We present a systematic approach to predict the molecular degradation of high-density polyethylene (HDPE) during mechanical recycling based on the polymerization catalyst. HDPE represents about 12.5 wt % of the polymer world production and is industrially mainly produced by Phillips (P-HDPE) and Ziegler-Natta catalyst (ZN-HDPE). Two blow-moulding P-and ZN-HDPE with identical melt flow indices (MFI) were subjected to mechanical recycling at an extrusion temperature of 170 degrees C and 210 degrees C, a screw speed of 180 rpm, and recycling times from 10 to 240 min. Chemical and rheological characterization revealed, that despite similar initial melt properties, P-HDPE and ZN-HDPE exhibited fully contrary degradation mechanisms: for recycled P-HDPE at 170 degrees C and 210 degrees C, the complex viscosity (|eta*|) and the molecular weight drastically increased after 10 min of recycling time due to star-like branching, followed by chain scission at 170 degrees C, but crosslinking at 210 degrees C, resulting in unprocessable, rubber-like material. In contrast, recycled ZN-HDPE exhibited a continuous drop in molecular weight and in |eta*|across all conditions. This work provides a polymerization catalyst-specific framework to predict and engineer thermo-mechanical molecular degradation pathways in HDPE recyclates, paving the way to tailored recycling strategies to obtain value-added materials.

The process for economic recovery of Li from slags produced during the recycling of lithium-ion batteries via a combined pyro- and hydrometallurgical process route needs to be optimized. This requires a detailed knowledge of the phase composition, metal distribution, and microstructure of the produced slags. In this work, a new twostage analytical approach is presented, which enables the geochemical, mineralogical, and structural investigation of these slags. The methodology was developed on samples of the model system Al2O3-SiO2-CaO-MnO-Li2O and is demonstrated here on an artificial Li- and Mn-rich slag sample. Rapid analytical methods (short-wave ultraviolet radiation and micro energy-dispersive X-ray fluorescence spectroscopy) are adapted for on-site recycling process monitoring. They are validated by state-of-the-art mineralogical (X-ray diffraction with Rietveld quantitative phase analysis), bulk chemical (X-ray fluorescence, inductively coupled plasma mass spectrometry), and microanalytical (electron probe microanalysis, scanning electron microscopy-based automated mineralogy, laser ablation inductively coupled plasma-time-of-flight mass spectrometry) techniques. Apparently contradictory results of the latter techniques are discussed and reconciled. The integration of the new routine and rapid analytical methods into the pyro- and hydrometallurgical recycling route for lithium-ion batteries will be discussed considering the key mineralogical questions to be answered in process development, industrial process control, and process route adaptation.

Phase change materials are crucial for many applications in thermal energy storage and the development of self-adaptive micro actuators. Organic phase change materials, particularly n-alkanes, have been successfully used for these purposes. Key challenges include expanding the range of applications by accessing additional phase transformation zones and their associated phase change energies. Blends of n-alkanes offer a way to tailor thermophysical properties. In this study, the thermophysical properties of the n-alkanes tricosane (C23) and hexatriacontane (C36), as well as their binary mixtures, are investigated over the temperature range of 30 to 80°C. We observed a melting-point depression of up to 18 K for hexatriacontane and a non-linear change in heat of fusion by up to 6 % over the composition. In particular, the change in melting point of these n-alkane mixtures shows potential to tailor the temperature window of this PCM. This work provides new thermophysical property data on these alkanes and addresses thermal rate effects and mixture data, creating a database to support the future development of latent heat storage systems or micro actuators based on tricosane and hexatriacontane blends.

In recent years upstream Li extraction from battery scraps and black mass has gained significantly in importance due to its potential for higher achievable overall Li yields and increased flexibility in downstream processing. Various process routes have been developed and partially industrially implemented. Three major process types were identified through a comprehensive assessment of scientific literature, patent literature, and structured interviews with industry experts. These process types are based on smelting with enrichment of Li in the slag or flue dust phase, roasting with subsequent selective Li leaching, and pure hydrometallurgical processes using either an oxidative or reductive leaching mechanism. Based on the available scientific, patent and expert knowledge, this review critically discusses the current state of development with respect to reaction mechanisms and process design, industrial implementation and engineering aspects, decarbonization potential, integration in the battery recycling chain and economics. Process routes based on roasting with subsequent selective Li leaching currently appear to represent the predominant industrial approach in Asia and are under development in Europe. The available evidence suggests that this preference is primarily associated with a favorable combination of sufficient achievable lithium yields, process robustness, suitability for the current market size, and economic considerations. Current industrial developments indicate that smelting routes involving lithium enrichment in the flue dust phase are likely to reach broader industrial implementation within the next decade, although their economic viability is expected to depend on substantially larger processing capacities. Currently, pure hydrometallurgical processes only play a minor role, with the exception of LFP black mass.

The molecular architecture, in terms of molecular weight and branching, linked with the semi-crystallinity of the polymer, plays a key role in solid-liquid equilibria in polyethylene-solvent systems. Lattice Cluster Theory, in combination with continuous thermodynamics, captures these molecular features and has been successfully applied in the past to predict solid-liquid equilibria of polymer solvent systems. While the solubility of linear lowdensity polyethylenes in chlorinated solvents has been studied in depth in the past, few investigations have addressed their solubility in less toxic and environmentally more friendly solvents, particularly in relation to the influence of molecular architecture. This study aims to fill this gap by investigating the relationship between molecular architecture of ethylene/1-octene copolymers, covering a wide range of branching levels from 3.5 to 54.6 CH/1000 C, and their solid-liquid phase transitions in butylal. By combining cross-fractionation chromatography, preparative crystallisation fractionation and Lattice Cluster Theory, the solid-liquid transitions of these material systems are elucidated and an architecture-solubility relationship is established. This approach provides detailed insights into how molecular architecture influences crystallisation behaviour, provides a basis for the design of ethylene/1-octene copolymer fractions with tailored microstructural features, and demonstrates the predictive power of Lattice Cluster Theory.

Efficient recycling of lithium metasilicate (Li 2SiO 3) from lithium-containing slag via a pyrometallurgical route demands a comprehensive understanding of its solidification process in the slag reactor. A simulation framework is developed to predict the heterogeneous phase distribution of Li 2SiO 3, the temperature and velocity fields considering density changes in the solidifying melt, on the apparatus scale. This framework integrates thermodynamic models via calculation of phase diagrams with the enthalpy-porosity technique and the volume of fluid method within a finite volume approach, ensuring thermodynamic consistency and adherence to mass balance. Thus, the formation of Li 2SiO 3 from the liquid slag composed of Li 2O-SiO 2 is described in space and temporal fields. Thereby, the interrelationship between the temperature field, enthalpy field, velocity field, and phase distribution of Li 2SiO 3 is revealed. It is shown that the lower temperature on reactor boundaries prompts the earlier formation of Li 2SiO 3 in the vicinity of the boundaries, which subsequently induces a downward flow due to the higher density of Li 2SiO 3. The predicted global mass fraction of Li 2SiO 3 under non-equilibrium conditions is 11.5 wt % lower than that calculated using the global equilibrium assumption. This demonstrates the global non-equilibrium behavior on the process scale and its consequences on slag solidification.

With the application of pyrometallurgical technology in the recycling of spent lithium-ion batteries, eucryptite has been found as an artificial mineral in various lithium-bearing slags. Unlike spodumene, eucryptite has a higher lithium content and does not require high temperature roasting prior to leaching. Therefore, the study of the floatability and leaching behavior of eucryptite and eucryptite-containing slags is crucial for optimizing the pyrometallurgical recycling route of spent lithium-ion batteries. In this study, fundamental research is carried out on micro-flotation, surface property analysis and leaching behaviour of the natural eucryptite minerals. In microflotation tests, eucryptite showed a significant difference in floatability when using sodium oleate and dodecylamine. The disparity in yield between different minerals when employing the same collector serves as the foundation for selective flotation separation. A greater disparity indicates a higher expected efficiency in separation. In the dodecylamine system, eucryptite showed a higher yield compared to the gangue mineral gehlenite, with a maximum yield difference of approximately 35 %. In addition, flotation tests on eucryptite-containing slag demonstrate the potential for separating eucryptite, gamma-lithium aluminate and the gangue mineral gehlenite from slag by multi-stage flotation. In the leaching test, the leaching efficiency of lithium in the natural eucryptite mineral approaches 97 % and in the slag approaches 100 %.

Various resins are commonly used for encapsulating electronic components across diverse applications, having the joint goal to prevent electronics to be contaminated with solvents from the environment. To mitigate the need for time-intensive experimental studies to analyses their long-term performance in terms of solvent uptake and swelling, computational simulations offer a promising path. This work presents a modeling approach where PC-SAFT (Perturbed Chain Statistical Associating Fluid Theory) is combined with the Maxwell-Stefan framework for simulating the solvent uptake and swelling behavior of silicone, polyurethane, and phenolic resins in various mixtures. The simulation-based results are validated via solvent uptake experiments, where the following solvents, water, heptane, isopropanol, methanol, and acetone are investigated. It turned out, that an excellent agreement between experimental solvent uptake data and simulation-based prediction occurred, which supports the strength of coupling PC-SAFT with Maxwell-Stefan framework for enhanced.

Various approaches are being investigated to recover valuable materials from end-of-life lithium-ion batteries, particularly for lithium nickel manganese cobalt oxide (NMC) and lithium iron phosphate (LFP) cathode chemistries. Graphite recovery has gained increasing interest due to its classification as a critical raw material, with Flotation being a promising process for its recovery from black mass. A requirement for successfully realizing this process is the removal of binders from the anode and cathode surfaces, which is usually achieved through thermal treatment. This paper investigates the thermal decomposition behavior of pure and mixed NMC/LFP materials under oxidative and inert atmospheres and examines how these differences affect subsequent flotation performance. Macro thermobalance analysis, combined with differential thermal analysis (DTA) and mass spectrometry for multidimensional thermal analysis, was used to understand possible reactions and obtain thermally treated samples for flotation. The thermally pretreated samples were then subjected to flotation to assess the influence of the mixing ratio and evaluate the thermal treatment's quality. Differences between roasting and pyrolysis were identified, with roasting exhibiting higher net exothermicity, which increased with rising NMC content. Fluorine behavior also differed: in LFP, it was released as hydrogen fluoride (HF) gas, whereas in NMC, it remained in the residue and could continue to react during thermal treatment and subsequent processes. The findings demonstrate that cathode composition significantly influences behavior in thermal treatment and has to be considered to optimise pretreatment strategies for effective graphite recovery.

A better understanding of high temperature processes in slags contributes to facilitate knowledge based design of the solidified product. Here, a slag analogue with a nominal composition of 17 wt% LiMnO2 and 83 wt% Ca2SiO4 was synthesized encountering fairly high cooling rates. The Mn species from 1223 K to 1773 K was simulated using a thermodynamic model assuming a homogeneous melt. The micro-composition including the Mn species of the solidified slag was determined experimentally and was used as basis for molecular dynamics (MD) simulation. The MD simulation provides information on structure and viscosity at high temperatures, otherwise difficult to access. These parameters significantly influence oxidation state of redox-active elements and the solidified product. The micro-composition analyzed by electron probe micro analysis (EPMA) and synchrotron based micro-X-ray fluorescence (micro-XRF) showed that Mn-rich and Ca-Si-rich phases are separated. While the Mn-O phases did not contain noticeable Ca, the Ca2SiO4 phase had incorporated 0.6 wt% of Mn. The slag solidified into round shaped and droplet shaped grains of a Li-Mn-oxide, some Mn3O4 and Ca2SiO4. The powder X-ray diffraction (PXRD) confirmed the formation of larnite, the identity of the Li-Mn-oxide however remained inconclusive. The Mn oxidation state (OS) was identified using synchrotron based micro-X-ray absorption near edge spectroscopy (micro-XANES). The Mn-O grains, matched well with Li-Mn-oxides and a Mn OS: +3 e.g. LiMn3+O2. Small areas matching Hausmannite (Mn2+Mn23+O4) were also identified. The OS of Mn in the silicate phase could not be identified. For comparison a slowly cooled slag analogue with similar composition however higher Si content, was also subjected to micro-XANES. The slowly cooled slag formed long Mn-rich needles in a matrix of large calcium silicate crystals. The Mn-rich crystals matched well with the XANES spectrum of a Mn3+ Li-oxide like LiMn3+O2. At the rim of the needles the Mn-spectra matched well the Hausmannite (Mn2+Mn23+O4) reference. In the silicate phases Mn had a OS: +2, unambiguously. The melt structure at different temperatures of two compositions i.e. LiMn3+O2 and Ca2SiO4 was simulated using molecular dynamics (MD). They serve as model compositions assuming a heterogeneous melt. The results show significant different degrees of polymerization and viscosity. Information from MD simulations can support the identification of potentially different oxygen permeability and with that prediction of oxidation states. The bulk composition was identified by inductively coupled plasma optical emission spectrometry (ICP-OES), bulk structure by PXRD and bulk species by lab-XANES. The synchrotron micro analysis including micro-XRD were performed at the microfocus beamline I18 at the Diamond Light Source. Pure reference compounds were prepared and characterized with the same multi-modal approach.

The relationship between macromolecular architecture and crystallization properties is a relevant research topic in polymer science and technology. The average degree of crystallinity of disperse polymers is a well-studied quantity and is accessible by various experimental methods. However, how the different macromolecular species contribute to the degree of crystallinity and, in particular, the relationship between a certain macromolecular architecture and the degree of crystallinity are not accessible today, neither experimentally nor theoretically. Therefore, in this work, a lattice cluster theory (LCT)-informed cross-fractionation chromatography (CFC) approach is developed to access the degree of crystallinity of single and nonlinear macromolecular species crystallizing from solution. The method entangles high-throughput experimental data from CFC with the LCT for semicrystalline polymers to predict the degree of crystallinity of polymer species with different molecular weights and branching. The approach is applied to a linear low-density polyethylene (ethylene/1-octene copolymer) and a high-density polyethylene, which have specific and different bivariate distributions. The degree of crystallinity of individual macromolecular species of these polymer samples is calculated, and the predicted average degree of crystallinity is compared with experimental measurements, thus successfully validating the approach. Furthermore, the average segment length between branches is introduced as a characteristic molecular feature of branched polyethylene, and its relationship with the degree of crystallinity of certain species is established.

The increasing demand for lithium in lithium-ion battery (LIB) applications necessitates innovative recycling strategies. Combined pyrometallurgical–hydrometallurgical recycling has gained increased attention for lithium recovery from slags. One challenge in the technological advancement of recycling lithium from spent LIBs with lithium-nickel-manganese-cobalt-oxide cathodes (NMC), characterized by a Li–Al–Si–Ca–Mn–O slag system, lies in the distribution of lithium across multiple silicate and oxide phases. Hence, the goal of this work is to significantly enrich the lithium in the single target phase γ-LiAlO2 with thermodynamic-based optimization for tailored slag designs. This is achieved by coupling a sophisticated thermodynamic database and model reassessment related to practical NMC-type LIB slag system composition fields with Pareto optimization. Extensive experimental investigations are performed for model and design validations, and procedures for selecting the best phase candidates with individual lithium content are systematically presented. A strong nonlinear influence of CaO on the formation of the target product γ-LiAlO2 could be revealed, where the addition of SiO2 for lithium slagging needs to be limited to enrich lithium in the target phase. Higher amounts of added CaO and SiO2, such as both at 30 wt %, result in the undesired transfer of lithium into other Li-containing phases. Based on this approach, an artificial slag is computationally designed for the first time, where theoretically 100% of the lithium is trapped in γ-LiAlO2. After production of this slag and experimental analysis, it was found that 96% of lithium was transferred into γ-LiAlO2. This demonstrates the great potential of thermodynamics-based artificial slag design for enhancing lithium recycling efficiency in LIB recycling processes.

Slags generated from pyrometallurgical processing of spent Li-ion batteries are reservoirs of Li compounds that, on recycling, can reintegrate Li into the material stream. In this context, γ-LiAlO2 is a promising candidate that potentially increases recycling efficiency due to its high Li content and favorable morphology for separation. However, its solidification kinetics depends on melt compositions and cooling strategies. The Engineered Artificial Minerals approach aims to optimize process conditions that maximize the desired solid phases. To realize this goal, understanding the coupled influence of external cooling kinetics and internal kinetics of solid/liquid interface migration and mass and thermal diffusion on solidification is critical. In this work, the solidification of γ-LiAlO2 from a Li2O-Al2O3 melt is computationally investigated by applying a non-equilibrium thermodynamic model to understand the influence of varying processing conditions on crystallization kinetics. A strategy is illustrated that allows the effective utilization of thermodynamic information obtained by the CALPHAD approach and molecular dynamics-generated diffusion coefficients to simulate kinetic-dependent solidification. Model calculations revealed that melts with compositions close to γ-LiAlO2 remain comparatively unaffected by the external heat extraction strategies due to rapid internal kinetic processes. Kinetic limitations, especially diffusion, become significant for high cooling rates as the melt composition deviates from the stoichiometric compound.

Engineered artificial minerals (EnAMs) are the core of a new concept of designing scavenger compounds for the recovery of critical elements from slags. It requires a fundamental understanding of solidification from complex oxide melts. Ion diffusivity and viscosity play vital roles in this process. In the melt, phase separations and ion transport give rise to gradients/increments in composition and, with it, to ion diffusivity, temperature, and viscosity. Due to this complexity, solidification phenomena are yet not well understood. If the melt is understood as increments of simple composition on a microscopic level, then the properties of these are more easily accessible from models and experiments. Here, we obtain these data for three stoichiometric lithium aluminum oxides. LiAlO2 is a promising EnAM for the recovery of lithium from lithium-ion battery pyrometallurgical processing. It is obtained through the addition of aluminum to the recycling slag melt. The high temperature properties spanning from below to above the liquidus temperature of three stoichiometric Li-Al-Oxides: Li5AlO4, LiAlO2, and LiAl5O8 are determined using molecular dynamic simulations. The compounds are also synthesized via the sol-gel route. The Li+ ion exhibits the largest diffusivity. They are quite mobile already below the liquidus temperature, i.e., for LiAlO2 at T = 1700 K, the diffusion coefficient of the lithium ion equals D = 3.0 x 10(-9) m(2) s(-1). The other ions Al3+ and O2- do not move considerably at that temperature. The diffusivity of Li+ is largest in the lithium-rich compound Li5AlO4 with D = 32 x 10(-9) m(2) s(-1) at 2500 K. The lower the viscosity, the higher the lithium content. The Li5AlO4 exhibits a viscosity of eta = 2.2 mPa s at 1328 K which matches well with the experimentally determined 2.5 mPa s at this temperature. The viscosity of LiAlO2 at 1800 K is more than two times higher. These data sets can help to describe the melts on a microscopic level and understand how the melt properties will change due to gradients in the Li/Al concentration.

During liquid-solid transformation, bulk mass and thermal diffusion, along with the evolved interfacial latent heat, work in tandem to generate interfacial thermodynamic and kinetic forces, the interplay of which decides the solidification velocity and consequently the solidified phase attributes. Hence, access to interface dynamics information in dependence of bulk transfer processes is pivotal to tailor the desired quantity of solid phases of unique compositions. It finds particular application for engineering concentrated Lithium (Li) phases out of Li-ion battery slags, thus generating a high value-added product from a conventional waste process stream. However, considerable challenge exists to predict the impact of the diverse external cooling rates on the evolving internal transfer processes and thus tuning solidification routes for achieving phases of interest. Hence, in this work, a thermodynamically consistent nonequilibrium model, by considering spatiotemporal temperature and concentration fields, is developed and applied to study solidification of Li2SiO3 from a Li2O-SiO2 melt that constitutes an important subsystem of the Li containing battery-recycling slags. The approach treats the sharp solid/liquid interface as a moving heat source. In the presence of different heat extraction profiles, it evaluates the spatial temperature heterogeneity and its implicit correlation to internal material fluxes resulting from maximization of dissipation and consequently the interrelation to interface velocities. Model calculations revealed that irrespective of the external cooling rate, for an initial short time duration, the magnitude of which increased with decreasing cooling rates, the interface velocities show a reducing trajectory directly relatable to the reducing thermodynamic forces due to localized interfacial temperature rise from the generated latent heat of fusion from the initial solidification. This is followed by a thermodynamically controlled regime, whereby for each cooling rate, the interface velocities increase until a maxima, the magnitude of which decreases with decreasing cooling rates. Finally, the interface propagation speeds decrease as controlled by the kinetic regime.

Developing efficient recycling processes with high recycling quotas for the recovery of graphite and other critical raw materials contained in LIBs is essential and prudent. This action holds the potential to substantially diminish the supply risk of raw materials for LIBs and enhance the sustainability of their production. An essential processing step in LIB recycling involves the thermal treatment of black mass to degrade the binder. This step is crucial as it enhances the recycling efficiency in subsequent processes, such as flotation and leaching-based processing. Therefore, this paper introduces a Representative Black Mass Model (RBMM) and develops a computational framework for the simulation of the thermal degradation of polymer-based binders in black mass (BM). The models utilize the discrete element method (DEM) with a coarse-graining (CG) scheme and the isoconversional method to predict binder degradation and the required heat. Thermogravimetric analysis (TGA) of the binder polyvinylidene fluoride (PVDF) is utilized to determine the model parameters. The model simulates a specific thermal treatment case on a laboratory scale and investigates the relationship between the scale factor and heating rate. The findings reveal that, for a particular BM system, a scaling factor of 100 regarding the particle diameter is applicable within a heating rate range of 2 to 22 K/min.

Efficient recovery of Li2SiO3 or other Li compounds from slag streams generating from pyrometallurgical treatment of lithium ion batteries (LIBs) requires fundamental understanding of the kinetics that govern slag solidification. In this work, a non-equilibrium thermodynamic model that incorporates mixed internal kinetics of diffusion and interface mobility, influenced by external cooling paths, is developed to investigate for the first time, the dependence of the phase evolution rate of Li2SiO3 from Li2O-SiO2 melt, on the available driving forces and time-dependent concentration fields. Experiments with different thermal profiles were performed for inverse identification of the kinetic coefficients. It turned out that different cooling rates (1.5Kmin  1, 5Kmin  1 and 10Kmin  1) depict an initial dominance of thermodynamic driving force superseded by kinetic forces in subsequent phase evolution. A certain interface velocity maximum is exhibited during phase formation, where the magnitude decreases progressively from 5.5 x 10  7ms  1 to 3.9 x 10  7ms  1 to 2.1 x 10  7ms  1 with a decrease of the cooling rates.

Pyro-metallurgical processing technology is widely used in the spent lithium-ion batteries recycling to recover valuable metals such as cobalt, nickel and copper, while lithium primarily remains in the slag. The effective valorization of slag, especially lithium recovery, constitutes a significant issue in contemporary pyrometallurgical processes due to the paucity of studies. This paper proposes a novel perspective by defining slag as an aggregate of engineered artificial minerals. Thus, not only the parameters of the beneficiation process can be studied to optimize the separation efficiency during treatment, but also the slag can be re-designed to optimize the carrier minerals of target elements and gangue mineral composition in the initial step with thermodynamic tools. In this paper, the engineering of artificial minerals (EnAM) method was applied to the slag design of the Li2O-CaO-Al2O3-SiO2-MnO system, and an initial attempt was made to apply EnAM method to the flotation study. A flotation study on enrichment effect of the target phase gamma-LiAlO2 from thermodynamic controlled slags is conducted.

This manuscript presents the results from the synthesis and characterization of a slag analogue with a nominal composition of 17 wt% LiMnO2 and 83 wt% Ca2SiO4 encountering fairly high cooling rates in order to study the evolution of Mn-species. The Mn species was also simulated from 1223 K to 1773 K using a thermodynamic model, assuming a homogeneous melt. The micro-composition including the Mn species of the solidified slag was determined experimentally, and was used as basis for molecular dynamics (MD) simulation. The MD simulation provides information on structure and viscosity at high temperatures, which are otherwise difficult to access. These parameters significantly influence oxidation state of redox-active elements and the solidified product. The micro-composition analyzed by electron probe micro analysis (EPMA) and synchrotron-based micro-X-ray fluorescence (micro-XRF) showed that Mn-rich and Ca-Si-rich phases are separated. While the Mn-O phases did not contain noticeable Ca, the Ca2SiO4 phase had incorporated 0.6 wt% of Mn. The slag solidified into round-shaped and droplet-shaped grains of a Li-Mn-oxide, some Mn3O4 and Ca2SiO4. The powder X-ray diffraction (PXRD) confirmed the formation of larnite; the identity of the Li-Mn-oxide, however, remained inconclusive. The Mn oxidation state (OS) was identified using synchrotron-based micro-X-ray absorption near edge spectroscopy (micro-XANES). The Mn-O grains matched well with Li-Mn-oxides and a Mn OS: +3, e.g., LiMn3+O2. Small areas matching hausmannite (Mn2+Mn23+O4) were also identified. The OS of Mn in the silicate phase could not be identified. For comparison, a slowly cooled slag analogue with similar composition, but higher Si content, was also subjected to micro-XANES. The slowly cooled slag formed long Mn-rich needles in a matrix of large calcium silicate crystals. The Mn-rich crystals matched well with the XANES spectrum of a Mn3+ Li-oxide like LiMn3+O2. At the rim of the needles, the Mn-spectra matched well the hausmannite (Mn2+Mn23+O4) reference. In the silicate phases, Mn had an OS: +2, unambiguously. The melt structure at different temperatures of two compositions, i.e., LiMn3+O2 and Ca2SiO4, was simulated using molecular dynamics (MD). They serve as model compositions, assuming a heterogeneous melt. The results show significant different degrees of polymerization and viscosity. Information from MD simulations can support the identification of potentially different oxygen permeability and with that prediction of oxidation states. The bulk composition was identified by inductively coupled plasma optical emission spectrometry (ICP-OES), bulk structure by PXRD and bulk species by lab-XANES. The synchrotron micro analysis including micro-XRD were performed at the microfocus beamline I18 at the Diamond Light Source. Pure reference compounds were prepared and characterized with the same multi-modal approach.

The limited life-cycle of lithium-ion batteries (LIBs) remains a significant issue for the industry. Recycling electrolytes from the batteries is one crucial aspect of LIBs recycling, which can conserve resources and reduce environmental pollution. The vapor-liquid equilibrium (VLE) data and models for the currently widely used carbonates, such as ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC), can play an important role in designing the recycling process. In this work, the VLE data of DEC and EC is measured for the first time. A sophisticated equation of state, the Perturbed-Chain Polar Statistical Associating Fluid Theory, is used to establish the VLE model, not only for the newly measured DEC and EC system but also for other carbonates and their mixtures. Through the discussion of how the molecular characteristics of carbonates influence the VLE behavior, the dipolar character of linear carbonate molecules has been revealed. This demonstrates the power and importance of sophisticated modelling approaches in investigating molecular behavior of electrolyte solvents in the context of LIB recycling. Hence, this work provides valuable experimental and model data for designing recycling processes of electrolyte solvents and offers molecular insight into carbonates.