The increasing demand for lithium-ion batteries (LIBs), primarily driven by the expanding electric vehicle market and the growing need for efficient energy storage, presents both significant opportunities and challenges. The efficient and cost-effective regeneration of spent LIBs is crucial to minimizing environmental impact and fostering a true circular economy for battery materials. Herein, an innovative one-step lithiation process is introduced for spent LiFePO4 cathodes, conducted in aqueous solution under ambient conditions. This method utilizes readily available and low-cost reagents, including a lithium source and ascorbic acid (vitamin C) as a green reducing agent, offering a substantial advantage over traditional techniques that require harsh conditions and complex setups. The lithiation reaction proceeds rapidly, producing pure and fully regenerated LFP. This environmentally friendly process was successfully demonstrated at the scale of 18650 cells with electrodes composed entirely of recycled LFP. These cells exhibit excellent electrochemical performance, even after 1000 cycles at 1C rate, comparable to those made with pristine LFP. By providing a sustainable, cost-effective, and easily scalable solution for LFP cathode regeneration, the approach supports the closure of the materials loop, contributing to the sustainable management of LIBs and advancing the shift toward a circular economy.

The lithium-ion batteries (LIBs) industry has expanded quickly despite technological constraints. Additionally, raw materials supply, end-of-life (EoL) management, and the creation of LIB manufacturing policies are receiving attention. All these concerns could be addressed simultaneously by integrating recycling of EoL cells from the early stages of the LIB manufacturing. This article presents perspectives on how to achieve this holistic integration through the means of digitalization. Various challenges of LIB recycling, and different digitalization tools are discussed, shedding light on the latter's potential applications and outcomes. Through the use of the discussed tools to create advanced Digital Twins, it would be possible to screen different recycling processing conditions and materials to achieve higher efficiency, increased safety, at a lower cost. In this regard digitalization of the recycling process for LIB cells, emerges as the key for achieving a collaborative, sustainable, and efficient battery value chain in the European Union. Lastly, in the view of the growing LIB market, this article is thought to be of interest for recycling stakeholders as they move towards a more circular economy model.

To date, the generation of natural hydrogen (H 2 ) from the alteration of Fe II ‐bearing minerals has mainly been studied through serpentinization in (ultra)mafic rocks. This study explores Banded Iron Formations (BIF), which are rich in Fe II minerals, as a potential source for H 2 . We conducted a hydrothermal experiment at 200°C with a combined magnetite‐siderite assemblage, two major components of BIF. The experiment, designed with a high water‐to‐rock ratio and a gas phase (W‐R = 300) enabled to assess mineral transformations during the alteration. Thermodynamic simulations were finally conducted, to explore H 2 ‐generating yields in more realistic geological scenarios (no gas phase, lower W‐R). Our experimental findings show that H 2 is produced through complete siderite dissolution and magnetite precipitation. Concomitantly, non‐stoichiometric primary magnetite (Fe II /Fe III < 0.5) did not enhance H 2 yield; instead, it acted as a sink for dissolved Fe 2+ , sequestrating about 10% of the iron from siderite without oxidation to recover a more ideal stoichiometry. This suggests that abundant, non‐stoichiometric magnetite in natural settings may reduce H 2 generation yields. Mass balance calculations indicate that 83% of the expected H 2 generated was unaccounted for, consistent with suspected CO 2 reduction and formation of dissolved organic compounds in the fluids. Thermodynamic simulations at varying W‐R ratios (from 300 to 1) reveal that H 2 yield ranges widely (39 mmol–73 μmol H 2 per kg of siderite), since lower W‐R prevent from siderite dissolution and enhance H 2 consumption via carbon reduction. These findings imply that low W‐R ratios in BIF ‐and other siderite‐bearing lithologies, may limit H 2 resources.

With the rise of electric mobility, the growing demand for batteries is expected to generate a significant stock of end-of-life batteries, making recycling an interesting solution to reduce environmental impact. Here, we propose a direct regeneration process in two steps based on a hydrothermal relithiation and post-annealing at moderate temperature. Two NMC-materials went through chemical delithiation and subsequent relithiation: NMC from scrap, which is recovered with the conductive carbon from its original formulation and reference NMC for comparison. The results demonstrate that relithiation was effective during the first solution step, leading to a partially active material. The post-annealing treatment enhances electrochemical performances and the best ones are obtained for the samples annealed at 400 °C. Therefore, the results confirm that the presence of residual carbon does not impact relithiation or compromise its efficiency. The latter conserves its conductive properties after the relithiation process. However, an amount of the carbon has been lost during the second step; then this loss was compensated with an addition of fresh carbon, providing satisfactory electrochemical performances.

The demand for lithium-ion batteries (LIBs) has surged in recent years, driven by the rapid growth of electric vehicles (EVs) and emerging energy storage technologies. Yet, this surge in demand has also resulted from a significant increase in the number of spent batteries. Given the potential for environment pollution wastage, it is absolutely crucial to prioritize the recovery and recycling of these used lithium-ion batteries. The common techniques employed in large-scale industrial settings for battery recycling are pyrometallurgy and hydrometallurgy. These are pivotal multi-step processes, particularly suitable for materials containing Cobalt (Co) and Nickel (Ni), such as NMC (LiNi x Mn y Co z O 2 ). Aside from NMC, there has been a surge in the adoption of LFP (LiFePO 4 ) as a cathode material target for lithium-ion batteries in electric vehicles worldwide over the past few decades. However, these established industrial recycling methods are not applicable to LFP due to the comparatively lower value of iron. This necessitates the pursuit of direct recycling approaches. In order to accomplish this goal, direct recycling stands out as the most suitable technique for regenerating spent batteries 1 . Unlike processes involving solution-based or high-temperature steps that entail potentially wasteful steps, this approach aims to reduce energy consumption and costs, all while maintaining environmental integrity through a judicious utilization of resources, materials, and energy. Consequently, our attention is directed towards this specific LFP material, prompting us to detail a direct recycling procedure for spent LFP cathodes via a chemical lithiation process at room temperature in a solution containing lithium iodide (LiI) and various solvents 2 (Fig. 1). References: (1) Y. Jin, T. Zhang, M. Zhang, Advances in intelligent regeneration of cathode materials for sustainable lithium-ion batteries, Adv. Energy Mater. 12 (2022), 2201526. (2) Ouaneche, T. et al. Room temperature efficient regeneration of spent LiFePO 4 by direct chemical lithiation. 579 , J. Power Sources (2023) 233248. Figure 1

The exponential production of lithium-ion batteries for electric vehicles (EVs) and electronic applications leads to the creation of a huge stock of batteries at the end of life. Considering the current economic, geopolitical and environmental context, the recycling of these spent batteries is becoming an urgent need in order to mitigate environmental pollution and limit the waste of valuable and critical resources 1 . In this work, we report a rewarding direct recycling process of spent LiFePO 4 cathode material by direct chemical lithiation in solution 2 . After safe opening of the spent commercial battery, a structural, morphological, spectroscopic and electrochemical characterization of the spent LFP cathode was carried out to identify the reason(s) of battery failure. The results obtained by XRD (Fig 1a) and Mössbauer spectroscopy (Fig 1b) show that the loss of lithium in the cathode (up to 50%) consumed during formation and growth of the SEI during cycling, is the major reason of the end of life of these batteries, in total agreement with the literature 3 . To address the lithium shortage problem, a recycling process via direct chemical lithiation in organic solution at room temperature of the LFP cathode has been implemented. Lithium iodide (LiI) dissolved in several solvents such as acetonitrile, cyclohexane, ethanol, DMSO, methanol and propan-1,2-diol was used as both the reductant and the lithiation agent. The best results were obtained with the cathode regenerated in ethanol, which is also the most captivating and environmentally friendly solvent. The different characterizations of this regenerated cathode allow evaluating the efficiency of the regeneration process. Mössbauer spectroscopy (Fig. 2a) confirms the total reduction of Fe III PO 4 to LiFe II PO 4 , while electrochemical characterization (Fig. 2b) shows encouraging properties with a reversible capacity of ~168 mAh/g for the regenerated LFP. References: (1) Neumann, J. et al. Recycling of Lithium‐Ion Batteries—Current State of the Art, Circular Economy, and Next Generation Recycling . Adv. Energy Mater. 12 , 2102917 (2022). (2) Ouaneche, T. et al. Room temperature efficient regeneration of spent LiFePO 4 by direct chemical lithiation. 579 , J. Power Sources (2023) 233248. (3) Zhou, S. et al. Direct recovery of scrapped LiFePO 4 by a green and low-cost electrochemical re-lithiation method. Green Chem. 24 , 6278–6286 (2022). Figure 1 : a) XRD pattern and b) Mössbauer spectrum of the recovered Li x FePO 4 powder. Figure 2 : a) Mössbauer spectrum and b) Charge-discharge galvanostatic curve at C/10 of the regenerated LFP cathode as positive electrode vs . Li + /Li 0 and its derivative curve. Figure 1

The lithiation reaction holds immense significance across various branches of chemistry, particularly in the realm of electrochemical energy storage. Here, we report a new method that enables a solvent-free process at room temperature, exhibiting remarkably swift reaction kinetics. Through this process, the chemical integration of Li+ into charged materials based on transition metals is achieved using lithium iodide, LiI. An evident application of this method lies in advancing the direct recycling of cathode materials reclaimed from spent batteries. Notably, the process facilitates the efficient and direct recycling of spent Li(1-x)FePO4 cathode material, sourced from a commercial LIB, without the need for any solvents or heat treatments. The regenerated material exhibits a fully reversible capacity of approximately 168 mAh/g against Li metal, even under high current density conditions, with a consistently stable coulombic efficiency surpassing 99% over 45 cycles. This regenerative approach holds the potential for seamless extension to other LIB cathode materials, including but not limited to LMFP, LMO, LCO and NMC.

Sodium-ion batteries continue to rise in the energy storage landscape, their increasing adoption being driven by factors such as cost-effectiveness and sustainability. As a consequence, there is a growing emphasis on the development of new electrode materials. Among these, olivine phosphates emerge as a promising family of cathode materials. However, viable synthesis routes are still lacking. In this study, cathode materials of olivine NaMn1-xFexPO4 (x=0.34 and 1) were prepared by directly sodiating Mn1-xFexPO4 through a solid-state process at 300 degrees C. X-ray diffraction, Mossbauer spectroscopy and electrochemical measurements were employed to study their structural and electrochemical features. NaMn0.66Fe0.34PO4 exhibits two pseudo-plateaus profile with an average potential of similar to 3.2 V vs. Na+/Na-0 with a reversible capacity reaching 75 mAh/g at C/20 via a monophasic (de)intercalation mechanism. In parallel, the intermediate composition Na0.5Mn0.66Fe0.34PO4 could be prepared via the solid-state reaction of NaMn0.66Fe0.34PO4 and Mn0.66Fe0.34PO4. Such a solvent-free sodiation process not only provides a simplified preparation of NMFP, but also offers easy scalability compared to the more laborious electrochemical sodiation route, making it an interesting prospect for future industrialization. Finally, this research confirms that the olivine NMFP is indeed an attractive candidate as a cathode material for SIBs.

Mn(II)-oxidizing organisms promote the biomineralization of manganese oxides with specific textures, under ambient conditions. Controlling the phases formed and their texture on a larger scale may offer environmentally relevant routes to manganese oxide synthesis, with potential technological applications, for example, for energy storage. In the present study, we sought to use biofilms to promote the formation of electroactive minerals and to control the texture of these biominerals down to the electrode scale (i.e., cm scale). We used the bacterium Pseudomonas putida strain MnB1 which can produce manganese oxide in a biofilm. We characterized the biofilm–mineral assembly using a combination of electron microscopy, synchrotron-based X-ray absorption spectroscopy, X-ray diffraction, thermogravimetric analysis and electron paramagnetic resonance spectroscopy. Under optimized conditions of biofilm growth on the surface of current collectors, mineralogical characterizations revealed the formation of several minerals including a slightly crystalline MnOx birnessite. Electrochemical measurements in a half-cell against Li(0) revealed the electrochemical signature of the Mn4+/Mn3+ redox couple indicating the electroactivity of the biomineralized biofilm without any post-synthesis chemical, physical or thermal treatment. These results provide a better understanding of the properties of biomineralized biofilms and their possible use in designing new routes for one-pot electrode synthesis.

Herein, we report a direct recycling process of the spent LiFePO4 by direct room temperature chemical lithiation. A fine characterization of a recovered LFP cathode from a spent commercial battery demonstrates that the end of life of the battery is mainly due to the lithium loss, while the structure of the LFP cathode material is globally preserved. It is shown here that such a cathode can be efficiently recovered by direct lithiation in solution using LiI in different solvents (acetonitrile, ethanol, cyclohexane, methanol, DMSO and propan-1,2-ol) with optimized experimental parameters. The best electrochemical performance is obtained with ethanol, one of the greenest and cheapest solvents, without any additional heat treatment. More interestingly, the regeneration of LFP can be achieved directly with the material cast onto its aluminum collector, which paves the way to more efficient recycling preserving the whole electrode formulation and avoiding a new electrode casting. The chemically lithiated LFP cathode in ethanol exhibits a full reversible capacity of ∼168 mAh/g vs. Li metal with a stable coulombic efficiency exceeding 98% for 25 cycles. In addition, this recovery process produces regenerated electrodes showing good electrochemical performance also at high current density.

Nanoparticles produced by bacteria, fungi, or plants generally have physicochemical properties such as size, shape, crystalline structure, magnetic properties, and stability which are difficult to obtain by chemical synthesis. For instance, Mn(II)-oxidizing organisms promote the biomineralization of manganese oxides with specific textures under ambient conditions. Controlling their crystallinity and texture may offer environmentally relevant routes of Mn oxide synthesis with potential technological applications, e.g., for energy storage. However, whereas the electrochemical activity of synthetic (abiotic) Mn oxides has been extensively studied, the electroactivity of Mn biominerals has been seldom investigated yet. Here we evaluated the electroactivity of biologically induced biominerals produced by the Mn(II)-oxidizer bacteria Pseudomonas putida strain MnB1. For this purpose, we explored the mechanisms of Mn biomineralization, including the kinetics of Mn(II) oxidation, under different conditions. Manganese speciation, biomineral structure, and texture as well as organic matter content were determined by a combination of X-ray diffraction, electron and X-ray microscopies, and thermogravimetric analyses coupled to mass spectrometry. Our results evidence the formation of an organic-inorganic composite material and a competition between the enzymatic (biotic) oxidation of Mn(II) to Mn(IV) yielding MnO2 birnessite and the abiotic formation of Mn(III), of which the ratio depends on oxygenation levels and activity of the bacteria. We reveal that a subtle control over the conditions of the microbial environment orients the birnessite to Mn(III)-phases ratio and the porosity of the assembly, which both strongly impact the bulk electroactivity of the composite biomineral. The electrochemical properties were tested in lithium battery configuration and exhibit very appealing performances (voltage, capacity, reversibility, and power capability), thanks to the specific texture resulting from the microbially driven synthesis route. Given that such electroactive Mn biominerals are widespread in the environment, our study opens an alternative route for the synthesis of performing electrode materials under environment-friendly conditions.

44 Single-phase maricite, NaFePO4, was synthesized from monosodium phosphate and 45 iron oxalate at 750°C, at atmospheric pressure. Thermal treatment of synthetic maricite in air 46 indicated oxidative decomposition into Na3Fe 3+ 2(PO4)3 nasicon and-Fe2O3 at temperatures 47 above 225°C. Intergrowth of the reaction products is found to occur at the nanoscale without 48 identified crystallographic relationship with the maricite precursor. Electrochemical activity of 49 the reaction product is confirmed with the reversible insertion of one Na at 2.55 V vs Na + /Na 0. 50 Keywords: sodium iron phosphate; maricite; sodium-ion batteries; oxidative decomposition; 51 NASICON 52 53 54

The last decades LiFePO4 (triphylite) has been extensively studied due to interesting electrochemical properties that make it an attractive positive electrode candidate for Li-ion batteries. LiFePO4 used as a cathode material exhibits a high retention in cycling, a structural stability of the delithiated phase FePO4 and a low cost of its components. Recent developments show the possibility of significantly increasing power densities. However, the LiFePO4 nanoparticles show significant amounts of structural defects according to the synthetic route used. For instance, the presence of Fe and vacancies in Li crystallographic sites (Pnma space group) has a significant effect on electrochemical behavior by hindering cation diffusion. LiFePO4 also has a high reactivity to O2 at moderate temperatures (300-500°C depending on the size) leading to the gradual diffusion of Fe from the core to the surface of the material accompanied by the formation of Fe2O3 nanoparticles. Therefore, the composition material LixFeyPO4 exhibits very high degree of crystalline defects. These transformations were evidenced by X-ray diffraction and electron diffraction at different temperatures. These olivine compounds outside stoichiometry have an order of defects leading to the formation of a superstructure. However, in order to get a better insight into the mechanisms related to these transformations, in situ investigation in a real-time is necessary. Environmental ETEM, in which a pression of O2 can be injected, coupled with a heating holder is a perfect characterization platform to monitor oxidation reactivity of LiFePO4 up to 700°C. This project focuses on the study of the structural mechanisms associated with the temperature reactivity of LiFePO4 under an oxidizing atmosphere using environmental TEM (TITAN). The aim is to quantify the kinetics of FeyOx nanoparticle formation, and the appearance of superstructures induced by Fe diffusion from the core to the surface of the material.

A novel layered Na3V(PO4)2 compound was synthesized and studied as a positive electrode material for Na-ion batteries for the first time. The as-prepared material exhibits two relatively high voltage plateaus at around 3.6 and 4.0 V vs Na+/Na. Operando X-ray diffraction investigation provides insight into the mechanisms of structural transformations upon cycling.

The effect of acidic conditions (in a pH range of 3 to 6) and temperature on the kinetics of the hydrothermal oxidation of ferrous iron contained in BOF steel slag has been tested in the 150 – 350°C range for acid acetic concentrations from 0 to 4M. Reaction progress was monitored with the amount of produced H2. Higher temperature and lower pH are found to enhance the hydrothermal oxidation kinetics of the slag. These two parameters are believed to increase iron dissolution rate which has already been identified as the rate limiting step of the hydrothermal oxidation of pure FeO. An activation energy of 28  4 kJ/mole is found for the hydrothermal oxidation of the steel slag which compares very well with that of pure FeO under similar conditions. In the case of the slag run in water at 300°C for 70.5 hours, magnetite product has been separated magnetically and characterized. Particles were found to fall in three size ranges: 10 – 30 nm, 100 – 300 nm and 1 – 10 µm. The smallest fraction (10 – 30 nm) is comparable to the 10 – 20 nm size range that is achieved when nanomagnetite are synthesized by co-precipitation methods. Obviously, the production of nanomagnetite enhances the economic interest of the hydrothermal processing of steel slags, which has already proven its capacity to produce high-purity H2.

The production of H-2 by oxidation of FeO, taken here as model compound for steel slags, has been investigated both in pure water and under acidic aqueous conditions in the 373 -573 K temperature range. Whereas after 65 h, H-2 yield was negligible in pure water at 423 K, the reaction 3 FeO(s) + H2O(l) -> Fe3O4(sc) + H-2(aq) reached near completion at the same temperature within 10 h in a solution containing 0.05 mol/l acetic acid. Increasing acetic acid concentration by one order of magnitude did not yield significantly more H-2. At identical initial pH, acetic acid was found to be more efficient than oxalic acid and hydrochloric acid at enhancing H-2 production. Acidic conditions increased FeO dissolution kinetics and, consequently, improved H-2 yield. The specific efficiency of acetic acid resides in its thermal stability as well as in the potential of ligand-promoted Fe(II) dissolution. We show that the positive kinetics effect of mild acetic acid solutions over H-2 yield evidenced on FeO does not apply directly to steel slags which buffer the pH to high values due to the presence of large amounts of CaO. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

A new process route for the valorization of BOF steel slags combining H2 production and CO2 mineral sequestration is investigated at 300°C (HT) under hydrothermal conditions. A BOF steel slag stored several weeks outdoor on the production site was used as starting material. To serve as a reference, room temperature (RT) carbonation of the same BOF steel slag has been monitored with in situ Raman spectroscopy and by measuring pH and PCO2 on a time-resolved basis. CO2 uptake under RT and HT are, respectively, 243 and 327 kg CO2/t of fresh steel slag, which add up with the 63 kg of atmospheric CO2 per ton already uptaken by the starting steel slag on the storage site. The CO2 gained by the sample at HT is bounded to the carbonation of brownmillerite. H2 yield decreased by about 30% in comparison to the same experiment performed without added CO2, due to sequestration of ferrous iron in a Mg-rich siderite phase. Ferric iron, initially present in brownmillerite, is partitioned between an Fe-rich clay mineral of saponite type and metastable hematite. Saponite is likely stabilized by the presence of Al, whereas hematite may represent a metastable product of brownmillerite carbonation. Mg-rich wüstite is involved in at least two competing reactions, i.e., oxidation into magnetite and carbonation into siderite. Results of both water-slag and water-CO2-slag experiments after 72 h are consistent with a kinetics enhancement of the former reaction when a CO2 partial pressure imposes a pH between 5 and 6. Three possible valorization routes, (1) RT carbonation prior to hydrothermal oxidation, (2) RT carbonation after hydrothermal treatment, and (3) combined HT carbonation and oxidation are discussed in light of the present results and literature data.

We report on a thorough structural study on two members of layered fluorocarbonates KMCO3F (M = Ca, Mn). The Ca-based member demonstrates a phase transition at ∼320 °C, evidenced for the first time. The crystal structure of the high temperature phase (HT-KCaCO3F) was solved using neutron powder diffraction. A new Mn-based phase KMnCO3F was synthesized, and its crystal structure was solved from electron diffraction tomography data and refined from a combination of X-ray synchrotron and neutron powder diffraction. In contrast to other members of the fluorocarbonate family, the carbonate groups in the KMnCO3F and HT-KCaCO3F structures are not fixed to two distinct orientations corresponding to mono- and bidentate coordinations of the M cation. In KMnCO3F, the carbonate group can be considered as nearly "monodentate", forming one short (2.14 Å) and one long (3.01 Å) Mn-O contact. This topology provides more flexibility to the MCO3 layer and enables diminishing the mismatch between the MCO3 and KF layers. This conclusion is corroborated by the HT-KCaCO3F structure, in which the carbonate groups can additionally be tilted away from the layer plane thus relieving the strain arising from geometrical mismatch between the layers. The correlation between denticity of the carbonate groups, their mobility, and cation size variance is discussed. KMnCO3 orders antiferromagnetically below TN = 40 K.