Interfacial Insights into the Polarization Protocol: Toward Reducing Corrosion and Improving the Cycle Life of Electrochemical Capacitors

The number of scientific publications on the impact of corrosion on current collectors on the working parameters of electrochemical capacitors is very limited. The aim of current research is to search for new, environmentally friendly chemical power sources and energy storage devices and to improve existing ones. Therefore, this article presents a simple and effective way to improve the life of a symmetric electrochemical capacitor by changing the direction of electrode polarization, which in turn inhibits the corrosion of the current collector. This slows the degradation of current collectors of positive electrode over long durations. However, activated carbon electrode corrosion also occurs. Experiments on capacitors with stainless steel and gold current collectors indicate that the lifespan of the latter is much longer than that of the former. Therefore, current collector corrosion has a distinct and detrimental impact on electrochemical capacitor operation. Moreover, the research results indicate that carbon corrosion results from current collector corrosive damage.

From waste to energy storage: calcinating and carbonizing chicken eggshells into electrode materials for supercapacitors and lithium-ion batteries

The presented study aims to explore the potential sources of common bio-wastes that could be successfully processed without any leftovers into materials for energy conversion and storage devices. We used chicken eggshells as an environmentally friendly precursor for electrode fillers in electrochemical capacitors (calcinated OS600 and OS900) and anode materials in Li-ion batteries (carbonized EM600 and EM900). Both groups of materials were obtained at two different temperatures to investigate the influence of their composition and properties on the electrochemical performance. Electrochemical capacitors with OS600 and OS900 substituted for 10 wt% of commercial activated carbon supplied similar capacitances, with OS600 stabilizing the long-term performance of the device. Also, both obtained anode materials are suitable for operation in Li-ion batteries, supplying a capacity of around 280 mA h g-1. Notably, EM900 is characterized by a well-developed structure, and as an anode, it exhibited better capacity retention of over 84%.

Enhanced cycle life of starter lighting ignition (SLI) type lead-acid batteries with electrolyte modified by ionic liquid

The aim of the presented work was to improve the lifetime of lead-acid SLI (starting, lighting and ignition) batteries through electrolyte modification with ionic liquids. The conducted research included the synthesis and determination of the influence of di(hexadecyldimethylammonium) and di(octadecyldimethylammonium) sulphates on the basic parameters (capacity, cranking performance) of the starter battery as well as parameters affecting its lifetime (dynamic charge acceptance, corrosion, water consumption). It has been shown that the addition of these compounds increases corrosion resistance and reduces water consumption, resulting in an increase in cyclic durability by up to 36%. The improvement is associated with the absorption of ionic liquid molecules into the mass of lead(ii) sulphate, which was confirmed by physicochemical and electrochemical studies.

Effect of Versenium Hydrogensulfate on Properties of Nickel Coatings

The salt of formula [H₂EDTA²⁺][HSO₄^-]₂ (dihydrogen ethylenediaminetetraacetate di(hydrogen sulfate(VI)) was used to examine the physicochemical properties of the resulting Ni layer and evaluate the applicability of the salt as a new additive for Watts-type baths. The Ni coatings deposited from baths containing [H₂EDTA²⁺][HSO₄^-]₂ were compared with those obtained from other baths. The nucleation of nickel on the electrode was proven to occur the slowest in the bath that contained the mixture of [H₂EDTA²⁺][HSO₄^-]₂ and saccharin compared with other baths. The addition of [H₂EDTA²⁺][HSO₄^-]₂ alone (bath III) generated a coating with a morphology similar to that obtained from bath I (without additives). Despite the similar morphology and wettability of the Ni-coated surfaces plated from various baths (all Ni coatings were hydrophilic with contact angles in the range of 68 to 77°), some differences in electrochemical properties were noted. The corrosion resistance for the coatings plated from baths II and IV containing saccharin (I_corr = 1.1 and 1.5 µA/cm², respectively) and the mixture of saccharin and [H₂EDTA²⁺][HSO₄^-]₂ (I_corr = 0.88 µA/cm²), respectively, was similar or even better than the coating obtained from baths without [H₂EDTA²⁺][HSO₄^-]₂ (I_corr = 9.02 µA/cm²).

Advances in the Removal of Cr(III) from Spent Industrial Effluents-A Review

The review presents advances in the removal of Cr(III) from the industrial effluents published in the last ten years. Although Cr(III) has low solubility and is less dangerous for the aquatic environment than Cr(VI), it cannot be released into the aquatic environment without limitations and its content in water should be restricted. The development of efficient techniques for the removal of Cr(III) is also a response to the problem of chromium wastewater containing Cr(VI) ions. Very often the first step in dealing with such wastewater is the reduction in chromium content. In some cases, removal of Cr(III) from wastewaters is an important step for pretreatment of solutions to prepare them for subsequent recovery of other metals. In the review, hydrometallurgical operations for Cr(III) removal are presented, including examples of Cr(III) recovery from real industrial effluents with precipitation, adsorption, ion exchange, extraction, membrane techniques, microbial-enhanced techniques, electrochemical methods. The advantages and disadvantages of the operations mentioned are also presented. Finally, perspectives for the future in line with circular economy and low-environmental impact are briefly discussed.

Electrocatalytic performance of oxygen-activated carbon fibre felt anodes mediating degradation mechanism of acetaminophen in aqueous environments

Carbon felts are flexible and scalable, have high specific areas, and are highly conductive materials that fit the requirements for both anodes and cathodes in advanced electrocatalytic processes. Advanced oxidative modification processes (thermal, chemical, and plasma-chemical) were applied to carbon felt anodes to enhance their efficiency towards electro-oxidation. The modification of the porous anodes results in increased kinetics of acetaminophen degradation in aqueous environments. The utilised oxidation techniques deliver single-step, straightforward, eco-friendly, and stable physiochemical reformation of carbon felt surfaces. The modifications caused minor changes in both the specific surface area and total pore volume corresponding with the surface morphology. A pristine carbon felt electrode was capable of decomposing up to 70% of the acetaminophen in a 240 min electrolysis process, while the oxygen-plasma treated electrode achieved a removal yield of 99.9% estimated utilising HPLC-UV-Vis. Here, the electro-induced incineration kinetics of acetaminophen resulted in a rate constant of 1.54 h^-1, with the second-best result of 0.59 h^-1 after oxidation in 30% H₂O₂. The kinetics of acetaminophen removal was synergistically studied by spectroscopic and electrochemical techniques, revealing various reaction pathways attributed to the formation of intermediate compounds such as p-aminophenol and others. The enhancement of the electrochemical oxidation rates towards acetaminophen was attributed to the appearance of surface carbonyl species. Our results indicate that the best-performing plasma-chemical treated CFE follows a heterogeneous mechanism with only approx. 40% removal due to direct electro-oxidation. The degradation mechanism of acetaminophen at the treated carbon felt anodes was proposed based on the detected intermediate products. Estimation of the cost-effectiveness of removal processes, in terms of energy consumption, was also elaborated. Although the study was focussed on acetaminophen, the achieved results could be adapted to also process emerging, hazardous pollutant groups such as anti-inflammatory pharmaceuticals.

Chromium(III) Removal from Nickel(II)-Containing Waste Solutions as a Pretreatment Step in a Hydrometallurgical Process

This paper presents Cr(III) removal from nickel sulfate waste solutions as a pretreatment step for the modification of hydrogen storage alloys. Adsorption with two cation exchange resins, Dowex G26 (strongly acidic) and MAC-3 (weakly acidic), and precipitation with various solutions were chosen as simple operations for Cr(III) removal from waste solutions. The adsorption of Cr(III) was investigated for both model and real waste nickel solutions. Dowex G26 appeared to be more efficient in Cr(III) removal (R_Cr(III) from 43 to 80%) than MAC-3 (R_Cr(III) from 40 to 53%). However, the adsorption from multi-component solutions (presence of Co(II), Ni(II) and Cr(III)) showed no selectivity in Cr(III) adsorption in comparison to those of Co(II) and Ni(II). Cr(III), Ni(II) and Co(II) were removed at a comparable level (30-36%) from a three-component solution of 10 g/dm³ of each metal ion, and a 56-72% removal of these ions was achieved from the real solution. Therefore, the precipitation of Cr(III) was carried out from a real waste nickel solution to compare its performance with adsorption. The best precipitation solution appeared to be 3 and 30% NaOH due to the quantitative precipitation of Cr(OH)₃ at pH 5 and relatively small co-precipitation of Ni(II) and Co(II) hydroxides (P_Co(II) = 20-52%, P_Ni(II) = 0-54%). Based on the results of the research, it can be concluded that precipitation with a NaOH solution is an efficient pretreatment operation of an electrolyte for further steps of the hydrometallurgical process of nickel electrodeposition and appears to be more selective in the elimination of Cr(III) than adsorption with Dowex G26 resin.

Control of hydrogen release during borohydride electrooxidation with porous carbon materials

Due to their highly tunable electrical and structural properties, carbon materials are widely used in fuel cells. This study reviews the latest modifications carried out in order to improve the electrochemical properties of carbon-based anodes in Direct Borohydride Fuel Cell (DBFC). However, in this type of fuel cell, various types of carbon (e.g. carbon black, activated carbons, carbon nanotubes, graphene and heteroatom-doped carbons and MOF-derived carbon materials) can provide not only catalyst support, but also hydrogen storage due to the extremely complex process of borohydride electrooxidation. Accurate control of porosity and carbon morphology is therefore necessary for high fuel cell efficiency. Finally, some prospects for the future development of carbon materials for DBFC design are presented. It should be emphasized, that the storage of hydrogen in solid form is a possible breakthrough for the future use of hydrogen as an ecological fuel, which is why scientific research in this topic is so important.

The borohydride electrooxidation process is complex. Technological application of carbon materials is manifested not only in their use as a catalyst support, but also as a physical trap for hydrogen generated during the parasitic hydrolysis.

Long-Chain Ionic Liquids Based on Monoquaternary DABCO Cations and TFSI Anions: Towards Stable Electrolytes for Electrochemical Capacitors

The desirable properties of ionic liquids (ILs) enable their use in various branches of chemistry, through a wide range of applications, e. g. as organic electrolytes. In the present study, an efficient two-step method was developed for the synthesis of long-chain ionic liquids with alkyl derivatives of DABCO as cations and bis(trifluoromethane)sulfonimide as anions. ILs obtained with high yields (≥91 %) were solids with melting points that increased with the rise in the number of carbon atoms of the alkyl substituent in the bicyclic cation. The structure of the compounds was confirmed by spectroscopic methods and elemental analysis. All compounds were soluble in the main solvents except water and hexane. The solubility in organic solvents such as acetonitrile allowed the use of synthesized ILs in electrochemical capacitors. Electrochemical tests revealed that the ILs enhanced the conductivity of organic electrolytes. This phenomenon improved the cyclability and reduced the internal resistance of the electrochemical capacitors.

Lignin-based dual component additives as effective electrode material for energy management systems

A functional PbO-lignin electrode hydrid material composite was designed and manufactured. Moreover, its connection efficiency was confirmed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). We noted that the superficial layers of PbO combined with layers of the biopolymer and that oxygen atoms present in both materials had influence on the chemical environment of the neighboring compound. Hence, it can be said that the addition of PbO significantly contributes to the improvement of thermal stability of the final inorganic-organic system. In the framework of the study, the dispersive, morphological and structural characteristics were determined using scanning electron microscopy (SEM) and laser diffraction method. Electrochemical studies indicated that the PbO-lignin material exhibits better electrochemical properties compared to PbO without the addition of kraft lignin (increased capacitance, lower charge transfer resistance), as the specific capacitance after 5000 charge/discharge cycles was still at 95% of the initial value. Such promising operating parameters show that this material can be successfully used as an electrode material for energy management systems.

Carbon Fiber and Nickel Coated Carbon Fiber-Silica Aerogel Nanocomposite as Low-Frequency Microwave Absorbing Materials

Silica aerogel-based materials exhibit a great potential for application in many industrial applications due to their unique porous structure. In the framework of this study, carbon fiber and nickel coated carbon fiber–silica aerogel nanocomposites were proposed as effective electromagnetic shielding material. Herein, the initial oxidation of the surface of carbon fibers allowed the deposition of a durable Ni metallic nanolayer. The fibers prepared in this way were then introduced into a silica aerogel structure, which resulted in obtaining two nanocomposites that differed in terms of fiber volume content (10% and 15%). In addition, analogous systems containing fibers without a metallic nanolayer were studied. The conducted research indicated that carbon fibers with a Ni nanolayer present in the silica aerogel structure negatively affected the structural properties of the composite, but were characterized by two-times higher electrical conductivity of the composite. This was because the nickel nanolayer effectively blocked the binding of the fiber surface to the silica skeleton, which resulted in an increase of the density of the composite and a reduction in the specific surface area. The thermal stability of the material also deteriorated. Nevertheless, a very high electromagnetic radiation absorption capacity between 40 and 56 dB in the frequency range from 8 to 18 GHz was obtained.

Hybrid electrochemical and biological treatment of herbicidal ionic liquids comprising the MCPA anion

The present study was focused on the application of an electrochemical oxidation process combined with biodegradation for the removal of novel Herbicidal Ionic Liquids (HILs) -promising protection plant products which incorporate herbicidal anions and ammonium cations. The influence of carbon chain length (n = 8, 10, 12, 14, 16, 18) in the dialkyldimethylammonium cations on electrochemical oxidation kinetics, degradation efficiency and biodegradation by activated sludge was investigated. It was established that the applied cation influenced the heterogeneous rate constant and diffusion coefficient of electrochemical oxidation. The oxidation efficiency ranged from 17% in case of HILs with C8 alkyl chain to approx. 60% in case of HILs comprising C14 and C16 alkyl chains after 3 h of electrochemical treatment. Subsequent biodegradation studies revealed that electrochemical oxidation improved the mineralization efficiency of the studied HILs. The mineralization efficiency of electrochemically-treated HILs ranged from 28% in case of HILs comprising the C8 alkyl chain to 57% in case of HILs with C14 and C16 alkyl chains after 28 days. In case of untreated HILs, the corresponding mineralization efficiency ranged from 0 to 8%, respectively. This confirms the feasibility of a hybrid electrochemical-biological approach for treatment of herbicidal ionic liquids based on MCPA.

Removal of herbicidal ionic liquids by electrochemical advanced oxidation processes combined with biological treatment

Recently a new group of ionic liquids (ILs) with herbicidal properties has been proposed for use in agriculture. Owing to the design of specific physicochemical properties, this group, referred to as herbicidal ionic liquids (HILs), allows for reducing herbicide field doses. Several ILs comprising phenoxy herbicides as anions and quaternary ammonium cations have been synthesized and tested under greenhouse and field conditions. However, since they are to be introduced into the environment, appropriate treatment technologies should be developed in order to ensure their proper removal and avoid possible contamination. In this study, didecyldimethylammonium (4-chloro-2-methylphenoxy) acetate was selected as a model HIL to evaluate the efficiency of a hybrid treatment method. Electrochemical oxidation or electro-Fenton was considered as a pretreatment step, whereas biodegradation was selected as the secondary treatment method. Both processes were carried out in current mode, at 10 mA with carbon felt as working electrode. The efficiency of degradation, oxidation and mineralization was evaluated after 6 h. Both processes decreased the total organic carbon and chemical oxygen demand (COD) values and increased the biochemical oxygen demand (BOD₅) on the COD ratio to a value close to 0.4, showing that the electrolyzed solutions can be considered as 'readily biodegradable.'

The impact of solvents on the singlet and triplet states of selected fluorine corroles – absorption, fluorescence, and optoacoustic studies

This paper examines the influence of aprotic solvents on the spectroscopic properties as well as the energy deactivation of two free-base corrole dyes substituted with C₆F₅ and/or 4-NO₂C₆H₄ groups.

Novel nanostructured hematite–spongin composite developed using an extreme biomimetic approach

The characteristic mineral-free fibrous skeletons (made of structural protein-spongin) of H. communis (Demospongiae: Porifera) was used as a structural template in hydrothermal synthesis of hematite (α-Fe₂O₃) nanoparticles.

Electrochemistry serving people and nature: high-energy ecocapacitors based on redox-active electrolytes

Positive Poles: A new type of electrochemical capacitor with two different aqueous solutions, separated by a Nafion membrane is described. High capacitance values as well as excellent energy/power characteristics are reported and discussed. The neutral character of the applied electrolytes makes this capacitor an environmentally friendly, easy to assemble, and cost-effective device for energy storage.

Supercapacitors Based on Nickel Oxide/Carbon Materials Composites

In the thesis, the properties of nickel oxide/active carbon composites as the electrode materials for supercapacitors are discussed. Composites with a different proportion of nickel oxide/carbon materials were prepared. A nickel oxide/carbon composite was prepared by chemically precipitating nickel hydroxide on an active carbon and heating the hydroxide at 300 ∘Cin the air. Phase compositions of the products were characterized using X-ray diffractometry (XRD). The morphology of the composites was observed by SEM. The electrochemical performances of composite electrodes used in electrochemical capacitors were studied in addition to the properties of electrode consisting of separate active carbon and nickel oxide only. The electrochemical measurements were carried out using cyclic voltammetry, galvanostatic charge/discharge, and impedance spectroscopy. The composites were tested in 6 M KOH aqueous electrolyte using two- and three-electrode Swagelok systems. The results showed that adding only a few percent of nickel oxide to active carbon provided the highest value of capacity. It is the confirmation of the fact that such an amount of nickel oxide is optimal to take advantage of both components of the composite, which additionally can be a good solution as a negative electrode in asymmetric configuration of electrode materials in an electrochemical capacitor.

Synthesis and properties of trigeminal tricationic ionic liquids

Novel trigeminal tricationic ionic liquids (TTILs) have been successfully synthesized in high yields by means of Menschutkin quaternization via an S(N)1 mechanism. This reaction presents a new convenient method for transforming glycerol into multifunctional compounds. The physical properties of a series of TTILs were characterized by using a variety of techniques. The prepared salts were tested for antimicrobial activity. Electrochemical characterization of TTILs was also performed, which allowed the estimation of the conductivity of these new compounds, to establish their electrochemical stability window and capacitance properties over a wide range of temperatures. A good correlation of the physical properties of TTILs with capacitance values was observed.