Morphology-controlled PANI nanowire electrode by using deposition scan rate in H<Subscript>2</Subscript>SO<Subscript>4</Subscript>/PVA polymer electrolyte for electrochemical capacitor

Polyaniline (PANI) nanowire electrode was successfully prepared using electrodeposition method. The morphology, thickness, and electrochemical performance of PANI electrode can be controlled by varying the deposition scan rates. Lower deposition scan rate results in compact and aggregates of PANI nanowire morphology. The uniform nanowire of PANI was obtained at the applied scan rate of 100 mV s^?1, and it was used as symmetric electrode coupled with H₂SO₄/polyvinyl alcohol (PVA) gel electrolyte. The different concentrations of H₂SO₄ acid in polymer electrolyte have influenced the electrochemical performance as well. The optimum specific capacitance and energy density of P100 PANI electrode in 3 M H₂SO₄/PVA gel polymer electrolyte was 377 F g^?1 and 95.4 Wh kg^?1 at the scan rate of 1 mV s^?1. The good stability of the electrode in this system is applicable to many wearable electronics applications.     

The effect of different concentrations of Na2SnO3 on the electrochemical behaviors of the Mg-8Li electrode

In this research, the effect of the different concentrations of NaSnO₃ as the electrolyte additive in 0.7 mol L^?1 NaCl solution on the electrochemical performances of the magnesium-8lithium (Mg-8Li) electrode are investigated by methods of potentiodynamic polarization, potentiostatic current-time, electrochemical impedance technique, and scanning electron microscopy (SEM). The corrosion resistance of the Mg-8Li electrode is improved when Na₂SnO₃ is added into the electrolyte solution. The potentiostatic current-time curves show that the electrochemical behaviors of the Mg-8Li electrode in the electrolyte solution containing 0.20 mmol L^?1 Na₂SnO₃ is the best. The electrochemical impedance spectroscopy results indicate that the polarization resistance of the Mg-8Li electrode decreases in the following order with the concentrations of Na₂SnO₃: 0.05 mmol L^?1?>?0.00 mmol L^?1?>?0.30 mmol L^?1?>?0.10 mmol L^?1?>?0.20 mmol L^?1. The scanning electron microscopy studies indicate that the electrolyte additive prevents the formation of the dense oxide film on the alloy surface and facilitates the peeling off of the oxidation products.     

Flexible polyethylene terephthalate (PET) electrodes based on single-walled carbon nanotubes (SWCNTs) for supercapacitor application

Flexible polyethylene terephthalate (PET) electrodes based on pristine single-walled carbon nanotubes (SWCNTs) and acid-treated single-walled carbon nanotubes (A-SWCNTs) were prepared by spray coating technique. Flexible A-SWCNTs electrodes showed enhanced electrochemical properties compared to the pristine SWCNTs electrodes. The electrochemical properties of the flexible A-SWCNTs electrodes were optimized with various types of aqueous electrolytes including sulfuric acid (H₂SO₄), sodium sulfate (Na₂SO₄), potassium chloride (KCl), sodium hydroxide (NaOH), and potassium hydroxide (KOH). The electrochemical performance of the A-SWCNTs electrodes as a function of bending to 30° were evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge (GCD) measurements in 1 M H₂SO₄. The specific capacitance value of the unbent A-SWCNTs electrode was 67 F g^?1, which decreased to 63 F g^?1 (94% retention) after 1000 GCD cycles. Interestingly, the specific capacitance of the unbent A-SWCNTs electrode with application of the 1000 GCD cycles was retained even after 500 bending to 30° with 6000 GCD cycles.     

Effect of sodium salts on the cycling performance of tin anode in sodium ion batteries

To determine the effect of electrolyte salts on the cycling properties of tin anodes in sodium ion batteries, sodium/tin cells were prepared using eight electrolytes containing NaCF₃SO₃, NaBF₄, NaClO₄, and NaPF₆ in ethylene carbonate-dimethyl carbonate (EC-DMC) and EC-DMC/fluoroethylene carbonate (FEC) solvents. The first charge capacity and cycling properties strongly depended on the electrolyte salts. Additionally, an appropriately chosen electrolyte salt in combination with the FEC additive improved the cycling properties of the tin electrode. The tin electrode in the presence of the FEC-containing NaPF₆-based electrolyte exhibited the best cycling properties. The first charge capacity and charge capacity after the 45th cycle were 220 and 189 mAh g^?1 _electrode, respectively at a current density of 84.7 mA g^?1 _electrode. The rate performance is also studied using the optimized electrolyte which reveals the ability of the electrode to perform in high current application. At a high current density of 4235 mA g^?1 _electrode, the capacity delivered is 24 mAh g^?1 _electrode. At a current rate of 1694 mA g^?1 _electrode, at the end of 1400th cycle, capacity is about 45 mAh g^?1 _electrode. The results of the study clearly indicate that the electrolyte salts critically affect the electrochemical performance of the tin anode in sodium ion batteries.     

Promising nitrogen-doped porous nanosheets carbon derived from pomegranate husk as advanced electrode materials for supercapacitors

Nitrogen-doped porous activated carbons (N-PHACs) have been successfully synthesized using pomegranate husk as carbon precursor via ZnCl₂-activation carbonization and subsequent urea-assisted hydrothermal nitrogen-doping method. The obtained N-PHACs possesses abundant mesoporous structure, high specific surface area (up to 1754.8 m² g^?1), pore volume (1.05 cm³ g^?1), and nitrogen-doping content (4.51 wt%). Besides, the N-PHACs-based material showed a high specific capacitance of 254 F g^?1 at a current density of 0.5 A g^?1 and excellent rate performance (73% capacitance retention ratio even at 20 A g^?1) in 2 M KOH aqueous electrolyte, which is attributed to the contribution of double-layer capacitance and pseudocapacitance. The assembled N-PHACs-based symmetric capacitor with a wide operating voltage range of 0–1.8 V exhibits a maximum energy density of 15.3 Wh kg^?1 at a power density of 225 W kg^?1 and superior cycle stability (only 6% loss after 5000 cycles) in 0.5 M Na₂SO₄ aqueous electrolyte. These exciting results suggest that the novel N-doping porous carbon material prepared by a green and low-cost design strategy has a potential application as high-performance electrode materials for supercapacitors.     

Investigation of liquid plasma catalysis on Ti electrodes for the decolorization of a brilliant red B solution

This investigation is intended to determine the catalytic effect of liquid plasma on TiO₂, generated in situ on Ti anodes submerged in Na₂SO₄ electrolyte solution by observing the efficiency of the reaction in decolorizing a brilliant red B solution under voltage-stabilized DC power. The orthogonal test was performed in order to obtain the optimal reaction conditions for the test device. When placed under a constant voltage of 550 V, and with an electrode depth of 2 mm, Na₂SO₄ concentration of 5 g/L, pH of 2, the maximum decolorization ratio of 100 mL brilliant red B solution with the concentration of 20 mg/L was 97.8% after 40 min. The reaction rate constant was about 0.102 min^?1, conforming to the first-order reaction kinetic model. Comparative tests were conducted with: Al electrode under 450 V; Mo electrode under 550 V; and a mixture of the electrolyte and TiO₂ powder. The results showed that liquid plasma – TiO₂ on the electrode of the catalytic system naturally integrated on the discharge electrode, with an increase in reaction rate by 26.8% while utilizing the same energy consumption.     

Development of gel polymer electrolytes for application in quantum dot-sensitized solar cells

A methylcellulose–polysulfide gel polymer electrolyte has been prepared for application in quantum dot-sensitized solar cells (QDSSCs) having the configuration FTO/TiO₂/CdS/ZnS/SiO₂/electrolyte/Pt(cathode). The electrolyte with the composition of 30.66 wt.% methylcellulose, 67.44 wt.% Na₂S, and 1.90 wt.% sulfur exhibits the highest conductivity of 0.183 S cm^?1 with the lowest activation energy of 6.14 kJ mol^?1. CdS quantum dot sensitizers have been deposited on TiO₂ film via the successive ionic layer absorption and reaction (SILAR) method. The QDSSC fabricated using the highest conducting electrolyte and CdS QD prepared with five SILAR cycles exhibits a power conversion efficiency (PCE) of 0.78%. After deposition of zinc sulfide (ZnS) and silicon dioxide SiO₂ passivation layers, the PCE of the QDSSC with photoanode arrangement of TiO₂/CdS(5)/ZnS(2)/SiO₂ increased to 1.42%, an improvement in performance by 82%.     

Phase transitions and energy storage properties of some compositions in the (1−x)Li2SO4–xNa2SO4 system

In the binary system (1?x)Li₂SO₄–xNa₂SO₄, the solid–solid phase transitions and energy storage properties of Li₂SO₄, Na₂SO₄, the binary compound LiNaSO₄ and two eutectoids (E₁: 0.726Li₂SO₄–0.274Na₂SO₄; E₂: 0.03Li₂SO₄–0.97Na₂SO₄) were investigated by X-ray diffraction and differential scanning calorimetry. Li₂SO₄ has a solid–solid phase transition at 578 °C with the transition enthalpy 252 J g^?1. The binary compound LiNaSO₄ gives a slightly lower enthalpy value, 214 J g^?1 and its transition temperature is clearly reduced to 514 °C. The transition enthalpy of the eutectoid E₁ is maintained to 177 J g^?1 and its transition temperature is further reduced to 474 °C. Li₂SO₄, LiNaSO₄ and the eutectoid E₁ are applicable phase transition materials because of their large transition enthalpies. The enthalpies of Na₂SO₄ and the eutectoid E₂ are not very high (～45 J g^?1), but their transition temperatures are quite low (～250 °C); thus their transition properties may be applied at such low temperatures.     

Performance evaluation of polyacrylamide/silver composite as electrode material in electrochemical capacitor

In this research, polyacrylamide/Ag composite is synthesized and used as an electrode in an electrochemical capacitor (EC). The characterization of the composite is performed by X-ray diffraction, scanning electron microscopy, and cyclic voltammetry methods. The electrochemical characterization is conducted in an electrolytic solution of KOH and an electrolytic solution of Na₂SO₄. The capacitance of the polyacrylamide/Ag composite is associated mainly with the reduction/oxidation of Ag. The specific capacitance of the EC using the KOH electrolyte is 950 Fg^?1, which is better than the capacitance in the Na₂SO₄ electrolyte. This behavior is explained by the respective physical characteristics of the two electrolytes.     

Charge storage performance of lithiated iron phosphate/activated carbon composite as symmetrical electrode for electrochemical capacitor

In this study, a symmetric electrochemical capacitor was fabricated by adopting a lithium iron phosphate (LiFePO₄)-activated carbon (AC) composite as the core electrode material in 1.0 M Na₂SO₃ and 1.0 M Li₂SO₄ aqueous electrolyte solutions. The composite electrodes were prepared via a facile mechanical mixing process. The structural properties of the nanocomposite electrodes were characterised by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis. The electrochemical performances of the prepared composite electrode were studied using cyclic voltammetry (CV), galvanostatic charge–discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that a maximum specific capacitance of 112.41 F/g was obtained a 40 wt% LiFePO₄ loading on an AC electrode compared with that of a pure AC electrode (76.24 F/g) in 1 M Na₂SO₃. The improvement in the capacitive performance of the 40 wt% LiFePO₄–AC composite electrode is believed to be attributed to the contribution of the synergistic effect of the electric double layer capacitance (EDLC) of the AC electrode and pseudocapacitance via the intercalation/extraction of H⁺, OH⁻, Na⁺ and SO₃²⁻ and Li⁺ ions in LiFePO₄ lattices. In contrast, it appears that the incorporation of LiFePO₄ into AC electrodes does not increase the charge storage capability when Li₂SO₄ is used as the electrolyte. This behaviour can be explained by the fact that the electrolyte system containing SO₄²⁻ only exhibits EDLC in the Fe-based electrodes. Additionally, Li⁺ ions that have lower conductivity and mobility may lead to poorer charge storage capability compared to Na⁺ ions. Overall, the results reveal that the AC composite electrodes with 40 wt% LiFePO₄ loading on a Na₂SO₃ neutral electrolyte exhibit high cycling stability and reversibility and thus display great potential for electrochemical capacitor applications.     

Nanocrystalline Li<Subscript>2</Subscript>TiO<Subscript>3</Subscript> electrodes for supercapattery application

Nanocrystalline Li₂TiO₃ was successfully synthesized using solid-state reaction method. The microstructural and electrochemical properties of the prepared material are systematically characterized. The X-ray diffraction pattern of the prepared material exhibits predominant (002) orientation related to the monoclinic structure with C2/c space group. HRTEM images and SAED analysis reveal the well-developed nanostructured particles with average size of ～40 nm. The electrochemical properties of the prepared sample are carried out using cyclic voltammetry (CV) and chronopotentiometry (CP) using Pt//Li₂TiO₃ cell in 1 mol L^?1 Li₂SO₄ aqueous electrolyte. The Li₂TiO₃ electrode exhibits a specific discharge capacity of 122 mAh g^?1; it can be used as anode in Li battery within the potential window 0.0–1.0 V, while investigated as a supercapacitor electrode, it delivers a specific capacitance of 317 F g^?1 at a current density of 1 mA g^?1 within the potential range ?0.4 to +0.4 V. The demonstration of both anodic and supercapacitor behavior concludes that the nanocrystalline Li₂TiO₃ is a suitable electrode material for supercapattery application.     

Preparation and characterization of sodium binary system (NaI–Na3PO4) inorganic solid electrolyte

New binary inorganic salt such as sodium iodide (NaI)–sodium phosphate (Na₃PO₄) has a great potential to be used as a solid electrolyte, and this solid electrolyte system exhibits high ionic conductivity up to 10^?4 S cm^?1. The solid electrolyte compounds were prepared by mechanical milling followed by pelletizing and sintering at low temperature. The electrical conductivity study was carried out as a function of NaI concentration by impedance spectroscopy technique and the maximum conductivity of (1.02?±?0.19)?×?10^?4 S cm^?1 at room temperature was obtained for the composition 0.50 NaI:0.50 Na₃PO₄. The increase in conductivity is probably due to the increase in number of mobile charge carriers through the conducting pathway provided by tetrahedral structures of Na₃PO₄. The presence of P–O and PO₄ ^3? bands was detected by the infrared technique Fourier transform infrared spectroscopy had been shifted indicating changes in polyhedral structure which in turn led to the formation of conducting channel by corner sharing or through edges. The mobility of the charge carriers in the various compositions of the binary system was investigated by using ²³Na magic angle spinning solid-state nuclear magnetic resonance. The narrowing of the line width ²³Na spectra in the optimum composition of the binary NaI–Na₃PO₄ system can be assigned to Na population with higher ion mobility. X-ray diffraction technique revealed that the addition of NaI resulted in reducing the crystallinity of the samples. Field emission scanning electron microscopy micrographs revealed finer microstructure of the milling samples with grains growth formation and densification upon sintering.     

Thermoluminescence characteristics of Na3 SO4 Cl:X (X=Ce,Dy, Mn) phosphor

In the present paper Na₃SO₄Cl:Ce, Na₃SO₄Cl:Dy, Na₃SO₄Cl:Mn, of Na₃SO₄Cl:Ce, Dy and Na₃SO₄Cl:Ce, Mn phosphor were synthesized by the wet chemical method. Thermoluminescence (TL) characteristics of Na₃SO₄Cl:Ce, Na₃SO₄Cl:Dy, Na₃SO₄Cl:Mn, Na₃SO₄Cl:Ce, Dy and Na₃SO₄Cl:Ce, Mn phosphors were studied for 5 Gy γ-ray dose. In TL glow curve, two peaks have been observed at 129°C and 224°C for different concentrations of Ce and Dy, whereas Mn peaks at 212°C. The same host is also tried for Ce, Dy (peaks at 126, 219) and Ce, Mn (248°C). A significant single peak is observed in the case of Na₃SO₄Cl:Mn and Na₃SO₄Cl:Ce, Mn. This may be due to the effect of activators. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.39 kGy h^?1 for 5 Gy γ-rays dose. It is also found that all the phosphors are less sensitive as compared with Thermoluminescence dosimetry-CaSO₄: Dy for the same γ-rays dose. The paper discuses the preliminary TL characteristics and effect of γ-rays on Na₃SO₄Cl:Ce, Na₃SO₄Cl:Dy, Na₃SO₄Cl:Mn, Na₃SO₄Cl:Ce, Dy and Na₃SO₄Cl:Ce, Mn phosphors.     

Study of the electrochemical performance of VO2+/VO2 + redox couple in sulfamic acid for vanadium redox flow battery

The present work was performed in order to evaluate sulfamic acid as the supporting electrolyte for VO²⁺/VO₂ ⁺ redox couple in vanadium redox flow battery. The oxidation process of VO²⁺ has similar electrochemical kinetics compared with the reduction process of VO₂ ⁺. The exchange current density and standard rate constant of VO²⁺/VO₂ ⁺ redox reaction on a graphite electrode in sulfamic acid are determined as 7.6?×?10^?4 A cm^?2 and 7.9?×?10^?5 cm s^?1, respectively. The energy efficiency of the cell employing sulfamic acid as supporting electrolyte in the positive side can reach 75.87 %, which is adequate for redox flow battery applied in energy storage. The addition of NH₄ ⁺ to the positive electrolyte can enhance the electrochemical performance of the cell, with larger discharge capacity and energy efficiency. The preliminary exploration shows that the vanadium sulfamate electrolyte is promising for vanadium redox flow battery and is worthy of further study.     

Potentiometric sensor for sulfur oxides using NASICON as a solid electrolyte

The ac conductivity of NASICON is higher by two orders of magnitude than that of Na₂SO₄ at 1000 K. The dc polarization measurement reveals that NASICON shows sodium ion conduction even at the temperature of about 1200 K, and that the electronic transference number is of the order of 10^?5. The SO₂-O₂-SO₃ concentration cell using NASICON electrolyte gives essentially the same electromotive force as in the cell using Na₂SO₄ electrolyte because a thin layer of Na₂SO₄ if formed on NASICON at the electrodes. The high sinterability of NASICON offers a dense electrolyte without permeation of gases. The SO_x sensor using NASICON electrolyte exhibits good response and excellent selectivity against CO₂ and NO₂.     

Phase transition of BiVO4 nanoparticles in molten salt and the enhancement of visible-light photocatalytic activity

BiVO₄ nanoparticles are prepared by molten salt method. Tetragonal BiVO₄ completely transforms to monoclinic phase after heating in molten LiNO₃ at 270 °C for 18 h. The average particle sizes of monoclinic BiVO₄ varied from 30 to 52 nm while the initial ratio of BiVO₄ to LiNO₃ changes from 1:6 to 1:24. The photocatalytic activity is evaluated by measuring decolorization of N,N,N′,N′-tetraethylated rhodamine dye solution under visible-light irradiation. Both of the de-ethylation and chromophore cleavage are responsible for the decolorization of RB. The sample with an average particle size of 52 nm and a moderate surface area of 10 m²/g exhibit the highest visible-light photocatalytic activity. The shift of Raman peak position indicates that the symmetry distortions in the local structure of the monoclinic BiVO₄. The variations of the local structure result in the modification of the electronic structure, which is responsible for the high visible-light photocatalytic activity.     

About Some Structural Differences of Certain Inorganic Salt Solutions in Natural and Heavy Water

Based on viscosity measurements of seven electrolyte soultions (KCl, K Br, KI, LiCl, Na₂CO₃, Li₂SO₄, and MnSO₄) in heavy water and the viscosity data of four electrolyte solutions (KCl, KBr, Kl, and Na₂CO₃) in ordinary water the activation energies of viscosity have been determined from the Pantchenkov equation. The dtermination were made at 25°, 35°, 45°, 60°, 75°, and 90°, at various concentrations up to near saturation. The activation energies of viscosity for pure heavy and ordinary water have been determined, too. The results allowed conclusions on the various influences of the investigated salts on the structure of heavy and ordinary water solutions.     

Based on Cu as framework constructed nanoporous CuO/Cu composites by a dealloy method for sodium-ion battery anode

Nanoporous CuO/Cu composites with a continuous channel structure were fabricated through a corroding Cu-Al alloy process. The width of the continuous channels was about 20~50 nm. Nanoporous structure could effectively sustain the volume expansion during the Na⁺ insertion/extraction process and shorten the Na⁺ diffusion length as well, which thus helps improve the Na⁺ storage performance. Moreover, the nanoporous structure can improve the contact area between the electrolyte and the electrode, leading to an increment in the number of Na⁺ insertion/extraction sites. When used as the anode for sodium-ion batteries, the CuO/Cu exhibited an initial capacity of ~?580 mAh g^?1, and the capacity is maintained at ~?200 mAh g^?1 after 200 cycles at a current density of 500 mA g^?1.     

Preparation and characterization of a new PEO-PPG blend polymer electrolyte system

This paper reports on preparation and characterization of thin films of a new zinc ion conducting blended polymer electrolyte system containing polyethylene oxide [PEO] and polypropylene glycol [PPG] complexed with zinc triflate [Zn(CF₃SO₃)₂] salt. The room temperature ionic conductivity (σ _298K) data of such PEO-PPG polymer blends prepared by solution casting technique were found to be of the order of 10^?5 S cm^?1, whereas the optimized composition containing 90:10 wt% ratio of PEO and PPG possessed an appreciably high ionic conductivity of 7.5?×?10^?5 S cm^?1. Subsequently, six different weight percentages of zinc triflate viz., 2.5, 5, 7.5, 10, 12.5 and 15, respectively, were added into the above polymer blend and resulting polymer-salt complexes were characterized by means of various analytical tools. Interestingly, the best conducting specimen namely 87.5 wt% (PEO:PPG)-12.5 wt% Zn(CF₃SO₃)₂ exhibited an enhanced room temperature ionic conductivity of 6.9?×?10^?4 S cm^?1 with an activation energy of 0.6 eV for ionic conduction. The present XRD results have indicated the occurrence of characteristic PEO peaks and effects of salt concentration on the observed intensity of these diffraction peaks. Appropriate values of degree of crystallinity for different samples were derived from both XRD and DSC analyses, while an examination of surface morphology of the blended polymer electrolyte system has revealed the formation of homogenous spherulites involving a rough surface and relevant zinc ionic transport number was found to be 0.59 at room temperature for the best conducting polymer electrolyte system thus developed.     

Structural, conductivity, and dielectric characterization of PEO–PEG blend composite polymer electrolyte dispersed with TiO2 nanoparticles

A solid polymer electrolyte (SPE) composites consisting blend of poly(ethylene oxide) (PEO) and poly(ethylene glycol) (PEG) as the polymer host with LiCF₃SO₃ as a Li⁺ cation salt and TiO₂ nanoparticle which acts as a filler were prepared using solution-casting technique. The SPE films were characterized by X-ray diffraction and Fourier transform infrared analysis to ensure complexation of the polymer composites. Frequency-dependent impedance spectroscopy observation was used to determine ionic conductivity and dielectric parameters. Ionic conductivity was found to vary with increasing salt and filler particle concentrations in the polymer blend complexes. The optimum ambient temperature conductivity achieved was 2.66?×?10^?4?S?cm^?1 for PEO (65 %), PEG (15 %), LiCF₃SO₃ (15 %), ethylene carbonate (5 %), and TiO₂ (3 %) using weight percentage. The dielectric relaxation time obtained from a loss tangent plot is fairly consistent with the conductivity studies. Both Arrhenius and VTF behaviors of all the composites confirm that the conductivity mechanism of the solid polymer electrolyte is thermally activated.