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196 results on '"Bieker, Peter"'

4. Converting a Commercial Separator into a Thin‐film Multi‐Layer Hybrid Solid Electrolyte for Li Metal Batteries.

Author

Herbers, Lukas, Fettkether, William, Stuckenberg, Silvan, Berghus, Debbie, Martin, Steve W., Winter, Martin, and Bieker, Peter

Subjects
SOLID electrolytes, SUPERIONIC conductors, POLYETHYLENE oxide, ALUMINUM phosphate, METALS, LITHIUM, POLYELECTROLYTES, ELECTRIC batteries
Abstract

To address the manifold challenges solid electrolytes (SE) do face in NMC‖Lithium metal batteries, we demonstrate that these can be overcome by converting a commercial Celgard 2500 separator into a jack of all trades hybrid solid electrolyte (HSE). This approach follows a multi‐layer electrolyte strategy, to better cope with the very different chemistries of the cathode, the bulk electrolyte material, and the Li metal anode. A cathode‐facing electrolyte layer based on lithium aluminum titanium phosphate (LATP) provides a high voltage stability of ≥4.5 V. High mechanical strength of the overall thin film electrolyte (≤50 μm) is achieved with a middle layer based on Celgard 2500. The layer on the anode side, based on polyethylene oxide (PEO), allows stable cycling of the lithium metal. High Coulombic efficiencies in NMC622‖Li metal cells (99.9 %) and LFP‖Li metal cells (99.9 %) enable long term cycling with high‐capacity retention of 46 % and 52 % after 1,000 cycles, respectively. [ABSTRACT FROM AUTHOR]

Published
2024
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9. The Influence of Polyethylene Oxide Degradation in Polymer‐Based Electrolytes for NMC and Lithium Metal Batteries.

Author

Herbers, Lukas, Minář, Jaroslav, Stuckenberg, Silvan, Küpers, Verena, Berghus, Debbie, Nowak, Sascha, Winter, Martin, and Bieker, Peter

Subjects
POLYETHYLENE oxide, ELECTROLYTES, POLYELECTROLYTES, SOLID electrolytes, DENDRITIC crystals, LOW density polyethylene
Abstract

A multilayered ternary solid polymer electrolyte (TSPE) is presented. First, the influence of polyethylene oxide degradation on cell failure, development of subsequent volatile degradation products, and cell impedance is analyzed. The low electrochemical stability window/oxidative stability (≥3.8 V) results in side‐chain oxidation and loss of active material. Subsequently, electrolyte stability is improved and a thin‐film (≤50 μm) TSPE with three functional layers is developed to match the wide‐ranging electrolyte requirements toward Li metal anodes and different cathode materials like LiNi0.6Mn0.2Co0.2O2 and LiFePO4 (NCM622, LFP). The high‐voltage stability of ≥4.75 V makes the TSPE a promising candidate in high‐voltage applications. Because of high Coulombic efficiencies in NMC622‖Li metal (99.7%) and LFP‖Li metal (99.9%) cells, the presented electrolyte enables stable long‐term cycling with great capacity retention of 86% and 94%, respectively. The temperature stability of >300 °C and the capability to prevent high surface area Li and dendrite formation (even at an areal capacity utilization of >40 mAh cm−2) contribute to high safety under a wide range of conditions. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Evaluating the Polymer Backbone – Vinylene versus Styrene – of Anisyl‐substituted Phenothiazines as Battery Electrode Materials.

Author

Desmaizieres, Gauthier, Perner, Verena, Wassy, Daniel, Kolek, Martin, Bieker, Peter, Winter, Martin, and Esser, Birgit

Subjects
REDOX polymers, STYRENE, ELECTRODES, SPINE, POLYMERS
Abstract

Organic electrode materials are capable candidates for next‐generation greener energy storage solutions. One advantage is that their electrochemical performance can be tuned by structural modification. We herein investigate anisyl‐substituted poly(vinyl‐) and poly(styrylphenothiazines) as positive electrode materials for dual‐ion batteries. π‐Interactions – characteristic to phenothiazine redox polymers – are facilitated in the poly(styrene) derivatives PSAPT and PSAPT‐X‐DVB due to the longer spacing between phenothiazine units and polymer backbone and lead to high cycling stabilities, but reduce their specific capacities. In the poly(vinylenes), the linear PVAPT shows high cycling stability but a dissolution/redeposition mechanism, diminishing its capacity, while the cross‐linked X‐PVAPT demonstrates high cycling stabilities at specific capacities up to 81 mAh g−1 paired with an excellent rate performance, where 10,000 cycles at 100 C rate proceed with 86 % capacity retention. [ABSTRACT FROM AUTHOR]

Published
2023
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22. Origin of shuttle-free sulfurized polyacrylonitrile in lithium-sulfur batteries

Author

Huang, Chen-Jui, primary, Cheng, Ju-Hsiang, additional, Su, Wei-Nien, additional, Partovi-Azar, Pouya, additional, Kuo, Liang-Yin, additional, Tsai, Meng-Che, additional, Lin, Ming-Hsien, additional, Panahian Jand, Sara, additional, Chan, Ting-Shan, additional, Wu, Nae-Lih, additional, Kaghazchi, Payam, additional, Dai, Hongjie, additional, Bieker, Peter Maria, additional, and Hwang, Bing-Joe, additional

Published
2021
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34. Lithium Powder Synthesis and Preparation of Powder‐Based Composite Electrodes for Application in Lithium Metal Batteries.

Author

Kolesnikov, Aleksei, Wulfers, Tristan, Kolek, Martin, Bieker, Peter, Stan, Marian Cristian, and Winter, Martin

Subjects
LITHIUM cells, ALLOY powders, METAL powders, POWDERS, NEGATIVE electrode, ELECTRODES, LITHIUM cell electrodes, SCIENTIFIC method
Abstract

The electrochemical performance of lithium metal batteries is affected by many factors, among which the negative electrode is crucial. Although much of the research is focused on lithium metal electrodes from metallic foils, lithium metal powder can also provide several advantages. Herein, the synthesis of lithium metal powder (Lip) using a droplet emulsion technique is described in detail and the scientific background of the method is provided. Furthermore, the electrochemical performance of the composite Lip‐based electrodes prepared with conductive carbon additive (Super C65) via the electrode paste‐casting method is reported. The results indicate that under the same material loading, the composite Lip‐based electrodes can provide at least twice the practical electrode capacity of pure Lip electrodes and with lower overpotentials, as shown in symmetric Li||Li cells. Full cells assembled with an NMC622 cathode and a composite Lip‐based electrode are cycled at least for 100 cycles and show improved cycling performance as compared with the full cells assembled with pure Lip electrodes. In addition, the results also conclude that there are four different types of charge storage mechanisms in these composite Lip‐based electrodes. These occurring mechanisms should be considered when engineering lithium metal electrodes with various designs. [ABSTRACT FROM AUTHOR]

Published
2022
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35. In situ 7 Li-NMR analysis of lithium metal surface deposits with varying electrolyte compositions and concentrations

Author

Küpers, Verena, Kolek, Martin, Bieker, Peter, Winter, Martin, and Brunklaus, Gunther

Subjects
ddc:540
Abstract

A major challenge of lithium metal electrodes, in theory a suitable choice for rechargeable high energy density batteries, comprises non-homogeneous lithium deposition and the growth of reactive high surface area lithium, which eventually yields active material losses and safety risks. While it is hard to fully avoid inhomogeneous deposits, the achievable morphology of the occurring lithium deposits critically determines the long-term cycling behaviour of the cells. In this work, we focus on a combined scanning electron microscopy (SEM) and 7Li nuclear magnetic resonance spectroscopy (7Li-NMR) study to unravel the impact of the choice of conducting salts (LiPF6 and LiTFSI), solvents (EC : DEC, 3 : 7, DME : DOL, 1 : 1), as well as their respective concentrations (1 M, 3 M) on the electrodeposition process, demonstrating that lithium deposition morphologies may be controlled to a large extent by proper choice of cycling conditions and electrolyte constituents. In addition, the applicability of 7Li-NMR spectroscopy to assess the resulting morphology is discussed. It was found, that lithium deposition analysis based on the 7Li chemical shift and intensity should be used carefully, as various morphologies can lead to similar results. Still, our case study reveals that the combination of SEM and NMR data is rather advantageous and offers complementary insights that may provide pathways for the future design of tailored electrolytes.

Published
2019
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36. Revealing Hidden Facts of Li Anode in Cycled Lithium–Oxygen Batteries through X-ray and Neutron Tomography

Author

Sun, Fu, Gao, Rui, Zhou, Dong, Osenberg, Markus, Dong, Kang, Kardjilov, Nikolay, Hilger, André, Markötter, Henning, Bieker, Peter Maria, Liu, Xiangfeng, and Manke, Ingo

Subjects
333.7
Abstract

ACS energy letters 4(1), 306 - 316 (2019). doi:10.1021/acsenergylett.8b02242, The gap between the successful application and perspective promise of lithium–oxygen battery (LOB) technology should be filled by an in-depth and comprehensive understanding of the underlying working and degradation mechanisms. Herein, the correlation between the morphological evolution of the Li anode and the overall cell electrochemical performance of cycled LOBs has been revealed for the first time by complementary X-ray and neutron tomography, together with further postmortem scanning electron microscopy, X-ray diffraction, and Fourier transfrom infrared spectroscopy characterizations. It has been disclosed with solid evidence that the irreversible transformation of anode Li associated with chemical/electrochemical side reactions does link intimately to the observed electrochemical performance decay. The current discoveries not only fundamentally enrich our knowledge of the underlying degradation and failure mechanisms of LOBs but also provide direction for future promising research activities aimed at further enhancing their performance., Published by American Chemical Society, Washington, DC

Published
2019
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44. Dibenzo[a,e]Cyclooctatetraene‐Functionalized Polymers as Potential Battery Electrode Materials.

Author

Desmaizieres, Gauthier, Speer, Martin E., Thiede, Inna, Gaiser, Philipp, Perner, Verena, Kolek, Martin, Bieker, Peter, Winter, Martin, and Esser, Birgit

Subjects
ELECTRODE potential, REDOX polymers, POLYMERS, NEGATIVE electrode, CYCLIC voltammetry, THIN films, ELECTRIC batteries
Abstract

Organic redox polymers are attractive electrode materials for more sustainable rechargeable batteries. To obtain full‐organic cells with high operating voltages, redox polymers with low potentials (<2 V versus Li|Li+) are required for the negative electrode. Dibenzo[a,e]cyclooctatetraene (DBCOT) is a promising redox‐active group in this respect, since it can be reversibly reduced in a two‐electron process at potentials below 1 V versus Li|Li+. Upon reduction, its conformation changes from tub‐shaped to planar, rendering DBCOT‐based polymers also of interest to molecular actuators. Here, the syntheses of three aliphatic DBCOT‐polymers and their electrochemical properties are presented. For this, a viable three‐step synthetic route to 2‐bromo‐functionalized DBCOT as polymer precursor is developed. Cyclic voltammetry (CV) measurements in solution and of thin films of the DBCOT‐polymers demonstrate their potential as battery electrode materials. Half‐cell measurements in batteries show pseudo capacitive behavior with Faradaic contributions, which demonstrate that electrode composition and fabrication will play an important role in the future to release the full redox activity of the DBCOT polymers. [ABSTRACT FROM AUTHOR]

Published
2021
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