The degradation of coated LiNi0.8Mn0.1Co0.1O2 (NMC811) cells with Silicon-Graphite (SiGr) composite anodes containing varying Si content is investigated using Differential Voltage Analysis (DVA), Incremental Capacity Analysis (ICA) and Distribution of Relaxation Times (DRT). ICA distinguishes Si from Gr specific degradation processes. It is observed an incomplete delithiation-related Si capacity loss in cells with 7 % and 11 % Si, which increases during early cycles and later stabilizes. Such behavior is not the reported permanent Si loss of active material, as the capacity of moderately and highly lithiated Si remains unchanged. Instead, a sudden rise in resistance at low states of charge is revealed. That is likely due to Si particle-particle contact loss during shrinkage, after particles are accommodated by a grown Solid Electrolyte Interphase (SEI) matrix and due to SEI cracks closure when particles contract. Data suggest a minimal threshold amount of Si may be necessary to trigger it, explained by Gr acting as electrical-contact keeper to Si particles. The proposed coupling of techniques made observable Si-driven effects in NMC811/SiGr cells, capacity fading primarily due to loss of lithium inventory and resistance increase dominated by the Si at lower voltages and by the NMC811 at medium and higher voltages.

Sodium-ion batteries (NIBs) have emerged as a promising alternative to lithium-ion batteries in many areas, including the mobility and grid-level storage sectors. They are now explicitly included in many technology–strategy roadmaps and are the subject of active research and development efforts around the globe. Current NIBs are enabled by three distinct chemical compositions, each of which has its own specific characteristics and, consequently, performance and economic considerations. This Review highlights the remaining scientific challenges for researchers and provides consumers with contemporary factual indicators to enable them to select the appropriate NIB for their needs. Sodium-ion batteries are emerging as a complementary technology to lithium-ion batteries, but are not yet ready for widespread practical adoption. This Review provides an overview of various sodium-ion chemistries with respect to key criteria, including sustainability, before discussing potential solutions, market prospects and future work.

The occurrence of an Internal Short-Circuit (ISC) in 18650 lithium-ion cells under thermal abuse conditions remains elusive. Equipped with Current Interrupt Devices (CID), the cell's voltage drop may introduce ambiguity, and potentially obscure the precise determination of an ISC. Therefore, comprehensive investigations were undertaken to rigorously explore the ISC and thermal runaway (TR) relationship. In this paper, and for the first time, a three-electrode 18650 lab-scale cell is tested in an Accelerated Rate Calorimeter (ARC) to analyze the potentials' variation under adiabatic conditions. Results have shown that the cell's voltage drop coincides with the positive potential drop (Ewe). Furthermore, tests on cells without CID have indicated that the accelerated TR is triggered following the massive ISC. Moreover, for a long time, the ISC has been associated with the melting of the separator. Hence, this study includes tests on identical lab-scale cells utilizing three types of separators: polyethylene, trilayer, and coated polypropylene. TR tests, conducted under adiabatic and ambient conditions, didn't reveal a significant impact of the separators. Given that the novel preliminary test developed in this study has demonstrated that the loss of their mechanical integrity happens at around the same temperature, the outcomes of the TR tests were comparable.

This paper focuses on the coupling of the Differential Voltage Analysis (dV/dQ vs Q) and the Distribution of Relaxation Times (DRT), whose benefits to electrodes development are illustrated by the tracking of degradation effects in the cycling aging of NMC811/Gr coin cells, with and without an NMC electrode coating. The former technique allows monitoring of individual electrode loss of active material (LAM), chemistry change and state of charge (SOC) alignment of the electrodes, whose variation is related mainly to loss of Li inventory (LLI). DRT is a time domain representation of the impedance that offers a high resolution of the resistance processes, complementing the DVA analysis by bringing kinetics degradation of the cells and by identifying in which electrode the main resistance processes are originated. The protocol inserting those techniques in an aging regime is a noninvasive approach, and it indicated the consumption of Li+ ions as the main reason for capacity decay in both cells, with reduced or minimal NMC LAM and chemistry change when coating is applied. From the perspective of power decay, the coating decelerated the impedance rise (IR), mostly related to resistance processes in the positive electrode.

An original synthesis route has been developed to optimize silicon's utility in replacing graphite as anode material in Li-ion batteries. This involves blending silicon with aluminum to enhance its conductivity. The silicon-aluminum is codeposited on a nanoporous titanium dioxide nanotube matrix, which serves as an active current collector, thereby eliminating the need for inactive binders and ensuring robust mechanical stability during cycling. The nanostructured negative electrode is fabricated through two electrochemical synthesis steps: first, the anodization of a titanium foil, followed by the coelectrodeposition of silicon and aluminum using a room temperature ionic liquid electrolyte. This coelectrodeposition enables the in situ integration of aluminum into the silicon deposit. The resulting Si-Al/TiO2 nanotube nanocomposite anode exhibits improved cyclic stability and enhanced rate capability. The observed enhancement in battery electrochemical performance underscores the significance of this electrochemical process in fabricating such nanostructured silicon negative composite electrodes.

Inhomogeneity in Li -ion cells leads to an underutilization of its energy and non -uniform degradation. In our previous work, the proof of concept was established for a setup with 4 tiny Varta cells connected in parallel, enabling to decouple the effect of the two parameters influencing inhomogeneous behavior. This is to mimic the thermal and potential gradients occurring in large -format commercial Li -ion cells. To represent the thermal gradient, the cells are placed at different temperature and is called T-dep setup; to represent the potential gradient, the cells have different shunt resistors connected in series to each of the tiny cells in the setup and is called Vdep setup. In this work, the above setup is used to perform long-term accelerated cycling tests (about 1100 cycles under 100 % Depth of Discharge, DOD) and their State of Health (SOH) is analyzed at periodic intervals. Two different degradation phenomena are primarily observed, namely reduction and oxidation of the solvent occurring at negative and positive electrodes, respectively. The solvent reduction results in a continuous growth of a passivation layer called Solid Electrolyte Interface (SEI). The coupled electrochemical model, from our previous work, is integrated to an aging model in this work. The model is parameterized using preliminary cycle aging data performed on individual pristine cells. The model captures the experimentally observed cell capacity fade trends, in both setups, quite well. A comparison of the cell interfacial resistance increase reveals that the model captures the experimental behavior quite well until about 400 cycles and underestimates after this point. Using this validated model, a comparison of capacity fade and impedance increase, of cells in setup and individually cycled cells, reveals that the setup conditions do not necessarily aggravate the inhomogeneous aging. Further analyses show that there is a reversal of cell utilization upon cycling, meaning degradation of less aged cells seems to accelerate compared to their more aged counterparts. Additional simulation analyses under narrow DOD cycling indicate that overall setup degradation rate increases but the inhomogeneity is not aggravated compared to individually cycled cells. All in all, V-dep setup aging results only in a reduced driving mileage while T-dep setup aging results in both reduced driving mileage and acceleration/deceleration capability.

First critical review paper on LIBs direct recycling strategies, covering a broader scope with the positive electrode, negative electrode, and electrolyte, while discussing the substantial challenges to their effective implementation.

This study explores a novel solvent-based delamination method that employs a mixture of triethyl phosphate (TEP), acetone, and carbon dioxide (CO2) under pressure and temperature for the efficient and fast direct recycling of positive electrode production scraps. Optimization of experimental conditions led to achieve 100% of delamination within 15 min at 120 degrees C and 100 bar, with a low solvent consumption of 1.5 of TEP to electrode ratio (w/w). The CO2 allows decreasing the viscosity of the TEP and acetone mixture and so increasing its diffusivity; favoring the binder dissolution and accelerating the delamination process versus other reported processes. This original approach not only enables the reduction of solvent consumption (by 6.7x), but removes the need for stirring, which is often detrimental to solvent-based approaches for scaling up the process while maintaining 100% of delamination. Subsequent to the delamination process, the active material LiNi0.6Mn0.2Co0.2O2 (NMC622) in powder form was easily and fully separated from the current collector, enabling a comprehensive characterization. A more in-depth focus on the electrochemically active material revealed that its chemical composition, crystal structure, and microstructure remained preserved throughout the recycling process. Ultimately, the electrochemical performance of the recycled NMC622 closely resembled that of the pristine NMC622, affirming the promising potential of this approach.

The development of batteries has become a major challenge and requires new operando techniques for tracking reaction kinetics in battery electrodes during operation. Taking Na3V2(PO4)(2)F-3 and LiFePO4 as examples of positive electrode materials, the present work deals with the design of an operando technique to measure the ionic and electronic transport properties of battery electrodes during polarization. In the case of LiFePO4, large electronic resistance changes were revealed when crossing the solid-solution domains. Such resistance changes are consistent with thermodynamic models proposing the existence of a diffuse phase boundary between Li-poor and Li-rich domains, as a result of the non-linear variation of the chemical potential of the LFP particles, which in turn leads to restricted lithium diffusion. Concerning Na3V2(PO4)(2)F-3, the important variations of electronic resistance measured were correlated with different phase changes and superstructures formed during the insertion-disinsertion of Na+ ions, as well as the polarization and entropy heat variations. These results are fully consistent with a substantial correlation of structural changes with transport properties and reaction kinetics, and thus, performances. More generally, this technique shows great promise as a tool to aid in designing battery electrodes with improved ionic and electronic percolations.

Exploring hybridization of Bi 2 S 3 nanorods with hard carbon substrate for sodium-ion batteries revealed enhanced performance with MPA modification, elucidating charge storage mechanisms and transformation dynamics, advancing battery electrode design.

The tetragonal ordered form of BaSnF4 is of particular interest, as its ionic conductivity is high enough to enable its uses as an electrolyte in all-solid-state fluoride-ion batteries. Despite several studies related to its synthesis, structure, and fluoride-ion diffusion mechanism, reported routes often yield impurities as well as unexplained variation in the unit-cell c-axis length. Here, we report on the single-phase synthesis of t-BaSnF4 via spark plasma sintering, a method that could be used to prepare bulk-type all-solid-state inorganic batteries in one step. By optimizing different parameters (temperature, setup features, etc.), we reached a high ionic conductivity of 5 x 10(-3) Scm(-1) at 30 degrees C. In addition, we show that two main factors affect the ionic conductivity. First, on a microstructural scale, the preferential growth of crystallites along the c-axis results in a decrease of the ionic conductivity of resulting powders because of the two-dimensional (2D) fluoride-ion diffusion in this material. Second, on the atomic scale, the increase of the unit-cell c-axis length is concomitant with a decrease of the ionic conductivity. A combined neutron diffraction and F-19 solid-state magic angle spinning (MAS) NMR study reveals that the observed increase of the unit-cell c-axis length is due to the partial occupancy of octahedral interstitial sites. NMR allows us to identify these interstitial sites (the F4 site) with distinct isotropic chemical shift values. Furthermore, variable-temperature F-19 solid-state MAS NMR reveals that these F4-ions do not exchange with fluoride-ions (F1 and F3) that are responsible for the transport properties. Hence, the occupancy of these interstitial sites tends to lower the 2D fluoride-ion conductivity, and the unit-cell c-axis length can be used as a guideline to ensure the preparation of highly conductive samples provided that the microstructure is controlled. Overall, this study provides a novel route to prepare pure t-BaSnF4 while establishing a better understanding of the factors affecting its transport properties.

We studied the electrochemical lithium intercalation in LiOHFeS. After a first irreversible reaction the resulting new material reversibly cycles one lithium atom involving the Fe3+/Fe2+ redox couple: Li2FeOS ↔ Li+ + e− + LiFeOS.

The demand for high energy density Li-ion batteries requires electrode materials with high capacity and long cycling stability. Silicon is among the most promising negative electrode materials due to its high theoretical capacity, abundant resources, and low working potential. However, its poor conductivity and significant volume expansion during cycling limit its practical application. To overcome these issues, this study develops a two-step synthesis method for a nanostructured composite based on silicon as the active material. First, a crumbled Ti3C2Tx (c-Ti3C2Tx) structure formed through electrostatic interaction between a Ti3C2Tx suspension and 1 M KOH. Then, an amorphous silicon layer is electrodeposited onto the c-Ti3C2Tx flakes in a room-temperature ionic liquid, creating the Si/c-Ti3C2Tx composite for the negative electrode of Li-ion batteries. The c-Ti3C2Tx structure enhances conductivity, provides mechanical stability to accommodate silicon's expansion, and offers nanostructured porosity for lithium-ion diffusion. The composite material demonstrates exceptional cycling stability, achieving a capacity of 1300 mAh g(-1) at C/5 with 91 % capacity retention after 100 cycles.

Utilizing nanostructures of Li-alloying anode materials (e.g., Si, Ge, Sn, etc.) has been proposed as a key strategy to improve the electrochemical performance. However, the main challenge lies in the costly and complex nanostructure synthesis processes. Notably, the nanostructure growth processes are mainly supported by Li-inactive templates, which later need to be removed, and the template removal process results in the destruction of the desired nanostructures. In this report, we demonstrated the use of a Li-active, self-organized TiO2 nanotube template to fabricate germanium (Ge)-based nanostructured anodes. This has been achieved as follows: first, TiO2 nanotubes are fabricated via electrochemical anodization of titanium foil. Then, the nanotubes are coated with a Ge film in the second step via electrodeposition. Besides the effective nanostructure growth using a Li-active template, the implemented electrochemical synthesis methods are cost-effective, accessible, and scalable. Furthermore, the electrochemical methods allow the fabrication of nanostructures with well-controlled structures, morphology, and compositions. Accordingly, a Ge-coated TiO2 nanotube (Ge@TiO2) nanocomposite anode has been successfully fabricated, and its electrochemical performance has been tested for Li-ion batteries. The study has shown the important roles of TiO2 nanotube arrays in improving the performance by providing strong mechanical support to buffer the volume expansion and offering a high surface area to enhance Ge-active mass loading. Moreover, the direct contact of the nanotubes with a Ti current collector facilitates one-dimensional (1D) electron transport and avoids the need of adding inactive binders or conductive additives.

The battery field has recently received unprecedented attention and investments in order to handle the upcoming demands of energy storage notably from the electric mobility sector. The pursuit of higher performance batteries that store more energy, charge faster and have a longer life cycle has been converted into studies for new electrode materials, coatings, electrolytes, among others that often find the common key challenge of the performance decline. The precise identification of the degradation mechanisms and their tracking along aging is thus essential to pave the way for the next generation batteries. For that several methods are employed although most of them are not in operando, not following the practical cell operation. In that context, this paper introduces a set of operando electrochemical techniques that are still largely underexploited but that can be coupled and offer broader comprehension of the degradation mechanisms through deeper than usual analysis of electrochemical data. Taking insertion cells (like Li ion or Na ion batteries) as example it is first shown how differential techniques like incremental capacity analysis (ICA or dQ/dV vs V) and differential voltage analysis (DVA or dV/dQ vs Q) allow to identify main degradation mechanisms in the positive and in the negative electrodes separately by following their active material masses and their curves dynamics (relative displacement of the potential x capacity curves, the slippage) in a two electrodes configuration. For that the in house and free access developed software Electrochemical Visualization Application (EVA) is employed. In addition, using defined protocols, other techniques as Distribution of Relaxation Times (DRT) are coupled to those first analyses in order to complement the understanding of the degradation mechanisms in each electrode. This presentation intends to show an introduction of how to deeper analyze electrochemical techniques to follow loss of mass and lithium ion inventory from each electrode along aging, how to use the DRT with the ICA and DVA to identify the evolution of Impedance from each electrode along aging and how to build protocols that allow to couple those techniques minimizing any eventual degradation interference from those techniques, that all shown through experimental results and with the aid of a free and open software for the part of the ICA and DVA analyses. Figure 1

To meet the expected performance requirements of lithium-ion batteries (LIBs), novel electrode materials, coatings and electrolytes have been studied in terms of their degradation mechanisms. Nevertheless, most of the methods used to track these mechanisms are not in operando, i.e., they do not follow them upon the practical LIB cell operation. The differential voltage analysis (DVA) and the incremental capacity analysis (ICA) constitute in operando techniques that can greatly help in monitoring batteries degradation mechanisms. We report here an in house developed software that allows the visualization of the DVA and the ICA curves of tested cells, with the possibility of rebuilding an experimental full-cell capacity vs. potential curve through fitting of its electrodes' half-cell capacity vs. potential curves. Those features can be applied to multiple charge-discharge cycles without data pretreatment, offering data exportation. We illustrate the functionalities of our software and indicate perspectives for its further development.

Correlating the input/output parameters of the manufacturing process aims to understand the link between the different steps of the Lithium-Ion Battery (LiB) electrode-making process. Fostering the interrelation of the properties in silicon/graphite blends for fabricating negative electrodes benefits the comprehension, quantification, and prediction of LiB output properties. Here, we report the impact of the manufacturing parameters during mixing, coating, and calendering on the properties of silicon/graphite blend negative electrodes. The mixing process was evaluated depending on the graphite content, where the viscosity increases with its percentage. Moreover, the slurry rheology directly impacts the electrode stability when the coating is done by using broader comma gaps. The calendering step evidences a porosity threshold necessary for adequate ionic resistance, tortuosity factor, and cycling life. Strong calendering increased the current collector adhesion, ionic resistance, tortuosity factor, and high cycling instability. On the other hand, better cyclabilities are obtained at moderate calendered electrodes, exhibiting the lowest ionic resistances and tortuosity factors.