Publications by authors named "Marco Evertz"

5 Publications

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Investigation of various layered lithium ion battery cathode materials by plasma- and X-ray-based element analytical techniques.

Anal Bioanal Chem 2019 Jan 29;411(1):277-285. Epub 2018 Oct 29.

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

In this work, the transition metal dissolution (TMD) from the respective ternary layered LiMO (M = Mn, Co, Ni, Al) cathode active material was investigated as well as the lithiation degrees of the cathodes after charge/discharge cyclic aging. Furthermore, increased nickel contents in LiNiCoMnO-based (NCM) cathode materials were studied, to elucidate their influence on capacity fading and TMD. It was found, that the TMD from nickel-rich cathode materials, e.g., LiNiCoMnO or LiNiCoMnO, did not differ significantly from the TMD from the stoichiometric LiNiCoMnO. In detail, the TMD from the cathode did not exceed a maximum of 0.2 wt% and was uniformly distributed on all analyzed cell parts (separator, anode, and electrolyte) using total reflection X-ray fluorescence. Moreover, the investigated electrolyte solutions showed that increased Ni contents come with more nickel dissolution of the respective material. Additionally, inductively coupled plasma optical emission spectroscopy analysis on the respective charge/discharge cyclic-aged cathode active materials revealed lithium losses of 20% after 50 cycles. However, only a minimum amount of capacity loss (= 1.5 mAh g) can be attributed to active material loss.
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http://dx.doi.org/10.1007/s00216-018-1441-8DOI Listing
January 2019

Adaptation and improvement of an elemental mapping method for lithium ion battery electrodes and separators by means of laser ablation-inductively coupled plasma-mass spectrometry.

Anal Bioanal Chem 2019 Jan 7;411(3):581-589. Epub 2018 Sep 7.

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

In this study, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was applied to previously aged carbonaceous anodes from lithium ion batteries (LIBs). The electrodes were treated by cyclic aging in a lithium ion cell set-up with LiNiMnO (LNMO) cathodes and hard carbon (HC)/mesocarbon microbead (MCMB) anodes. An inhomogeneous transition metal deposition pattern could be induced by replacing the spacer in a standard coin cell set-up with a washer. The inhomogeneity pattern matched the dimension of the washer depicted by the hole in the center. These transition metal (TM) patterns were used to optimize higher lateral scanning speeds and frequencies on the spatial resolution of the mapping experiments using LA-ICP-MS. Higher scanning speeds had an observable influence on the resolution of the obtained image and an overall saving of 60% with regard to time and gas consumption could be achieved. Additionally, the optimized method was applied to the cathode and separator in order to visualize the distribution and deposition pattern, respectively.
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http://dx.doi.org/10.1007/s00216-018-1351-9DOI Listing
January 2019

Graphite Recycling from Spent Lithium-Ion Batteries.

ChemSusChem 2016 Dec 9;9(24):3473-3484. Epub 2016 Dec 9.

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

The present work reports on challenges in utilization of spent lithium-ion batteries (LIBs)-an increasingly important aspect associated with a significantly rising demand for electric vehicles (EVs). In this context, the feasibility of anode recycling in combination with three different electrolyte extraction concepts is investigated. The first method is based on a thermal treatment of graphite without electrolyte recovery. The second method additionally utilizes a subcritical carbon-dioxide (subcritical CO )-assisted electrolyte extraction prior to thermal treatment. And the final investigated approach uses supercritical carbon dioxide (scCO ) as extractant, subsequently followed by the thermal treatment. It is demonstrated that the best performance of recycled graphite anodes can be achieved when electrolyte extraction is performed using subcritical CO . Comparative studies reveal that, in the best case, the electrochemical performance of recycled graphite exceeds the benchmark consisting of a newly synthesized graphite anode. As essential efforts towards electrolyte extraction and cathode recycling have been made in the past, the electrochemical behavior of recycled graphite, demonstrating the best performance, is investigated in combination with a recycled LiNi Co Mn O cathode.
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http://dx.doi.org/10.1002/cssc.201601062DOI Listing
December 2016

Nanostructured ZnFe2O4 as Anode Material for Lithium-Ion Batteries: Ionic Liquid-Assisted Synthesis and Performance Evaluation with Special Emphasis on Comparative Metal Dissolution.

Acta Chim Slov 2016 ;63(3):470-83

In this work, a ZnFe2O4 anode material was successfully synthesized by a novel ionic liquid-assisted synthesis method followed by a carbon coating procedure. The as-prepared ZnFe2O4 particles demonstrate a relatively homogeneous particle size distribution with particle diameters ranging from 40 to 80 nm. This material, which is well known to offer an interesting combination of an alloying and conversion mechanism, is capable of accommodating nine equivalents of lithium per unit formula, resulting in a high specific capacity (≥ 1,000 mAh g-1). The resulting composite anode material displayed a stable capacity of ca. 1,091 mAh g-1 for 190 cycles at a medium de-lithiation potential of 1.7 V and at a charge/discharge rate of 1C. Furthermore, the material displays an excellent high rate capability up to 20C, displaying a reversible capacity of still 216 mAh g-1. Studies on Fe and Zn losses of the ZnFe2O4 active material by dissolution in the electrolyte were performed and compared to those of silicon-, germanium- and tin-based high-capacity anode materials. In conclusion, ion dissolution from metal containing anode materials should not be underestimated in view of its impact on the overall cell performance and cycling stability.
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http://dx.doi.org/10.17344/acsi.2016.2243DOI Listing
July 2017

High Voltage LiNiMnO/LiTiO Lithium Ion Cells at Elevated Temperatures: Carbonate- versus Ionic Liquid-Based Electrolytes.

ACS Appl Mater Interfaces 2016 Oct 23;8(39):25971-25978. Epub 2016 Sep 23.

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

Thanks to its high operating voltage, the LiNiMnO (LNMO) spinel represents a promising next-generation cathode material candidate for Lithium ion batteries. However, LNMO-based full-cells with organic carbonate solvent electrolytes suffer from severe capacity fading issues, associated with electrolyte decomposition and concurrent degradative reactions at the electrode/electrolyte interface, especially at elevated temperatures. As promising alternatives, two selected LiTFSI/pyrrolidinium bis(trifluoromethane-sulfonyl)imide room temperature ionic liquid (RTIL) based electrolytes with inherent thermal stability were investigated in this work. Linear sweep voltammetry (LSV) profiles of the investigated LiTFSI/RTIL electrolytes display much higher oxidative stability compared to the state-of-the-art LiPF/organic carbonate based electrolyte at elevated temperatures. Cycling performance of the LNMO/LiTiO (LTO) full-cells with LiTFSI/RTIL electrolytes reveals remarkable improvements with respect to capacity retention and Coulombic efficiency. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns indicate maintained pristine morphology and structure of LNMO particles after 50 cycles at 0.5C. The investigated LiTFSI/RTIL based electrolytes outperform the LiPF/organic carbonate-based electrolyte in terms of cycling performance in LNMO/LTO full-cells at elevated temperatures.
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http://dx.doi.org/10.1021/acsami.6b07687DOI Listing
October 2016
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