Pracownicy

Streszczenie:
Naturally abundant materials play a crucial role in the development of sustainable electrochemical energy storage (EES) devices including batteries and supercapacitors (SCs). This is due to limited available resources with regards to energy storage materials, and the environmental pollution produced by the toxic materials utilized in conventional EESs. In the current review, development in the field of natural bast fibres (jute, flax, hemp and kenaf) based EES devices performances is highlighted. This review emphasizes methods such as the direct use of modified fibres and activated carbon from biomass for the design of EES devices. Activated fibres were developed using both physical and chemical activation methods. Key challenges including active electrode materials preparation, capacitive retention, and the implementation of the fibre based EES devices are critically discussed. Furthermore, the recent surge in the use of wearables and portable technologies that demand further development of flexible/non-flexible EES devices are also explored. Future trends and perspectives on materials development, power management interface, recycling, biodegradability and circular economy are also addressed. It is concluded that the development of new renewable energy systems using bast fibres has many remarkable advances in device performance. For this, an innovative approach is required to develop high energy density bast fibre based sustainable EES devices which will be potentially implemented for clean energy solutions.

Słowa kluczowe:
Biomass derived carbon, Electrochemical energy storage, Supercapacitor, Modified fibres, Natural fibres

Streszczenie:
The emergence of portable electronics in miniaturized and intelligent devices demands high-performance supercapacitors (SC) and batteries as power sources. For the fabrication of such energy storage devices, conducting polymers (CPs) have significant advantages due to their high theoretical capacitive performance and conductivity. In this work, we developed two CPs including polyaniline and polythiophene through a low-cost chemically synthesized approach and the film-by-spin coating method. The structural and morphological properties of the CPs are analyzed using Fourier-transform infrared spectroscopy (FTIR), contact angle measurement, and scanning electron microscopy (SEM). Based on these CPs, novel pristine polyaniline and polythiophene-based SCs (PASC and PTSC) are developed. The prepared CPs contribute to high electrochemical performances due to their high conductive nature of the electrode and conjugated polymer materials reaction. Hence both electrochemical double-layer formation and pseudocapacitance contributed to the energy-storing performances of the device. Electrochemical impedance spectroscopic analysis (0.1 Hz to 100 kHz) demonstrates faster ionic exchange and high capacitance of the PASC electrode as compared to PTSC in H3PO4 electrolyte. The PASC devices exhibit specific capacitance of 13.22 mF·cm−2 with energy and power densities of 1.175 μW·h·cm−2 and 4.99 μW·cm−2 at a current of 50 μA. Compared to PTSC (specific capacitance 3.30 mF·cm−2) the PASC shows four times higher specific capacitance due to its improved surface, structural and electrical properties. The electrochemical performance reveals the superior SC performance for this type of CP electrode.

Słowa kluczowe:
Conductive polymers, Spin coating, Polyaniline, Polythiophene, Supercapacitor, Electrochemical performances

Streszczenie:
The sustainable transformation of bio-waste into usable, material has gained great scientific interest. In this paper, we have presented preparation of an activated carbon material from a natural mushroom (Suillus boletus) and explor its properties for supercapacitor and dye adsorption applications. The produced cell exhibited a single electrode capacitance of ∼247 F g−1 with the energy and power density of ∼35 Wh kg−1 and 1.3 kW kg−1, respectively. The cell worked well for ∼20,000 cycles with ∼30% initial declination in capacitance. Three cells connected in series glowed a 2.0 V LED for ∼1.5 min. Moreover, ultrafast adsorption of methylene blue dye onto the prepared carbon as an adsorbent was recorded with ∼100% removal efficiency in an equilibrium time of three minutes. The performed tests indicate that the mushroom-derived activated carbon has the potential to become a high-performance electrode material for supercapacitors and an adsorbent for real-time wastewater treatment applications.

Słowa kluczowe:
Activated carbon, Amorphous material, Biomass, Polymer gel electrolyte, Supercapacitor, Dye adsorption

Streszczenie:
Utilization of CoO@Co3O4-x-Ag (x denotes 1, 3, and 5 wt% of Ag) nanocomposites as supercapacitor electrodes is the main aim of this study. A new low-temperature wet chemical approach is proposed to modify the commercial cobalt oxide material with silver nanoparticle (NP) balls of size 1–5 nm. The structure and morphology of the as-prepared nanocomposites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption–desorption measurements. Hydrogels known to be soft but stable structures were used here as perfect carriers for conductive nanoparticles such as carbons. Furthermore, hydrogels with a large amount of water in their network can give more flexibility to the system. Fabrication of an electrochemical cell can be achieved by combining these materials with a layer-by-layer structure. The performance characteristics of the cells were examined by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge discharge (GCD). Cobalt oxide modified with 5 wt% Ag gave the best supercapacitor results, and the cell offers a specific capacitance of ∼38 mF cm−2 in two-electrode configurations.

Streszczenie:
The electrochemical properties of metal oxides are very attractive and fascinating in general, making them a potential candidate for supercapacitor application. Vanadium oxide is of particular interest because it possesses a variety of valence states and is also cost effective with low toxicity and a wide voltage window. In the present study, vanadium oxide nanorods were synthesized using a modified sol–gel technique at low temperature. Surface morphology and crystallinity studies were carried out by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy analysis. To the best of our knowledge, the as-prepared nanorods were tested with magnesium ion based polymer gel electrolyte for the first time. The prepared supercapacitor cell exhibits high capacitance values of the order of ~ 141.8 F g−1 with power density of ~ 2.3 kW kg−1 and energy density of ~ 19.1 Wh kg−1. The cells show excellent rate capability and good cycling stability.

Streszczenie:
Carbon/graphene quantum dots are 0D fluorescent carbon materials with sizes ranging from 2 nm to around 50 nm, with some attractive properties and diverse applications. Different synthesis routes, bandgap variation, higher stability, low toxicity with tunable emission, and the variation of physical and chemical properties with change in size have drawn immense attention to its potential application in different optoelectronics-based materials, especially advanced light-emitting diodes and energy storage devices. WLEDs are a strong candidate for the future of solid-state lighting due to their higher luminance and luminous efficiency. High-performance batteries play an important part in terms of energy saving and storage. In this review article, the authors provide a comparative analysis of recent and ongoing advances in synthesis (top-down and bottom-up), properties, and wide applications in different kinds of next-generation light-emitting diodes such as WLEDs, and energy storage devices such as batteries (Li-B, Na-B) and supercapacitors. Furthermore, they discuss the potential applications and progress of carbon dots in battery applications such as electrode materials. The authors also summarise the developmental stages and challenges in the existing field, the state-of-the-art of carbon/graphene quantum dots, and the potential and possible solutions for the same.

Słowa kluczowe:
carbon dots, graphene quantum dots, white-LED, supercapacitors, Na-ion batteries, Li-ion batteries

Streszczenie:
In the present work, we report the synthesis of surface modified activated carbon (AC). The surface of the activated carbon have been modified by using silver nanoparticles. The synthesis process is simple, cost effective and environment friendly. The modified-AC powders have been characterized by using X-ray diffraction, scanning electron microscopy and surface area and pore size measurements. The electrochemical performance of the prepared materials have been tested by fabricating symmetric configuration of EDLC by using magnesium-ion based polymer electrolytes. The cells have been tested by using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge technique. AC with 3 wt% of silver presents best results with specific capacitance of the order of 398 F g−1 energy density and power density of 55 Wh kg−1 and 2.4 kW kg−1 making it an interesting material for supercapacitor application.

Słowa kluczowe:
supercapacitor, activated carbon-silver composite, gel polymer electrolyte, electrochemical studies

Streszczenie:
In this work, a facile, wet chemical synthesis was utilized to achieve a series of lithium manganese oxide (LiMn2O4, (LMO) with 1–5%wt. graphene oxide (GO) composites. The average crystallite sizes estimated by the Rietveld method of LMO/GO nanocomposites were in the range of 18–27 nm. The electrochemical performance was studied using CR2013 coin-type cell batteries prepared from pristine LMO material and LMO modified with 5%wt. GO. Synthesized materials were tested as positive electrodes for Li-ion batteries in the voltage range between 3.0 and 4.3 V at room temperature. The specific discharge capacity after 100 cycles for LMO and LMO/5%wt. GO were 84 and 83 mAh g^−1, respectively. The LMO material modified with 5%wt. of graphene oxide flakes retained more than 91% of its initial specific capacity, as compared with the 86% of pristine LMO material.

Słowa kluczowe:
lithium manganese oxide, LiMn2O4, graphene oxide, cathode material, lithium ion battery

Streszczenie:
In the present article, an ionic liquid-based polymer gel electrolyte was synthesized by using poly(vinylidene fluoride-co-hexafluo-ropropylene) (PVdF-HFP) as a host polymer. The electrolyte films were synthesized by using the solution casting technique. The as-prepared films were free-standing and transparent with good dimensional stability. Optimized electrolyte films exhibit a maximum room-temperature ionic conductivity of σ = 8.9 × 10^−3 S·cm^−1. The temperature dependence of the prepared polymer gel electrolytes follows the thermally activated behavior of the Vogel–Tammann–Fulcher equation. The total ionic transference number was ≈0.91 with a wider electrochemical potential window of 4.0 V for the prepared electrolyte film which contains 30 wt % of the ionic liquid. The optimized films have good potential to be used as electrolyte materials for energy storage applications.

Słowa kluczowe:
ionic liquid, polymer gel electrolytes, solution casting technique, transference number

Streszczenie:
A novel solution combustion synthesis of nanoscale spinel-structured Co3O4 powder was proposed in this work. The obtained material was composed of loosely arranged nanoparticles whose average diameter was about 36 nm. The as-prepared cobalt oxide powder was also tested as the anode material for Li-ion batteries and revealed specific capacities of 1060 and 533 mAh·g^−1 after 100 cycles at charge–discharge current densities of 100 and 500 mA·g^−1, respectively. Moreover, electrochemical measurements indicate that even though the synthesized nanomaterial possesses a low active surface area, it exhibits a relatively high specific capacity measured at 100 mA·g^−1 after 100 cycles and a quite good rate capability at current densities between 50 and 5000 mA·g^−1.

Słowa kluczowe:
anode material, cobalt oxide, lithium-ion battery, solution combustion synthesis, transition metal oxide

Streszczenie:
Activated carbons are one of the possible electrode materials for supercapacitors (SCs), which are widely used in commercial applications. Herein, we reported the synthesis of a novel activated carbon derived through a cavitation process from the mixture of native European deciduous trees, Birch, Fagaceae, and Carpinus betulus (commonly known as European hornbeam), which was employed as the electrode material in SC. From the morphological and structural characterization, we observed that the prepared sample is a desirable carbon with good porosity and high specific surface area of about 614 m^2 g^-1. The electrochemical properties of the synthesized material were evaluated with a three-electrode configuration in 1.0 M H2SO4 electrolyte. It was found that in device mode, the carbon material delivers a specific capacitance of 24 F g^-1 at 0.25 A g^-1 with excellent cycling stability of over 10000 consecutive charge/discharge cycles. Thus, our studies demonstrate the facile synthesis of biomass-derived carbon and its application as a versatile electrode material for SC applications.

Słowa kluczowe:
biomass, carbon material, deciduous trees, electrode material, supercapacitor

Streszczenie:
In the present studies, the effect of ionic liquid 1-Ethyl-2,3-dimethylimidazoliumtetrafluoroborate (EDiMIM)(BF4) on ionic conductivity of gel polymer electrolyte using poly(vinylidene fluoride-co-hexafluoropropylene) [PVdF(HFP)] and magnesium perchlorate [Mg(ClO4)2] as salt was investigated. The maximum room temperature ionic conductivity for the optimized system was found to be of the order of 8.4 × 10^–3 S cm^−1. The optimized composition reflects Vogel-Tammann-Fulcher (VTF) behavior in the temperature range of 25 °C to 100 °C. The X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy studies confirm the uniform blending of ionic liquid, polymer, and salts along with the enhanced amorphous nature of the optimized system. Dielectric and modulus spectra studies provide the information of electrode polarization as well as dipole relaxation properties of polymeric materials. The optimized electrolyte system possesses a sufficiently large electrochemical window of the order of 6.0 V with stainless steel electrodes.

Słowa kluczowe:
gel polymer electrolyte, ionic liquid, ionic conductivity, temperature dependence, supercapacitors

Streszczenie:
Electrospinning is a widely investigated process for forming nanofibers. Nanofibers in drug delivery systems are extensively tested due to its remarkable properties e.g. small pore size or large surface area. Recent articles have informed about formation of fibers using triaxial electrospinning in drug delivery systems. This paper summarizes the process of triaxial electrospinning and its application in drug delivery. Triaxial electrospinning has advantages in forming complex nanostructures for specific drug delivery applications. This paper summarizes the possibility to use triaxial electrospinning to resolve the problem of limited drug solubility, to protect biomolecules from hostile environment, and to control drug release kinetics, with the possibility of loading of various drugs. There are literature data evidencing the possibility to achieve sustained release with a border case of zero rate order kinetics. There is no doubt that triaxial electrospinning opens a new way to develop sophisticated nanomaterials for achieving the desired functional performances and to expand the applications in the drug delivery area. Triaxial electrospinning method is interdisciplinary area with great potential in nanotechnology.

Słowa kluczowe:
triaxial electrospinning, complex nanostructures, drug delivery, desired functional performance, sustained/controlled release

Streszczenie:
In the present study sodium ion conducting polymer blend electrolytes has been prepared using poly (vinylidene fluoride – hexafluoro – propylene) (PVdF-HFP), poly (methyl methacrylate) (PMMA), and sodium thiocyanate (NaSCN) salt by solution-cast technique. The highest ionic conductivity of the optimized blend polymer electrolyte system [PVdF(HFP)-PMMA (4:1)] (20 wt%)-[NaSCN (1 M)] (80 wt%) has been found to be 4.54 × 10^−2 S cm^−1 at room temperature. The temperature dependence conductivity plot shows the Arrhenius behaviour and its activation energy calculated from the plot were found to be 0.13 eV. The structural and morphological studies of polymer blend electrolyte were investigated by XRD, SEM and FTIR spectroscopy. Complex formation between polymer and salt has been confirmed by these studies. The thermal properties of optimized electrolyte system were examined by differential scanning calorimetry (DSC) techniques. The ionic transport number was calculated using d.c polarization techniques and was found to be 0.92, which shows that electrolyte system is predominantly ionic in nature. The electrochemical potential window of optimized polymer blend electrolyte was tested and observed to be ~2.8 V.

Słowa kluczowe:
polymer blends electrolyte, solution cast technique, sodium ion, FTIR, DSC

Streszczenie:
In the present studies, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), ionic liquid {1-Ethyl-3-methylimidazolium bromide} (EMIM)(Br), and magnesium perchlorate Mg(ClO4)2 as salt were used to synthesize free standing electrolyte films by using solution cast technique. The prepared electrolyte films were investigated by using various structural and electrochemical techniques like scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) as well as ionic and temperature dependence studies. It has been observed that addition of ionic liquid significantly increases the properties like ionic conductivity, thermal stability, transparency etc. The maximum room temperature ionic conductivity for the optimized system was found to be of the order of 2.05 × 10^−2 S cm^−1 which is suitable for device fabrication point of view. The optimized electrolyte films are suitable for supercapacitor application.

Słowa kluczowe:
gel polymer electrolytes, ionic liquid, solution cast technique, supercapacitors

Streszczenie:
Patterning of lines of holes on a layer of positive photoresist SXAR-P3500/6 (Allresist GmbH, Strausberg, Germany) spin-coated on a quartz substrate is carried out by using scanning near-field optical lithography. A green 532 nm-wavelength laser, focused on a backside of a nanoprobe of 90 nm diameter, is used as a light source. As a result, after optimization of parameters like laser power, exposure time, or sleep time, it is confirmed that it is possible to obtain a uniform nanopattern structure in the photoresist layer. In addition, the lines of holes are characterized by a uniform depth (71–87nm) and relatively high aspect ratio ranging from 0.22 to 0.26. Numerical modelling performed with a rigorous method shows that such a structure can be potentially used as a phase zone plate.

Słowa kluczowe:
optical lithography, photoresist, quartz, hole nanopatterning

Streszczenie:
Almondshell-basedchemicallytreatedandactivated nanoporous charcoal powder (AS(T)) has been successfully prepared by chemical activation method using potassium hydroxide (KOH) as an activating agent. The as-synthesized AS(T)wassystematicallycharacterizedbyvarioustechniques like N2 adsorption, scanning electron microscopy (SEM), Xray diffraction, and thermogravimetric analysis. The AS(T)based nanoporous activated charcoal is tested as an electrode material with ionic liquid-based polymer gel electrolyte for electrochemical double-layer capacitors (EDLCs). EDLCs prepared from AS(T) exhibit specific capacitance of 986.3 mF cm−2 (equivalent to single-electrodespecific capacitance of 563.6 F g−1). The energy density of 62.8 Wh kg−1 and power density of 2.1 kW kg−1 have been observed for nanoporous AS(T)-based EDLCs.

Słowa kluczowe:
Almond shell, Nanoporous carbon, Ionicliquid, Electrochemical double-layer capacitor

Streszczenie:
Low cost with high specific capacitance and energy density is the critical and main requirement for practical supercapacitors. In the present work, nano porous activated carbon having specific surface area of 400 m2 g-1 from sugarcane waste (bagasse) has been synthesized and characterized as an electrode material for supercapacitor applications using ionic liquid based polymer gel electrolytes. The fabricated cell shows the overall specific capacitance of 372 mF cm-2 which is equivalent to single electrode specific capacitance of 248 F g-1. The corresponding energy and power density of 16.3Wh kg-1 and 1.66 kWkg-1 were achieved for EDLCs.

Słowa kluczowe:
Supercapacitors, Activated Carbon, Polymer gel electrolyte, Surface modification

Słowa kluczowe:
Supercapacitors, MWCNTs, Polymer gel electrolyte, Surface modification

Słowa kluczowe:
Supercapacitors, Activated carbon, Polymer gel electrolyte