A Post-Mortem Study of Stacked 16 Ah Graphite//LiFePO₄ Pouch Cells Cycled at 5 °C

Herein, the post-mortem study on 16 Ah graphite//LiFePO4 pouch cells is reported. Aiming to understand their failure mechanism, taking place when cycling at low temperature, the analysis of the cell components taken from different portions of the stacks and from different positions in the electrodes, is performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoemission spectroscopy (XPS). Also, the recovered electrodes are used to reassemble half-cells for further cycle tests. The combination of the several techniques detects an inhomogeneous ageing of the electrodes along the stack and from the center to the edge of the electrode, most probably due to differences in the pressure experienced by the electrodes. Interestingly, XPS reveals that more electrolyte decomposition took place at the edge of the electrodes and at the outer part of the cell stack independently of the ageing conditions. Finally, the use of high cycling currents buffers the low temperature detrimental effects, resulting in longer cycle life and less inhomogeneities

SYNTHESE ET ETUDE ELECTROCHIMIQUE DE NITRURES MIXTES DE LITHIUM ET DE METAL DE TYPE Li3-xMxN (M = Co, Cu, Ni) UTILISABLES COMME ELECTRODE NEGATIVE DANS LES ACCUMULATEURS LI-ION.

In this study, we focus on the synthesis of ternary nitrides with the general formulation Li3-nxMx[]nx-xN (Mn+ = Co2+, Cu+ and Ni2+, [] represents vacancies) by a solid state route, under a controlled atmosphere, for a large composition range (0 < x = 0.6). The lattice parameters evolution obtained for these nitrides and a detailed analysis of X-ray diffraction data show the presence of Co2+ and Ni2+ in the interlayer spacing and the simultaneous presence of vacancies in the nitride layer. In the case of copper materials, Cu+ ions are present in the interlayer site, without any vacancies in the nitride layer. Once we master all parameters of the synthesis, we study the structural characterization and the electrochemical properties of each compound in terms of specific capacity, rechargeability, cycle life and kinetics. In all cases, we demonstrate that the redox systems involve several metal oxidation states, but also oxidation of nitrogen through (metal-N) entities. Galvanostatic performances are largely dependent on the metal and the potential range. Intercalation compounds are concerned in the potential range [0.02 – 1.0] V vs. Li+/Li because they involve the electrochemical systems CoII/CoI and NiII/NiI, with reversible Li insertion in vacancies and stable but low capacities (180 mAh.g-1). An optimisation of the electrochemical performances is possible when the potential range is extended up to 1.1 V. Thus, a stable specific capacity of about 320 mAh.g-1 is recovered after hundred of cycles, for the material Li2.23Co0.39N.Dans ce travail on réalise la synthèse de nitrures doubles de lithium et de métal de type Li3-nxMx[]nx-xN (Mn+ = Co2+, Cu+ et Ni2+, [] représente les lacunes en ions Li+) par une méthode céramique, sous atmosphère contrôlée, pour une large gamme de composition (0 < x = 0,6). L'évolution des paramètres de maille de ces nitrures et l'analyse fine des diagrammes de diffraction des rayons X indiquent la présence de Co2+ et de Ni2+ en position interfeuillets, ainsi que la présence simultanée de lacunes dans le plan azoté. Dans le cas du cuivre, des ions Cu+ interfeuillets sont présents, sans lacunes dans le plan azoté. Après avoir acquis la maîtrise des paramètres de synthèse, nous réalisons la caractérisation structurale et l'étude des propriétés électrochimiques de chaque matériau en terme de capacité spécifique, rechargeabilité, durée de vie, cinétique, etc. On démontre dans tous les cas que les systèmes redox impliqués font intervenir les divers degrés d'oxydation des métaux mais également ceux de l'azote à travers d'entités (métal-N).Les performances en cyclage galvanostatique sont largement dépendantes du métal et du domaine de potentiel concerné. Des matériaux d'intercalation du lithium sont concernés dans le domaine de potentiel [0,02 – 1,0] V vs Li+/Li car ils ne font intervenir que les systèmes CoII/CoI et NiII/NiI, avec insertion du lithium dans les lacunes, et des capacités stables mais restreintes (180 mAh.g-1). Une optimisation des performances est possible si on étend le domaine de cyclage à 1,1 V, avec une capacité spécifique stable de l'ordre de 320 mAh.g-1 sur plusieurs centaines de cycles, pour le matériau Li2,23Co0,39N

Synthèse et étude électrochimique de nitrures mixtes de lithium et de métal de type li3-xMxN (M = Co, Cu, Ni) utilisables comme électrode négative dans les accumulateurs Li-ion

Dans ce travail on réalise la synthèse de nitrures doubles de lithium et de métal de type Li3-nxMx[]nx-xN (Mn+ = Co2+, Cu+ et Ni2+, [] représente les lacunes en ions Li+) par une méthode céramique, sous atmosphère contrôlée, pour une large gamme de composition (0 < x <= 0,6). L évolution des paramètres de maille de ces nitrures et l analyse fine des diagrammes de diffraction des rayons X indiquent la présence de Co2+ et de Ni2+ en position interfeuillets, ainsi que la présence simultanée de lacunes dans le plan azoté. Dans le cas du cuivre, des ions Cu+ interfeuillets sont présents, sans lacunes dans le plan azoté. Après avoir acquis la maîtrise des paramètres de synthèse, nous réalisons la caractérisation structurale et l étude des propriétés électrochimiques de chaque matériau en terme de capacité spécifique, rechargeabilité, durée de vie, cinétique, etc. On démontre dans tous les cas que les systèmes redox impliqués font intervenir les divers degrés d oxydation des métaux mais également ceux de l azote à travers d entités (métal-N).Les performances en cyclage galvanostatique sont largement dépendantes du métal et du domaine de potentiel concerné. Des matériaux d intercalation du lithium sont concernés dans le domaine de potentiel [0,02 1,0] V vs Li+/Li car ils ne font intervenir que les systèmes CoII/CoI et NiII/NiI, avec insertion du lithium dans les lacunes, et des capacités stables mais restreintes (180 mAh.g-1). Une optimisation des performances est possible si on étend le domaine de cyclage à 1,1 V, avec une capacité spécifique stable de l ordre de 320 mAh.g-1 sur plusieurs centaines de cycles, pour le matériau Li2,23Co0,39N.In this study, we focus on the synthesis of ternary nitrides with the general formulation Li3-nxMx[]nx-xN (Mn+ = Co2+, Cu+ and Ni2+, [] represents vacancies) by a solid state route, under a controlled atmosphere, for a large composition range (0 < x <= 0.6). The lattice parameters evolution obtained for these nitrides and a detailed analysis of X-ray diffraction data show the presence of Co2+ and Ni2+ in the interlayer spacing and the simultaneous presence of vacancies in the nitride layer. In the case of copper materials, Cu+ ions are present in the interlayer site, without any vacancies in the nitride layer. Once we master all parameters of the synthesis, we study the structural characterization and the electrochemical properties of each compound in terms of specific capacity, rechargeability, cycle life and kinetics. In all cases, we demonstrate that the redox systems involve several metal oxidation states, but also oxidation of nitrogen through (metal-N) entities. Galvanostatic performances are largely dependent on the metal and the potential range. Intercalation compounds are concerned in the potential range [0.02 1.0] V vs. Li+/Li because they involve the electrochemical systems CoII/CoI and NiII/NiI, with reversible Li insertion in vacancies and stable but low capacities (180 mAh.g-1). An optimisation of the electrochemical performances is possible when the potential range is extended up to 1.1 V. Thus, a stable specific capacity of about 320 mAh.g-1 is recovered after hundred of cycles, for the material Li2.23Co0.39N.PARIS12-CRETEIL BU Multidisc. (940282102) / SudocSudocFranceF

Structural and Electrochemical Characterization of Thioantimoniate Sodium Solid Electrolyte

In the last couple of years, a major breakthrough has been achieved as several antimony-based sodium sulfide solid electrolytes (SSEs) substituted by aliovalent elements such as W have delivered high ionic conductivities up to 41 mS/cm at 25°C. (Hayashi et al., 2019; Fuchs et al., 2020; Feng et al., 2021) These Na-defective ionic superconductors outperform even the best lithium SEs, such as Li10GeP2S12 (10 mS/cm at 25°C). To date, little is known about the synthesis of this family of materials and the transport properties of these cubic phases defined in the I-43m (no. 217) space group. We have been working on obtaining the Na2.88Sb0.88W0.12S4 variant (hereafter, NSWS) by single step mechanochemical synthesis. Two samples were prepared with different milling conditions: (a) one milled during 10 h at 510 rpm, and (b) one milled during 10 h at 700 rpm. The corresponding synchrotron X-ray diffractograms are displayed in Fig. 1(a), showing a crystalline phase that corresponds to a mixture of the cubic I-43m and the tetragonal P-421c phases. Additional characterisations were carried out by using scanning electron microscope (SEM) to determine the morphology of the crystalline samples. As can be seen in Fig. 1(b), a wide distribution of particle sizes can be noticed with a certain degree of agglomeration. We can also notice two types of particle morphology which can indicate the presence of two different phase, in agreement with the XRD data

Structural and Electrochemical Characterization of Thioantimoniate Sodium Solid Electrolyte

In the last couple of years, a major breakthrough has been achieved as several antimony-based sodium sulfide solid electrolytes (SSEs) substituted by aliovalent elements such as W have delivered high ionic conductivities up to 41 mS/cm at 25°C. (Hayashi et al., 2019; Fuchs et al., 2020; Feng et al., 2021) These Na-defective ionic superconductors outperform even the best lithium SEs, such as Li10GeP2S12 (10 mS/cm at 25°C). To date, little is known about the synthesis of this family of materials and the transport properties of these cubic phases defined in the I-43m (no. 217) space group. We have been working on obtaining the Na2.88Sb0.88W0.12S4 variant (hereafter, NSWS) by single step mechanochemical synthesis. Two samples were prepared with different milling conditions: (a) one milled during 10 h at 510 rpm, and (b) one milled during 10 h at 700 rpm. The corresponding synchrotron X-ray diffractograms are displayed in Fig. 1(a), showing a crystalline phase that corresponds to a mixture of the cubic I-43m and the tetragonal P-421c phases. Additional characterisations were carried out by using scanning electron microscope (SEM) to determine the morphology of the crystalline samples. As can be seen in Fig. 1(b), a wide distribution of particle sizes can be noticed with a certain degree of agglomeration. We can also notice two types of particle morphology which can indicate the presence of two different phase, in agreement with the XRD data

Structural and Electrochemical Characterization of Thioantimoniate Sodium Solid Electrolyte

In the last couple of years, a major breakthrough has been achieved as several antimony-based sodium sulfide solid electrolytes (SSEs) substituted by aliovalent elements such as W have delivered high ionic conductivities up to 41 mS/cm at 25°C. (Hayashi et al., 2019; Fuchs et al., 2020; Feng et al., 2021) These Na-defective ionic superconductors outperform even the best lithium SEs, such as Li10GeP2S12 (10 mS/cm at 25°C). To date, little is known about the synthesis of this family of materials and the transport properties of these cubic phases defined in the I-43m (no. 217) space group. We have been working on obtaining the Na2.88Sb0.88W0.12S4 variant (hereafter, NSWS) by single step mechanochemical synthesis. Two samples were prepared with different milling conditions: (a) one milled during 10 h at 510 rpm, and (b) one milled during 10 h at 700 rpm. The corresponding synchrotron X-ray diffractograms are displayed in Fig. 1(a), showing a crystalline phase that corresponds to a mixture of the cubic I-43m and the tetragonal P-421c phases. Additional characterisations were carried out by using scanning electron microscope (SEM) to determine the morphology of the crystalline samples. As can be seen in Fig. 1(b), a wide distribution of particle sizes can be noticed with a certain degree of agglomeration. We can also notice two types of particle morphology which can indicate the presence of two different phase, in agreement with the XRD data

Synthesis and structural and electrochemical characterization of sodium based thiophosphates electrolytes for all solid state batteries

International audienceAlong with the continuous population growth, which according to United Nations is projected to have reached 8 billion in November this year [1], the ever-increasing demand for reliable energy sources becomes the main concern of researchers coming from many different fields of work. To withstand the challenges posed by the current energetic systems, technological developments are pushed towards renewable and decentralized energy sources [2]. To take the most advantage of those, frequently intermittent in nature, reliable energy storage systems are required [3]. Electrochemical energy storage offers several desirable characteristics that include high efficiency, flexibility to meet different grid functions, long cycle life, and little maintenance [4]. All-solid-state batteries (ASSBs) pose advantages regarding the state-of-the-art liquid-based systems as their chemistry can be based on non-flammable materials and they operate at wider temperature ranges while having the potential to enable metallic anode [5]. As lithium is still a critical resource, sodium-based batteries arise among other viable technologies and developing ASSBs using Na as a charge carrier establishes an appealing alternative.Thiophosphate-based solid electrolytes can reach ionic conductivities beyond 1 mS·cm−1, enabling the viability for commercial applications [6]. However, synthesis, handling and processing of these materials are challenging as plenty of variables affect their electrochemical response.In this talk we present three different forms of Na solid electrolytes (SEs), a novel amorphous Na3PS4 phase (NPS-amorph), a crystalline one defined in the cubic I–43m (217) space group (NPS-cryst), and a crystalline Na3SbS4-based SE with W aliovalent partial substitution defined in the same 217 space group (NSWS-cryst). All three samples were obtained by mechanochemical synthesis route. Their structure and morphology, assessed by XRD and SEM EDS, respectively, are discussed and compared. Their intrinsic electrochemical properties, like the ionic conductivity (measured by electrochemical impedance spectroscopy), and their electrochemical stability windows (evaluated by cyclic voltammetry) will be correlated to their structural nature

Synthesis and structural and electrochemical characterization of sodium based thiophosphates electrolytes for all solid state batteries

International audienceAlong with the continuous population growth, which according to United Nations is projected to have reached 8 billion in November this year [1], the ever-increasing demand for reliable energy sources becomes the main concern of researchers coming from many different fields of work. To withstand the challenges posed by the current energetic systems, technological developments are pushed towards renewable and decentralized energy sources [2]. To take the most advantage of those, frequently intermittent in nature, reliable energy storage systems are required [3]. Electrochemical energy storage offers several desirable characteristics that include high efficiency, flexibility to meet different grid functions, long cycle life, and little maintenance [4]. All-solid-state batteries (ASSBs) pose advantages regarding the state-of-the-art liquid-based systems as their chemistry can be based on non-flammable materials and they operate at wider temperature ranges while having the potential to enable metallic anode [5]. As lithium is still a critical resource, sodium-based batteries arise among other viable technologies and developing ASSBs using Na as a charge carrier establishes an appealing alternative.Thiophosphate-based solid electrolytes can reach ionic conductivities beyond 1 mS·cm−1, enabling the viability for commercial applications [6]. However, synthesis, handling and processing of these materials are challenging as plenty of variables affect their electrochemical response.In this talk we present three different forms of Na solid electrolytes (SEs), a novel amorphous Na3PS4 phase (NPS-amorph), a crystalline one defined in the cubic I–43m (217) space group (NPS-cryst), and a crystalline Na3SbS4-based SE with W aliovalent partial substitution defined in the same 217 space group (NSWS-cryst). All three samples were obtained by mechanochemical synthesis route. Their structure and morphology, assessed by XRD and SEM EDS, respectively, are discussed and compared. Their intrinsic electrochemical properties, like the ionic conductivity (measured by electrochemical impedance spectroscopy), and their electrochemical stability windows (evaluated by cyclic voltammetry) will be correlated to their structural nature

Synthesis and structural and electrochemical characterization of sodium based thiophosphates electrolytes for all solid state batteries

International audienceAlong with the continuous population growth, which according to United Nations is projected to have reached 8 billion in November this year [1], the ever-increasing demand for reliable energy sources becomes the main concern of researchers coming from many different fields of work. To withstand the challenges posed by the current energetic systems, technological developments are pushed towards renewable and decentralized energy sources [2]. To take the most advantage of those, frequently intermittent in nature, reliable energy storage systems are required [3]. Electrochemical energy storage offers several desirable characteristics that include high efficiency, flexibility to meet different grid functions, long cycle life, and little maintenance [4]. All-solid-state batteries (ASSBs) pose advantages regarding the state-of-the-art liquid-based systems as their chemistry can be based on non-flammable materials and they operate at wider temperature ranges while having the potential to enable metallic anode [5]. As lithium is still a critical resource, sodium-based batteries arise among other viable technologies and developing ASSBs using Na as a charge carrier establishes an appealing alternative.Thiophosphate-based solid electrolytes can reach ionic conductivities beyond 1 mS·cm−1, enabling the viability for commercial applications [6]. However, synthesis, handling and processing of these materials are challenging as plenty of variables affect their electrochemical response.In this talk we present three different forms of Na solid electrolytes (SEs), a novel amorphous Na3PS4 phase (NPS-amorph), a crystalline one defined in the cubic I–43m (217) space group (NPS-cryst), and a crystalline Na3SbS4-based SE with W aliovalent partial substitution defined in the same 217 space group (NSWS-cryst). All three samples were obtained by mechanochemical synthesis route. Their structure and morphology, assessed by XRD and SEM EDS, respectively, are discussed and compared. Their intrinsic electrochemical properties, like the ionic conductivity (measured by electrochemical impedance spectroscopy), and their electrochemical stability windows (evaluated by cyclic voltammetry) will be correlated to their structural nature

Structural and electrochemical characterization of sodium solid electrolyte

In the last couple of years, a major breakthrough has been achieved as several antimony-based sodium sulfide solid electrolytes (SSEs) substituted by aliovalent elements such as W have delivered high ionic conductivities up to 41 mS/cm at 25°C. (Hayashi et al., 2019; Fuchs et al., 2020; Feng et al., 2021) These Na-defective ionic superconductors outperform even the best lithium SEs, such as Li10GeP2S12 (10 mS/cm at 25°C). To date, little is known about the synthesis of this family of materials and the transport properties of these cubic phases defined in the I-43m (no. 217) space group.We have been working on obtaining the Na2.85P0.85W0.15S4 variant (hereafter, NPWS) by single step mechanochemical synthesis. Two samples were prepared with different milling conditions: (a) one milled during 10 h at 510 rpm, and (b) one milled during 10 h at 700 rpm. The corresponding synchrotron X-ray diffractograms are displayed in Fig. 1(a), showing a crystalline phase that corresponds to a mixture of the cubic I-43m and the tetragonal P-421c phases. Additional characterisations were carried out by using scanning electron microscope (SEM) to determine the morphology of the crystalline samples. As can be seen in Fig. 1(b), a wide distribution of particle sizes can be noticed with a certain degree of agglomeration. We can also notice two types of particle morphology which can indicate the presence of two different phase, in agreement with the XRD data.Although we obtain conductivities close to 1 mS/cm, they are far below the reported values. We conclude, based on our hypotheses, that either the materials are not pure, and/or the Na ion transport through the material is synthesis dependent. An operando thermodiffraction experiment performed on the NPWS samples at D2B instrument at the Institut Laue-Langevin and ID31 at the European Synchrotron Radiation Facility help us determining the optimal temperature conditions for the formation of the NPWS crystalline phase in the I-43m space group and gave insight about the probable Na-ion transport processes as a function of the temperature