Eric De Vito

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Papers by Eric De Vito

Contribution of Combined Surface Analysis to the Understanding of Degradation Mechanisms of Li-Ion Negative Electrodes

Meeting abstracts, 2018

Li-ion technology is among the most commercially viable solutions for electrochemical storage, pa... more Li-ion technology is among the most commercially viable solutions for electrochemical storage, particularly for the electric vehicle (VE) market. The fading of such systems is often related to the degradation of the electrode active materials in various ageing conditions; it is thus mandatory to better understand the causes of these failures. It is well known that the nature and amount of the solid electrolyte interphase (SEI) which forms at the surface of the active material during cycling, can be one of the main issues preventing durability of the cells. For that purpose, our lab is actively working on the characterization of such degradation mechanisms, trying to understand some fundamental aspects of lithiation or lithiation loss mechanisms, nature and dynamics of the SEI etc. Previous works allowed us to describe some fundamental aspects of silicon electrodes degradation in various configurations by using XPS, AES and ToF-SIMS combined with in situ FIB (known as FIB-ToF-SIMS) cross analysis [1-3]. This has recently been applied to the study of commercial graphite electrodes [4]. In this study, the electrodes have been cycled (vs NMC positive electrodes) at 5°C following 2 end-of-voltage windows strategies: 2.70V-4.20V (0%SOC-100%SOC), 3.42V-4.08V (10%SOC-90%SOC).The relationship between the end-of-voltage windows and the SOC limits were measured in the beginning of life at 25°C, and so these voltage ranges do not correspond strictly to specified SOC ranges for other temperatures, C-rates, or after ageing. It is observed that the former are fading a lot faster than the latter (cycled in the limited 3.42-4.08 V potential range). The relationship between the end-of-voltage windows and the SOC limits were measured in the beginning of life at 25°C, and so these voltage ranges do not correspond strictly to specified SOC ranges for other temperatures, C-rates, or after ageing. It is observed that the former are fading a lot faster than the latter (cycled in the limited 3.42-4.08 V potential range). ). A complete characterization study, involving also XRD and NMR, showed that the generation of SEI is much more important between 90 and 100% SOC, inducing lithium trapping in the graphite particles while also favoring some lithium plating. A scheme (Fig.1) has been proposed to explain the evolution of such electrodes in these particular cycling conditions. These results show the high impact of cycling policy on the integrity of Li-ion cells. They also emphasize the ability of FIB-ToF-SIMS, used in combination with XPS (as used in [2] and [4] but applied in this study to graphite electrodes), to unveil the underlying ageing mechanisms of Li-ion negative electrodes. [1] E. Radvanyi et al, Phys. Chem. Chem. Phys., 2014,16, 17142-17153 [2] A. Bordes et al, Chem. Mater., 2016, 28 (5), 1566-1573 [3] N. Dupré et al, Chem. Mater., 2016, 28 (8), 2557-2572 [4] B. Pilipili Matadi et al, J. Electrochem. Soc., 2017, 164 (12), A2374-A2389 Figure 1

Effect of Sb and Na Incorporation in Cu 2 ZnSnS 4 Solar Cells

Physica Status Solidi A-applications and Materials Science, Apr 3, 2019

Cu2ZnSnS4-based solar cells suffer from limited power conversion efficiency and relative small gr... more Cu2ZnSnS4-based solar cells suffer from limited power conversion efficiency and relative small grain size compared to selenium containing absorbers. Introduction of Na in Cu2ZnSnS4 absorbers either during the synthesis or after this step has been used to improve device performances and to determine whether its effect is based on structural properties improvement (grain size enhancement, better crystallization) or on opto-electronic properties improvement (defect passivation). In both cases, presence of Na in the absorber notably improves current and voltage of the solar cells, but the effect is more pronounced when Na is present during synthesis. Quantum efficiency analysis shows that these improvements can be related to longer minority carrier diffusion length and reduced absorber/buffer interface recombination. Introducing Na in the process mostly leads to preferential (112) orientation of the crystal which is clearly correlated with better device performances. Otherwise, the performance limitation due to small grain size has been discarded by the joint use of Sb and Na, which has a significant impact on grain size but does not affect solar cells efficiency.

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VAMAS TWA2 interlaboratory comparison: Surface analysis of TiO2 nanoparticles using ToF-SIMS

Journal of Vacuum Science & Technology A

Due to the extremely high specific surface area of nanoparticles and corresponding potential for ... more Due to the extremely high specific surface area of nanoparticles and corresponding potential for adsorption, the results of surface analysis can be highly dependent on the history of the particles, particularly regarding sample preparation and storage. The sample preparation method has, therefore, the potential to have a significant influence on the results. This report describes an interlaboratory comparison (ILC) with the aim of assessing which sample preparation methods for ToF-SIMS analysis of nanoparticles provided the most intra- and interlaboratory consistency and the least amount of sample contamination. The BAM reference material BAM-P110 (TiO2 nanoparticles with a mean Feret diameter of 19 nm) was used as a sample representing typical nanoparticles. A total of 11 participants returned ToF-SIMS data, in positive and (optionally) negative polarity, using sample preparation methods of “stick-and-go” as well as optionally “drop-dry” and “spin-coat.” The results showed that the...

ALD-grown tin oxide as an electron selective layer for perovskite/silicon tandem cells

SILICONPV 2022, THE 12TH INTERNATIONAL CONFERENCE ON CRYSTALLINE SILICON PHOTOVOLTAICS

Silicon nanocrystals grown on amorphous silicon carbide alloy thin films for third generation photovoltaics

HAL (Le Centre pour la Communication Scientifique Directe), 2012

Study of ALD-grown Tin Oxide as an Electron Selective Layer for NIP Perovskite-Based Solar Cells

2022 IEEE 49th Photovoltaics Specialists Conference (PVSC)

XPS spectroscopic and electrochemical study of passivation and localized corrosion of austenitic stainless steels treated by ionic implantation of molybdenum

Laser powder bed fusion (L-PBF) of Cu and CuCrZr parts: Influence of an absorptive physical vapor deposition (PVD) coating on the printing process

Additive Manufacturing, 2021

Abstract Laser powder bed fusion (L-PBF) of copper and copper alloys remain a challenge because o... more Abstract Laser powder bed fusion (L-PBF) of copper and copper alloys remain a challenge because of its low optical absorption and high thermal conductivity. L-PBF experiments were performed to print 2D (patches) and 3D (cubes) objects with pure copper under a low laser power (270 W max.). Patches reveal different surface morphologies allowing to select the best printing conditions for cubes. The highest reached cube relative density is 87.9%. To increase this value, a 1064 nm-absorptive physical vapor deposition (PVD) CrZr coating was performed on the copper powder to enhance its optical absorption. X-ray Photoelectron Spectrometry (XPS) and Auger measurements reveal the coating is oxidized, but increases the resulting CuCrZr powder optical absorption from 39% (value for pure Cu) to 81.8%. The CuCrZr powder was then used in the L-PBF process, and patches and cubes were successfully printed. The highest CuCrZr cube relative density reached 94.3%, highlighting the positive influence of a powder coating to create hard-to-melt metals or hard-to-atomized alloys under low laser power.

(Battery Division Technology Award) Some Directions for Performance Improvement of Li-Ion Batteries out of Usual Paths

ECS Meeting Abstracts, 2016

Recent developments at IMN will be shared on several research directions out of usual paths for p... more Recent developments at IMN will be shared on several research directions out of usual paths for performance improvement of Li-ion batteries. We will focus on innovative surface modifications of electrode components, new electrode compositions and architectures, and failure mechanism upon cycling by in-depth characterization through coupled advanced spectroscopic techniques. A molecular grafting approach has been proposed as a way to modify the interfacial chemical reactivity of oxide materials, which is detrimental to their long-term energy storage properties as electrodes of Li-ion batteries. Surface derivatization of powder oxide materials such as Li1.2V3O8 and Li(Mn,Ni)2O4 was accomplished by in situ electrografting of a diazonium salt during Li-ion intercalation, leading to a covalently bonded organic multilayer. Charge transfer is not impeded, while electrolyte decomposition is inhibited thus increasing the cycle life and decreasing the self-discharge. Carbon additives of class...

Some Directions for Performance Improvement of Li-Ion Batteries out of Usual Paths

HAL (Le Centre pour la Communication Scientifique Directe), 2016

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Coupling Surface Imaging, FIB, and Spectroscopies to Understand Silicon Anodes Lithiation and Ageing Mechanisms

ECS Meeting Abstracts, 2016

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Coupling Tof-SIMS and XPS for a Better Understanding of Lithiation Mechanism of Silicon Electrodes for Li-Ion Batteries

Meeting abstracts, 2015

Li-ion batteries technology is an attractive energy storage system for many specific applications... more Li-ion batteries technology is an attractive energy storage system for many specific applications like portable devices. To follow the growing energy demand of new devices, their energy density needs to be improved. Silicon-based anode is a serious option since it offers a specific capacity almost ten times higher than carbonaceous materials. However, cycling performances of Si electrodes, particularly in term of coulombic efficiency, remain so far inadequate for a use in practical LIBs, due to huge volume changes upon alloying and de-alloying with lithium. A fine understanding of the lithiation mechanism of silicon electrodes will help to design more robust architectures. Indeed, the degradation mechanisms upon electrochemical cycling are still under debate. In this work, an amorphous silicon thin film has been used as a model for a better understanding of lithiation mechanism appearing in more complex systems such as Si composites electrodes. Lithium distribution in the Si layer has been thoroughly investigated by coupling powerful characterization tools: X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (ToF-SIMS). In particular, cross-analyses of different lithiation states have been carried out by using an airtight transfer vessel between a glove box and XPS and ToF-SIMS spectrometers. Results reveal a lithiation front moving forward over the state of charge. The quantification of the LixSi alloy indicates a higher lithium amount compared to literature[1]. This anomaly leads to a description of the lithiation mechanism based on the presence of fast diffusion paths for Li throughout the Si layer reaching the Cu collector. These paths would be a second driving force for silicon alloying. To corroborate this mechanism, complementary analyses were performed: SEM observation of a FIB cut, TEM involving cryo-ultramicrotomy under protected atmosphere and Auger spectrometry. 1. Radvanyi, E., De Vito, E. and al., Study of lithiation mechanisms in silicon electrodes by Auger Electron Spectroscopy. Journal of Materials Chemistry A, 2013. 1(16): p. 4956-4965. Figure 1

Lithium isotope tracing in silicon-based electrodes using solid-state MAS NMR: a powerful comprehensive tool for the characterization of lithium batteries

Physical Chemistry Chemical Physics

A simple methodology based on high-resolution solid-state NMR was used for the determination of t... more

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Study of the influence of the formation protocol on the SEI layer formed at the graphite electrode surface of a non-aqueous potassium-ion hybrid supercapacitor (KIC) through STEM and XPS analyses

Sustainable Energy & Fuels

A correlation between the evolution of the KF content in the SEI and the evolution of cycling per... more

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High-resolution isotopic analysis of lithium by micro laser-induced breakdown self-reversal isotopic spectrometry (LIBRIS) for isotopic labelling of lithium in solid-state electrolyte of lithium batteries

Spectrochimica Acta Part B: Atomic Spectroscopy

Electrochemical and X-ray Photoelectron Spectroscopic Study of Early SEI Formation and Evolution on Si and Si@C Nanoparticle-Based Electrodes

Materials

Carbon coatings can help to stabilize the electrochemical performance of high-energy anodes using... more Carbon coatings can help to stabilize the electrochemical performance of high-energy anodes using silicon nanoparticles as the active material. In this work, the comparison of the behavior and chemical composition of the Solid Electrolyte Interphase (SEI) was carried out between Si nanoparticles and carbon-coated Si nanoparticles (Si@C). A combination of two complementary analytical techniques, Electrochemical Impedance Spectroscopy and X-ray Photoelectron Spectroscopy (XPS), was used to determine the intrinsic characteristics of the SEI. It was demonstrated that the SEI on Si particles is more resistive than the SEI on the Si@C particles. XPS demonstrated that the interface on the Si particles contains more oxygen when not covered with carbon, which shows that a protective layer of carbon helps to reduce the number of inorganic components, leading to more resistive SEI. The combination of those two analytical techniques is implemented to highlight the features and evolution of inte...

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Dynamics of the ⁶Li/⁷Li Exchange at a Graphite–Solid Electrolyte Interphase: A Time of Flight–Secondary Ion Mass Spectrometry Study

The Journal of Physical Chemistry, 2021

Li-ion batteries. From the present to the future

Si–C/G based anode swelling and porosity evolution in 18650 casing and in pouch cell

Journal of Power Sources, 2021

Silicon lithiation induces a high material expansion which leads to significant swelling and mech... more Silicon lithiation induces a high material expansion which leads to significant swelling and mechanical pressure at the anode and cell level. In this study, the effect of the various mechanical constrains on the swelling behaviour of pouch cell and cylindrical cell (18650) with high performance silicon carbon graphite (Si-C/G) anode material was evaluated. In case of 18650 cells, strain gauges were used to evaluate the strains and pressure generated from anode swelling during cycling process; in addition, individual cell components thickness change was captured at 8 different states of charge (SOC) during a cycle by in situ 3D imaging with X-Ray micro computed-tomography (voxel size 1.6µm) combined with a specific image treatment. For bi-layer pouch cells, operando swelling was measured using an inhouse high precision (< 0.1µm) compression setup with simultaneous pressure and thickness recording as well as dynamic pressure regulation system. Combining these unique experimental techniques and the modelling of Si-C/G active material swelling in function of the SOC we were able to provide insights in porosity changes of anodes for the two cell formats.

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Multiprobe Study of the Solid Electrolyte Interphase on Silicon-Based Electrodes in Full-Cell Configuration

Chemistry of materials : a publication of the American Chemical Society, Jan 26, 2016

The failure mechanism of silicon-based electrodes has been studied only in a half-cell configurat... more The failure mechanism of silicon-based electrodes has been studied only in a half-cell configuration so far. Here, a combination of (7)Li, (19)F MAS NMR, XPS, TOF-SIMS, and STEM-EELS, provides an in-depth characterization of the solid electrolyte interphase (SEI) formation on the surface of silicon and its evolution upon aging and cycling with LiNi1/3Mn1/3Co1/3O2 as the positive electrode in a full Li-ion cell configuration. This multiprobe approach indicates that the electrolyte degradation process observed in the case of full Li-ion cells exhibits many similarities to what has been observed in the case of half-cells in previous works, in particular during the early stages of the cycling. Like in the case of Si/Li half-cells, the development of the inorganic part of the SEI mostly occurs during the early stage of cycling while an incessant degradation of the organic solvents of the electrolyte occurs upon cycling. However, for extended cycling, all the lithium available for cycling...

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