Operando analysis of processes at porous carbon-electrolyte interface within…

Presenter: Prof. Enn Lust
Title: Operando analysis of processes at porous carbon-electrolyte interface within very wide region of cell potentials
Affiliation: University of Tartu

Abstract

Various micro-mesoporous carbon materials for Li-ion and Na-ion batteries, fuel cells and supercapacitors have been synthesized and the electrochemical processes at micro-mesoporous carbon | non-aqueous electrolyte and micro-mesoporous carbon | ionic liquid interface have been characterized by an in-situ surface normalized intensity Fourier transform infra-red (SNIFTIRS), synchrotron radiation initiated in situ X-ray photoelectron spectroscopy (SR-XPS), small angle and wide angle X-ray and neutron scattering (SANS), etc. techniques. Before an in situ/operando studies various physical characterization methods like the gas phase adsorption, Raman, Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM) have been applied and the surface roughness analysis has been conducted. Comparison of “conventional” data will be compared with operando data.

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Improving the cycling stability of high voltage LNMO by…

Presenter: Dr. Christian Elkjær
Title: Towards Automatic Disassembly of EV-Batteries
Affiliation: Haldor Topsoe A/S

Abstract

Li₁Ni_0.5Mn_1.5O₄ is a promising cobalt free cathode material that offers high energy density at a competitive price. Due to the high operating voltage of 4.7 V vs. Li/Li+, LNMO based batteries however suffers from limited lifetime due to instabilities of the various components in the cell. At Haldor Topsøe we develop LNMO and have focused much of our research in the detailed understanding of the structure and chemistry of the cathode material by using our existing facilities for microstructural characterization of catalyst materials by e.g. XRD and electron microscopy. In this presentation, we will show how the size of the spinel lattice is closely correlated with the amount of Mn³⁺ in the structure as measured electrochemically and how this is related to the composition of the LNMO as measured by electron microscopy. Further, these parameters have a profound influence on the integrity of the cathode material, and thereby the cycling stability, in half-cells.

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High capacity, low cobalt-containing cathode materials for LIBs

Presenter: Dr. Pekka Tynjälä
Title: High capacity, low cobalt-containing cathode materials for LIBs
Affiliation: University of Oulu

Abstract

This study aimed the development of high capacity, high nickel-containing and low cobalt-containing cathode materials (LiNixCoyMe1-x-yO2, x ≥ 0.8-1.0). These materials typically have high energy densities (>200 mAh/g) but suffer from low thermal stability and capacity fading during the cycling. Mixed transition metal hydroxide precursors were prepared with chemical co-precipitation followed by lithiation. Cathode materials were modified by coating and doping in order to improve the chemical and thermal stability and to prevent the capacity fading. Cathode materials were characterized by FESEM (morphology), tap density, powder XRD (crystalline phases), XPS, Raman and ICP-OES or AAS (metal content). Electrochemical measurements were carried out in a galvanostatic charge/discharge cycling using coin cells with lithium metal as anode or pouch cells with graphite anode. Based on the results, modified cathode materials showed high energy density (>200 mAh/g) and good cyclability.

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Improvement of the Li-ion battery degradation mechanisms determination by…

Presenter: Kirill Murashko
Title: Improvement of the Li-ion battery degradation mechanisms determination by heat flux data integration in BMS
Affiliation: University of Eastern Finland

Abstract

The analysis of a possibility to improve the Li-ion batteries degradation mechanisms determination with help of the heat flux measurements is presented. The measured heat flux and temperature data from the cylindrical cells surface are used for the modification of a differential voltage (DV) analysis method and improving its applicability in a battery management system. Power and energy type cylindrical Li-ion cells are considered. The effects of the C-rate constant current and an ambient temperature on the ordinary and modified DC curves used in the DV analysis method are studied. The analyse showed that the modified DV curve can provide information about capacity fading and prevailing degradation mechanism at higher than 1 C-rate current when the application of the ordinary DV curve is not be possible. Moreover, the modified DV curve allows identification of the changes in the entropic heat generation, which may improve the Li-ion battery degradation mechanisms determination.

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Mobility on Li metal surfaces

Presenter: Sondre K. Schnell
Title: Mobility on Li metal surfaces
Affiliation: Norwegian University of Science and Technology

Abstract

Lithium-ion based batteries completely dominating the market for secondary cell batteries. Both in consumer electronics and automotive industry, Li-based cells are dominating the market. Even with Li being such an important part of modern technology, the chemical- and material properties of Li is not well understood, and even very fundamental properties of the Li-metal, such as surface stability and mobility of adatoms on Li-metal surfaces has not been researched. In recent work, we have studied the mobility and stability of various Li-metal surfaces and compared these with similar structures for the Magnesium metal surfaces. Using density functional theory, we study the mobility, surface stability, and effect of crystal structure and surface facet for Li- and Mg-metal. The results indicate that low mobility on the surface of Li might be a contributing factor to significant dendrite growth.

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Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life…

Presenter: Guiomar Hernández
Title: Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation
Affiliation: Uppsala University

Abstract

Safety and cycling stability are still the main concerns towards developing high energy density lithium metal batteries. In this regard, electrolytes play an important role as they are able to form a stable passivating layer called solid electrolyte interphase (SEI). This layer is able to suppress continuous electrolyte degradation improving the cyclability of the batteries. Although fluoroethylene carbonate (FEC) has been found to be a particularly effective SEI-forming additive, its combination with the conventional LiPF6 salt accelerates the electrolyte degradation. Herein we have study the trigger and mechanism of such degradation with liquid- and solid-state NMR. Furthermore, additives to avoid such degradation have been investigated to improve chemical and electrochemical stability of electrolytes to be used in LiNi1/3Mn1/3Co1/3O2/Li metal batteries at high temperatures.

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Disordered transition metal oxide Li-ion electrode materials

Presenter: Dorthe B. Ravnsbæk
Title: Disordered transition metal oxide Li-ion electrode materials
Affiliation: University of Southern Denmark

Abstract

Development of electrode materials for intercalation type batteries have in the past focused on highly crystalline materials. However, recent years have seen an increased interest for disordered materials, e.g. with the discovery of multiple high capacity electrodes based on disordered rock-salt structures or even completely amorphous materials exhibiting higher capacities than their crystalline counterparts. Still very little is known about the structural mechanisms behind order-disorder transitions induced by ion-intercalation or about ion-storage mechanisms in disordered materials. 

Using a combination of X-ray scattering, electron microscopy and electrochemical analysis, we have studied a series of high-capacity disordered and amorphous electrode materials such as TiO2, V2O5, MnOx. This allows us to map out the structural evolution during battery charge and discharge at the atomic- and nano-scale, and to understand the ion-storage mechanisms in such materials.

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Time- and spatially resolved in situ studies of batteries

Presenter: Prof. Poul Norby
Title: Time- and spatially resolved in situ studies of batteries
Affiliation: Technical University of Denmark

Abstract

Detailed knowledge about structural and microstructural properties of electrode materials during battery operation can be obtained from in situ and operando X-ray and neutron diffraction, scattering and imaging experiments. The spatial distribution of phases during charge/discharge is often not homogeneous and inhomogeneity in the electrodes can have a substantial effect on the properties of the battery, e.g. influencing the rate capability, cycle life and energy capacity. We will develop time- and spatially resolved in situ and operando methods to investigate development of structural and microstructural properties and at the same time determine changes in phase distribution in battery electrodes and apply the methods to commercial and prototype batteries. As an example we have combined time- and spatially resolved synchrotron X-ray diffraction to investigate the phase distribution to study a Zn-air battery during discharge/charge.

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