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The development of tools for examining and predicting battery performance represents a significant challenge for the field of monitoring, as it is dependent on nondestructive evaluation (NDE) techniques to provide key behavior descriptors. As the thermal behavior of a battery impacts its internal chemistry, thermal imaging represents an in operando NDE technique capable of providing valuable information to facilitate an understanding of a battery’s overall electrochemical performance. However, previous attempts to directly link thermal imaging analyses to internal chemistry have—so far—proved challenging due in part to the complexities of the relationships between the thermal and the electrochemical battery behavior. In this article, we propose and describe a more refined approach in which correlation between thermal imaging results and internal battery reactions is first established, providing a foundation for determining descriptors for developing early fault detection. Here, this approach is experimentally validated, through the use of a combination of electrochemical, in operando infrared thermography, and post-mortem analyses, which were undertaken in order to characterize selected lead-acid batteries. These results—and their implications for early fault detection—are discussed, along with the challenges facing in operando battery thermal imaging, laying a foundation for developing the understanding vital to future iterative design improvements.

Lithium-ion batteries (LIBs) are today considered as one of the best solutions towards an energy model based on renewable sources and zero-emission electric vehicles. However, the increased production of LIBs raises concerns regarding cost and availability of key materials such as lithium, cobalt or graphite. Indeed, after almost 20 years of cost decrease, the price of lithium-ion batteries is slowing down [1]. This is related to the fact that a lot of raw materials and metals (mainly copper, aluminum and cobalt) that are used in LiBs have increased relentlessly their prices because of its continuous demand. In this sense, are needed better performing, more price competitive and sustainable battery storage solutions beyond lithium that take into consideration the overall value chain, from access to raw material, innovative advanced materials, production, recycling and second life. In this context, disposal and recycling are essential for the sustainability of this market and new recycling processes for LIBs are needed. Today there are processes that can recover high-value raw materials from LIBs (mainly copper, aluminum, and cobalt) but direct recycling of materials such as LiFePO4 (LFP) that has less economic value and are environmentally much more sustainable represents an economic challenge for the battery market and future research. NaFePO4 (NFP) has been indeed proposed as one of the cheapest and most sustainable sodium-ion (Na-ion) cathode materials, [2-3] but it is not a thermodynamically stable phase and it is necessary to obtain it from LFP through redox reactions usually using expensive, toxic and hazardous reagents, cutting down its commercialization.[3-5] LFP recovering from spent LIBs can contribute to reducing the manufacturing costs of the NFP and increase the interest to recycle Li-ion batteries based on LFP cathodes. In the perspective of a circular economy market, we propose in this work to explore the recovery of aged LFP electrodes and their reuse in new Na-ion batteries.

Application of Li-ion batteries for transportation not only requires long cycling life but also the preservation of the electrochemical performance during the resting period. For certain car usage this resting time could be predominant compared with the cycling activity and is referred to as calendar aging. To understand the aging mechanisms during calendar aging, an extensive post-mortem study was conducted on commercial 16 Ah NMC/graphite pouch cells stored at 5, 25, 45, and 60 °C. The post-mortem analyses were performed in parallel within three separate laboratories across Europe. They included visual inspection and structural and microstructural analysis along with a combination of analytical techniques to determine accurately the composition of positive (NMC) and negative (graphite) electrodes and the electrolyte. A direct correlation was established between the calendar-aging temperature and the degradation of the cells. The measurements revealed a severe deterioration phenomenon for the electrodes ...

Lithium sulphur batteries are promising candidates for upcoming/future energy storage systems due to their theoretical specific energy (2500 Wh kg−1). Poor cycle life and low capacity retention are main issues restraining their commercialization. To achieve high energy density, metallic lithium or concentrated alloy negatives are required wherein both the challenge of high reactivity leading to degradation, and safety issues have to be dealt with. LiNO3 has been reported as an electrolyte additive to produce passivation layer on the metallic lithium anode. However, the passivation layer thickness cannot be controlled. In order to have similar passivation effect with controlled thickness and to avoid undesirable reaction on the surface of the lithium metal, Li3N protective layers has been investigated. This study demonstrates the effect of coating techniques and feasibility of Li3N protective layers for Li metal anodes in Li-S cells using just a standard sulphur/ carbon composite electrode, thereby independent from the effects of binders or any porous cathode architecture. A first approach to study the surface morphology of Li with Li3N layers in Li-S batteries has been made. Improved cycling efficiency and good lithium plating/stripping characteristics were observed with a smooth surface morphology of Li metal. A viable in-situ approach of depositing Li3N layer on the Li metal anode using ([(CH3)3SiN3]) as electrolyte additive is proposed.

International audience; Metallic lithium deposition is a typical aging mechanism observed in lithium-ion cells at low temperature and/or at high charge rate. Lithium dendrite growth not only leads to strong capacity fading, it also causes safety concerns such as short-circuits in the cell. In applications such as electric vehicles, the use of lithium-ion batteries combines discharging, long rest time and charging phases. It is foremost a matter of lifetime and safety from the perspective of the consumer or the investor. This study presents the post-mortem analyses of commercial 16 Ah Graphite/NMC (Nickel Manganese Cobalt layered oxide) Li-ion pouch cells. The cells were degraded by calendar aging at high temperature with or without periodic capacity tests. Unexpected local depositions of metallic lithium were confirmed on graphite electrodes by Nuclear Magnetic Resonance (NMR). Biphenyl, a monomer additive present in the liquid electrolyte, generates gas during its polymerization reaction occurring at high temperature and at high state of charge. As a result, dry-out areas are present between the electrodes leading to high impedance regions and no charge transfer between the electrodes. It is at the border of these areas that lithium metal is deposited.

Improvement of life-time is an important issue in the development of Li-ion batteries. Aging mechanisms limiting the life-time can efficiently be characterized by physico-chemical analysis of aged cells with a variety of complementary methods. This study reviews the state-of-the-art literature on Post-Mortem analysis of Li-ion cells, including disassembly methodology as well as physico-chemical characterization methods for battery materials. A detailed scheme for Post-Mortem analysis is deduced from literature, including pre-inspection, conditions and safe environment for disassembly of cells, as well as separation and post-processing of components. Special attention is paid to the characterization of aged materials including anodes, cathodes, separators, and electrolyte. More specifically, microscopy, chemical methods sensitive to electrode surfaces or to electrode bulk, and electrolyte analysis are reviewed in detail. The techniques are complemented by electrochemical measurements using reconstruction methods for electrodes built into half and full cells with reference electrode. The changes happening to the materials during aging as well as abilities of the reviewed analysis methods to observe them are critically discussed.

The nature of the alkaline electrolyte (based on KOH, NaOH, LiOH), in which Co{sub 3}O{sub 4} spinel type phases are synthesized by electrooxidation of CoO, is shown to play a key role on the composition, the structure and the electronic conductivity of the materials. In the materials, prepared in pure LiOH electrolyte or in mixed ternary electrolyte (KOH, NaOH, LiOH), Co{sup 4+} ions are present in the octahedral framework, which entails electronic delocalization in the cobalt T{sub 2g} band and a high conductivity. The structure of the sample, synthesized in KOH, is on the opposite closer to that of ideal Co{sub 3}O{sub 4}, with only Co{sup 3+} in the octahedral sublattice, which leads to a semi-conducting behavior. Whatever the initial material, a thermal treatment induces an increase of the Co{sup 4+}/Co{sup 3+} ratio in the octahedral network, resulting in a significant increase of the electronic conductivity. - Graphical abstract: In 'Co{sub 3}O{sub 4}' type spinel phases synthesized by eleectrooxidation, the nature of the alkaline electrolyte allows to monitor the amounts of hydrogen and lithium, inserted in spinel framework and therefore the electronic conductivity. Whatever the initial synthesis electrolyte, a moderate thermal treatment of the materials induces a significant increase ofmore » the electronic conductivity, due to a structural reorganization (illustrated by the evolution of the cell parameter) and an increase of the Co{sup 4+}/Co{sup 3+} ratio in the octahedral framework.« less

International audience; A series of “Li1+z/2(Ni0.425Mn0.425Co0.15)1−z/2O2−zFz” materials was prepared by a coprecipitation route and their structure was characterized using X-ray diffraction (XRD), as well as 7Li and 19F Magic Angle Spinning (MAS) NMR spectroscopy. Two hypotheses were considered: (i) formation of layered oxyfluoride materials and (ii) formation of a mixture between the layered material and LiF. Structural parameters were refined by the Rietveld method, using XRD diffraction data. The refinement results did not allow us to choose between these two hypotheses: no significant change in crystallinity and structural parameters was observed irrespective of the fluorine ratio. 7Li and 19F MAS NMR analyses showed signals with isotropic positions characteristic of LiF, but envelopes characteristic of very strong dipolar interactions with the electron spins of the material, demonstrating that LiF was not incorporated into the layered oxide structure but was instead present as a coating.

Mixtures of tin(II) chloride and tin(II)-sodium–potassium chlorides were converted into phosphate salts by reaction with ammonium dihydrogen-phosphate at 400 °C. Element analyses showed that no loss occurred during the treatment, and Mossbauer and wet analyses indicated no change in tin valence. The converted tin phosphate and tin–sodium–potassium phosphates were then dissolved into silicate glasses at 1350 °C without loss. Structural analyses were realized with 31P, 29Si, 119Sn NMR and 119Sn Mossbauer, which revealed a complete dissociation of tin phosphate into the silicates. Phosphate units consisted in ortho- and pyro-phosphates. Tin(II) was partially oxidized into tin(IV), but there was no evidence for a phase separation into SnO2 or SnP2O7, tin being mainly bonded to silicate units. These results are discussed in terms of O2− exchange between phosphate and silicate units during the melting process.

x SnO–(100 – x) P2O5 glasses (0.30 ≤ x ≤ 0.75) were prepared under argon atmosphere. The Sn2+/Sntotal ratio, determined by wet chemical analysis, varies from 90 to 99% depending on glass composition. Glass transition temperatures are very low, and no effect of Sn4+could be detected. Glass structure was characterised with 31P and 119Sn NMR. There is no evidence for a specific Qn site bonded to Sn4+, but taking into account the amount of Sn4+ enabled to obtain Qn distribution close to calculated values for binary site distribution. 119Sn NMR spectra were recorded in static conditions. Chemical shift anisotropy (CSA) of glasses were compared to crystalline reference compounds. Tin(II) local environment in glasses is close to a trigonal pyramid, and Sn4+ NMR parameters are in accordance with a local environment similar to SnP2O7. To cite this article: E. Bekaert et al., C. R. Chimie 7 (2004).

Li-ion batteries are good candidates for electric vehicles and stationary applications due to their high power and energy densities. It is well known that the lifetime of lithium ion batteries is limited by undesirable side reactions. Moreover, these side reactions can affect different parts of the battery including the electrolyte, the active material, binder, conducting agents, current collectors and the separator. Over time, this fact leads to a gradual capacity fade and the end of life of the battery. Thus, the understanding of degradation mechanisms in lithium ion batteries is considered to be of great importance. In this work, the “post mortem analyses“ of NMC/graphite commercial pouch cells has been performed. For this, a standard procedure for cell opening and preparation of the samples has been defined. As safety plays an important role in the dissemination of batteries, full discharge of the investigated cells has been carried out [1,2,3]. Furthermore, a controlled environment such as an Ar-filled glove box has been used during cell opening in order to avoid material decomposition [4,5]. Once the electrodes have been separated, the conductive salt has been removed to prevent corrosion. Diagnostic evaluation of the first degradation mechanisms has been studied by ex-situ destructive physico-chemical and electrochemical analyses of the cell components. The crystallographic and morphological studies of the electrodes have been carried out by X-ray diffraction (XRD) and electron microscopy (SEM). Additionally, elemental analysis of the electrode composition has been determined by EDS and ICP techniques. In order to evaluate the electrochemical characterization of the harvested electrodes, galvanostatic testing in half-cell configuration has been performed. The research leading to these results has been performed within the MAT4BAT project (http://www.mat4bat.eu) [1] D. Aurbach, B. Markovsky, A. Rodkin, M. Cojocaru, E. Levi, H.-J. Kim, Electrochimica Acta 47 (2002) 1899. [2] Y. Kobayashi, T. Kobayashi, K. Shono, Y. Ohno, Y. Mita, H. Miyashiro, Journal of the Electrochemical Society 160 (2013) A1181. [3] T. Waldmann, M. Wilka, M. Kasper, M. Fleischhammer, M. Wohlfahrt-Mehrens, Journal of Power Sources 262 (2014) 129. [4] H.-Y. Amanieu, D. Rosato, M. Sebastiani, F. Massimi, D.C. Lupascu, Materials Science and Engineering: A 593 (2014) 92. [5] C. Wu, Y. Bai, F. Wu, Journal of Power Sources 189 (2009) 89.

International audience; Several Li−Sn crystalline phases, LiSn, Li7Sn3, Li5Sn2, Li13Sn5, Li7Sn2, and Li22Sn5, were prepared by ball-milling and studied by 7Li MAS NMR spectroscopy with silica as a diluting agent to avoid field penetration limitations. All phases except for LiSn exhibit exchanged NMR signals at room temperature for the various types of Li present in the unit cells, in the 10 to 100 ppm range. Electronic structure calculations based on first-principles method led to a rather good correlation between the participation of the Li 2s orbital to the density of states (DOS) at the Fermi level and the corresponding NMR Knight shift for the two Li crystallographic types in the case of LiSn, and for the weighted average of the different crystallographic types in the case of the NMR-exchanged signals for the other compounds.

Nanocrystalline RuO2 was electrochemically lithiated using a 6Li-enriched negative electrode, and selected samples at various states of lithiation-delithiation were characterized ex situ by 6Li mag...

A thermal treatment of Co3O4 type spinel phases, synthesized by electrooxidation of CoO powder in a mixed alkaline electrolyte (KOH, LiOH, NaOH), is shown to have an important influence on the electronic conductivity properties of the materials. The initial spinel phase contains hydrogen, lithium, cobalt vacancies, and especially Co4+ ions within the structure, leading to an electronic conductivity significantly larger than that of stoichiometric Co3O4. The thermal treatment, followed by in situ X-ray diffraction, TGA-MS and electronic conductivity measurements, induces a water release, coupled with an increase of the Co/O atomic ratio and a structural reorganization. The resulting cationic redistribution within the spinel framework entails an increase of the Co4+ amount in the [Co2O4] network and therefore of the electronic conductivity (by 3 orders of magnitude).

International audience; The Li reactivity of NiP2 is investigated by means of electrochemical tests, in situ XRD, and 31P NMR characterizations as well as first principles DFT calculations. A two-step insertion/conversion reaction is shown to transform the NiP2 starting electrode into an intermediate Li2NiP2 single phase and then to convert into the Li3P/Ni° nanocomposite. The ternary phase is fully characterized and is shown to be structurally very close to the starting NiP2 regarding the Ni ions environment. This demonstrates that its formation results from a P-redox insertion mechanism associated with a very good reversibility. However, its nucleation upon delithiation from the fully converted Li3P/Ni composite is shown to be kinetically limited (poor structural relationship) which strongly suggests that restricted lithiation is required for best cycleability of the NiP2/Li cell.

International audience; Nanocrystalline RuO2 was electrochemically lithiated using a 6Li-enriched negative electrode, and selected samples at various states of lithiation-delithiation were characterized ex situ by 6Li magic-angle spinning nuclear magnetic resonance (6Li MAS NMR). In the first plateau (up to one Li per RuO2), a signal with considerable shift and loss of intensity is observed, showing a strongly paramagnetic character for the LiRuO2 phase. A signal due to solid electrolyte interphase (SEI) appears at 0 ppm on this first plateau, but significantly grows only on the subsequent conversion plateau (from 1 to 4 Li/RuO2). Li2O is detected only at the very end of the latter plateau. On further lithiation (4 to 5.5 Li/RuO2), the magnitude of the Li2O signal remains constant, and a new signal at 4 ppm appears, that we can assign to interfacial Li hypothesized earlier in this system. Upon subsequent delithiation, NMR shows that the interfacial Li first disappears, then Li2O also disappears, and the reconstructed Li-RuO2 phase is clearly different from the one formed during the initial lithiation of RuO2. Besides, the SEI signal slightly changes but does not decrease in magnitude upon delithiation. NMR results are in satisfactory agreement with the characteristic features of the proposed “job-sharing” mechanism.

International audience; A thermal treatment of Co3O4 type spinel phases, synthesized by electrooxidation of CoO powder in a mixed alkaline electrolyte (KOH, LiOH, NaOH), is shown to have an important influence on the electronic conductivity properties of the materials. The initial spinel phase contains hydrogen, lithium, cobalt vacancies, and especially Co4+ ions within the structure, leading to an electronic conductivity significantly larger than that of stoichiometric Co3O4. The thermal treatment, followed by in situ X-ray diffraction, TGA-MS and electronic conductivity measurements, induces a water release, coupled with an increase of the Co/O atomic ratio and a structural reorganization. The resulting cationic redistribution within the spinel framework entails an increase of the Co 4+ amount in the [Co2O4] network and therefore of the electronic conductivity (by 3 orders of magnitude).

International audience; A series of binary transition metal phosphides (Ni3P, Ni12P5, Ni2P, Ni5P4, NiP, NiP2, FeP, FeP2, FeP4, VP2, CoP) were investigated by solid state 31P MAS NMR, leading to rather different lineshapes, shifts, relaxation times, and temperature-dependences. The electronic structures of these compounds were computed using various DFT codes, based either on plane waves PAW potentials (VASP), or on all-electron basis sets in the FPLAPW formalism (Wien2K). Depending on the electronic features of the phosphide, self-interaction corrected formalisms (DFT+U or PBE0 hybrid functional) were also used to reach a better description of the electronic ground state and to establish a correlation with the shape and the nature of the NMR signals. As a result of the analysis, the main categories are diamagnetic compounds (FeP4, NiP2) and metallic ones, either real (VP2) or with some electronic localisation in band tails (Ni12P5, Ni2P, Ni5P4, NiP), or with spin-polarized conduction bands (CoP, FeP). FeP2 appears somewhat ambiguous, both based on the various computational results and on the NMR characteristics. Besides, FeP4 is the only compound for which very clear J couplings resulting from P-P bonds were observed.

International audience; We report on the Li electrochemical reactivity of amorphous and crystalline VP2, synthesized by ball-milling and by 600 °C heat treatment of a ball-milled sample, respectively. The amorphous sample can reversibly react with 3.5 Li per formula unit as compared to solely 2.5 for the crystalline one. However in both cases there is a rapid capacity decay upon cycling that is more pronounced in the case of the crystalline sample. Complementary X-rays, HTREM and NMR tend to show that the Li reactivity mechanism differs from the classical conversion reactions since neither V nanoparticles nor the formation of Li3P were detected, as opposed to some of the other MP2 compounds (M = Ni or Cu). Besides structural phase variations within the 3d metal-based binary phosphide series, the possibility of a change in the nature of the redox centre upon lithiation from cation (M) to anion (P) is evoked.

Li-ion batteries are good candidates for electric vehicles and stationary applications due to their high power and energy density. Despite significant improvement over the last decade, lifetime and safety remain major issues for large-scale applications. Thus, a better understanding of factors governing battery lifetime and performance loss is crucial. Various types of Li-ion batteries are commercially available and their characteristics and performance depend strongly on the combination of active materials, cell design and manufacturing process. Therefore, the determination of specific degradation mechanisms and their correlation with cell performances is crucial for working on cell concepts that can meet target lifetimes [1-3]. In this work, cycling performance fade of LiFePO4-based cylindrical batteries is evaluated under deep charge/discharge steps (100% DOD). The cycling conditions were chosen to represent highly demanding condition of operation, which covers the analysis of ageing phenomena under the largest possible operating DOD. Diagnostic evaluation of the ageing mechanisms included in-situ electrochemical measurements, and ex-situ destructive physico-chemical and electrochemical analyses of cell components. A thorough study on the degradation mechanisms in different areas of the battery is realised in order to establish a geometrical mapping of the cell degradation. This allows identifying areas of inhomogeneous degradation along the jelly-roll of the battery. Degradation mechanisms were evaluated by microstructural (SEM) and crystallographic (XRD) analyses. Elemental analysis of the electrode composition was determined by EDS and ICP techniques. The electrochemical performances of selected areas of the harvested electrodes were determined by galvanostatic testing in half-cell configuration. These results were combined with non-destructive cell electrochemical measurements to provide a global view of the main degradation processes. [1] M. Safari and C. Delacourt, Journal of the Electrochemical Society, 2011. 158(12): p. A1436-A1447. [2] M. Dubarry and B.Y. Liaw, Journal of Power Sources, 2009. 194(1): p. 541-549. [3] D.P. Abraham, J. Liu, C.H. Chen, Y.E. Hyung, M. Stoll, N. Elsen, S. MacLaren, R. Twesten, R. Haasch, E. Sammann, I. Petrov, K. Amine, and G. Henriksen, Journal of Power Sources, 2003. 119-121: p. 511-516.

Sodium–lead–cadmium phosphate glasses having a mol% composition (40− y )Na 2 O– y CdO–10PbO–50P 2 O 5 (0≤ y ≤40) were prepared by using the melt–quench technique. They have been characterised by infrared spectroscopy, Raman spectroscopy and 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR). Infrared and Raman spectroscopies reveal the formation of P–O–Pb and P–O–Cd bonds, which replace P–O – + Na bonds. MAS-NMR spectroscopy shows that no metaphosphate network depolymerisation occurs when y increases. Thus, both PbO and CdO act as the network modifiers. Systematic variations of the glass transition temperature, density, and molar volume observed are in agreement with these results. Ionic conductivity is correlated to the structural model.

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A one-step synthesis method was used, with LiF or NiF 2 as fluorine precursor, to prepare Li 1.1 (Ni 0.425 Mn 0.425 Co 0.15 ) 0.9 O 1.8 F 0.2 materials. 7 Li and 19 F magic angle spinning NMR analyses revealed the presence of fluorine as LiF at the surface of the Li(Ni 0.425 Mn 0.425 Co 0.15 )O 2 particles, rejecting the formation of fluorine-substituted Li 1.1 (Ni 0.425 Mn 0.425 Co 0.15 ) 0.9 O 8 F 0.2 materials. These results highlighted that change in cell parameters with increasing fluorine content is not by itself proof for effective fluorine substitution for oxygen in layered oxides and that heterogeneity in the transition metal and fluoride-ion distribution at the crystallite scale can be at the origin of these modifications. LiF was shown to be present as small particles in some grain boundaries but not as a continuous layer covering the particles surface. Improved cycling stability was observed for these LiF-coated materials, showing that effective fluorine substitution for oxygen is not required for improvement of the cyclability of these layered oxides; a surface modification can be sufficient and can also have a huge impact.