Different Types Of Electrolytes Research Articles

Supercapacitors: An Efficient Way for Energy Storage Application.

To date, batteries are the most widely used energy storage devices, fulfilling the requirements of different industrial and consumer applications. However, the efficient use of renewable energy sources and the emergence of wearable electronics has created the need for new requirements such as high-speed energy delivery, faster charge-discharge speeds, longer lifetimes, and reusability. This leads to the need for supercapacitors, which can be a good complement to batteries. However, one of their drawbacks is their lower energy storage capability, which has triggered worldwide research efforts to increase their energy density. With the introduction of novel nanostructured materials, hierarchical pore structures, hybrid devices combining these materials, and unconventional electrolytes, significant developments have been reported in the literature. This paper reviews the short history of the evolution of supercapacitors and the fundamental aspects of supercapacitors, positioning them among other energy-storage systems. The main electrochemical measurement methods used to characterize their energy storage features are discussed with a focus on their specific characteristics and limitations. High importance is given to the integral components of the supercapacitor cell, particularly to the electrode materials and the different types of electrolytes that determine the performance of the supercapacitor device (e.g., storage capability, power output, cycling stability). Current directions in the development of electrode materials, including carbonaceous forms, transition metal-based compounds, conducting polymers, and novel materials are discussed. The synergy between the electrode material and the current collector is a key factor, as well as the fine-tuning of the electrode material and electrolyte.

Study on the Effect of Electrolytes on Processing Efficiency and Accuracy of Titanium Alloy Utilizing Laser and Shaped Tube Electrochemical Machining.

Electrochemical machining (ECM) has become more prevalent in titanium alloy processing. However, the presence of the passivation layer on the titanium alloys significantly impacts the performance of ECM. In an attempt to overcome the passivation effects, a high-temperature electrolyte or the addition of halogen ions to the electrolyte has been used. Still, it often results in compromised machining accuracy and surface roughness. This study applied laser and shaped tube electrolytic machining (Laser-STEM) for titanium alloy drilling, where the laser was guided to the machining zone via total internal reflection. The performance of Laser-STEM using different types of electrolytes was compared. Further, the effects of laser power and pulse voltage on the machining side gap, material removal rate (MRR), and surface roughness were experimentally studied while drilling small holes in titanium alloy. The results indicated that the use of passivating electrolytes improved the machining precision, while the MRR decreased with an increase in laser power during Laser-STEM. The MRR showed an increase while using aggressive electrolytes; however, at the same time, the machining precision deteriorated with the increase in laser power. Particularly, the maximum feeding rate of 6.0 mm/min for the tool electrode was achieved using NaCl solution as the electrolyte during Laser-STEM, marking a 100% increase compared to the rate without the use of a laser. Moreover, the model and equivalent circuits were also established to illustrate the material removal mechanisms of Laser-STEM in different electrolytes. Lastly, the processing of deep small holes with a diameter of 1.5 mm, a depth of 38 mm, and a surface roughness of Ra 2 µm was achieved via Laser-STEM without the presence of a recast layer and heat-affected zones. In addition, the cross-inner flow channels in the titanium alloys were effectively processed.

Investigation of cell-accelerated corrosion (CAC) on the CoCrMo alloy with segregation banding: Hip implant applications

Metal alloy microstructure plays a crucial role in corrosion associated with total hip replacement (THR). THR is a prominent strategy that uses metal implants such as cobalt-chromium-molybdenum (CoCrMo) alloys due to their advantageous biological and mechanical properties. Despite all benefits, these implants undergo corrosion and wear processes in-vivo in a synergistic manner called tribocorrosion. Also, the implant retrieval findings reported that fretting corrosion occurred in-vivo, evidenced by the damage patterns that appeared on the THR junction interfaces. There is no scientific data on the studies reporting the fretting corrosion patterns of CoCrMo microstructures in the presence of specific biological treatments to date. In the current study, Flat-on-flat fretting corrosion set-up was customized and used to study the tribocorrosion patterns of fretting corrosion to understand the role of alloy microstructure. Alloy microstructural differences were created with the implant stock metal's longitudinal and transverse cutting orientations. As a result, the transverse created the non-banded, homogenous microstructure, whereas the longitudinal cut resulted in the banded, non-homogenous microstructure on the surface of the alloy (in this manuscript, the terms homogenous and banded were used). The induced currents were monitored using a three-electrode system. Three different types of electrolytes were utilized to study the fretting corrosion patterns with both homogeneous and banded microstructures: 1. Control media 2. Spent media (the macrophage cell cultured media) 3. Challenged media (media collected after the macrophage was treated with CoCrMo particles). From the electrochemical results, in the potentiostat conditions, the banded group exhibited a higher induced current in both challenged and spent electrolyte environments than in control due to the synergistic activity of CoCrMo particles and macrophage demonstrating more corrosion loss. Additionally, both Bode and Nyquist plots reported a clear difference between the banded and homogeneous microstructure, especially with challenged electrolytes becoming more corrosion-resistant post-fretting than pre-fretting results. The banded microstructure showed a unique shape of the fretting loop, which may be due to tribochemical reactions. Therefore, from the electrochemical, mechanical, and surface analysis data results, the transverse/homogenous/non-banded alloy microstructure groups show a higher resistance to fretting-corrosion damage.

Reliable Organic Carbonyl Electrode Materials Enabled by Electrolyte and Interfacial Chemistry Regulation.

ConspectusLithium-ion batteries (LIBs) have achieved great success and dominated the market of portable electronics and electric vehicles owing to their high energy density and long-term cyclability. However, if applying LIBs for large-scale energy storage scenarios, such as regulating the output of electricity generated by sustainable energy in the future age of carbon neutrality, the current electrochemistry of LIBs based on Li-ion interaction/deinteraction between a transition-metal oxide cathode and graphite anode will suffer from problems of scarce natural resources (e.g., Li, Co, and Ni) and high energy consumption/CO2 emission involved in the production of electrodes. Similarly, other commercial batteries such as lead-acid batteries and nickel-metal hydride batteries are also plagued by these issues.In contrast, organic electrode materials, especially carbonyl materials, exhibit advantages of abundant resources, renewability, high capacity, environmental friendliness, and structural designability and have shown great promise for various rechargeable batteries in recent years. However, organic carbonyl electrode materials generally exhibit unsatisfactory cycling stability and rate performance, which are highly dependent on the electrolyte and interfacial chemistry. Appropriate electrolytes and a stable electrode/electrolyte interface would be beneficial for preventing the dissolution of organic carbonyl electrode materials and/or their redox intermediates in electrolytes and promoting fast ion transport between the electrode and electrolyte. In this regard, designing an appropriate electrolyte and constructing a stable electrode/electrolyte interface are the keys to enhancing the comprehensive performance of organic carbonyl electrode materials.In this Account, on the basis of our progress and related works from other groups in the past decade, we afford an overview of understanding the effects of electrolyte and interfacial chemistry on the electrochemical performance of organic carbonyl electrode materials. We will start by briefly introducing the basic properties, working mechanisms, and issues of organic carbonyl electrode materials. Then, the implications of electrolyte and electrode/electrolyte interfacial chemistry on electrochemical performance will be summarized and highlighted through discussing the performance of organic carbonyl electrodes in different types of electrolytes (organic liquid and aqueous and solid-state electrolytes). Meanwhile, the design principles of electrolytes and interfacial chemistry for organic carbonyl electrodes are also discussed. A representative example is that organic carbonyl electrode materials often exhibit better electrochemical performance in ether-based electrolytes than in ester-based electrolytes, which could be mainly attributed to the stable and robust solid electrolyte interphase (SEI) formed on carbonyl electrodes in the ether-based electrolyte. This example demonstrates the importance of investigating the electrode/electrolyte interfacial chemistry of organic carbonyl electrode materials. Finally, future perspectives on designing appropriate electrolytes and understanding electrode/electrolyte interfacial chemistry will also be discussed. It is meaningful to thoroughly reveal the dynamic evolution of the electrode/electrolyte interface during discharge/charge processes and evaluate the compatibility between electrolytes and organic carbonyl electrode materials under practical conditions using limited quantities of electrolytes and high areal-specific-capacity electrodes in the future. This Account could attract more attention to electrolytes and the electrode/electrolyte interfacial chemistry of organic carbonyl electrode materials and finally promote their future commercial applications.

Enhanced microalgal hydrogen production subsisting on visible light TiO2 nanotubes photocatalyst pre-treated palm kernel expeller

The present study investigated the application of photocatalytic process using TiO2 nanotubes (NTs) photocatalyst as an effective pre-treatment method for palm kernel expeller (PKE) in increasing its biodegradability to enhance the microalgal hydrogen production via dark fermentation. A series of TiO2 NTs photocatalysts were synthesized via employing electrochemical anodization of Ti foil at various voltages each in different types of electrolytes (choline chloride-ethylene glycol (ChCl-EG), choline chloride-urea (ChCl-U), choline chloride-glycerol (ChCl-Gly)). Increasing trend of average NTs diameters at 26.14 ± 1.30, 73.01 ± 1.94 and 122.00 ± 13.32 nm was observed for 25, 30 and 35 V in synthesizing TiO2 NTs using suitable ChCl-EG electrolyte, respectively. The high 35 V had resulted in noticeable pore ruptures within this TiO2 NTs photocatalyst. The PKE pre-treated by TiO2 NTs photocatalyst anodized at optimum 30 V in ChCl-EG electrolyte had demonstrated the highest releases of biochemical oxygen demand (BOD5) and soluble chemical oxygen demand (SCOD) concentrations at 594 and 607 mg/L, respectively. Moreover, the microalgal efficiency of BOD5 conversion and hydrogen yield were also consistently maintained from third cycle of TiO2 NTs photocatalyst's reutilizations, signifying the stability of TiO2 NTs photocatalyst.

Process capability of electrochemical discharge machining: A review

Electrochemical discharge machining (ECDM) is a hybrid machining formed by combining the principles of electrochemical machining and electrical discharge machining. The ECDM is unconventional micromachining that can fabricate holes, blind holes, micro-cavities and grooves on brittle insulating materials such as quartz, glass, silicon wafers and different composites that are difficult to machine. These non-conducting materials have sundry applications such as Micro Electric-Mechanical Systems, biomedical and electronics items. The ECDM provides maximum material removal rate and good surface quality with minor tool wear. The study describes how different process parameters affect machining. The assessment mainly focuses on various tool electrode geometries and materials that are used in ECDM. The present article investigates the ramifications of different types of electrolytes and additives mixed in electrolytes used during the ECDM process on the machined zone. This paper comprehensively reviews the effect of change in applied voltage, machining gap and an inter-electrode gap in the ECDM and it also analyses the fabrication of different materials including glass, quartz, ceramics and composites.

Performance Analysis of Different Types of Solid Electrolytes

The development and interest in environmentally friendly cars nowadays present new challenges to the lithium-ion batteries. With the safety problems caused by the liquid electrolyte in conventional batteries, the development of new electrolytes is becoming increasingly urgent. Based on the existing literature, this paper discusses the following: (1) the advantages and disadvantages of solid-state electrolytes; (2) Requirements for solid electrolytes; (3) Classification and characteristics of solid electrolytes; (4) Properties of different types of electrolytes; (5) Future application and research direction. Performance and possible applications of different solid-state electrolytes are presented in this paper. Specifically, it is found that inorganic solid electrolytes are the best in ion transference number, making them suitable for quick charging batteries. Polymer-based solid electrolytes perform better at electrochemical window, so they can be used to enhance the energy density of batteries. Polyethylene glycol (PEG) based composite solid electrolytes and sulfide solid electrolytes have the highest ionic conductivity, so they are optimum materials for high-rate performance batteries.

The Many Deaths of Supercapacitors: Degradation, Aging, and Performance Fading

AbstractHigh‐performance electrochemical applications have expedited the research in high‐power devices. As such, supercapacitors, including electrical double‐layer capacitors (EDLCs) and pseudocapacitors, have gained significant attention due to their high power density, long cycle life, and fast charging capabilities. Yet, no device lasts forever. It is essential to understand the mechanisms behind performance degradation and aging so that these bottlenecks can be addressed and tailored solutions can be developed. Herein, the factors contributing to the aging and degradation of supercapacitors, including electrode materials, electrolytes, and other aspects of the system, such as pore blocking, electrode compositions, functional groups, and corrosion of current collectors are examined. The monitoring and characterizing of the performance degradation of supercapacitors, including electrochemical methods, in situ, and ex situ techniques are explored. In addition, the degradation mechanisms of different types of electrolytes and electrode materials and the effects of aging from an industrial application standpoint are analyzed. Next, how electrode degradations and electrolyte decompositions can lead to failure, and pore blocking, electrode composition, and other factors that affect the device's lifespan are examined. Finally, the future directions and challenges for reducing supercapacitors' performance degradation, including developing new materials and methods for characterizing and monitoring the devices are summarized.

Electrochemical Noise Measurements on Titanium Regarding Implant Applications

The suitability of electrochemical noise measurements to gather information on the corrosion behavior of titanium implants is explored. Rod‐shaped titanium samples have been immersed in different types of electrolytes, and the generated electrochemical noise is evaluated. The electrolytes include simulated body fluids, namely phosphate‐buffered saline and artificial saliva. Different data evaluation methods have been explored. The evaluation of the time‐domain data and further statistical methods shows promising results. Noise resistance values ranging from 0.09 MΩ for 3.5 wt% H2SO4 solution up to 0.45 MΩ for simulated body fluids have been recorded. It is possible to determine the dominating corrosion modes on the sample surface and reach results in alignment with expectations and established knowledge on corrosion mechanisms.

Experimental investigation of electrolytically treated and silane grafted carbon fiber-reinforced thermoplastic polyurethane composites

In this study, the continuous fiber rowing of 12K carbon was electrolytically oxidized by incorporating three different types of electrolytes: Ammonium bicarbonate, Sulfuric acid, and Sodium hydroxide at various concentrations. Upon chemical treatment, the fibers were grafted with 3-Aminopropyl-triethoxysilane (APTS), a silane coupling agent, to achieve better interlocking and compatibility with the thermoplastic polyurethane (TPU) matrix. Mechanical properties were analyzed by tensile tests, morphological analysis was carried out through Scanning Electron Microscopy, and spectral analysis was studied through X-ray photoelectron spectroscopy (XPS) characterizations. The results show that 10% sulfuric acid treatment plus APTS grafted carbon fiber/TPU composites showed an average tensile load capacity of 2528 N, about 39% higher than raw carbon/TPU. The morphological analysis provided compelling evidence for the increase in mechanical properties of modified fiber composites as the interfacial bonding between the electrolytically modified and silane coated fiber/TPU composites was much better than the raw fiber/TPU composites. Further, XPS results confirm that the atomic percentages of Carbon have been reduced, whereas the percentage of oxygen and nitrogen have increased. These compositional changes indicate that the overall interaction between the fiber and the matrix has been enhanced, accounting for improved compatibility between the two interacting phases.

A simplified model for the impact of dielectric polarization of a charged droplet on its diffusiophoresis

This study aims to quantify the impact of the dielectric permittivity of a droplet on its diffusiophoresis in different types of electrolytes. The dielectric droplet polarizes by the diffusion field along with the local electric field created by the interactions of the double layer with the imposed ionic concentration gradient, which generates an induced surface charge density anti-symmetrically distributed on the droplet surface. This induced surface charge influences both electrophoresis and chemiphoresis parts. Based on a low imposed concentration gradient, a simplified model is derived through a first-order perturbation technique. Dielectric polarization of the droplet attenuates the spinning force at the interface. This creates the mobility of a droplet of higher dielectric permittivity in the presence of a stronger diffusion field significantly higher than that of a perfectly dielectric droplet, and its value depends on the polarity of the droplet surface charge. In the absence of the diffusion field, the mobility of a conducting droplet remains a positive immaterial of the polarity of its surface charge density. We find that the impact of the dielectric polarization becomes significant as the surface charge density increases and attenuates with the increase in droplet viscosity. For a dielectric droplet at a thinner Debye length, a step-jump in mobility occurs at a higher value of the surface charge density. Such a type of step-jump in mobility does not appear for the conducting droplet due to the absence of the Maxwell stress at the interface.

Insights into the solvation chemistry in liquid electrolytes for lithium-based rechargeable batteries.

Lithium-based rechargeable batteries have dominated the energy storage field and attracted considerable research interest due to their excellent electrochemical performance. As indispensable and ubiquitous components, electrolytes play a pivotal role in not only transporting lithium ions, but also expanding the electrochemical stable potential window, suppressing the side reactions, and manipulating the redox mechanism, all of which are closely associated with the behavior of solvation chemistry in electrolytes. Thus, comprehensively understanding the solvation chemistry in electrolytes is of significant importance. Here we critically reviewed the development of electrolytes in various lithium-based rechargeable batteries including lithium-metal batteries (LMBs), nonaqueous lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs), lithium-oxygen batteries (LOBs), and aqueous lithium-ion batteries (ALIBs), and emphasized the effects of interactions between cations, anions, and solvents on solvation chemistry, and functions of solvation chemistry in different types of electrolytes (strong solvating electrolytes, moderate solvating electrolytes, and weak solvating electrolytes) on the electrochemical performance and redox mechanism in the abovementioned rechargeable batteries. Specifically, the significant effects of solvation chemistry on the stability of electrode-electrolyte interphases, suppression of lithium dendrites in LMBs, inhibition of the co-intercalation of solvents in LIBs, improvement of anodic stability at high cut-off voltages in LMBs, LIBs and ALIBs, regulation of redox pathways in LSBs and LOBs, and inhibition of hydrogen/oxygen evolution reactions in LOBs are thoroughly summarized. Finally, the review concludes with a prospective outlook, where practical issues of electrolytes, advanced in situ/operando techniques to illustrate the mechanism of solvation chemistry, and advanced theoretical calculation and simulation techniques such as "material knowledge informed machine learning" and "artificial intelligence (AI) + big data" driven strategies for high-performance electrolytes have been proposed.

Purification, crystal structure and properties of azoxytriazolone (AZTO)

In this work, the azoxytriazolone (AZTO) was synthesized by electrochemical reduction 5-nitro-1,2,4-triazol-3-one (NTO) under different types of electrolytes which were Na2SO4 and H2SO4. By comparing the yield of AZTO/azoTO synthesized under different electrolyte conditions, the work found that sulfuric acid as the electrolyte has a positive effect on the synthesis of AZTO. On this basis, the high-concentration AZTO was prepared by regulating the concentrations of sulfuric acid (0.05M, 0.1M, 0.5M, 1M). Finally, by introducing an appropriate amount of NaOH, we successfully achieved the separation and purification of AZTO from the mixture of AZTO and azoTO. In addition, single crystal AZTO was also prepared in this experiment to test its crystal structure, which illustrated that the crystal density of AZTO is 1.902 g/cm3 at 193 K, belonging to the monoclinic crystal system with space group P21/n. The thermal properties results of AZTO showed that the thermal stability properties of AZTO were affected by AZTO/azoTO ratio, and the thermal decomposition peak of pure AZTO is 352°C when the content of azoTO is zero. On the contrary, the BAM susceptibility tester test demonstrated the impact susceptibility is 30 J and the friction susceptibility is greater than 360 N of AZTO, which are unaffected on azoTO. According to the K-J empirical formula, the blasting velocity and detonation pressure of AZTO were 7713.5 m/s and 26.1 GPa, respectively. The influences of different types of electrolytes and sulfuric acid concentrations on the yield of AZTO were evaluated, and the relevant reaction mechanism of electrochemical synthesis of AZTO and azoTO was supplemented in this paper.

Contribution of electrolyte in parametric optimization of perfluorooctanoic acid during electro-oxidation: Active chlorinated and sulfonated by-products formation and distribution

The present study investigated the roles of peroxydisulfate (PDS) radicals and sulfate radicals (SO4•−) that formed from sulfate (SO42−) during electrochemical oxidation of perfluorooctanoic acid (PFOA). The effect of operating parameters such as different types of electrolytes (NaCl, NaClO4, and Na2SO4), initial pH, current density, dose of electrolyte, and initial concentration of PFOA using electrochemical oxidation for perfluorooctanoic acid (PFOA) decomposition study was investigated. A difference in the removal efficiency with different electrolytes (i.e., Cl−, ClO4−, and SO42−) illustrated an increasing effect of electrooxidation of PFOA in the order of ClO4− < Cl− < SO42−, which suggested that •OH induced oxidation and direct e− transfer reaction continued to play a crucial role in oxidation of PFOA. At the optimum treatment condition of j = 225.2 Am−2, Na2SO4 concentration = 1.5 gL−1, [PFOA]o = 50 mgL−1 and initial pH = 3.8 maximum PFOA removal of 92% and TOC removal of 80% was investigated at 240 min. The formation of three shorter-chain perfluorocarboxylates (i.e., perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), and perfluoropentanoic acid (PFPeA) and formate (HCOO−) ions were detected as by-products of PFOA electro-oxidation, showing that the C–C bond first broken in C7F15 and then mineralized into CO2, and fluoride ion (F−). The fluorine recovery as F− ions and the organic fluorine as the shorter-chain by-products were also obtained. The degradation kinetic has also been studied using the nth-order kinetic model.

Fabrication of micro-channels using a micro-electrochemical spark machining process

In the current study, electrochemical discharge machining (ECDM) is used to create micro-channels on Glass fibre reinforced plastic (GFRP). The study takes into account the changeable input factors, such as voltage, duty factor, and different types of electrolytes. (NaOH, KOH, and mixed (NaOH + KOH). The delamination factor (DF) and average micro-channel width (AWM) are used to assess the quality of the machining operation. Process parameter optimization is done using the Taguchi method. The result reveals that the voltage is the most significant parameter for both AWM and DF, followed by electrolyte type and duty factor. The minimum AWM and DF are observed for NaOH electrolytes as compared to other used electrolytes. The minimum AWM is 529.8 µm and DF is 1.03, obtained at constant machining parameters 50 V, duty factor: 35 % in the presence of NaOH electrolyte.

Electrolytes for Multivalent Metal-Ion Batteries: Current Status and Future Prospect.

Electrochemical energy storage has experienced unprecedented advancements in recent years and extensive discussions and reviews on the progress of multivalent metal-ion batteries have been made mainly from the aspect of electrode materials, but relatively little work comprehensively discusses and provides an outlook on the development of electrolytes in these systems. Under this circumstance, this Review will initially introduce different types of electrolytes in current multivalent metal-ion batteries and explain the basic ion conduction mechanisms, preparation methods, and pros and cons. On this basis, we will discuss in detail the research and development of electrolytes for multivalent metal-ion batteries in recent years, and finally, critical challenges and prospects for the application of electrolytes in multivalent metal-ion batteries will be put forward.

Hip implant modular junction: The role of CoCrMo alloy microstructure on fretting-corrosion

Cobalt-chromium-molybdenum (CoCrMo) alloy is one of the most used metals in total hip replacement (THR) due to the alloy's superior corrosion qualities and biocompatibility. Over time these prostheses may undergo wear and corrosion processes in a synergistic process known as tribocorrosion. Implant retrieval studies have shown that damage patterns on THR modular junction surfaces indicating specifically in vivo fretting-corrosion to take place. To date, there have been no studies on the fretting-corrosion behaviors of CoCrMo alloy under the consideration of specific microstructural features. A custom-built flat-on-flat fretting-corrosion setup was utilized to test the synergistic tribocorrosion behavior of fretting-corrosion. The difference in microstructure was generated through the cutting orientations of the transverse and the longitudinal direction of the bar stock material, where the longitudinal cut exhibits a characteristic banded microstructure (banded group) and the transverse cut a homogenous microstructure (unbanded group). A three-electrode system was employed to monitor the induced currents. Two different types of electrolytes were used in the current study: 1. Bovine calf serum (BCS-30 g/L protein) (normal conditions) 2. BCS with Lipopolysaccharide (LPS, 0.15 μg/ml) (simulated infectious conditions). In the free potential mode, banded samples showed an increased potential compared to the unbanded samples. In potentiostatic conditions, the banded group also exhibited a higher induced current in both electrolyte environments, indicating more corrosion loss. Both Nyquist and Bode plots showed both orientations of metal becoming more corrosion resistant post-fretting when compared to pre-fretting data. The longitudinal group at OCP demonstrated a unique shape of the fretting-loop, which might be related to tribochemical reactions. Based on the mechanical, electrochemical, and surface characterization data, the transverse group (unbanded) microstructures demonstrates a higher resistance to fretting-corrosion damage.

Investigation of the Limits of the Linearized Poisson–Boltzmann Equation

This work presents a comparison between a numerical solution of the Poisson-Boltzmann equation and the analytical solution of its linearized version through the Debye-Hückel equations considering both size-dissimilar and common ion diameters approaches. In order to verify the limits in which the linearized Poisson-Boltzmann equation is capable to satisfactorily reproduce the nonlinear version of Poisson-Boltzmann, we calculate mean ionic activity coefficients for different types of electrolytes as various temperatures. The divergence between the linearized and full Poisson-Boltzmann equations is higher for lower molalities, and both solutions tend to converge toward higher molalities. For electrolytes of lower valencies (1:1, 1:2, 2:1, and 1:3) and higher distances of closest approach, the full version of the Debye-Hückel equation is capable of representing the activity coefficients with a low divergence from the nonlinear Poisson-Boltzmann. The size-dissimilar full version of Debye-Hückel represents a clear improvement over the extended version that uses only common ion diameters when compared to the numerical solution of the Poisson-Boltzmann equation. We have derived a salt-specific index (Θ) to gradually classify electrolytes in order of increasing influence of nonlinear ion-ion interactions, which differentiate the Debye-Hückel equations from the nonlinear Poisson-Boltzmann equation.

A Review of Fabrication Technologies for Carbon Electrode-Based Micro-Supercapacitors

The very fast evolution in wearable electronics drives the need for energy storage micro-devices, which have to be flexible. Micro-supercapacitors are of high interest because of their high power density, long cycle lifetime and fast charge and discharge. Recent developments on micro-supercapacitors focus on improving the energy density, overall electrochemical performance, and mechanical properties. In this review, the different types of micro-supercapacitors and configurations are briefly introduced. Then, the advances in carbon electrode materials are presented, including activated carbon, carbon nanotubes, graphene, onion-like carbon, and carbide-derived carbon. The different types of electrolytes used in studies on micro-supercapacitors are also treated, including aqueous, organic, ionic liquid, solid-state, and quasi-solid-state electrolytes. Furthermore, the latest developments in fabrication techniques for micro-supercapacitors, such as different deposition, coating, etching, and printing technologies, are discussed in this review on carbon electrode-based micro-supercapacitors.

Numerical study on ion transport and electro-convective mixing of power-law fluid in a heterogeneous micro-constrained channel

Mixing performance with variable solubility in a modulated micro-channel filled with non-Newtonian power-law fluid is studied. A combined geometrical and surface potential heterogeneity of one wall of the channel is considered to promote mixing of eluted species with electrolytes. The stability and energy budget analysis are made to check the flow distortion due to the presence of heterogeneity in channel geometry as well as surface charge density. The analytical solutions for the electric potential and velocity are obtained for different types of electrolytes through the Debye–Hückel approximation. The Poisson–Nernst–Planck–Navier–Stokes equations are computed to evaluate the electroosmotic flow due to the non-Newtonian fluid, charge distributions, and species concentrations. Convective flow induced by the patterned surface is taken into account to achieve an efficient mixing of two different streams of fluid injected in the channel. The combined effect of in-build pressure gradient and external electric field drives the species transport in the modulate channel. Comparisons of species mixing efficiency and pressure drop are made for different forms of the surface heterogeneity and values of over-potential. The numerical validation is made by comparing with the available experimental results. Our results show that mixing efficiency can be enhanced by the combined effect of geometric modulation and surface potential heterogeneity. Linear stability analysis and energy budget analysis show that the periodic nature of velocity due to nonlinearity is predicted through phase diagram analysis.