Ce travail se situe à l’intersection des trois disciplines : méthodes numériques, techniques expérimentales et du machine learning, a pour but de proposer une famille de techniques d’identification par analyse inverse des lois de comportement en mécanique. Dans le domaine d’identification des matériaux, l’indentation instrumentée est particulièrement attractive, car elle permet de procéder à des essais non-destructifs sur l’échantillon ou sur une structure en service. L’essai d’indentation, similaire à un test de dureté, consiste à enfoncer la pointe de l’indenteur à une faible profondeur dans la matière tout en enregistrant le déplacement en fonction de la force appliquée. L’identification des propriétés élastoplastiques des matériaux est basée alors sur l’exploitation de la courbe force-déplacement (courbe P-h). Toutefois, le problème inverse est souvent mal posé et des problèmes d’unicité mènent à la notion de paires de "matériaux mystiques" produisant, dans des conditions d’essai donnés, des courbes P-h identiques, malgré des propriétés différentes. L’idée de notre travail est de compléter la procédure d’identification en faisant appel à des dispositifs expérimentaux récents, notamment à la microscopie laser, permettant de mesurer la carte 3D de l’empreinte résiduelle obtenue après le retrait de l’indenteur. Pour aborder la question de la richesse d’information de l’empreinte par rapport à la courbe P-h seule, nous proposons de construire, dans un espace affine réduit, la variété des formes d’empreinte admissibles au sens d’une loi de comportement et du modèle d’éléments finis de l’essai. La mesure de la dimension intrinsèque nous indique alors le nombre maximal de paramètres potentiellement identifiables. Cela nous permet de proposer et de valider numériquement des nouveaux procédés expérimentaux, plus représentatifs, à partir des données synthétiques, ainsi que des algorithmes d’identification associés. La prise en compte de l’erreur de modèle et de l’erreur de mesure, nous mène ensuite à proposer un ensemble d’algorithmes de projection d’empreintes expérimentales, réalisées en collaboration avec l’INSA de Rennes sur la variété synthétique. Nous abordons alors le problème d’identification des propriétés d’écrouissage de plusieurs matériaux de complexité croissante et départageons des "jumeaux mystiques" par des essais de multi-indentation, basés sur l’exploitation de l’empreinte seule ou en complément de la courbe P-h. / The thesis lies at the intersection of three disciplines : numerical methods, experimental techniques, and machine learning. The primary aim of this work is to develop a group of algorithms for characterization by inverse analysis of a material’s constitutive law. In the field of material characterization, indentation test is especially attractive since it is considered non-destructive, and may be performed even on a structure in service. The test, similar to a hardness test, consists in penetrating an indenter into the surface of the material. The force exerted on the indenter is recorded against the penetration depth over a series of time instants, leading to a force-displacement (P-h) curve, which is the most frequently used source of information for the identification of material properties. However, the inverse problem based solely on this curve tends to be ill-posed, leading to nonunique identification solution, i.e., the "mystical material pair", for whom the corresponding force-displacement curves are almost identical despite the very different material properties. The basic idea is then to complete the identification process with innovative experimental measurements, such as laser microscope, which allows measuring the 3D residual imprint after the withdrawal of the indenter. To address the advantage of this measurement over P-h curve, we propose to construct, within a reduced affine space, a manifold of shapes admissible to the postulated constitutive law, experimental and simulation setups, based on synthetic data. The intrinsic dimensionality of the manifold limits the number of identifiable parameters allowing to validate numerically experimental procedures. Considering both the model and measurement errors, we develop a series of local manifold learning algorithms to solve the inverse problem iteratively for experimental results obtained in cooperation with INSA de Rennes. This approach allows us to characterize diverse metallic materials of increasing complexity, based on actual experimental measurements. For example, for the Hollomon’s law, the mystical pair is alleviated in using a single imprint, while for the Voce law, a multi-depth experimental protocol is proposed to differentiate mystical siblings.

Wireless communications have been an indispensable aspect of everyday life, and there is an increasing consumer demand for accessing several wireless communication technologies from a single, compact, mobile device. System-on-package (SOP) technology is an advanced packaging technology that has been proven to realize the convergence of multiple functions into miniaturized, high-performance systems to meet this demand. With the advancements in the SOP technology, the miniaturization of the front-end module has been achieved using embedded passives in multilayer packages. However, the integration of the antenna directly on the module package is still the barrier to achieve a fully-integrated, high-performance RF SOP system. The main reason for this missing link is that integrating the antenna on the package requires miniaturizing the antenna, which is a difficult task. The focus of this dissertation is to design high-performance antennas along with developing techniques for miniaturization and system-on-package (SOP) integration of these antennas to achieve fully-integrated SOP systems using advanced multilayer organic substrates and thin-film magneto-dielectric materials. The targeted spectrum for the antenna designs are 2.4/5 GHz WLAN/WiMAX and 60 GHz WPAN bands. Several novel antenna designs and configurations to integrate the antenna on the package along with the module are discussed in this dissertation. The advanced polymers used in this research are Liquid Crystalline Polymer (LCP), RXP, and thin-film magneto-dielectrics.

The current clinical management of abdominal aortic aneurysm (AAA) disease is based on measuring the aneurysm maximum diameter to decide when timely intervention can be recommended to a patient. However, other parameters may also play a role in causing or predisposing the AAA to either an early or delayed rupture relative to its size. Therefore, patient-specific assessment of rupture risk based on physical principles such as individualized biomechanics can be conducive to the development of a vascular tool with translational potential. To that end, the present doctoral research materialized into a framework for image based patient-specific vascular biomechanics assessment. A robust generalized approach is described herein for image-based volume mesh generation of complex multidomain bifurcated vascular trees with the capability of incorporating regionally varying wall thickness. The developed framework is assessed for geometrical accuracy, mesh quality, and optimal computational performance. The relative influence of the shape and the constitutive wall material property on the AAA wall mechanics was explored. This study resulted in statistically insignificant differences in peak wall stress among 28 AAA geometries of similar maximum diameter (in the 50 – 55 mm range) when modeled with five different hyperelastic isotropic constitutive equations. Relative influence of regionally varying vs. uniform wall thickness distribution on the AAA wall mechanics was also assessed to find statistically significant differences in spatial maxima of wall stresses, strains, and strain energy densities among the same 28 AAA geometries modeled with patient-specific non-uniform wall thickness and two uniform wall thickness assumptions. Finally, the feasibility of estimating in vivo wall strains from individual clinical images was evaluated. Such study resulted in a framework for in vivo 3D strain distributions based on ECG gated, unenhanced, dynamic magnetic resonance images acquired for 20 phases in the cardiac cycle. Future efforts should be focused on further development of the framework for in vivo estimation of regionally varying hyperelastic, anisotropic constitutive material models with active mechanics components and the integration of such framework with an open source finite element solver with the goal of increasing the translational potential of these tools for individualized prediction of AAA rupture risk in the clinic.

A ce jour il n'est toujours pas possible de prédire avec exactitude le phénomène d'érosion par cavitation. La raison principale est qu'il est difficile de caractériser l'agressivité de l'écoulement. Cette thèse propose d'utiliser une méthode inverse pour estimer l'agressivité de l'écoulement à partir de l'observation des cratères (pits) imprimées sur la surface dans les premiers instants de l'érosion de cavitation. Trois matériaux ont été testés dans la veine d'écoulement PREVERO disponible au LEGI de Grenoble dans les mêmes conditions expérimentales. La géométrie des pits laissés sur la surface est précisément mesurée à l'aide d'une méthode systématique permettant de s'affranchir de l'effet de rugosité. Supposant que chaque pit a été généré par une bulle unique dont le champ de pression est assimilé à une forme Gaussienne, des calculs par éléments finis permettent d'estimer le chargement qui a créé l'empreinte résiduelle. On montre que la distribution des chargements suit une loi universelle indépendante du matériau testé; le matériau le plus tendre (alliage d'aluminium) mesurant les plus faibles impacts tandis que le matériau le plus résistant (Acier inoxydable) donne accès aux plus grandes pressions d'impact. On en conclu que le matériau peut être utilisé comme capteur de pression mesurant le niveau d'agressivité de l'écoulement. La méthode inverse repose sur une caractérisation mécanique des matériaux prenant en compte la sensibilité de la contrainte à la vitesse de déformation. On montre que les essais de nanoindentation sont mieux adaptés que les essais de compression pour déterminer les paramètres de la loi de comportement, notamment pour l'alliage d'aluminium pour lequel la microstructure est très hétérogène. Des essais de compression à haute vitesse par barres de Hopkinson complètent la loi de comportement en donnant la sensibilité à la vitesse de déformation. Des simulations prenant en compte la dynamique du chargement montrent que des impacts de fort amplitude mais appliqués sur un temps court ne laissent pas d'empreinte résiduelle si la fréquence est plus élevée que la fréquence naturelle du matériau assimilé à un oscillateur amorti. Un mécanisme d'accumulation dynamique de la déformation plastique pouvant conduire à la rupture par fatigue est proposé. Finalement, la courbe de perte de masse est simulée en appliquant aléatoirement sur un maillage 3D, la population d'impacts estimée par la méthode inverse. / Numerical prediction of cavitation erosion requires the knowledge of flow aggressiveness, both of which have been challenging issues till-date. This thesis proposes to use an inverse method to estimate the aggressiveness of the flow from the observation of the pits printed on the surface in the first moments of the cavitation erosion. Three materials were tested in the same experimental conditions in the cavitation tunnel PREVERO available LEGI Grenoble. The geometry of the pits left on the surface is precisely measured using a systematic method to overcome the roughness effect. Assuming that each pit was generated by a single bubble collapse whose pressure field is treated as a Gaussian shape, finite element calculations are run for estimating the load that created each residual imprint. It is shown that the load distribution falls on a master curve independent of the tested material; the softer material (aluminum alloy) measuring the lowest impacts while the most resistant material (duplex stainless steel) provides access to the largest impact pressures. It is concluded that the material can be used as a pressure sensor measuring the level of aggressiveness of the flow. The inverse method is based on a material characterization taking into account strain rate effects. It is shown that nanoindentation tests are more suitable than compression tests to determine the parameters of the behavior law, particularly for the aluminum alloy for which the microstructure is very heterogeneous. High-speed compression tests with split Hopkinson pressure bars complement the constitutive law giving the sensitivity to the strain rate. Simulations considering the dynamic loading show that impacts of strong amplitude but applied in a short time do not leave any residual pit if the frequency is higher than the natural frequency of the material treated as a damped oscillator. A dynamic mechanism of plastic strain accumulation that could eventually lead to fatigue failure is proposed. Finally, the mass loss curve of cavitation erosion is simulated by applying randomly on a 3D mesh, the impact force population estimated by the inverse method.

Key factors that influence the design of paved and unpaved roads are the strength and stiffness of the pavement layers. Among other factors, the strength of pavements depends on the thickness and quality of the aggregates used in the pavement base layer. In India and many other countries, there is a high demand for good quality aggregates and the availability of aggregate resources is limited. There is a need for the development of sustainable construction methods which can handle aggregate requirements with least available resources and provide good performance. Hence it is imperative to strive for alternatives to achieve improved quality of pavements using supplementary potential materials and methods. The strength of pavement increases with increase in the thickness of the base which has a direct implication on construction cost whereas decreasing the thickness of the base makes it weak which results in low load bearing capacity especially for unpaved roads. The use of different types of geosynthetics like geocell and geogrid are a potential and reliable solution for the lack of availability of aggregates and studies are conducted in this direction. To better understand the performance of any geosynthetically reinforced base layers, it is essential to characterize the pavement material by studying the behavior of these materials under static as well as repeated loading. For unpaved roads, the base layer, made of granular aggregates plays a crucial role in the reduction of permanent deformation of the pavements. The resilient modulus (Mr) of these materials is a key parameter for predicting the structural response of pavements and for characterizing materials in pavement design and evaluation. Usually, during the design of flexible pavements, pavement materials are treated as homogeneous and isotropic. The use of rollers in the field during pavement construction leads to a higher compaction of material in the vertical direction which introduces stress-induced anisotropy in the base material. The effect of stress-induced anisotropy on the properties of the granular material is studied and discussed in the first part of the research by conducting repeated load triaxial tests. Isotropic consolidated and anisotropically consolidated samples were prepared to investigate the behavior of base materials under stress induced anisotropic conditions. An additional axial load was applied on the isotropically consolidated sample to create anisotropically consolidated sample. The axial loading was provided such that the stress ratio (σ1/σ3), during anisotropic consolidation was kept constant for all the tests at different confining pressures. The effect of repeated loading on the permanent deformation and the resilient modulus for both isotropically and anisotropically consolidated samples, at different confining pressure and loading conditions, are discussed. The behavior of both anisotropically and isotropically consolidated samples has been explained using the record of the excess pore pressures generated during the experiments. The experimental studies show that the permanent strains measured in the vertical direction of the anisotropically consolidated samples are less compared to the results obtained for isotropically consolidated samples. The resilient moduli of the anisotropically consolidated samples were also observed to be higher than that of the isotropically consolidated sample. The study conducted on the pore pressure of both the samples explains better performance of the anisotropically consolidated samples. The studies showed that the isotropically consolidated samples showed higher pore pressures compared to the anisotropically consolidated specimens. Another factor which influences the resilient modulus of the pavement materials is the geosynthetic reinforcement. Geocell and geogrid reinforced triaxial samples were prepared to study the effect of reinforcement in the resilient modulus of the base materials. From the literature, it can be seen that most of the research in the triaxial testing equipment were carried out in the non-destructive range of confining pressure and deviatoric stress. Several studies have been conducted by the researchers to visualize the pavement response in the elastic range. However, the studies in the plastic creep range and incremental collapse range were highly limited. In the current study, testing is carried out on the triaxial samples for two different stress ranges. In the first sections, loading was applied in the elastic and elastic shakedown range as per AASTHO T-307. For various loading sequences, a comparative analysis has been done for the resilient modulus of the geogrid and geocell. In the next section, the loading was applied on the sample in the plastic shakedown range and incremental collapse range. The results of the permanent strains and resilient modulus of the sections are compared with the corresponding results of the unreinforced section. In the plastic shakedown and incremental collapse range also the permanent strains of reinforced samples were less than those observed in the unreinforced section. The performance of geosynthetically reinforced pavement layers can be better understood by studying the samples prepared under realistic field conditions. In the case of triaxial experiments the sample size is very less compared to the field conditions and the effect of other pavement layers on the performance of the base layers cannot be studied on triaxial samples. Samples were prepared in the laboratory by modeling the pavement sections in a cuboidal tank, in which different pavement layers are laid one over the other, and a static loading or repeated loading is applied to overcome the bottleneck of small sample size in the triaxial setup. The experiments were conducted on the unreinforced section; geocell reinforced section and geogrid reinforced section placed above strong and weak subgrade. The results of the study are examined regarding the resilient deformation, permanent deformation, pressure distribution and strain measurements for different thicknesses of base layers under repeated loading. The initial parts of the study present the results of experiments and analysis of the results to understand the behavior of geocell reinforced granular base during repeated loading. In this study, an attempt is made to understand the various factors which influence the behavior of geocell reinforced granular base under repeated loading by conducting plate load tests. The loads applied on the pavements are much higher than the standard axle loading used for the design of pavements. High pressure was applied on all the test sections to simulate these higher loading conditions in the field. The optimum width and height of the geocell to be provided, to get maximum reduction in permanent deformation is studied in detail. The effect of resilient deformation of reinforced and unreinforced base layers is quantified by calculating the resilient modulus of these layers. The studies showed that the geocell reinforcement was effective in reducing the permanent and resilient deformations of base layer when compared to the unreinforced samples. The resilient modulus calculated was higher for the reinforced sample with half of the thickness of the unreinforced sample. The effect of reinforcement in the stress distribution within the base layer is also studied by measuring the pressures at different depths of the base layer. The results showed that the pressure getting transferred to the subgrade level was much lower in the case of geocell reinforced base layer. The ultimate aim of any pavement design method is to reduce the distress in the subgrade level and thus leading to increased life of pavements. Pressures at the subgrade level for reinforced and unreinforced sections are studied in detail, the main parameter under study being the stress distribution angle, to investigate the distress in the subgrade level. It was observed that the geocell reinforced sample showed higher stress distribution angle when compared to its unreinforced counterpart. Another important factor that has to be studied is the strains at the subgrade level since it is the governing factor of causing rutting in the pavements. From the experiments conducted in the study, it was shown that the reinforcement is very effective in reducing the strains at the top of subgrades. The implications of the current study are brought out in terms of improved pavement performance as the carbon emission reductions. It is important to analyze the performance of reinforced section under realistic field conditions. To do that experiment were conducted on reinforced and unreinforced base layers placed on top of weak subgrade material. The study showed that the reinforcements are effective in reducing the deformations under weak subgrade conditions also but not as effective as it was under strong subgrade case. The experimental results were then validated with the two-dimensional mechanistic-empirical model for geocell reinforced unpaved roads for predicting the performance of pavements under a significant number of cycles. The modified permanent deformation model which incorporates the triaxial test results and strains measured directly from the base sections were used to model and validate. Plate load experiments were also conducted on base layers reinforced with geogrid to understand the behavior of these reinforced samples under repeated loading. Several factors like the width of the geogrid to be provided and the depth of placing the geogrid in the base layer were studied in detail to achieve maximum reduction in deformations. Permanent and resilient deformation studies were carried out for both reinforced and unreinforced sections of varying thicknesses, and a comparison was made to understand the effect of reinforcement. The geogrid reinforcement could effectively reduce the permanent and resilient deformations when compared to the unreinforced sections. A study was also carried out on the resilient modulus, which explained the better performance of the geogrid reinforced samples by showing higher resilient modulus for reinforced samples than the unreinforced specimens. The performance of the geogrid reinforced base layers was further verified by studying the pressure distribution at the subgrade level and by calculating the stress distribution angle corresponding to the reinforced and unreinforced samples. The strains at the subgrade level were also studied and compared with the unreinforced sample which showed a better performance of geogrid reinforced samples. The results from the strain gauges fixed in the geogrid were further used to model and validate the permanent deformation model. Experiments were conducted on geogrid-reinforced base layer placed above weak subgrade conditions. The results showed that the reinforcement was effective in reducing the deformations under weak subgrade conditions also. Apart from conducting the laboratory studies, experimental results were numerically modeled to accurately back-calculate the resilient moduli of the layers used in the study. 3D numerical modeling of the unreinforced and honeycomb shaped geocell reinforced layers were carried out using finite element package of ANSYS. The subgrade layer, geocell material, and infill material were modeled with different material models to match the real case scenario. The modeling was done for both static and repeated load conditions. The material properties were changed in a systematic fashion until the vertical deformations of the loading plate matched with the corresponding values measured during the experiment. The experimental study indicates that the geocell reinforcement distributes the load in the lateral direction to a relatively shallow depth when compared to the unreinforced section. Numerical modeling further strengthened the results of the experimental studies since the modeling results were in sync with the experimental data.

A compositionally graded Ti-xCr (10≤x≤30 wt%) alloy has been fabricated using Laser Engineered Net Shaping (LENSTM) to study the microstructural phase evolution along a compositional gradient in both as-deposited and heat treated conditions (1000°C followed by furnace cooling or air cooling). The alloys were characterized by SEM BSE imaging, XRD, EBSD, TEM and micro-hardness measurements to determine processing-structure-property relations. For the as-deposited alloy, α-Ti, β-Ti, and TiCr2 (C15 Laves) phases exist in varying phase fractions, which were influential in determining hardness values. With the furnace cooled alloy, there was more homogeneous nucleation of α phase throughout the sample with a larger phase fraction of TiCr2 resulting in increased hardness values. When compared to the air cooled alloy, there was absence of wide scale nucleation of α phase and formation of ω phase within the β phase due to the quicker cooling from elevated temperature. At lower concentrations of Cr, the kinetics resulted in a diffusionless phase transformation of ω phase with increased hardness and a lower phase fraction of TiCr2. In contrast at higher Cr concentrations, α phase separation reaction occurs where the β phase is spinodally decomposed to Cr solute-lean β1 and solute-rich β2 resulting in reduced hardness.

No description available.

<p>In the United States, buildings are responsible for almost 40% of the country’s total energy consumption and 38% of the total greenhouse gas emissions. Researchers are constantly seeking sustainable and efficient energy generation solutions for buildings as society continues to cope with the intensifying energy crisis and environmental deterioration. Thermoelectric technology is one such solution that potentially can lead to significant energy recovery and conversion between waste or excess thermal energy and electrical energy. One promising application is integrating thermoelectric materials into the building envelope (TBE) for power generation and building heating and cooling without transporting energy among subsystems and refrigerant use. TBE can combine structural support and thermal storage with power generation and thermal-activated cooling and heating, thereby contributing to sustainable living and energy. </p> <p>TBE technology is still in its early development stages. This dissertation aimed to develop a fundamental understanding of the characteristics, behaviors, operation, and control of TBE systems as energy-efficient measures for thermal energy harvesting and thermal comfort regulation and to address the significant research gaps concerning high-conversion efficiency materials and optimal module configuration as well as system deployment related to real-world applications. Accordingly, this dissertation focused on the following three key objectives: (1) development and characterization of new thermoelectric composite materials; (2) identification of optimal designs and controls of TBE and established mathematical models for performance simulation; and (3) quantification of the energy-saving benefits of TBE. </p> <p>The following five aspects specifically were investigated:</p> <p>(1)<em> Material development and characterization</em>. New thermoelectric cement composites were developed with cement and various additives, material concentrations, and fabrication methods in the laboratory. Their thermoelectric properties (e.g., Seebeck coefficient, thermal conductivity, electrical conductivity, power factor, and the figure of merit) were measured simultaneously and characterized at 300–350 K.</p> <p>(2)<em> Module evaluation.</em> Commercially available thermoelectric modules (TEMs) were assessed using well-designed test apparatus in both the heat pumping and power generation modes. The test results validated the numerical model, which assisted with performance comparison and material selection between cement-based and commercial TEMs for the TBE prototype.</p> <p>(3)<em> Prototype assessment. </em>A convective TBE prototype and a radiant TBE prototype were designed, assembled, and evaluated in a pair of controlled testing chambers. The TBE’s surface temperature, thermal capacity, and COP were assessed under summer and winter conditions. </p> <p>(4)<em> Prototype modeling. </em>The first-principle-based numerical models of both the convective and radiant TBE prototypes were developed in Modelica. The modeling results indicated good agreement with the experimental data. The verified models were used to study the impacts of the design parameters and operating conditions on the heat pumping performance of TBE.</p> <p>(5)<em> System simulation. </em>A TBE building system model was established by integrating the TBE prototype model within a building’s heat balance model, considering the building construction, climate condition, power control, etc. Its seasonal performance under various climate conditions was studied to identify the potential optimal operation and energy savings. </p> <p>This dissertation confirmed several key findings in the areas of material development, system design and operation, and energy savings. The TBE achieved higher efficiency with a heat pump for heating than for cooling generally. The TBE heating system performed better than a conventional electric heater (efficiency assumed at 0.9). The measures that improved TBE heating efficiency were enhancing the material’s thermoelectric properties, optimizing the geometry and number of TEMs, and improving the boundary heat transfer of TEMs. </p> <p>This dissertation concluded that the TBE system is a promising alternative to conventional heating systems in buildings. Furthermore, the knowledge gained will strengthen the understanding of thermoelectrics in the building domain and guide further development in TBE, as well as facilitate the operation of net-zero energy and carbon-neutral buildings. </p>

No description available.

An urgent transformation from fossil fuels to cleaner energy sources to combat climate change has led to the utilization of renewable energies like solar, wind, and tidal power. However, the intermittency of these sources hinders their wider implementation. To address this, large-scale electrical energy storage (EES) systems are needed. These systems store excess energy during periods of surplus and release it during peak demand, enhancing grid reliability. Secondary batteries have been developed as promising EES solutions due to their reliability, independence from weather, and ease of maintenance. While lithium-ion batteries (LIBs) are popular as secondary batteries, their limited lithium supply, and rising costs demand for cost-effective alternatives. This study focuses on developing sodium iron fluorophosphate (Na2FePO4F) as a promising cathode material for SIBs. Because of its iron-based composition, which is generated from sustainable sources, Na2FePO4F offers a potential solution to the cost and supply difficulties related with LIBs. However, challenges exist, including low electronic conductivity and inferior electrochemical performance. To address these challenges, this research explores mechanochemically assisted solid-state synthesis routes as a low-cost and environmentally friendly approach. The characterization and performance evaluation of Na2FePO4F (NFPF) and NFPF/C positive electrode materials for sodium-ion batteries (SIBs) were systematically investigated through a range of analytical techniques, including XRD, TGA, SEM-EDS, FT-IR, and Raman analyses. A single-step solid-state synthesis demonstrates effectiveness in producing NFPF and NFPF/C-positive electrode materials. Moreover, Fe2O3 nanoparticles serve as the primary iron source in the solid-state synthesis of iron-based fluorophosphate Na2FePO4F/C, successfully producing both NFPF pristine phase and NFPF carbon-coated active materials. Finally, a comparison between the two synthesis pathways reveals that the active material from single-step solid-state synthesis exhibits a superior initial discharge specific capacity of 74.24 mAh⋅g−1 at 0.005 C, outperforming the double-step solid-state synthesis. These findings can contribute to the development of affordable and sustainable energy storage solutions, offering alternatives to traditional LIBs. / En akut omvandling från fossila bränslen till renare energikällor för att bekämpa klimatförändringarna har lett till ett utnyttjande av förnybar energi som sol-, vind- och tidvattenkraft. Emellertid hindrar dessa källors intermittenser deras bredare genomförande. För att komma till rätta med detta behövs storskaliga system för lagring av elektrisk energi (EES). Dessa system lagrar överskottsenergi under perioder med överskott och släpper ut den under toppbelastning, vilket förbättrar nätets tillförlitlighet. Sekundära batterier har utvecklats som lovande EES-lösningar på grund av deras tillförlitlighet, väderberoende och enkla underhåll. Medan litiumjonbatterier (LIB) är populära som sekundära batterier, kräver deras begränsade litiumtillgång och stigande kostnader kostnadseffektiva alternativ. Denna studie fokuserar på att utveckla natriumjärnfluorfosfat (Na2FePO4F) som ett lovande katodmaterial för SIB. På grund av sin järnbaserade sammansättning, som genereras från hållbara källor, erbjuder Na2FePO4F en potentiell lösning på kostnads- och försörjningssvårigheter relaterade till LIB. Men det finns utmaningar, inklusive låg elektronisk konduktivitet och sämre elektrokemisk prestanda. För att möta dessa utmaningar undersöker denna forskning mekanokemiskt assisterade syntesvägar i fast tillstånd som ett billigt och miljövänligt tillvägagångssätt. Karakteriseringen och prestandautvärderingen av Na2FePO4F (NFPF) och NFPF/C positiva elektrodmaterial för natriumjonbatterier (SIB) undersöktes systematiskt genom en rad analytiska tekniker, inklusive XRD, TGA, SEM-EDS, FT-IR och Raman analyser. En enstegs solid state-syntes visar effektivitet vid framställning av NFPF och NFPF/C-positiva elektrodmaterial. Dessutom tjänar Fe2O3-nanopartiklar som den primära järnkällan i solid state-syntesen av järnbaserat fluorfosfat Na2FePO4F/C, vilket framgångsrikt producerar både NFPF orörd fas och NFPF kolbelagda aktiva material. Slutligen avslöjar en jämförelse mellan de två syntesvägarna att det aktiva materialet från enstegs-solid-state-syntes uppvisar en överlägsen initial urladdningsspecifik kapacitet på 74,24 mAh⋅g−1 vid 0,005 C, vilket överträffar dubbelstegs-solid-state-syntesen. Dessa resultat kan bidra till utvecklingen av prisvärda och hållbara energilagringslösningar, som erbjuder alternativ till traditionella LIB.