy, yet technical, economic, and policy innovations are needed to expand adoption. We see longer battery lifetimes and low capacity degradation rates are the most impactful technological parameters. Economic efforts should aim to reduce balance of plant costs and create better market opportunities for stationary storage, whereas policies should provide a strong regulatory framework to facilitate multipurpose usage and sector coupling.
  • Publication
    Novel method for the parameterization of a reliable equivalent circuit model for the precise simulation of a battery cell's electric behavior
    ( 2021)
    Bruch, M.
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    Millet, L.
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    Kowal, J.
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    Vetter, M.
    This article presents a novel approach to extract the equivalent circuit model parameter from a pulse test. The presented results corroborate that this novel heuristic methodology can very accurately fit the voltage response of the battery, while drastically reducing the dependence of the parametrization on set boundary conditions and initial guess values. The method's robustness is verified by fitting the voltage response of a mock battery model with pre-defined parameters. It could be shown that the suggested method is able to precisely extract the set parameters from the simulated voltage. Furthermore, the model values obtained from the test of a lithium ion battery cell correlate with physical parameter and other investigation methods like the calculation of the distribution of relaxation times (DRT). As a result, an accurate equivalent circuit model of the cell was created. The restriction as to universal validity of the empirical equivalent circuit model was significantly reduced by limiting the voltage of the RC element with highest time constant. Finally, a robust battery cell model with only a minor root-mean-square error of 1.30% was obtained.
  • Publication
    Review of Stationary Energy Storage Systems Applications, their Placement, and Techno-Economic Potential
    ( 2021)
    Wüllner, J.
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    Reiners, N.
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    Millet, L.
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    Salibi, M.
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    Stortz, F.
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    Vetter, M.
    Purpose of Review: This review paper attempts to give a general overview on the BESS applications that demonstrate a high potential in the past few years, identifying most relevant operators â or providers â with the corresponding placement for such. Together with a description of value proposition schemes, observed trends, and research fields, a collection of relevant project references is gathered. Recent Findings: Many publications and communications try to describe the services that battery energy storage systems can provide to each of the stakeholders, even though they might greatly differ based on national regulatory frameworks. The actual most relevant 6 applications in the view of the authors are described in more detail. Summary: In this paper, there has been pointed special attention on the BESS opportunities for each operator and their corresponding potential on revenue stacking. Additionally, the most important identified scientific papers for the 6 most important applications in the view of the authors are presented.
  • Publication
    Further development of non-contact and non-destructive methods for the localization of defects inside battery cells
    ( 2021)
    Pitta Bauermann, L.
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    Engeser, J.
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    Heuer, A.
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    Vetter, M.
    Reliable non-contact and non-destructive testings are useful for the verification of quality and safety standards of battery cells. The battery cells are commonly electrically characterized. In this case a possible failure is detected but neither identified nor localized. With non-invasive internal visualization of battery cells detailed information about such failures is obtained. Scanning Acoustic Microscopy (SAM) in the reflection-mode is a non-destructive ultrasonic tool, with which the interior of battery cells can be visualized with a good resolution. This method is still relatively unknown in the battery community. SAM is suitable for the visualization of defects like electrolyte leakage, faulty electrodes and gas accumulation inside battery cells. These failures are detected through the local atypical reflection of acoustic waves at faulty interfaces. The transducer with the appropriated frequency is scanned along the x and y directions providing a complete visualization of a battery cell in few minutes. In a so-called C-scan mode, two-dimensional acoustic micrographs are generated from the detected echoes. Individual images are produced from the reflected wavefronts obtained at specific time delays allowing additionally information about the depth of the investigated failures by using the X-scan mode. In this case several micrographs with defined depths are generated, by dividing the reflectogram into gates according to the selected interval of time delay, or time-of-flight (TOF). Acoustic cross-sections, also called B-Scan mode, are obtained by scanning the sample along a defined vertical plane. This fast and non-destructive visualisation tool can be used for the quality control of battery cells during their production or as end-of-line test. It allows the adjustment of the production in time, decreasing the wastage of resources. The evaluation of used battery cells for a second-life can be a field for this technology. SAM also brings a valuable contribution on the assistance in choosing representative spots of battery cells for post-mortem analyses.
  • Publication
    Meaningful Characterization of Battery Cells and Systems with Current Pulses
    ( 2021)
    Bruch, M.
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    Kevlishvili, N.
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    Hofmann, L.
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    Lux, S.
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    Vetter, M.