Sylvie Grugeon

Sodium-ion batteries are emerging as supplementary technology to lithium-ion batteries. This study focuses on investigating the thermal stability of Na3V2(PO4)2F3 (NVPF) || hard carbon (HC) sodium-ion cells through the lens of Solid Electrolyte Interphase. Differential Scanning Calorimetry demonstrated a clear increase in SEI stability formed with improved electrolyte formulations (NaFSI and additives). At cell level, Accelerating Rate Calorimetric tests were performed on pristine versus aged batteries. Ramp heating analysis revealed consistent thermal behavior, with SEI degradation initiating near 155 °C and thermal runaway (TR) triggering around 210 °C in both pristine and aged batteries. However, Heat Wait Search analysis on aged cells exhibited less severe TR compared to pristine batteries. The higher onset temperature observed in aged batteries was attributed to enhanced thermal stability of the re-formed SEI, while the reduced thermal severity was proven to be unlinked to the lower energy density.

We investigated the surprising ionic conductivity trend of a series of hybrid complexes based on lithium iodide (LiI) associated with different size of crown ethers. Through a combination of experimental and theoretical methods, LiI hybrid complexes were characterized to rationalize the unexpected tendency of ionic conductivity. Our findings revealed that the solvation structure of the lithium iodide (LiI) complex of crown ethers is influenced by the size of the crown ether. Consequently, the solvation structure of the complex affects the transport properties. Notably, we observed a unique sandwich-like complex is formed between two 12C4 molecules and the Li cation during classical NVT molecular dynamics (MD) simulation, which is rarely observed with larger crown ethers. Based on this observation, we postulate that the idiosyncratic structure of [Li ⊂ 12C4][I] increases the ratio of SSIP solvation structure, ultimately resulting in higher ionic conductivity compared to [Li ⊂ 15C5][I], despite 15C5 is a larger crown ether than 12C4. We also propose a hypothesis, based on the MD simulation, that adjusting the size of crown ether molecules can potentially enhance the transference number.

Solvent‐free (SF) manufacturing of lithium‐ion battery (LIB) electrodes is safer and more environmentally friendly than the traditional slurry casting approach. However, as a young technique, SF manufacturing is under development of its pathways and operation conditions. In different SF processes reported in literature, extrusion is a common step. A detailed model of this process would be extremely computationally demanding. This work proposes a novel simplified discrete element model at the mesoscopic scale for the extrusion during SF manufacturing of LIB electrodes. In addition to active material particles, we consider fluid‐like solid particles to approximate the molten polymer and the carbon additive phases. The formulation and other process parameters are taken from our experimental facility that uses extrusion to fabricate filaments for 3D printing of LIB cells. The extrusion is carried out in a conical twin screw extruder. Our approach allows to obtain representative electrode microstructures after extrusion, where electrical conductivity, ionic effective diffusivity, tortuosity factor and porosity are calculated. The model is a proof of concept that is employed to investigate the influence of the extruder speed and the cohesion level on the resulting electrode properties.

This paper provides a holistic view of the different studies related to gassing in NMC/graphite lithium-ion batteries over the past couple of decades of scientific development. It underlines the difficulty of predicting the concentration and the proportion of gas released upon cycling and storage and to get a clear mechanistic insight into the reduction and oxidation pathways of electrolyte solvents, the thermal electrolyte degradation, as well as the reactions that involve secondary sources such as water, NMC surface species and cross-talk reactions. Though many relevant experiments such as operando gas analysis using isotope-labeled solvents or two-compartment cells have been conducted, they failed, for instance, to determine the exact mechanism leading to the generation of CO and CO₂ gas. Last but not least, this paper discusses different strategies that are currently proposed to reduce or eliminate gassing such as the use of electrolyte additives that enable singlet oxygen quenching or scavenging, NMC coatings that limit the contact with electrolyte and different lithium salts to prevent thermal electrolyte degradation.

Additive manufacturing, also called 3D printing, has the potential to enable the development of flexible, wearable and customizable batteries of any shape, maximizing energy storage while also reducing dead-weight and volume. In this work, for the first time, three-dimensional complex electrode structures of high-energy density LiNi_1/3Mn_1/3Co_1/3O₂(NMC 111) material are developed by means of a vat photopolymerization (VPP) process combined with an innovative precursor approach. This innovative approach involves the solubilization of metal precursor salts into a UV-photopolymerizable resin, so that detrimental light scattering and increased viscosity are minimized, followed by the in-situ synthesis of NMC 111 during thermal post-processing of the printed item. The absence of solid particles within the initial resin allows the production of smaller printed features that are crucial for 3D battery design. The formulation of the UV-photopolymerizable composite resin and 3D printing of complex structures, followed by an optimization of the thermal post-processing yielding NMC 111 is thoroughly described in this study. Based on these results, this work addresses one of the key aspects for 3D printed batteries via a precursor approach: the need for a compromise between electrochemical and mechanical performance in order to obtain fully functional 3D printed electrodes. In addition, it discusses the gaps that limit the multi-material 3D printing of batteries via the VPP process.

With the aim of establishing a data simultaneous comparison, the Principal Component Analysis (PCA) statistical tool was applied to LiNi _0.6 Mn _0.2 Co _0.2 O ₂ /graphite Li-ion cells electrolyte’s decomposition products detected by UHPLC-ESI-HRMS. Herein, we illustrate how the chemometric tool associated with mass spectrometry data can be relevant to provide information about the presence of unusual molecules. Indeed, pristine Triton X-100 surfactant molecules used in the electrode elaboration process were detected after the impregnation stage. However, as they chemically react and oxidize at a potential lower than 4.5 V vs Li/Li ⁺ , only surfactant derivatives and classical ageing molecules were observed, respectively, after storage and cycling stages at 55 °C, leading to a triangle-type correlation circle. On the other hand, global schemes of LiPF ₆ -based electrolyte degradation pathways were elaborated from a comparative study with literature to help interpret results in future electrolyte ageing studies.

In this paper, the development of an environmentally-friendly lithium-terephtalate/polylactic acid (Li₂TP/PLA) composite filament, for its use, once 3D-printed via Fused Deposition Modeling (FDM), as negative electrode of a lithium-ion battery is reported. Solvent-free formulation of the 3D-printable filament is achieved through the direct introduction of synthesized Li₂TP particles and PLA polymer powder within an extruder. Printability is improved through the incorporation of poly(ethylene glycol) dimethyl ether average M_n∼500 (PEGDME500) as plasticizer, while electrical performances are enhanced through the introduction of carbon black (CB). Thermal, electrical, morphological, electrochemical and printability characteristics are discussed thoroughly. By taking advantage of the 3D-printing slicer software capabilities, an innovative route is proposed to improve the liquid electrolyte impregnation within the 3D-printed electrodes.

A reliable heating device coupled with a FTIR gas analyzer has been tailored with the aim of evaluating the role of state-of-the-art lithium-ion battery components and environmental conditions on thermal and toxic hazards. Here, we demonstrate its effectiveness in accurately assessing the role of fully charged 0.6 Ah pouch cells confinement, electrolyte composition and separator coating on heat release and toxic gas generation-related risks. The fire safety international standards developed by the ISO TC92 SC3 subcommittee were used to determine the asphyxiant and irritant gases toxicity. Cells tighting confinement proves to be a very efficient way to diminish and delay (from 180 to 245 °C) the thermal runaway phenomenon occurrence and relating toxic gas release. Vinylene carbonate as electrolyte additive is able to shift (+20 °C) the onset temperature, while substitution of 1/3 M LiPF₆ by LiFSI does not modify the thermal behavior, nor the toxic risks. The coating of a tri-layer separator influences the irritant gas toxicity related risk, by decreasing fluorinated components release. This study highlights that some improvements regarding LIB safety can be achieved through appropriate component selection and cells integration design at a module/pack level.