Luleå University of Technology Publications
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Water-lubricated high-performance polymers
No full textPolymer-composites are indispensable tribo-materials in a wide range of engineering applications, including gears, bearings, joint implants, and automotive components. In many of these applications the presence of liquid lubricant is unavoidable, requiring a thorough understanding of composite behaviour under lubricated conditions. However, with growing emphasis on environmental safety, the use of petroleum oil-based lubricants, especially near aqueous environments, such as ships, pumps and turbines, has become increasingly dubious. Estimates suggest that of the 30–40 million tonnes of lubricant used annually, around 55% may eventually re-enter the environment, with approximately 95% of these being petroleum-based. These systems contribute to emissions and resource depletion, driving interest in the development of lubricant technologies free from petroleum-derived products. Some potential replacements to them are acceptable alternate lubricants like esters and glycerol, or mere water, which is abundantly available and emission free. The tribological performance of polymer composites often differs between dry and lubricated conditions, as contribution from polymer and fillers are observed to vary across environments. While numerous studies have explored the role of various fillers in water lubricated conditions, limited knowledge is available on other alternate lubricants. More recently, the focus on polymer-composite side has shifted towards multi-filler systems, which, when working synergistically, can provide superior performance compared to having a single filler. However, the existing literature lacks clarity on several key aspects: including the individual roles of filler material and scale; the nature and effect of filler–filler and filler–lubricant interactions to overall performance. This thesis investigates these gaps and provides deeper insights into the mechanisms governing the lubricated tribological behaviour of multi-filler polymer composites
Biokolproduktion i fluidiserad bädd reaktörer
No full textThis study explores the production of biocarbon from forest biomass through pyrolysis in fluidized bed reactors, emphasizing the relationship between the operating conditions, ash behavior, and physicochemical properties of the resulting solid biocarbon. Fluidized bed reactors offer distinct advantages for biocarbon production, including efficient heat transfer, isothermal operation, and scalability. These characteristics make them particularly suitable for integration into existing energy infrastructures. A key strategy investigated in this study is the use of a weakly oxidizing atmosphere composed of recycled flue gases from combustion processes as the fluidization medium. This approach enables heat integration with fluidized bed boilers and reduces the need for external inert gases, thereby lowering operational costs and improving the overall energy efficiency and circularity of the system. The impact of this atmosphere on biocarbon yield and composition was studied in detail, particularly regarding its influence on the behavior of ash-forming elements and textural properties. Special attention is given to the transformation and retention of ash-forming elements, such as potassium and phosphorus, which affect the suitability of biocarbon for industrial applications. The experimental and modeling results show that fluidized bed conditions favor the selective removal and distribution of these elements. Analytical techniques, including inductively coupled plasma (ICP), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and thermodynamic equilibrium calculations (TECs), were used to assess the mechanisms of ash transformation. In parallel, the evolution of particle properties, such as size, density, porosity, and surface area, was evaluated under different conversion regimes. Structural degradation owing to attrition and fragmentation was found to play significant roles in carbon retention and fines generation. Preliminary pilot-scale tests conducted with a different woody feedstock showed trends similar to those observed at the laboratory scale when comparable devolatilization severities were applied, reinforcing the transferability of key process–property relationships. Overall, these findings support the development of integrated and sustainable fluidized bed systems for biocarbon production, offering practical pathways to reduce fossil carbon use and improve resource efficiency in biomass valorization processes
Assessment of Waveform Distortion Interactions in Electric Railway Power Systems
No full textRailway electrified systems are one of the most popular and essential forms of transportation globally, and the performance of those systems impacts society. The electric railway power systems (ERPS) comprehend the infrastructure and apparatus that aims to deliver power for the rolling stocks in different types of railway transportation. Due to the broad application of static power electronics, ERPS is characterized by several sources of waveform distortion. Waveform distortion is a critical power quality (PQ) issue and a challenge to managing electromagnetic compatibility (EMC) in railway systems. It englobes harmonics (disturbances synchronous with the fundamental power frequency up to 2 kHz), interharmonics (disturbances asynchronous with the fundamental power frequency up to 2 kHz), and supraharmonics (synchronous and asynchronous disturbances between 2 and 150 kHz). The ERPS has several system complexities that should be taken into consideration when assessing waveform distortion related to the characteristics of the phenomena: extensive distribution system with intricate circuit arrangements and moving single-phase loads; multiple voltage levels and electromagnetic environments, including railway grid and subsystems, as well as public grid; waveform distortion has time-varying behavior dependent on operating states of rolling stock, traffic plan, grid balancing, and spatial position of the vehicles; a mix between traditional equipment or infrastructure and population of new power electronic conversion stages with a lack of guidelines and standardization; and variety of waveform distortion sources and signatures. The objective of this research is to gain knowledge and a better understanding of waveform distortion, including not only harmonics but also interharmonics and supraharmonics in railways systems, to characterize emission sources, propagation, the impact of the operation on time-varying behaviors in several scales, interaction among systems and subsystems, and adverse effects. The focus of the work is alternating current (AC) electrified railways, with a deeper assessment of, but not limited to, the railway system solution of Sweden (15 kV 16 ⅔ Hz). The development and scope of this work provide a comprehensive literature review of waveform distortion assessment for electrical railway power systems and build up a framework for future contributions, characterization of waveform distortion for electrical railway power systems using measurements, conduct detailed measurements on waveform distortion in a traction converter station, modeling waveform distortion propagation for ERPS considering complexities of the system, application of unsupervised deep learning (DL) methods to find patterns in waveform distortion data and investigation of the impacts related with those issues. The research contributions from those defined scopes are summarized below. · Identification of the challenges of waveform distortion assessment in ERPS and categorizing the available literature to address some of those challenges. · Characterization and screening of the waveform distortion time-varying dependencies in different time scales. · Providing a methodology for assessing time-varying waveform distortion in railway systems, adapting traditional methodologies, advanced statistical analysis, and machine learning approaches. · Modeling waveform distortion interaction within the ERPS in Sweden, incorporating challenges such as moving loads, meshed grid analyses, and a wide range of disturbances propagation in ERPS. · Addressing the different mechanisms affecting waveform distortion at the catenary and public grid sides. · Investigation of the impact of waveform distortion performance on associated equipment. The work provides crucial steps for better establishing a PQ framework and future standardization for waveform distortion in ERPS by exploring multiple aspects and directions on the assessment side
Tribological performance of novel bio-based polymer composites
No full textVarious industrial and societal developments in recent times are connected to climate change, sustainability, and green technology. Among these are legislations and directives from governing bodies and institutions, as well as research efforts and investments from academia and industry. One major example of an institution getting involved is that of the United Nations (UN) who published their UN Sustainable Development Goals (SDG) in 2015, in which they define pathways to a more sustainable future. A number of these goals are directly associated with the adaptation and development of sustainable engineering solutions, including enhanced resource and energy efficiency. The selection of materials in a tribological context (i.e. the study of surfaces in contact and motion) plays a major role in achieving these objectives, directly impacting resource efficiency. Frictional losses in machines and equipment and the wear of their constituents have a direct impact on the energy efficiency and sustainability of systems. An important class of tribo-materials are polymeric components. Especially thermoplastic polymers and their composites have gained significant importance in sectors like green energy production or transportation over the last few decades due to their favourable strength-to-weight ratio, corrosion resistance and, in many cases, self-lubricity, as well as their overall tailorable properties. However, they are mostly produced from ecologically undesirable fossil-based resources. Bio-based options both for reinforcements and matrix polymers to this day often lack strength or consistency of properties. In the spirit of these aspects, this thesis explores the development and characterisation of high-performing thermoplastic composites containing or consisting of bio-based materials, focusing on their thermal and mechanical properties, morphology, and tribological performance. Polyoxymethylene (POM) and polyamide 11 (PA11) were selected as matrix materials in this work as they are already widely employed in tribological applications, but often in combination with fossil-based reinforcements. They possess appreciable mechanical strength, temperature stability, and chemical resistance. Their higher hydrophilicity compared to other common engineering thermoplastics, furthermore, makes them favourable choices for combining with natural-based materials. PA11 moreover contributes to the aspect of sustainability by virtue of being fully bio-based. Short regenerated cellulose fibres and cellulose nanocrystals (CNC) were selected as reinforcements based on their outstanding mechanical strength and higher thermal stability compared to other bio-based fillers. The short cellulose fibres were added to POM, while the CNCs were incorporated into PA11, both via melt-mixing processes leading to homogeneously dispersed systems in both cases. The gathered results on the POM composites showed a significant increase in strength under tension and flexion at the highest fibre content as well as a rise in crystallinity upon introduction of the reinforcements. Tribological evaluations have shown that the fibre addition led to an in individual cases substantial and in general noticeable reduction of the wear coefficient at a wide range of conditions, both in preliminary tests and in the subsequent p · v range assessment. The effect on the coefficient of friction, however, was on average detrimental, especially at the lower tested speed of 0.5 m · s−1. Nevertheless, the short cellulose fibres stabilised the friction behaviour of POM at harsher p · v conditions. A main reason for these improvements was the change in tribofilm formation towards a higher coverage of the wear track, protecting the polymer samples from the asperities of the countersurface discs. Using CNC, notable improvements of the crystallinity, compressive strength and thermal stability of the polymer and its properties were achieved. The CNC also reduced the wear coefficient of PA11 by close to 90 % and was instrumental for the tribofilm formation on the countersurfaces. Additionally, the coefficient of friction decreased as well, most likely explained through the increased presence of polymeric material on the countersurface discs, while also crystallinity further increased through possible strain-induced crystallisation. Raman spectroscopy, moreover, was proven to be a capable non-destructive evaluation method for tribofilm morphology, providing highly valuable insights for understanding wear and friction mechanisms that are otherwise often difficult to obtain. The effect of annealing at different parameters on the PA11-based composites was evaluated as well and found to be an important influence factor for crystallinity, crystal structure and tribological properties. Further improvements of especially the wear coefficient were obtained, leading to a total reduction of more than an order of magnitude when compared to the as-processed neat PA11. Reducing the coefficient of friction by thermal post-processing was successful as well, which again is assumed to be rooted in the aforementioned change in tribofilm formation and appearance as well as adjustments of the crystal structure, as proven by X-ray diffraction (XRD) experiments. Overall, the cellulosic materials at both size scales improved the wear resistance of either matrix polymer significantly, while also in certain circumstances providing a lower coefficient of friction. In conclusion, this work shows the potential of bio-based reinforcements and composites to be successfully employed as engineering composite materials for load-bearing applications
Behandling av partiklar och metaller från dagvatten : Laboratoriemetoder och utvärdering i fält
No full textSuspended solids and metals are recognized as key pollutants in stormwater runoff. Thus, stormwater treatment systems have become increasingly vital components of urban infrastructure, playing a key role in reducing pollutant loads entering receiving water bodies. This thesis focuses on evaluating the treatment of solids and metals in stormwater systems, through both controlled laboratory experiments and field-based assessments. Synthetic stormwater is widely used as a substitute for real runoff in both laboratory and field experiments. Its main advantages are the ability to control influent quality and quantity, as well as to improve the repeatability of experiments. However, no standardized formulation currently exists. A critical review which was conducted to evaluate the use of synthetic stormwater in experimental stormwater research revealed substantial variation among studies. Based on these findings, a narrower set of pollutant concentration ranges was suggested to enhance the comparability, repeatability, and reproducibility of future experiments. The experiments evaluating design parameters of a suggested Bottom Grid Structure demonstrated that hydraulic modifications of settling areas in the stormwater treatment systems could enhance sedimentation, though the results were not directly scalable to field conditions. Among the variable factors in the experiment, inclined cell walls of the Bottom Grid Structure had the strongest effect, increasing sedimentation by up to 22% compared to control runs. Column studies showed peat and bark to be the most effective filter materials for dissolved Zn removal, although the use of peat is associated with significant drawbacks regarding other pollutants and uncertainties about its long-term performance. Evaluated zeolite filter system treating copper roof runoff achieved high removal of Cu (49–85%) and Zn (48–94%) but exhibited declining performance over time. A field study examining the performance of two EcoVault facilities revealed relatively low TSS removal (40–46%), substantially below both previous EcoVault studies and manufacturer claims. Dissolved metals were inadequately removed, likely due to elevated hydraulic loading rates and progressive filter clogging. Sedimentation was identified as the dominant treatment mechanism, while the zeolite filter cassettes provided negligible additional metal removal. The field experiments underscored the importance of site-specific design of stormwater treatment systems, especially in cases where the influent is dominated by dissolved metals. Despite their limited performance, underground treatment systems remain a practical solution in densely built urban environments where surface space is constrained. However, targeted design improvements are essential to enhance treatment efficiency. Furthermore, comparisons with commonly used models for the prediction of the performance of stormwater treatment systems revealed that actual removal rates were approximately 50% lower than estimated values, highlighting the need for additional field-based data to improve model calibration and support the development of more reliable and context-sensitive stormwater treatment strategies
Performance of Lower-Carbon Concretes After High-Temperature Exposure
No full textThis research was initiated in response to the urgent need to reduce CO₂ emissions, the ongoing green transition within the building materials sector, and the persistent gap in both knowledge and practice regarding the performance of environmentally friendly concretes under high-temperature exposure. The study investigates the behaviour of concrete and paste mixtures incorporating ground granulated blast furnace slag (GGBFS) and calcium sulfoaluminate (CSA) cement following one hour of exposure to elevated temperatures. Mechanical testing, chemical analysis, including real-time monitoring during heating, and microstructural observations were used to evaluate thermal damage and to understand the materials’ response under those conditions. Various binder types, fillers, fibres, and admixtures were examined to assess their influence and to identify both strengths and limitations. The results demonstrated a beneficial effect of GGBFS in systems based on Portland cement, particularly in enhancing residual strength and thermal stability. In CSA-based systems, the inclusion of eggshell powder (ESP) was found to contribute positively to post-fire performance. On the other hand, certain admixtures caused unexpected disturbances at high temperatures, suggesting the need for careful compatibility and awareness of mix when designing thermally resistant concretes. The experimental programs were designed as an initial step toward broader exploration and formed a key component of an ongoing research effort. The findings are intended to support and complement existing studies in both academia and industry, with the goal of improving the fire resistance and overall durability of sustainable concrete materials
Experiments and CFD simulations of spillway discharge distribution
No full textHydropower plants in Sweden has a long history dating back to the early 20th century. In the design of these, now old facilities, expected probable flows were based on recorded precipitation data. As a safety valve of the dam various types of spillway can be installed, to either spill water when no power is produced. Or to regulate water levels above and below the dam to prevent or mitigate flooding, and to be able to prevent overtopping of a dam. As the climate is ever changing, and now average temperatures climb, this leads to an increase in both average annual precipitation and likelihood of expected flood events in Sweden. This leads to a case of old infrastructure designed for old conditions, which now may exceed flow discharge capabilities for safe operations. A need for reevaluation of the existing dam fleet is needed to explore if it can face the new conditions brought by increased precipitation. Previous work has been done by Computational Fluid Dynamics (CFD) to compare scale model data of existing dams, recorded when they were designed. Such comparisons show mostly low differences between the CFD simulations and scale model results, in the range of 1-2%. Some show as much as 10%. With CFD now being a standard tool in many industries involving fluid mechanics, there are several guidelines on how to perform CFD with respect to quality. However CFD is an approximate science and the physics needs to be simplified by a number of models with inherent limitations. Hence to gain trust in CFD simulations for dam operators there needs to be validation cases. Validation cases for single outlet spillway setup exist, but dams often do not have geometries as simple as the existing validation cases. Hence, a need for well defined experiments for CFD validation of hydraulic designs. This thesis aims to provide experimental data suitable for use in evaluating CFD methods for assessing spillway capacity. To this endeavour a purpose built experimental setup was designed to produce experimental data of a quality and complexity not found elsewhere today. The main feature of the experiment is three outlets with the capability of recording the discharge passing through each outlet individually. Other tools used for evaluating flow conditions in the channel include Acoustic Doppler Velocimetry. The results consists of experimental data gathered for three different variations of the experimental geometry. First a Deep channel flowing past a sharp corner, which produced low velocities in the channel leading up to the outlets. A second variation where the channel floor was raised to induce larger velocities in the flow leading up to the outlets, for increased differences in the flow distribution between the different outlets. As a final variation, the channel width was reduced leading to even higher velocities, and larger differences in both waterlevels at different points in the experimental channel, and in the discharge recorded in the different outlets. The distribution of the flow discharge across the outlets varies with the different geometries, and with the different inflows tested. At low flows differences in distribution between the outlets were negligible, especially with the first channel layout. At higher flows the differences grow, and show clear differences that should be replicable in simulations. Thus showing results that could be used for validation of CFD methods in regards to flow distribution across a spillway with multiple outlets. Additional data to use for validation include ADV data gathered in the channel leading up to the outlets, which documents recirculation zones introduced due to the geometries. As potentially simulations could produce flow distribution results that are correct while not simulating flow behaviour correctly
The Effectiveness of Environmental Regulations: Design, Implementation and Institutional Context
No full textThis doctoral thesis consists of an introductory preface and five independent papers, which all address the effectiveness of environmental regulations. The focus is on how regulatory design and implementation as well as institutional context could influence the outcomes of industrial pollution control. Paper I investigates the impact of performance standards on the Chemical Oxygen Demand (COD) discharges from Swedish pulp and paper mills over a four-decade long period. The analysis employs an instrumental variable estimation of the fixed effects panel data model and data for 22 individual mills. The results show that these COD standards have led to significant reductions in water pollution from the mills. However, the magnitudes of this effect differ across two regulatory regimes in Sweden, thus highlighting the role of the institutional context in which the environmental regulations have been embedded. Paper II focuses on how the adoption of compliance periods, i.e., granting industry extended deadlines to comply with new standards, has affected pollution reductions. This regulatory tool is discussed conceptually, and the empirical analysis relies on an extended version of the above data set, and a Panel Vector Autoregressive model. The results illustrate that the combination of COD discharge standards and compliance periods has been effective in reducing water pollution. High regulatory capacity will improve the effectiveness of this type of regulation. Paper III investigates the factors that help explain the duration of environmental licensing processes and devotes particular attention to the role of incomplete license applications. Theoretically, the industrial actors might have an incentive to submit environmental impact assessments (EIAs) that have a high risk of being deemed inadequate by the authorities. The analysis relies on an Accelerated Failure Time (AFT) model and data covering 1606 environmental licensing processes in Sweden, and that reached a final decision during the time-period 2018-2022. The results confirm that the high prevalence of incomplete applications has been strongly correlated with prolonged environmental licensing processes. The purpose of Paper IV is to investigate how environmental licensing procedures can be implemented, and the regulatory requirements designed, to regulate pollution without jeopardizing investments in novel zero-carbon or digital projects. This is achieved in the context of two licensing processes: Northvolt’s battery factory in the city of Skellefteå and Facebook’s data center in Luleå. The empirical analysis builds on an analytical framework, which provides the conceptual anchor for 20 semi-structured interviews with key persons involved in these two processes. The findings are consistent with the notion that well-functioning licensing processes will be characterized by three general attributes: flexibility, predictability and knowledge. These can be attained within the realms of existing legislation, in turn suggesting that successful green and digital transitions are likely not contingent on comprehensive legal reforms. Finally, Paper V provides a brief and conceptual discussion of the choice between economic instruments, e.g., taxes, and performance standards in environmental policy. This paper questions the claim that the former unequivocally represents a superior policy approach for mitigating pollution. Based on recent research, it is argued that the zero-carbon transition involves specific challenges that tend to strengthen the case for the use of standards. Moreover, standards-based regulations are not necessarily implemented as crudely as some economic models assume, and efforts could be undertaken to reduce compliance costs and encourage green technological change. Overall, the findings in this thesis are consistent with the notion that such efforts ought to acknowledge the entire set-up of the regulatory system, including knowledge generation and information-sharing as well as the nature of the relationship between regulators and industry
Artificiell Intelligens i Experimentell Strömningsmekanik : Partikelbaserad Optisk Flödesuppskattning
No full textArtificial intelligence (AI) is reshaping the landscape of experimental fluid mechanics by transforming how flow information is extracted, interpreted, and modeled. Despite its potential, adoption remains cautious, constrained by the perception that Artificial Neural Networks (ANNs) operate as opaque 'black boxes' lacking explicit physical grounding. This dissertation addresses that skepticism by demonstrating that, when purposefully designed, adapted, and constrained by governing equations, Deep Learning can function as a transparent and reliable extension of classical measurement science, capable of reconstructing temporally consistent and physically meaningful results directly from raw measurements. As experimental and computational capabilities expand, fluid mechanics now operate in a regime where the volume, resolution, and dimensionality of data far exceed what classical analysis frameworks were designed to handle. Extracting coherent flow information from such datasets requires methods capable of modeling nonlinear image dynamics, capturing long-range spatial interactions, and integrating temporal evolution. Deep Learning, with its inherent quality of hierarchical representation learning, offers an alternative paradigm: one that learns motion representations directly from raw experimental data. However, its successful integration into measurement science requires rigorous benchmarking, explicit physical grounding, and architectural innovation. This work advances the state-of-the-art in Particle Image Velocimetry (PIV) through the development of Deep Learning-based architectures for optical flow estimation, that couple spatial attention, temporal reasoning, and physics-informed learning. The thesis begins with a systematic experimental evaluation of recurrent optical-flow estimation neural networks on canonical cylinder-wake datasets, quantifying how performance of these networks varies with seeding density, particle size, and flow regime (Paper A). These analyses reveal that while well-established Deep Learning-based models for PIV, such as RAFT-PIV (Recurrent All-Pairs Field Transforms) successfully recover dominant flow structures, their accuracy degrades in regions of strong shear, separation, or low signal-to-noise ratio, highlighting the need for architectures that reason globally and adapt to experimental variability. To address these limitations, a Vision Transformer (ViT)-based architecture, Twins-PIVNet, is introduced to leverage spatial self-attention for capturing multi-scale particle motion beyond the reach of conventional convolutional networks (Paper B). By learning global contextual relationships directly from raw particle images, Twins-PIVNet improves robustness and accuracy across a broad range of flow regimes and achieves sub-second inference, demonstrating the effectiveness of attention-based feature extraction for handling real-world PIV complexity. Temporal coherence, an essential yet often overlooked attribute of experimental velocimetry, is then addressed through TriP-Net model, a multi-frame architecture that departs from the traditional two-frame paradigm used in most Deep Learning-based PIV (Paper C). By incorporating three consecutive particle images, TriP-Net captures higher-order temporal dynamics, yielding velocity fields with smoother evolution and reduced continuity errors. Building on this foundation, the framework is further extended into ADHD-PIV, a physics-informed architecture trained on four-frame sequences (Paper D). By coupling self-attention with recurrent updates and embedding adaptively weighted divergence and acceleration constraints, ADHD-PIV produces flow fields that better respect conservation laws and maintain stability over extended temporal windows. Together, these contributions move Deep Learning-based PIV from purely spatial inference toward fully temporal, physics-constrained flow reconstruction. Collectively, these developments establish a unified and scalable methodology for Deep Learning in experimental fluid mechanics, one that is data-efficient, interpretable, and firmly grounded in physical principles. The models presented in this thesis reconstruct flow fields with sub-pixel precision and enhanced temporal coherence, enabling real-time analysis suitable for intelligent Digital Twins and advanced optical metrology (Paper E). By integrating high-fidelity experiments with self-supervised and physics-aware learning strategies, the work demonstrates how AI can evolve from a post-processing tool into a core component of measurement science, supporting real-time sensing, predictive diagnostics, and adaptive control. Ultimately, this thesis contributes both conceptually and practically to the integration of Artificial Intelligence in fluid mechanics, showing that trust in artificial neural networks arises not from revealing their internal algebra but from embedding the governing laws of fluid motion within them. The findings redefine how experimental flow measurements are performed and offer a pathway toward autonomous diagnostics and adaptive Digital Twin systems for complex thermal–fluid environments
Designed Fluorine-Free Ionic Liquid-Based Electrolytes for Next-Generation Supercapacitors
No full textEnergy storage is a crucial element of green transition that drives the growth of technology, and its importance is progressively increasing. The expanding demand for reliable power sources necessitates the development of innovative methods to balance energy production and consumption. Among energy storage devices (ESDs), supercapacitors are considered superior due to their outstanding power, swift charging, long lifespan, and sustainability. The ion mobilities in supercapacitors are mainly determined by the electrolyte, which further influences the charge transfer, voltage, and total power holding capacity. Due to the critical role of electrolytes in supercapacitors, several advancements are made in the design of the electrolyte to increase voltage strength and energy density. The electrolytes for supercapacitors include aqueous-based, organic solvent-based, ionic liquids (ILs) and solid-state electrolytes. Among them, IL-based electrolytes are the most suitable electrolytes due to their combination of beneficial physical and electrochemical properties. However, more than 95 % of the IL-based electrolytes are heavily based on fluorinated compounds, which are creating serious problems not only in the synthesis and implementation levels but also at the recycling stage. There is an urge to develop fluorine-free and non-flammable functional electrolytes for enabling next-generation supercapacitors. This thesis is an attempt to elevate energy storage technology by providing economically and environmentally efficient solutions in terms of fluorine-free IL-based electrolytes for next-generation supercapacitors. The main aim is to design and identify Fluorine-Free Ionic Liquids (FFILs) as electrolytes for efficient next-generation supercapacitors. The first part of this thesis (Paper I) is focused on the synthesis, physical characterization, and transport as well as electrochemical properties of a novel class of ten FFILs derived from biomass. The biomass derived anions such as furan-2-carboxylate [FuA] and tetrahydrofuran-2-carboxylate [HFuA] are coupled to a range of nitrogen heterocyclic cations to create the FFILs, for which the nature of cation controlled their properties. The second part (Paper II) is dedicated to the synthesis and characterization of dialkylphosphate-based FFILs, that offered high thermal decomposition and low glass transition temperatures, and high ionic conductivities as well as high electrochemical stabilities. Further, their performance as electrolytes in symmetric supercapacitors showed high coulombic efficiency and capacity retention even after long charge-discharge cycles. The part three (Paper III) presents the synthesis, physical and electrochemical characterization of two novel fluorine-free zinc salts and their electrolytes derived from artificial sweeteners. The three-component zinc electrolytes are composed of either zinc saccharinate (Zn(Sac)2 or zinc acesulfamate Zn(Asf)2 salt, tetrabutylphosphonium saccharinate [P4444][Sac] IL, and γ-valarolactone (VL). These electrolytes demonstrated significantly long cycle life in Zn||Zn symmetric cells, while maintaining high capacity retention after extended cycles at a lower current density in an asymmetric hybrid supercapacitors (Zn||Ac)