Publications by authors named "Martin Winter"

124 Publications

Acoustic Ejection Mass Spectrometry: A Fully Automatable Technology for High-Throughput Screening in Drug Discovery.

SLAS Discov 2021 Jul 26:24725552211028135. Epub 2021 Jul 26.

Drug Discovery Sciences, Boehringer Ingelheim Pharma, Biberach an der Riß, Germany.

Acoustic droplet ejection (ADE)-open port interface (OPI)-mass spectrometry (MS) has recently been introduced as a versatile analytical method that combines fast and contactless acoustic sampling with sensitive and accurate electrospray ionization (ESI)-MS-based analyte detection. The potential of the technology to provide label-free measurements in subsecond analytical cycle times makes it an attractive option for high-throughput screening (HTS). Here, we report the first implementation of ADE-OPI-MS in a fully automated HTS environment, based on the example of a biochemical assay aiming at the identification of small-molecule inhibitors of the cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthase (cGAS). First, we describe the optimization of the method to enable sensitive and accurate determination of enzyme activity and inhibition in miniaturized 1536-well microtiter plate format. Then we show both results from a validation single-concentration screen using a test set of 5500 compounds, and the subsequent concentration-response testing of selected hits in direct comparison with a previously established matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) readout. Finally, we present the development of an in-line OPI cleaning procedure aiming to match the instrument robustness required for large-scale HTS campaigns. Overall, this work points to critical method development parameters and provides guidance for the establishment of integrated ADE-OPI-MS as HTS-compatible technology for early drug discovery.
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http://dx.doi.org/10.1177/24725552211028135DOI Listing
July 2021

Effective Solid Electrolyte Interphase Formation on Lithium Metal Anodes by Mechanochemical Modification.

ACS Appl Mater Interfaces 2021 Jul 15;13(29):34227-34237. Epub 2021 Jul 15.

Forschungszentrum Jülich GmbH (IEK-12) Helmholtz-Institute Münster, Corrensstraße 46, Münster 48149, Germany.

Lithium metal batteries are gaining increasing attention due to their potential for significantly higher theoretical energy density than conventional lithium ion batteries. Here, we present a novel mechanochemical modification method for lithium metal anodes, involving roll-pressing the lithium metal foil in contact with ionic liquid-based solutions, enabling the formation of an artificial solid electrolyte interphase with favorable properties such as an improved lithium ion transport and, most importantly, the suppression of dendrite growth, allowing homogeneous electrodeposition/-dissolution using conventional and highly conductive room temperature alkyl carbonate-based electrolytes. As a result, stable cycling in symmetrical Li∥Li cells is achieved even at a high current density of 10 mA cm. Furthermore, the rate capability and the capacity retention in NMC∥Li cells are significantly improved.
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http://dx.doi.org/10.1021/acsami.1c07490DOI Listing
July 2021

Meat and social change: Sociological perspectives on the consumption and production of animals.

OZS Osterr Z Soziol 2021 Jul 7:1-16. Epub 2021 Jul 7.

Department of Sociology, Technical University of Darmstadt, Dolivostraße 15, 64293 Darmstadt, Germany.

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http://dx.doi.org/10.1007/s11614-021-00453-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262125PMC
July 2021

Scalable Synthesis of MAX Phase Precursors toward Titanium-Based MXenes for Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2021 Jun 1;13(22):26074-26083. Epub 2021 Jun 1.

Institute of Energy and Climate Research: Materials Synthesis and Processing (IEK-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany.

MXenes have emerged as one of the most interesting material classes, owing to their outstanding physical and chemical properties enabling the application in vastly different fields such as electrochemical energy storage (EES). MXenes are commonly synthesized by the use of their parent phase, , MAX phases, where "M" corresponds to a transition metal, "A" to a group IV element, and "X" to carbon and/or nitrogen. As MXenes display characteristic pseudocapacitive behaviors in EES technologies, their use as a high-power material can be useful for many battery-like applications. Here, a comprehensive study on the synthesis and characterization of morphologically different titanium-based MXenes, , TiC and TiC, and their use for lithium-ion batteries is presented. First, the successful synthesis of large batches (≈1 kg) of the MAX phases TiAlC and TiAlC is shown, and the underlying materials are characterized mainly by focusing on their structural properties and phase purity. Second, multi- and few-layered MXenes are successfully synthesized and characterized, especially toward their ever-present surface groups, influencing the electrochemical behavior to a large extent. Especially multi- and few-layered TiC are achieved, exhibiting almost no oxidation and similar content of surface groups. These attributes enable the precise comparison of the electrochemical behavior between morphologically different MXenes. Since the preparation method for few-layered MXenes is adapted to process both active materials in a "classical" electrode paste processing method, a better comparison between both materials is possible by avoiding macroscopic differences. Therefore, in a final step, the aforementioned electrochemical performance is evaluated to decipher the impact of the morphology difference of the titanium-based MXenes. Most importantly, the delamination leads to an increased non-diffusion-limited contribution to the overall pseudocapacity by enhancing the electrolyte access to the redox-active sites.
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http://dx.doi.org/10.1021/acsami.1c05889DOI Listing
June 2021

Direct Multielement Analysis of Polydisperse Microparticles by Classification-Single-Particle ICP-OES in the Field of Lithium-Ion Battery Electrode Materials.

Anal Chem 2021 May 11;93(20):7532-7539. Epub 2021 May 11.

MEET Battery Research Center, University of Münster, Corrensstraße 46, 48149 Münster, Germany.

The chemical and structural complexity of lithium-ion battery electrodes and their constituting materials requires comprehensive characterization techniques to reveal degradation phenomena at the mesoscale. For the first time, application of single-particle inductively coupled plasma-optical emission spectroscopy enables the investigation of the chemomechanical interplay on the particle level of lithium transition-metal oxide [, Li(NiCoMn)O] cathode materials. The sample-inherent polydisperse size distribution of particles ranging up to 10 μm was effectively restricted with the use of a custom-made gravitational-counter-flow classifier to facilitate complete particle vaporization and excitation. After classification, the particles were transported directly to the plasma by means of an argon flow to prevent chemical alterations in aqueous media due to potentially occurring Li-H exchange reactions. The size-separated particles were monitored online by flow cell particle analysis (FPA). The influence of different gas flow settings and plasma parameters on the peak emission intensity of Li and Mn was evaluated. A particle size detection limit of ∼0.5 μm was estimated based on the 3σ criterion of the baselines and the measured peak intensities for Li and Mn considering the particle size distribution as obtained by FPA. The corresponding analyte masses at the detection limits were ∼30 and ∼180 fg for Li and Mn, respectively. Furthermore, an approach for a matrix-matched external calibration with electrochemically delithiated lithium transition-metal oxides is presented.
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http://dx.doi.org/10.1021/acs.analchem.1c01283DOI Listing
May 2021

Area Oversizing of Lithium Metal Electrodes in Solid-State Batteries: Relevance for Overvoltage and thus Performance?

ChemSusChem 2021 May 28;14(10):2144. Epub 2021 Apr 28.

Helmholtz Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149, Münster, Germany.

Invited for this month's cover is the group of Dr. Johannes Kasnatscheew from the Research Center Jülich GmbH. The image shows how area oversizing of lithium can affect the overall power of batteries, in particular at lower temperature. The Full Paper itself is available at 10.1002/cssc.202100213.
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http://dx.doi.org/10.1002/cssc.202100778DOI Listing
May 2021

Area Oversizing of Lithium Metal Electrodes in Solid-State Batteries: Relevance for Overvoltage and thus Performance?

ChemSusChem 2021 May 9;14(10):2163-2169. Epub 2021 Apr 9.

Helmholtz Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149, Münster, Germany.

Systematic and systemic research and development of solid electrolytes for lithium batteries requires a reliable and reproducible benchmark cell system. Therefore, factors relevant for performance, such as temperature, voltage operation range, or specific current, should be defined and reported. However, performance can also be sensitive to apparently inconspicuous and overlooked factors, such as area oversizing of the lithium electrode and the solid electrolyte membrane (relative to the cathode area). In this study, area oversizing is found to diminish polarization and improves the performance in LiNi Mn Co O (NMC622)||Li cells, with a more pronounced effect under kinetically harsh conditions (e. g., low temperature and/or high current density). For validity reasons, the polarization behavior is also investigated in Li||Li symmetric cells. Given the mathematical conformity of the characteristic overvoltage behavior with the Sand's equation, the beneficial effect is attributed to lower depletion of Li ions at the electrode/electrolyte interface. In this regard, the highest possible effect of area oversizing on the performance is discussed, that is when the accompanied decrease in current density and overvoltage overcomes the Sand's threshold limit. This scenario entirely prevents the capacity decay attributable to Li depletion and is in line with the mathematically predicted values.
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http://dx.doi.org/10.1002/cssc.202100213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8251826PMC
May 2021

New Insights into the N-S Bond Formation of a Sulfurized-Polyacrylonitrile Cathode Material for Lithium-Sulfur Batteries.

ACS Appl Mater Interfaces 2021 Mar 22;13(12):14230-14238. Epub 2021 Mar 22.

Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.

Sulfurized polyacrylonitrile (S-cPAN) has been recognized as a particularly promising cathode material for lithium-sulfur (Li-S) batteries due to its ultra-stable cycling performance and high degree of sulfur utilization. Though the synthetic conditions and routes for modification of S-cPAN have been extensively studied, details of the molecular structure of S-cPAN remain yet unclear. Herein, a more reasonable molecular structure consisting of pyridinic/pyrrolic nitrogen (N/N) is proposed, based on the analysis of combined X-ray photoelectron spectroscopy, C/N solid-state nuclear magnetic resonance, and density functional theory data. The coexistence of vicinal N/N entities plays a vital role in attracting S molecules and facilitating N-S bond formation apart from the generally accepted C-S bond in S-cPAN, which could explain the extraordinary electrochemical features of S-cPAN among various nitrogen-containing sulfurized polymers. This study provides new insights and a better understanding of structural details and relevant bond formation mechanisms in S-cPAN, providing a foundation for the design of new types of sulfurized cathode materials suitable for application in next-generation high-performance Li-S batteries.
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http://dx.doi.org/10.1021/acsami.0c22811DOI Listing
March 2021

Dibenzo[a,e]Cyclooctatetraene-Functionalized Polymers as Potential Battery Electrode Materials.

Macromol Rapid Commun 2021 Mar 3:e2000725. Epub 2021 Mar 3.

Institute for Organic Chemistry, University of Freiburg, Albertstraße 21, Freiburg, 79104, Germany.

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.
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http://dx.doi.org/10.1002/marc.202000725DOI Listing
March 2021

Insights into the Solubility of Poly(vinylphenothiazine) in Carbonate-Based Battery Electrolytes.

ACS Appl Mater Interfaces 2021 Mar 1;13(10):12442-12453. Epub 2021 Mar 1.

MEET Battery Research Center, Institute of Physical Chemistry, University of Münster, Corrensstraße 46, 48149 Münster, Germany.

Organic materials are promising candidates for next-generation battery systems. However, many organic battery materials suffer from high solubility in common battery electrolytes. Such solubility can be overcome by introducing tailored high-molecular-weight polymer structures, for example, by cross-linking, requiring enhanced synthetic efforts. We herein propose a different strategy by optimizing the battery electrolyte to obtain insolubility of non-cross-linked poly(3-vinyl--methylphenothiazine) (). Successive investigation and theoretical insights into carbonate-based electrolytes and their interplay with led to a strong decrease in the solubility of the redox polymer in ethylene carbonate/ethyl methyl carbonate (3:7) with 1 M LiPF. This allowed accessing its full theoretical specific capacity by changing the charge/discharge mechanism compared to previous reports. Through electrochemical, spectroscopic, and theoretical investigations, we show that changing the constituents of the electrolyte significantly influences the interactions between the electrolyte molecules and the redox polymer . Our study demonstrates that choosing the ideal electrolyte composition without chemical modification of the active material is a successful strategy to enhance the performance of organic polymer-based batteries.
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http://dx.doi.org/10.1021/acsami.0c20012DOI Listing
March 2021

Cation-Assisted Lithium-Ion Transport for High-Performance PEO-based Ternary Solid Polymer Electrolytes.

Angew Chem Int Ed Engl 2021 May 4;60(21):11919-11927. Epub 2021 May 4.

Helmholtz Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstr. 46, 48149, Münster, Germany.

N-alkyl-N-alkyl pyrrolidinium-based ionic liquids (ILs) are promising candidates as non-flammable plasticizers for lowering the operation temperature of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs), but they present limitations in terms of lithium-ion transport, such as a much lower lithium transference number. Thus, a pyrrolidinium cation was prepared with an oligo(ethylene oxide) substituent with seven repeating units. We show, by a combination of experimental characterizations and simulations, that the cation's solvating properties allow faster lithium-ion transport than alkyl-substituted analogues when incorporated in SPEs. This proceeds not only by accelerating the conduction modes of PEO, but also by enabling new conduction modes linked to the solvation of lithium by a single IL cation. This, combined with favorable interfacial properties versus lithium metal, leads to significantly improved performance on lithium-metal polymer batteries.
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http://dx.doi.org/10.1002/anie.202016716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252488PMC
May 2021

Solvent Co-intercalation into Few-layered TiCT MXenes in Lithium Ion Batteries Induced by Acidic or Basic Post-treatment.

ACS Nano 2021 Feb 1;15(2):3295-3308. Epub 2021 Feb 1.

MEET Battery Research Center, Institute of Physical Chemistry, University of Münster, Corrensstraße 46, 48149 Münster, Germany.

MXenes, as an emerging class of 2D materials, display distinctive physical and chemical properties, which are highly suitable for high-power battery applications, such as lithium ion batteries (LIBs). TiCT (T = O, OH, F, Cl) is one of the most investigated MXenes to this day; however, most scientific research studies only focus on the design of multilayered or monolayer MXenes. Here, we present a comprehensive study on the synthesis of few-layered TiCT materials and their use in LIB cells, in particular for high-rate applications. The synthesized TiCT MXenes are characterized complementary XRD, Raman spectroscopy, XPS, EDX, SEM, TGA, and nitrogen adsorption techniques to clarify the structural and chemical changes, especially regarding the surface groups and intercalated cations/water molecules. The structural changes are correlated with respect to the acidic and basic post-treatment of TiCT. Furthermore, the detected alterations are put into an electrochemical perspective galvanostatic and potentiostatic investigations to study the pseudocapacitive behavior of few-layered TiCT, exhibiting a stable capacity of 155 mAh g for 1000 cycles at 5 A g. The acidic treatment of TiCT synthesized the formation of HF through LiF/HCl is able to increase the initial capacity in comparison to the pristine or basic treatment. To gain further insights into the structural changes occurring during (de)lithiation, XRD is applied for LIB cells in a voltage range from 0.01 to 3 V to give fundamental mechanistic insights into the structural changes occurring during the first cycles. Thereby, the increased initial capacity observed for acidic-treated MXenes can be explained by the reduced co-intercalation of solvent molecules.
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http://dx.doi.org/10.1021/acsnano.0c10153DOI Listing
February 2021

Kinetical threshold limits in solid-state lithium batteries: Data on practical relevance of sand equation.

Data Brief 2021 Feb 23;34:106688. Epub 2020 Dec 23.

Helmholtz-Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany.

The here shown data support the article "The Sand Equation and its Enormous Practical Relevance for Solid-State Lithium Metal Batteries". [1] In this data set, all cells include the poly (ethylene oxide)-based solid polymer electrolyte (PEO-based SPE). The behaviour in symmetric Li||Li cells are provided in a three-electrode cell setup, thus with the use of a reference electrode. Moreover, the Sand behaviour is reported for varied negative electrodes with the focus on polarization onset, defined as transition time. The data of the electrochemical response after the variation of additional parameter, SPE thicknesses, are shown, as well. The theoretical Sand equation is linked with practically obtained values also for varied Li salt concentration. Finally, the discharge behaviour is provided including further charge/discharge cycles with the use of LiNiMnCoO (NMC622) as active material for positive electrodes.
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http://dx.doi.org/10.1016/j.dib.2020.106688DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7786044PMC
February 2021

A rechargeable zinc-air battery based on zinc peroxide chemistry.

Science 2021 01;371(6524):46-51

MEET Battery Research Center, Institute of Physical Chemistry, University of Münster, Münster, Germany.

Rechargeable alkaline zinc-air batteries promise high energy density and safety but suffer from the sluggish 4 electron (e)/oxygen (O) chemistry that requires participation of water and from the electrochemical irreversibility originating from parasitic reactions caused by caustic electrolytes and atmospheric carbon dioxide. Here, we report a zinc-O/zinc peroxide (ZnO) chemistry that proceeds through a 2e/O process in nonalkaline aqueous electrolytes, which enables highly reversible redox reactions in zinc-air batteries. This ZnO chemistry was made possible by a water-poor and zinc ion (Zn)-rich inner Helmholtz layer on the air cathode caused by the hydrophobic trifluoromethanesulfonate anions. The nonalkaline zinc-air battery thus constructed not only tolerates stable operations in ambient air but also exhibits substantially better reversibility than its alkaline counterpart.
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http://dx.doi.org/10.1126/science.abb9554DOI Listing
January 2021

Exploiting the Degradation Mechanism of NCM523 || Graphite Lithium-Ion Full Cells Operated at High Voltage.

ChemSusChem 2021 Jan 29;14(2):491. Epub 2020 Dec 29.

University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstr. 46, 48149, Münster, Germany.

Invited for this month's cover is the group of Tobias Placke and Martin Winter at the MEET Battery Research Center (University of Münster). The image shows the failure mechanism of high-voltage operated NCM523 || graphite lithium-ion cells, that is, the dissolution of transition metals (Mn, Co, Ni) from the NCM523 cathode and subsequent deposition at the graphite anode, resulting in formation of Li metal dendrites. The Full Paper itself is available at 10.1002/cssc.202002113.
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http://dx.doi.org/10.1002/cssc.202002870DOI Listing
January 2021

Impact of the Crystalline LiSi Phase on the Self-Discharge Mechanism of Silicon Negative Electrodes in Organic Electrolytes.

ACS Appl Mater Interfaces 2020 Dec 1;12(50):55903-55912. Epub 2020 Dec 1.

School of Mathematics and Sciences, Chemistry Department, Carl von Ossietzky University of Oldenburg, D-26111 Oldenburg, Germany.

Because of their high specific capacity and rather low operating potential, silicon-based negative electrode materials for lithium-ion batteries have been the subject of extensive research over the past 2 decades. Although the understanding of the (de)lithiation behavior of silicon has significantly increased, several major challenges have not been solved yet, hindering its broad commercial application. One major issue is the low initial Coulombic efficiency and the ever-present self-discharge of silicon electrodes. Self-discharge itself affects the long-term stability of electrochemical storage systems and, additionally, must be taken into consideration for inevitable prelithiation approaches. The impact of the crystalline LiSi phase is of great interest as the phase transformation between crystalline () and amorphous () phases not only increases the specific surface area but also causes huge polarization. Moreover, there is the possibility for electrochemical over-lithiation toward the LiSi phase because of the electron-deficient LiSi phase, which can be highly reactive toward the electrolyte. This poses the question about the impact of the -LiSi phase on the self-discharge behavior in comparison to its amorphous counterpart. Here, silicon thin films used as model electrodes are lithiated to cut-off potentials of 10 mV and 50 mV Li|Li ( and ) in order to systematically investigate their self-discharge mechanism open-circuit potential () measurements and to visualize the solid electrolyte interphase (SEI) growth by means of scanning electrochemical microscopy. We show that the -LiSi phase is formed for the electrode, while it is not found for the electrode. In turn, the electrode displays an almost linear self-discharge behavior, whereas the electrode reaches a plateau at 380 mV Li|Li, which is due to the phase transition from -LiSi to the -LiSi phase. At this plateau potential, the phase transformation at the Si|electrolyte interface results in an electronically more insulating and more uniform SEI ( electrode), while the electrode displays a less uniform SEI layer. In summary, the self-discharge mechanism of silicon electrodes and, hence, the irreversible decomposition of the electrolyte and the corresponding SEI formation process heavily depend on the structural nature of the underlying lithium-silicon phase.
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http://dx.doi.org/10.1021/acsami.0c16742DOI Listing
December 2020

Exploiting the Degradation Mechanism of NCM523 Graphite Lithium-Ion Full Cells Operated at High Voltage.

ChemSusChem 2021 Jan 10;14(2):595-613. Epub 2020 Nov 10.

University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstr. 46, 48149, Münster, Germany.

Layered oxides, particularly including Li[Ni Co Mn ]O (NCMxyz) materials, such as NCM523, are the most promising cathode materials for high-energy lithium-ion batteries (LIBs). One major strategy to increase the energy density of LIBs is to expand the cell voltage (>4.3 V). However, high-voltage NCM graphite full cells typically suffer from drastic capacity fading, often referred to as "rollover" failure. In this study, the underlying degradation mechanisms responsible for failure of NCM523 graphite full cells operated at 4.5 V are unraveled by a comprehensive study including the variation of different electrode and cell parameters. It is found that the "rollover" failure after around 50 cycles can be attributed to severe solid electrolyte interphase growth, owing to formation of thick deposits at the graphite anode surface through deposition of transition metals migrating from the cathode to the anode. These deposits induce the formation of Li metal dendrites, which, in the worst cases, result in a "rollover" failure owing to the generation of (micro-) short circuits. Finally, approaches to overcome this dramatic failure mechanism are presented, for example, by use of single-crystal NCM523 materials, showing no "rollover" failure even after 200 cycles. The suppression of cross-talk phenomena in high-voltage LIB cells is of utmost importance for achieving high cycling stability.
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http://dx.doi.org/10.1002/cssc.202002113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7894331PMC
January 2021

MALDI-TOF-Based Affinity Selection Mass Spectrometry for Automated Screening of Protein-Ligand Interactions at High Throughput.

SLAS Discov 2021 Jan 17;26(1):44-57. Epub 2020 Oct 17.

Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany.

Demonstration of in vitro target engagement for small-molecule ligands by measuring binding to a molecular target is an established approach in early drug discovery and a pivotal step in high-throughput screening (HTS)-based compound triaging. We describe the setup, evaluation, and application of a ligand binding assay platform combining automated affinity selection (AS)-based sample preparation and label-free matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. The platform enables mass spectrometry (MS)-based HTS for small-molecule target interactions from single-compound incubation mixtures and is embedded into a regular assay automation environment. Efficient separation of target-ligand complexes is achieved by in-plate size exclusion chromatography (SEC), and small-molecule ligands are subsequently identified by MALDI-TOF analysis. In contrast to alternative HTS-capable binding assay formats, MALDI-TOF AS-MS is capable of identifying orthosteric and allosteric ligands, as shown for the model system protein tyrosine phosphatase 1B (PTP1B), irrespective of protein function. Furthermore, determining relative binding affinities (RBAs) enabled ligand ranking in accordance with functional inhibition and reference data for PTP1B and a number of diverse protein targets. Finally, we present a validation screen of more than 23,000 compounds within 24 h, demonstrating the general applicability of the platform for the HTS-compatible assessment of protein-ligand interactions.
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http://dx.doi.org/10.1177/2472555220959266DOI Listing
January 2021

Tailoring of Gradient Particles of Li-Rich Layered Cathodes with Mitigated Voltage Decay for Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2020 Sep 11;12(39):43596-43604. Epub 2020 Sep 11.

Helmholtz-Institute Muenster (HI MS), IEK-12, Forschungszentrum Juelich GmbH, Corrensstr. 46, D-48149 Muenster, Germany.

Voltage decay during cycling is still a major issue for Li-rich cathodes in lithium ion batteries. Recently, the increase of Ni content has been recognized as an effective way to mitigate this problem, although it leads to lower-capacity materials. To find a balance between voltage decay and high capacity, particles of Li-rich materials with concentration gradients of transition metals have been prepared. Since voltage decay is caused by oxygen loss and phase transition that occur mainly on the particle surface, the Ni content is designed with a negative gradient of concentration from the surface to the bulk of particles. To do so, microsized LiNiCoMnO particles are mixed with much smaller LiNiCoMnO particles to form deposits of small particles onto larger particles. The concentration gradient of Ni is achieved as the Ni ions in LiNiCoMnO penetrate into LiNiCoMnO during a calcination post-treatment. Gradient samples show superior cycling performance and voltage retention as well as improved safety. This systematic study explores a material model combining Li-rich and high-Ni layered cathodes that is shown to be effective in creating a balance between mitigated voltage decay and high energy density.
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http://dx.doi.org/10.1021/acsami.0c10410DOI Listing
September 2020

Small Groups, Big Impact: Eliminating Li Traps in Single-Ion Conducting Polymer Electrolytes.

iScience 2020 Aug 29;23(8):101417. Epub 2020 Jul 29.

Helmholtz-Institute Münster, IEK-12, Forschungszentrum Jülich, Corrensstr. 46, 48149 Münster, Germany. Electronic address:

Single-ion conducting polymer electrolytes exhibit great potential for next-generation high-energy-density Li metal batteries, although the lack of sufficient molecular-scale insights into lithium transport mechanisms and reliable understanding of key correlations often limit the scope of modification and design of new materials. Moreover, the sensitivity to small variations of polymer chemical structures (e.g., selection of specific linkages or chemical groups) is often overlooked as potential design parameter. In this study, combined molecular dynamics simulations and experimental investigations reveal molecular-scale correlations among variations in polymer structures and Li transport capabilities. Based on polyamide-based single-ion conducting quasi-solid polymer electrolytes, it is demonstrated that small modifications of the polymer backbone significantly enhance the Li transport while governing the resulting membrane morphology. Based on the obtained insights, tailored materials with significantly improved ionic conductivity and excellent electrochemical performance are achieved and their applicability in LFP||Li and NMC||Li cells is successfully demonstrated.
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http://dx.doi.org/10.1016/j.isci.2020.101417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7452907PMC
August 2020

Ultrahigh-Throughput ESI-MS: Sampling Pushed to Six Samples per Second by Acoustic Ejection Mass Spectrometry.

Anal Chem 2020 09 3;92(18):12242-12249. Epub 2020 Sep 3.

Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany.

We present an acoustic ejection mass spectrometry (AEMS) setup for contactless electrospray ionization mass spectrometry (ESI-MS)-based sample injection at a sampling rate faster than current ESI and matrix-assisted laser desorption ionization (MALDI) techniques. For the direct transfer of samples out of 384-well plates into a modified ESI source, an open port interface (OPI) was combined with a modified acoustic droplet ejection (ADE) system. AEMS has the potential to eliminate bottlenecks known from classical MS approaches, such as speed, reproducibility, carryover, ion suppression, as well as sample preparation and consumption. This setup provided a drastically reduced transfer distance between OPI and ESI electrode for optimum throughput performance and broadens the scope of applications for this emerging technique. To simulate label-free applications of drug metabolism and pharmacokinetics (DMPK) analysis and high-throughput screening (HTS) campaigns, two stress tests were performed regarding ion suppression and system endurance in combination with minor sample preparation. The maximum sampling rate was 6 Hz for dextromethorphan and -dextrorphan (each 100 nM) for 1152 injections in 63 s at full width at half-maximum (FWHM) of 105 ms and a relative standard deviation (%RSD) of 7.7/7.5% without internal standard correction. Enzyme assay buffer and crude dog plasma caused signal suppression of 51/73% at %RSD of 5.7/6.7% ( = 120). An HTS endurance buffer was used for >25 000 injections with minor OPI pollution and constant signals (%RSD = 8.5%, FWHM of 177 ms ± 8.5%, = 10 557). The optimized hardware and method setup resulted in high-throughput performance and enables further implementation in a fully automated platform for ESI-MS-based high-throughput screening.
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http://dx.doi.org/10.1021/acs.analchem.0c01632DOI Listing
September 2020

An In Situ Cross-Linked Nonaqueous Polymer Electrolyte for Zinc-Metal Polymer Batteries and Hybrid Supercapacitors.

Small 2020 Sep 30;16(35):e2002528. Epub 2020 Jul 30.

Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, Maharashtra, 411008, India.

This work reports the facile synthesis of nonaqueous zinc-ion conducting polymer electrolyte (ZIP) membranes using an ultraviolet (UV)-light-induced photopolymerization technique, with room temperature (RT) ionic conductivity values in the order of 10 S cm . The ZIP membranes demonstrate excellent physicochemical and electrochemical properties, including an electrochemical stability window of >2.4 V versus Zn|Zn and dendrite-free plating/stripping processes in symmetric Zn||Zn cells. Besides, a UV-polymerization-assisted in situ process is developed to produce ZIP (abbreviated i-ZIP), which is adopted for the first time to fabricate a nonaqueous zinc-metal polymer battery (ZMPB; VOPO |i-ZIP|Zn) and zinc-metal hybrid polymer supercapacitor (ZMPS; activated carbon|i-ZIP|Zn) cells. The VOPO cathode employed in ZMPB possesses a layered morphology, exhibiting a high average operating voltage of ≈1.2 V. As compared to the conventional polymer cell assembling approach using the ex situ process, the in situ process is simple and it enhances the overall electrochemical performance, which enables the widespread intrusion of ZMPBs and ZMPSs into the application domain. Indeed, considering the promising aspects of the proposed ZIP and its easy processability, this work opens up a new direction for the emergence of the zinc-based energy storage technologies.
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http://dx.doi.org/10.1002/smll.202002528DOI Listing
September 2020

Conventional Electrolyte and Inactive Electrode Materials in Lithium-Ion Batteries: Determining Cumulative Impact of Oxidative Decomposition at High Voltage.

ChemSusChem 2020 Oct 17;13(19):5301-5307. Epub 2020 Aug 17.

Helmholtz-Institute Münster (HI MS) IEK-12, Forschungszentrum Jülich GmbH, Corrensstrasse 46, 48149, Münster, Germany.

High-voltage electrodes based on, for example, LiNi Mn 0 (LNMO) active material require oxidative stability of inactive materials up to 4.95 V vs. Li|Li . Referring to literature, they are frequently supposed to be unstable, though conclusions are still controversial and clearly depend on the used investigation method. For example, the galvanostatic method, as a common method in battery research, points to the opposite, thus to a stability of the inactive materials, which can be derived from, for example, the high decomposition plateau at 5.56 V vs. Li|Li and stable performance of the LNMO charge/discharge cycling. This work aims to unravel this apparent contradiction of the galvanostatic method with the literature by a thorough investigation of possible trace oxidation reactions in cumulative manner, that is, over many charge/discharge cycles. Indeed, the cumulated irreversible specific capacity amounts to ≈10 mAh g during the initial 50 charge/discharge cycles, which is determined by imitating extreme LNMO high-voltage conditions using electrodes solely consisting of inactive materials. This can explain the ambiguities in stability interpretations of the galvanostatic method and the literature, as the respective irreversible specific capacity is obviously too low for distinct detection in conventional galvanostatic approaches and can be only detected at extreme high-voltage conditions. In this regard, the technique of chronoamperometry is shown to be an effective and proper complementary tool for electrochemical stability research in a qualitative and quantitative manner.
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http://dx.doi.org/10.1002/cssc.202001530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7589409PMC
October 2020

Accessing copper oxidation states of dissolved negative electrode current collectors in lithium ion batteries.

Electrophoresis 2020 10 20;41(18-19):1568-1575. Epub 2020 Jul 20.

MEET Battery Research Center, Institute of Physical Chemistry, University of Münster, Münster, Germany.

A novel capillary electrophoresis (CE) method with ultraviolet-visible spectroscopy (UV-Vis) detection for the investigation of dissolved Cu and Cu in lithium ion battery (LIB) electrolytes was developed. This method is of relevance, as the current collector at the anode of LIBs may dissolve under certain operation conditions. In order to preserve the actual oxidation states of dissolved copper in the electrolytes and to prevent any precipitation during sample preparation and CE measurements, neocuproine (NC) and ethylenediamine tetraacetic (EDTA) were effectively applied as complexing agents for both ionic copper species. However, precipitation and loss of the Cu -NC-complex for quantification occurred in presence of the commonly applied conducting salt lithium hexafluorophosphate (LiPF ). Therefore, acetonitrile (ACN) was added to the sample in order to suppress this precipitation. Dissolution experiments with copper-based negative electrode current collectors in a LIB electrolyte were conducted at 60°C under non-oxidizing atmosphere. First findings regarding the copper species via CE revealed dissolved Cu and mainly Cu . However, primarily Cu dissolved from the passivating oxide layer (Cu O and CuO) of the current collector due to the formation of acidic electrolyte decomposition products. Due to the instability of Cu in the electrolyte a further disproportionation reaction to Cu and Cu occurred. The results show the high potential of this CE method for prospective investigations regarding the current collector stability in new battery electrode formulations and correlations of dissolution events with dissolution mechanisms and battery cell operation conditions.
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http://dx.doi.org/10.1002/elps.202000155DOI Listing
October 2020

Elimination of "Voltage Noise" of Poly (Ethylene Oxide)-Based Solid Electrolytes in High-Voltage Lithium Batteries: Linear versus Network Polymers.

iScience 2020 Jun 3;23(6):101225. Epub 2020 Jun 3.

Helmholtz-Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany. Electronic address:

Frequently, poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) reveal a failure with high-voltage electrodes, e.g. LiNiMnCoO in lithium metal batteries, which can be monitored as an arbitrary appearance of a "voltage noise" during charge and can be attributed to Li dendrite-induced cell micro short circuits. This failure behavior disappears when incorporating linear PEO-based SPE in a semi-interpenetrating network (s-IPN) and even enables an adequate charge/discharge cycling performance at 40°C. An impact of any electrolyte oxidation reactions on the performance difference can be excluded, as both SPEs reveal similar (high) bulk oxidation onset potentials of ≈4.6 V versus Li|Li. Instead, improved mechanical properties of the SPE, as revealed by compression tests, are assumed to be determining, as they mechanically better withstand Li dendrite penetration and better maintain the distance of the two electrodes, both rendering cell shorts less likely.
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http://dx.doi.org/10.1016/j.isci.2020.101225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7305408PMC
June 2020

Investigating the oxidation state of Fe from LiFePO -based lithium ion battery cathodes via capillary electrophoresis.

Electrophoresis 2020 10 29;41(18-19):1549-1556. Epub 2020 Jun 29.

MEET Battery Research Center, Institute of Physical Chemistry, University of Münster, Münster, Germany.

A capillary electrophoresis (CE) method with ultraviolet/visible (UV-Vis) spectroscopy for iron speciation in lithium ion battery (LIB) electrolytes was developed. The complexation of Fe with 1,10-phenantroline (o-phen) and of Fe with ethylenediamine tetraacetic acid (EDTA) revealed effective stabilization of both iron species during sample preparation and CE measurements. For the investigation of small electrolyte volumes from LIB cells, a sample buffer with optimal sample pH was developed to inhibit precipitation of Fe during complexation of Fe with o-phen. However, the presence of the conducting salt lithium hexafluorophosphate (LiPF ) in the electrolyte led to the precipitation of the complex [Fe(o-phen) ](PF ) . Addition of acetonitrile (ACN) to the sample successfully re-dissolved this Fe -complex to retain the quantification of both species. Further optimization of the method successfully prevented the oxidation of dissolved Fe with ambient oxygen during sample preparation, by previously stabilizing the sample with HCl or by working under counterflow of argon. Following dissolution experiments with the positive electrode material LiFePO (LFP) in LIB electrolytes under dry room conditions at 20°C and 60°C mainly revealed iron dissolution at elevated temperatures due to the formation of acidic electrolyte decomposition products. Despite the primary oxidation state of iron in LFP of +2, both iron species were detected in the electrolytes that derive from oxidation of dissolved Fe by remaining molecular oxygen in the sample vials during the dissolution experiments.
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http://dx.doi.org/10.1002/elps.202000097DOI Listing
October 2020

Fast sample preparation for organo(fluoro)phosphate quantification approaches in lithium ion battery electrolytes by means of gas chromatographic techniques.

J Chromatogr A 2020 Aug 27;1624:461258. Epub 2020 May 27.

University of Münster, MEET Battery Research Center, Corrensstraße 46, 48149Münster, Germany. Electronic address:

Lithium ion batteries are essential power sources in portable electronics, electric vehicles and as energy storage devices for renewable energies. During harsh battery cell operation as well as at elevated temperatures, the electrolyte decomposes and inter alia organo(fluoro)phosphates are formed due to hydrolysis of the conducting salt lithium hexafluorophosphate (LiPF). Since these phosphorus-containing decomposition products possess a potential toxicity based on structural similarities compared to chemical warfare agents, quantification is of high interest regarding safety estimates. In this study, two comprehensive approaches for the precipitation of highly concentrated PF were investigated, allowing the separation from target analytes (organo(fluoro)phosphates) and improving mass spectrometry-based quantification techniques. Trimethyl phosphate was used as a polar, non-acidic organophosphate reference substance for method development via liquid chromatography-mass spectrometry. Six solvents were examined regarding precipitation reaction and selectivity. Thermally degraded electrolytes were analyzed after precipitation by means of gas chromatography-flame ionization detector, demonstrating the applicability of the developed sample preparations. The optimized method was applied successfully without influencing any volatile and non-acidic decomposition products. Using optimized conditions, a precipitation rate of 98% PF was achieved. Consequently, a fast and easy sample preparation for gas chromatographic investigations on lithium ion battery electrolytes was implemented, applicable for routine analysis.
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http://dx.doi.org/10.1016/j.chroma.2020.461258DOI Listing
August 2020

Wetting Phenomena and their Effect on the Electrochemical Performance of Surface-Tailored Lithium Metal Electrodes in Contact with Cross-linked Polymeric Electrolytes.

Angew Chem Int Ed Engl 2020 Sep 4;59(39):17145-17153. Epub 2020 Aug 4.

MEET Battery Research Center, Institute of Physical Chemistry, University of Münster, Corrensstraße 46, 48149, Münster, Germany.

Li metal batteries (LMBs) containing cross-linked polymer electrolytes (PEs) are auspicious candidates for next-generation batteries. However, the wetting behavior of PEs on uneven Li metal surfaces has been neglected in most studies. Herein, it is shown that microscale defect sites with curved edges play an important role in a wettability-dependent electrodeposition. The wettability and the viscoelastic properties of PEs are correlated, and the impact of wettability on the nucleation and diffusion near the Li|PE interface is distinguished. It is found that the curvature of the edges is a key factor for the investigation of wetting phenomena. The appearance of microscale defects and phase separation are identified as main causes for erratic nucleation. It is emphasized that the implementation of stable and consistent long-term cycling performance of LMBs using PEs requires a deeper understanding of the "soft-solid"-solid contact between PEs and inherently rough Li metal surfaces.
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http://dx.doi.org/10.1002/anie.202001816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7540057PMC
September 2020

A method for quantitative analysis of gases evolving during formation applied on LiNiMnCoO ∣∣ natural graphite lithium ion battery cells using gas chromatography - barrier discharge ionization detector.

J Chromatogr A 2020 Jul 29;1622:461122. Epub 2020 Apr 29.

University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149 Münster, Germany. Electronic address:

To understand the overall processes behind the decomposition of state-of-the-art organic liquid electrolytes in lithium ion batteries (LIBs), it is necessary to investigate and quantify the permanent gases and light hydrocarbons evolving during electrolyte decomposition. In this work a convenient way of sampling gas from pouch cells without any previous preparation of the cell as well as a comprehensive gas chromatographic (GC) investigation of the gas phase is shown. A barrier discharge ionization detector (BID) was utilized for gas quantification and a multi component gas standard in combination with a gas mixing device was implemented to prepare calibration standards for validation. Therefore, sensitivity, linearity and reproducibility as well as the limits of detection (LOD) and limits of quantification (LOQ) were determined. Gas samples from pouch cells using LiNiMnCoO as cathode material and natural graphite (NMC622 ∣∣ NG) as anode material were analysed after formation. Gas volume and gas composition are key factors for a sufficient formation of LIBs and of interest for research with respect to the development of new materials and additives.
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http://dx.doi.org/10.1016/j.chroma.2020.461122DOI Listing
July 2020

Synthesis of High Surface Area α-KMnO Nanoneedles Using Extract of Broccoli as Bioactive Reducing Agent and Application in Lithium Battery.

Materials (Basel) 2020 Mar 11;13(6). Epub 2020 Mar 11.

Institut de Minéralogie, Physique des Matériaux et Cosmologie (IMPMC), Sorbonne Université, CNRS-UMR 7590, 4 place Jussieu, 75252 Paris, France.

With the aim to reduce the entire cost of lithium-ion batteries and to diminish the environmental impact, the extract of broccoli is used as a strong benign reducing agent for potassium permanganate to synthesize α-KMnO cathode material with pure nanostructured phase. Material purity is confirmed by X-ray powder diffraction and thermogravimetric analyses. Images of transmission electron microscopy show samples with a spider-net shape consisting of very fine interconnected nanoneedles. The nanostructure is characterized by crystallite of 4.4 nm in diameter and large surface area of 160.7 m g. The material delivers an initial capacity of 211 mAh g with high Coulombic efficiency of 99% and 82% capacity retention after 100 cycles. Thus, α-KMnO synthesized via a green process exhibits very promising electrochemical performance in terms of initial capacity, cycling stability and rate capability.
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http://dx.doi.org/10.3390/ma13061269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142612PMC
March 2020
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