| 1. |
- Ahmed, Mukhtiar, et al.
(författare)
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Pyrrolidium- and Imidazolium-Based Ionic Liquids and Electrolytes with Flexible Oligoether Anions
- 2024
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Ingår i: ChemPhysChem. - : John Wiley & Sons. - 1439-7641 .- 1439-4235. ; 25:9
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Tidskriftsartikel (refereegranskat)abstract
- A new class of fluorine-free ionic liquids (ILs) and electrolytes based on aliphatic flexible oligoether anions, 2-(2-methoxyethoxy)acetate (MEA) and 2-[2-(2-methoxyethoxy)ethoxy]acetate (MEEA), coupled with pyrrolidinium and imidazolium cations is introduced. For the ILs with MEEA anions, Li+ conducting electrolytes are created by doping the ILs with 30 mol % of LiMEEA. The structural flexibility of the oligoether functionality in the anion results in glass transition temperatures (Tg) as low as −60 °C for the neat ILs and the electrolytes. The imidazolium-based ILs and electrolytes reveal better thermal stabilities but higher Tg and lower electrochemical stabilities than the corresponding pyrrolidinium-based analogues. All neat ILs show comparable transport properties for the cations and these decrease by the addition of lithium salt – the pyrrolidinium-based electrolyte being affected the most.
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| 4. |
- Reddy, Akepati Bhaskar, Dr. 1990-, et al.
(författare)
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Ionic liquids enhance electrical conductivity of greases: an impedance spectroscopy study
- 2024
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Ingår i: Colloids and Surfaces A. - : Elsevier. - 0927-7757 .- 1873-4359. ; 683
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Tidskriftsartikel (refereegranskat)abstract
- Ionic liquids (ILs) have emerged as viable solutions for developing new-age lubricants, both as neat lubricants and lubricant additives. Enabled by the presence of discrete ions, ILs have the possibility to render electrically conductive lubricants, which is a feasible strategy for developing lubricant systems compatible with modern e-drive conditions. However, this requires the characterization of the electrical properties of lubricants, which is a bottleneck for developing electrically conductive greases, given their complex architecture. This work introduces an electrochemical impedance spectroscopy measurement methodology to evaluate grease samples' electrical properties. Compared to the commonly used conductivity meters, this method, through its multi-frequency alternating current (AC) impedance approach, can effectively distinguish the individual contributions of the bulk and the sample-electrode interface to the measured electrical response. Impedance spectra of grease samples are obtained using an electrochemical cell with parallel plate electrodes, mounted on a temperature-controlled cell stand and coupled with a potentiostat. The grease's bulk conductivity is extracted by fitting the impedance data to relevant equivalent electrical circuits. The bulk conductivity of lithium complex grease doped with ILs is evaluated and compared to greases with conventional conductivity additives (copper powder and conductive carbon black). The analysis of temperature-dependent conductivity reveals the rather different conductivity mechanisms for different additives. For greases doped with ILs, a comparison against the electrical conductivity of neat ILs reveals that, in addition to the ion dissociation, the interaction of the ions with the different grease components (base oil, thickener) is crucial in defining the grease conductivity.
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| 5. |
- Tatrari, Gaurav, et al.
(författare)
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Charge storage performance of a structurally flexible hybrid ionic liquid electrolyte
- 2024
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Ingår i: Energy Storage. - : John Wiley & Sons. - 2578-4862 .- 2578-4862.
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Tidskriftsartikel (refereegranskat)abstract
- The electrochemical and charge storage performance of a fluorine-free structurally flexible hybrid pyrrolidinium-based ionic liquid electrolyte (HILE) in a symmetric graphite-based supercapacitor is thoroughly investigated. The HILE revealed thermal decomposition at above 230°C, a glass transition (Tg) temperature of below −70°C, and ionic conductivity of 0.16 mS cm−1 at 30°C. The chemical and electrochemical properties are investigated using a systematic variable temperature 1H and 31P NMR spectroscopy and diffusometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The supercapacitor demonstrated a notable specific capacitance of 186 F g−1 at a scan rate of 1 mV s−1 and a specific capacitance of 122 F g−1 at a current density of 0.5 A g−1. The maximum energy density of 48.8 Wh kg−1, a power density of 450 W kg−1 at a current density of 0.5 A g−1, and a potential window of 4 V were obtained. Altogether, this study demonstrates that the new HILE can be used in symmetric graphite-based supercapacitors over a wide potential window of 4 V and a temperature range from −20°C to 90°C.
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| 6. |
- Tatrari, Gaurav, et al.
(författare)
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Designed metal-organic framework composites for metal-ion batteries and metal-ion capacitors
- 2024
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Ingår i: Coordination chemistry reviews. - : Elsevier. - 0010-8545 .- 1873-3840. ; 512
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Forskningsöversikt (refereegranskat)abstract
- The utilization of metal–organic frameworks (MOFs) in energy storage applications is constrained by their limited electrical conductivity and insufficient chemical robustness, posing various challenges and limitations. Nevertheless, research has demonstrated that MOF structures with exceptional porosity and adaptable architectures yield a wide range of composites, presenting promising prospects for improving their electrochemical performance in energy storage devices. When combined with other advanced materials, MOFs form composite structures overcoming these constraints by exhibiting superior electrical conductivity, electrochemical activity, and stability in comparison to pure MOFs. This article comprehensively overviews the designed chemistry of MOF-composites for metal-ion batteries (MIBs) and metal-ion capacitors (MICs). The synthesis and properties of various composites involving MOFs, including MOF-MXene, MOF-carbon nanomaterials (CNM)/graphene/carbon, MOF-transition metal oxide (TMO), MOF/polymers, MOF-derived layered double hydroxide (LDH), as well as the challenges and mitigation strategies have been discussed. A brief overview of MOF-composites as electrode materials for MIBs, including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (KIBs) is presented. The recent developments in MICs, such as lithium-ion capacitors (LICs), magnesium-ion capacitors (MGICs), zinc-ion capacitors (ZICs), sodium-ion capacitors (SICs), and potassium-ion capacitors (KICs) have also been included. Furthermore, the electrochemical performance of the MOF composites has been assessed using a range of metrics, including output voltage, capacity, cycle stability, energy density (ED), and power density (PD). A comprehensive analysis has also been conducted to identify potential obstacles and possible mitigations to explore future possibilities. Overall, a comprehension of MOF-based materials and potential approaches for enhancing the futuristic progression of MOF-composite materials for MIBs and MICs have been elucidated.
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| 7. |
- Tatrari, Gaurav, et al.
(författare)
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Synthesis, thermoelectric and energy storage performance of transition metal oxides composites
- 2024
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Ingår i: Coordination chemistry reviews. - : Elsevier. - 0010-8545 .- 1873-3840. ; 498
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Forskningsöversikt (refereegranskat)abstract
- Due to their intriguing electronic properties and structural composition, transition metal oxides (TMOs) such as AOx, AxOx, and AxB3-xOx; A, B = Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, etc., and their designed composites have tremendous potential in energy storage devices such as supercapacitors (SCs) and metal ion batteries (MIBs). Some outstanding properties of TMOs and their composites for applications as electrode materials in energy storage devices include their high conductivity, charge storage characteristics, doping potential, and composite forming propensity. The significant interactions of TMOs with heteroatoms, conductive polymers, and carbon nanomaterials (CNMs) drastically change the reactive parameters and electrical characteristics. This review covers the most recent advances in TMO research and development, ranging from mechanism design to device performance, with a main focus on essentials such as design, synthesis, manufacturing, and energy-storing properties. The electrochemical pyrolysis, in-situ preparation, solvothermal/hydrothermal approach, and other critical approaches and their implications are also discussed. The synergetic improvement of designed TMO/graphene, TMO/rGO, TMO/heteroatoms, TMO/polymers, TMO/halide/hydride, TMO/Chalcogens through ionic interactions, and investigation of the electrode–electrolyte interfaces have been discussed in detail. In addition, the effect of electrolytes, surface behavior, and performance evaluation parameters on the SC device performance have been included. Furthermore, parameters and models, reliability design and profile lifetime, common mistakes in performance evaluation of SC, and other obstacles and mitigation have been described in depth. Altogether, a well-grasped overview and potential strategies extended from the overall analysis of electrode materials and electrolytes are offered to lift advancement in developing futuristic materials for energy storage applications.
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| 8. |
- Xu, Yanqi, et al.
(författare)
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Fluorine-Free “Solvent-in-Salt” Sodium Battery Electrolytes: Solvation Structure and Dynamics
- 2024
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Ingår i: Energy Advances. - : Royal Society of Chemistry. - 2753-1457. ; 3:3, s. 564-573
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Tidskriftsartikel (refereegranskat)abstract
- The solvation structure, dynamics, and transport properties, as well as thermal and electrochemical stabilities of “solvent-in-salt” (SIS) electrolytes, also known as highly concentrated electrolytes, are far from fully understood. Furthermore, these special types of electrolytes are almost without exception based on fluorinated salts. In contrast, here we report on fluorine-free SIS electrolytes comprising ambient temperature liquid sodium bis(2-(2-ethoxyethoxy)ethyl)phosphate (NaDEEP) salt and tris(2-(2-ethoxyethoxy)ethyl)phosphate (TEOP) solvent, for which the ionic conductivities and ion diffusivities are altered profoundly as the salt concentration is increased. A careful molecular level analysis reveals a microstructure with a “solvent-rich” phase with almost an order of magnitude faster ion diffusion than in a “salt-rich” phase. Aggregated ionic structures in these SIS electrolytes lead to higher ionic conductivities alongside lower glass transition temperatures, <−80 °C, but also agreeable thermal stabilities, up to 270 °C, and improved anodic stabilities, possibly up to 7.8 V vs. Na/Na+ and at least >5 V vs. Na/Na+. Altogether, this provides a foundation for both better understanding and further development of fluorine-free SIS electrolytes for sodium batteries.
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