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Introduction
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Publications
Publications (40)
Numerous sophisticated diagnostic techniques have been designed to monitor Electrode-Electrolyte Interfaces that mainly govern the lifetime and reliability of batteries. Among them, is the electrochemical quartz crystal microbalance that offers valuable insights of the interfaces once the required conditions of the deposited film in terms of viscoe...
Monitoring the dynamic chemical and thermal state of a cell during operation is crucial to making meaningful advancements in battery technology as safety and reliability cannot be compromised. Here we demonstrate the feasibility of incorporating optical fibre Bragg grating sensors into commercial 18650 cells. By adjusting fibre morphologies, wavele...
Water electrolysis is considered as a promising way to store and convert excess renewable energies into hydrogen, which is of high value for many chemical transformation processes such as the Haber-Bosch process. However, to allow for the wide-spread of the polymer electrolyte membrane water electrolysis (PEMWE) technology, the main challenge lies...
The production of hydrogen at a large scale by the environmentally-friendly electrolysis process is currently hampered by the slow kinetics of the oxygen evolution reaction (OER). We report a solid electrocatalyst α-Li2IrO3 which upon oxidation/delithiation chemically reacts with water to form a hydrated birnessite phase, the OER activity of which...
Great hopes are placed on all-solid state Li-metal batteries (ASSB’s) to boost the energy density of the current Li-ion technology. Though, these devices still present a number of unresolved issues that keep them far from commercialization such as interfacial instability, lithium dendrite formation and lack of mechanical integrity during cycling. T...
Recent studies have revealed the critical role played by the electrolyte composition on the oxygen evolution reaction (OER) kinetics on the surface of highly active catalysts. While numerous works were devoted to understand the effect of the electrolyte composition on the physical properties of catalysts’ surface, very little is known yet about its...
Recently, because of sustainability issues dictated by societal demands, more importance has been given to aqueous systems and especially to proton-based batteries. However, the mechanisms behind the processes leading to energy storage in such systems are still not elucidated. Under this scope, our study is structured on the selection of a model el...
Significance
Carbon dioxide electroreduction may constitute a key technology in coming years to valorize CO 2 as high value-added chemicals such as hydrocarbons and a way to store intermittent solar energy durably. Based on readily available technologies, systems combining a photovoltaic (PV) cell with an electrolyzer cell (EC) for CO 2 reduction t...
Recently, Ir(V)‐based perovskite‐like materials were proposed as oxygen evolution reaction (OER) catalysts in acidic media with promising performance. However, iridium dissolution and surface reconstruction were observed, questioning the real active sites on the surface of these catalysts. In this work, Sr2MIr(V)O6 (M = Fe, Co) and Sr2Fe0.5Ir0.5(V)...
Recently, Ir(V)‐based perovskite‐like materials were proposed as oxygen evolution reaction (OER) catalysts in acidic media with promising performance. However, iridium dissolution and surface reconstruction were observed, questioning the real active sites on the surface of these catalysts. In this work, Sr2MIr(V)O6 (M = Fe, Co) and Sr2Fe0.5Ir0.5(V)...
Li-ion batteries have been the object of tremendous progress over the last decade; however their energy density should still be increased to power electric vehicles. Following this aim, the energy density of the cathode material can be drastically boosted by making use of anionic redox although it often comes along with material degradation. In thi...
The search for high Li-ion conducting ceramics has regained tremendous interest triggered by the renaissance of the all-solid-state battery. Within this context we herein reveal the impact of structural polymorphism of lithium copper pyroborate Li6CuB4O10 on its ionic conductivity. Using combined in situ synchrotron X-ray and neutron powder diffrac...
Silicon electrodes are attracting for lithium-ion batteries but their use is impeded by their poor mechanical stability upon operation (huge volume variation takes place upon electrochemical Li insertion in and extraction from the material) and a poorly-controlled growth of surface layers resulting from the electrolyte decomposition products (the s...
Realization of the vulnerability of current rechargeable battery systems drives the research of solid electrolytes. In the search for a new Li ion conductor, we explore the rich crystal chemistry of Li4Zn(PO4)2 which presents a low temperature monoclinic (α-) and a high temperature orthorhombic (β-) polymorph. We solved the crystal structure of the...
The lithiation mechanism of methylated amorphous silicon, a-Si1−x(CH3)x:H, with various methyl contents (x = 0 - 0.12) is investigated using operando attenuated total reflection Fourier transform infrared spectroscopy. As in hydrogenated amorphous silicon, a-Si:H, the first lithiation proceeds via a two-phase mechanism. The concentration of the inv...
The large abundance of Na combined with the feasibility of Na-based insertion compounds, such as Na3V2(PO4)2F3, makes the Na-ion battery an attractive technology compared with Li-ion battery for a few applications. Nonetheless, one identified limitation of the Na3V2(PO4)2F3/HC system is its poor long-term cycling performance at elevated temperature...
The search for Li ions conducting ceramics is burgeoning, owing to the regain interest for solid state batteries. Here we investigate the effect of Mg substitutions on the ionic conductivity of the A2SnO3 (A = Li, Na) phases. Pure A1.8Mg0.1SnO3 and A2.2Mg0.1Sn0.9O3 were structurally characterized and their ionic conductivity was measured by AC impe...
The Na–air battery, because of its high energy density and low charging overpotential, is a promising candidate for low-cost energy storage, hence leading to intensive research. However, to achieve such a battery, the role of the positive electrode material in the discharge process must be understood. This issue is herein addressed by exploring the...
Herein we investigate the influence of the sodium salt anion on the performance of Na-O2 batteries. To illustrate the solvent-solute interactions in various solvents, we use 23Na-NMR to probe the electronic environment of Na+ in presence of different anions (ClO4-, PF6-, OTf- or TFSi-). Strong solvation of either the Na+ or the salt anion leads to...
Stabilizing new host structures through potassium extraction from K-based polyanionic materials has been proven to be an interesting approach to develop new Li+/Na+ insertion materials. Pursuing the same trend, we here report the feasibility of preparing langbeinite "Fe2(SO4)3" via electrochemical and chemical oxidation of K2Fe2(SO4)3. Additionally...
In the search for new cathode materials for sodium ion batteries, the exploration of polyanionic compounds has led to attractive candidates in terms of high redox potential and cycling stability. Herein we report the synthesis of the two new sodium transition-metal pentaborates Na3MB5O10 (M = Fe, Co), where Na3FeB5O10 represents the first sodium ir...
Microsized Sn presents stable cyclic performance in glyme-based electrolyte, which brings 19% increase in energy density of Sn/Na3V2(PO4)3 cells as compared to the cells using hard carbon anode. The NaSn intermediate phases are also clarified.
In view of increasing the energy density of battery systems for e.g. electric vehicles by lowering the dead weight penalty associated with the heavy polyanions replacing oxygen in traditional electrode materials, the title phases are prepared by ball milling of dehydrated α-VOSO4 and A2SO4 in stoichiometric proportions followed by annealing under A...
We herein report the synthesis, crystal structure, and electrochemical performances of a new Li-based vanadium oxysulfate phase, Li2VO(SO4)2, whose structure is built on vanadyl-containing VO5 square based pyramids and SO4 groups linked by vertices to form layers. Li2VO(SO4)2 presents a redox activity at 4.7 V vs. Li⁺/Li⁰ with a reversible capacity...
The Na–O2 battery offers an interesting alternative to the Li–O2 battery, which is still the source of a number of unsolved scientific questions. In spite of both being alkali metal–O2 batteries, they display significant differences. For instance, Li–O2 batteries form Li2O2 as the discharge product at the cathode, whereas Na–O2 batteries usually fo...
Progresses on novel positive electrode materials of rechargeable Li-ion batteries showing safety, sustainability and cost advantages have been recently achieved with the arrival of polyanionic compounds. Pursuing chemical substitutions on the anionic sites our group has synthesized a triplite LiFeSO 4 F 1,2 phase with a redox voltage of 3.9 V vs. L...
In the search for new cathode materials for Li-ion batteries, borate (BO33-) based compounds have gained much interest during the last two decades due to the lowest molecular weight of the borate polyanions which leads to active materials with increased theoretical capacities. In this context we herein report the electrochemical activity versus lit...
The title compound is prepared by ball milling and annealing of a stoichiometric mixture of anhydrous LiF and CuSO4 (Al2O3 boat, 400—415 °C, 8 h).
Silicon electrodes represent a great potential on increasing the energy density of Li-ion batteries, but stabilization during cycling is an important issue to be solved for enabling a reliable application. Such stabilization has been sought for by surface grafting of hydrogenated amorphous silicon (a-Si:H) electrodes. Grafting a molecular monolayer...
Li-rich layered oxides, e.g. Li[Li0.20Ni0.13Mn0.54Co0.13]O2 (LR-NMC), lead high energy density Li-ion battery cathodes, thanks to the reversible redox of oxygen anions that boost charge storage capacity. Unfortunately, their commercialization has been stalled by practical issues (i.e. voltage hysteresis, poor rate capability, and voltage fade) and...
Multiple-internal-reflection infrared spectroscopy allows for the study of thin-film amorphous silicon electrodes in situ and in operando, in conditions typical of those used in Li-ion batteries. It brings an enhanced sensitivity, and the attenuated-total-reflection geometry allows for the extraction of quantitative information. When electrodes are...
Silicon is considered as a promising anode material for Li-ion batteries due to its ability to insert large amounts of lithium, delivering a very high theoretical specific capacity of 3579 mAh/g, which is almost 10 times higher than graphite electrode (372 mAh/g). Nevertheless, a high volume variation (280 % for Li 15 Si 4 ) during lithiation leadi...
In-situ spectroscopic characterization of electrode/ electrolyte interfaces is of paramount importance in order to complement classical electrochemical investigation tools and obtain a full understanding of the investigated electrochemical systems. This approach has been shown to be quite useful for semiconductor electrodes, since the chemistry of...
