The utilization of 2,5-ditertbutyl hydroquinone (DTBHQ) as a potential active material in aqueous zinc-ion batteries (AZIBs) was studied for the first time. Thanks to its two hydrophobic groups, DTBHQ demonstrates a maximum solubility of 629 µM/L, significantly lower than that of other reported small quinone derivatives for AZIBs. This property translates to remarkable long-term capacity retention, even at a high electrolyte to active mass ratio. Significantly, our findings provide unequivocal support for a proton insertion mechanism as the main electrochemical process in the solid state in mono- and divalent aqueous electrolytes, thereby challenging the prevailing notion of metal-ion rocking-chair and zinc-ion mechanisms widely reported for aqueous batteries. This novel insight that holds for electrolytes based on metal- (K+, Zn2+ and Mg2+) and non-metal cations (NH4+ and NH3OH+) has profound implications for the understanding and development of aqueous batteries since the operating reduction potential was found to be directly proportional to the pKa values of the predominant acid/base couple of the tested aqueous electrolytes.
Abstract Multiphase flowmeters (MPFM) are used to measure oil, water, and gas volumetric flow rates in real time without phase separation. Field-proven MPFM play an important role in oilfield operations as the trusted flow measurements enable production optimization and flow assurance. However, accurate multiphase flow metering requires knowledge of the reservoir fluid properties. Therefore, operators require reliable methods to keep the MPFM configuration updated and representative of the production fluids. This is particularly important for subsea fields where physical access to the MPFM can be difficult. This paper describes a successful remote water-phase characterization leading to reconfiguration of a dual-energy spectral gamma ray MPFM for an oil well in a deepwater field offshore Ghana. Reconfiguration of the MPFM was performed using data from when the well was shut in and the flowmeter venturi throat was filled with water at static flow conditions. The data was taken from Subsea Live data-driven performance service from OneSubsea (the vendor), which offers real-time data for health, operational and production insights for subsea assets. The mass attenuation coefficients for water were updated in the MPFM configuration to more representative values, determined using historical data. After the remote reconfiguration, the reconfigured MPFM demonstrated good accuracy when benchmarked against topside separator measurements, showing a proper agreement between the estimated in-situ values using historical flow metering data and the experimental measurements for both high energy and low energy water mass attenuation coefficients.
Aqueous batteries face the challenge of limited energy density due to parasitic gas production from hydrogen and oxygen evolution reactions, particularly at the negative electrode. This study investigates the electrochemical properties and mechanisms of proton intercalation in anatase TiO2 featuring vacancies (Vac-TiO2), stabilized via a low-temperature sol–gel process. XRD refinement analysis, supported by thermal analysis, estimated 17% cationic vacancies, while 1H MAS NMR spectroscopy revealed stabilization of these vacancies by OH groups. The presence of cationic vacancies led to changes in the oxide anion sublattice, which accommodate proton insertion. Electrochemical assessments in acetate buffer electrolyte demonstrated Vac-TiO2's ability to delay the hydrogen evolution reaction and enhance proton capacity, validated by pH-dependent studies, DFT calculations, and kinetic analyses. Notably, the occurrence of undercoordinated oxide anions was shown to induce the insertion of H+ at higher potential values, and the insertion mechanism was suggested to occur via a solid-solution mechanism. Owing to these features, Vac-TiO2 exhibited superior cyclability and performance compared to pure anatase TiO2, highlighting its potential for sustainable proton intercalation processes. In half-cell configurations, Vac-TiO2 showed a high Coulombic efficiency (CE exceeding 90% after 48 cycles), while full cells (MnO2||Vac-TiO2) demonstrated an excellent cycling stability (CE exceeding 95.4% over 1000 cycles), high power density (10.5 kW·kg–1 vs 6.2 kW·kg–1), and improved self-discharge. This study paves the way for innovative approaches to improving proton intercalation materials, positioning Vac-TiO2 as a viable candidate for next-generation energy storage solutions.
In biodiesel preparation from vegetable oils and alcohol through transesterification processin the presence of a catalyst, excess alcohol, typically 100% more than the theoretical molarrequirement, is used in existing batch and continuous-flow processes in order to drive the reversibletransesterification reaction to a high enough conversion rate. The excess alcohol needs to berecovered in a separate process which involves additional operating and energy costs. In this study,a novel reactor system using reactive distillation (RD) technique was developed and studied forbiodiesel preparation from yellow mustard seed oil. The main objective was to dramatically reducethe use of excess alcohol in the feeding steam, which reduces the cost in downstream alcoholrecover processes, and meanwhile maintain a high alcohol-to-oil molar ratio inside of the RD reactor,which ensures the completion of the transesterification of seed oil to biodiesel. A lab scale sieve-trayRD reactor system was developed and used in this study. Process parameters were studied on theeffect of reduced alcohol to oil ratio on the overall quality of biodiesel product and the efficiency ofsuch an RD reactor. Product parameters such as methyl ester content, viscosity, total glycerol, andmethanol content were analyzed as per ASTM methods. Preliminary results showed that processparameters of methanol-to-oil ratio of 4:1 (molar) and a column temperature of 65 C produced abiodiesel that met the ASTM standards for total glycerol and viscosity.
Objective: To investigate the effects of groove angle on tensile and impact strength of the joints. Methods: To achieve above objective various groove designs having included angle of 50°, 60° and 70° were prepared using a shaper. The weld grooves were completely filled using shielded metal arc welding process. All the weld joints were subjected to visual inspection, dye penetration test and radiographic test. Then tensile and impact specimens were removed from these joints. The tensile and impact specimens were machined in accordance with ASTM E8M-09 and ASTM E23-12C specifications. The tensile and impact strength was evaluated using universal testing machine. Findings: The tensile strength of the specimen having groove angle as 50° is 513.68 MPa which is more than that of the specimen having 60° and 70° groove angle. The tensile strength of base material used is 540 MPa. It is clear that the tensile of the joint is less than base material used. The joint efficiency obtained is 95.12% which is the highest compared with other joint i.e. 60° and 70°. It is further observed maximum impact strength achieved is 53.45 Joule at 50° groove angle. The tensile and impact strength provided by the joint having groove angle as 70° is 471.29 MPa and 39.15 J respectively which is minimum amongst all the joints produced.It can be concluded that 50° groove angle is the best groove design. Moreover less number of welding electrodes is required to fill this joint compared with 60° or 70° groove angle. Hence it is more economical also. Application: This research is useful for industries which are engaged in fabrication work for designing of correct and economical welding grooves. Keywords: Groove Design, Impact Strength, Radiography, Shielded Metal Arc Welding, Tensile Strength
Supercapacitors (SCs) are now competing with Li-ion batteries for large scale use in various niche technologies owing to their distinctive merits of rapid charging-discharging process, long lifespan, superior durability, high specific power and low maintenance. As we develop better understanding of the thermodynamics, kinetics and ion transport mechanism in electrode materials used in supercapacitors, rapid growth in this energy storage technology is envisaged. In addition to electrode materials, supercapacitor geometries and configurations will also have to be investigated to bring step change in device performance. For example, development of asymmetric supercapacitors (ASCs) has seen tremendous growth in recent times. Most used SCs today are mostly fabricated using nano-structured transition metal oxides (TMOs). TMOs such as MoO 3 , V 2 O 5 and WO 3 with higher work function or electron chemical potential act as hole-injection materials and hold great promise for application as negative electrode materials. In comparison, TMOs like ZrO 2 , MnO 2 and SnO 2 , etc with low work function or electron chemical potential behave like electron-injection materials and are mostly suitable for positive electrodes. Such TMOs have rich redox chemistry (oxidation/reduction, intercalation/de-intercalation, chemisorption, etc.) but overcoming their limited specific power remains a challenge. As a result, composite of TMOs with multiwall carbon nanotubes (MWCNTs) is becoming popular. The operating voltage window of an asymmetric cell is a convoluted effect of overpotential provided by the electrolytes and the difference of work functions of negative (Φ n ) and positive (Φ p ) electrodes i.e., Φ n -Φ p . Therefore, ASCs fabricated using TMOs with a large difference in their respective work functions and neutral aqueous electrolytes (having highly solvated ions) may be operated up to voltages as high as 2.2 V. The methodology of carefully unbalancing the device has also been recently proposed to increase the operating voltage window. In this paper, we show a novel strategy i.e., use of optimized concentration of redox additive electrolyte to bring significant enhancement in the specific energy whilst maintaining power of asymmetric supercapacitors. Very few studies have been undertaken to explore the use of redox additives in the 3-electrode or symmetric cells. It is shown that the charge-balanced ASCs can be operated up to 2.2 V leading to specific energy and power as high as ~65 Wh kg -1 and ~950 W kg -1 , respectively. The specific energy value is significantly enhanced on addition of the optimized quantity of redox additive viz., potassium iodide (KI). More specifically, increase of ~105% in the specific energy value was observed with good cyclic stability even after 3,000 charge-discharge operations. With such high specific energy and power values, the proposed ASCs have the capacity for large scale integration in applications such as portable electronics devices, back-up power supplies, hybrid electric vehicles and energy harvesting devices. In most of these applications, temperature effect of the storage device will be important. The fabricated ASCs show stable performance upto 70 o C, which make them ideal for above mentioned applications. It is shown that the temperature mainly affects the capacitance fade during galvanostatic charging-discharging. The improvement in the specific capacitance at elevated temperatures is strongly governed by the activation energy of diffusions for ionic species and chemical potential of ionic species. Besides, the capacitance fade at higher temperatures is primarily attributed to (a) the total “time spent” at a given temperature during cycling and (b) a reduced kinetic barrier for iodine/iodide redox pairs at the positive electrode/electrolyte interface. This report provides significant information about the effect of temperature on the electrochemical performance of ASCs based on redox additive aqueous electrolytes.
Abstract Multiphase metering has enabled addressing a number of flow assurance challenges, including the detection of scale formation. This capability is especially appreciated in subsea fields, where the physical access is restricted and flow assurance challenges can be detrimental to maintaining production with a reasonable cost. The scale detection capability of the multiphase flowmeters using live multiphase flow data facilitates a proactive approach by the operators to detect and remediate productivity and flow assurance issues arising out of scale deposition. A successful early-stage detection of scales in an oil well in deepwater field offshore Ghana via remote monitoring of multiphase metering data is reported. The displacement of the operating point of the multiphase meter and the swift developments in a matter of days provided the necessary live data for the hypothesis of the scale formation in the meter's venturi. Necessary mitigation action was taken and increases in production due to removal of scale demonstrated presence of scale. An in-house-developed remote surveillance and diagnostic system carried out this detection. The results of this project demonstrate the practical capability of remote monitoring of multiphase metering data for flow assurance purposes.
A high-performance asymmetric supercapacitor was fabricated using MWCNTs/NiS composite and GNPs as electrodes, exhibiting high specific capacitance of ∼181 F g−1 at 1 A g−1 current density and excellent cyclic stability with 92% retention after 1000 cycles at 2 A g−1 current density.
Despite the potential of lithium-sulfur batteries to reach practical energy densities of 500–600 Wh/kg, there are still many problems plaguing their development. The sulfur cathode suffers from low electrochemical utilization and poor cycle life owing to the insulating nature of S and the Li 2 S discharge product, and the shuttling of lithium polysulfide species especially at high areal mass loadings. Enormous progress has been achieved in terms of capacity and static life during the past few years to overcome these issues, by employing various carbon and inorganic materials (metal oxides, metal-organic frameworks). Recently, non-stoichiometric metal oxides have been employed as sulfur host materials due to their high conductivity and ability to bind polysulfides chemically through unsaturated metal ion sites. However, the formation of metal-suboxides involves a high-temperature calcination process, which usually results in dense host materials with lower accessible surface area, and a reduced host/polysulfide interaction. Moreover, these studies are often reported with low sulfur loadings (1–2 mg/cm 2 ) resulting in lower areal capacity. Herein, we report the use of electrospun vanadium monoxide/carbon nanofibers (VCNFs) as cathode host in Li-S batteries, which provide high electrical conductivity for better sulfur utilization and strong Lewis acid-base interaction with polysulfides to suppress shuttle. The developed cathode possesses hierarchical micro-mesoporous architecture with inter-fiber spacing and a high surface area of 181 m 2/ g. The unique architecture overcomes the challenges associated with dense, low active surface area based powered oxide materials. The developed VCNFs-S cathodes with a high sulfur loading of 3 mg/cm 2 exhibit initial discharge capacities of ∼1350, ∼1247, and ∼1113 mAh g –1 at 0.1, 0.2, and 0.5 C rates, respectively, with long-term cycling (Fig 1a) over 200 cycles at 0.5 C rate. Moreover, at ~7mg/cm 2 , Li-S cells exhibit high areal capacity of 8 mAh/cm 2 at a current density of C/10 up to 50 cycles (Fig 1b). The high surface area results in active reaction sites spread throughout the VCNFs, improving the accessible reaction area for better binding of polysulfides, enabling the smooth operation at high-loading in Li-S system. Using postmortem X-ray photoelectron spectroscopy analysis, this study reveals the presence of strong Lewis acid–base interaction between VO (3d 3 ) and S x 2– through the coordinate covalent V–S bond formation. Additionally, freestanding nature of the cathodes eradicate the need of additional inactive elements, viz., binders, additional current collectors (Al-foil), and additives. Our results highlight the importance of developing high surface area metal-suboxides/monoxide-based conducting polar host materials for next-generation Li–S batteries. Figure 1
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