Search

Definition: Binder materials are needed to keep particles of active masses in electrodes for batteries and supercapacitors together and to ensure their adherence to the current collector. Mostly synthetic polymeric materials are used. Because they are electrochemically inert, they do not add to the storage capacity of the electrode. Intrinsically conducting polymers ICPs such as polyaniline, polythiophene or polypyrrole can provide these functions also. They show electronic conduction because of mobile charge carriers generated in them by oxidation or reduction. In addition to providing the binder-function, they improve electronic conductance of the electrode mass because of their inherent conductivity and can also contribute to the charge storage capability of the electrode in the range of potential of the redox activity of ICPs in the used electrolyte solution. In most reports on the application of ICPs as component of conductive binders, their incorporation results in enhanced specific capacity and notable improvement of C-rate capability of electrodes. In addition, ICP binders provide partial or complete wrapping of grains of active electrode materials, which effectively inhibits the interaction with the electrolyte, suppressing side reactions and degradation of functional properties. [ABSTRACT FROM AUTHOR]

In this study, we report on the electrochemical properties of hydrothermally synthesized MoS2 composites for use in lithium-ion batteries. A widespread method was modified for facile synthesis of pristine MoS2 and its composites with PEDOT:PSS, rGO, or both. The electrochemical performance of the materials was investigated using cyclic voltammetry and galvanostatic charge-discharge measurements. The addition of rGO significantly enhances the specific capacity and stability of MoS2, with the MoS2/rGO composite exhibiting specific capacity in the second cycle of 748 mA·h·g−1 and a capacity retention of 63% through the 400th cycle. The composites exhibited a phenomenon of capacity increase after reaching a minimum, with this effect being most pronounced in the case of MoS2/rGO. This composite reached its lower capacity value at the 143rd cycle (211 mA·h·g−1), and then recovered to 224% of the minimum capacity (472 mA·h·g−1). We attribute this behavior to an increase in the availability of active particles over the course of cycling by milling the active components into smaller and thus more accessible species of Li2S and S. The intensity of the effect of rGO is due to its intrinsically large surface area and two-dimensional layered structure, which enhances the distribution of redox-active particles within the material layers and prevents agglomeration. Our results contribute to the existing evidence of the improved electrochemical performance of MoS2 in Li-ion batteries with layered graphitic compounds and provide promising avenues for further research of the unique behavior of conversion materials. [ABSTRACT FROM AUTHOR]

In this paper, a simple and stable composite electrode PEDOT:PSS/Pd based on the intrinsically conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was fabricated by drop-casting. The preliminary formation of water dispersion of PEDOT:PSS with Pd nanoparticles was followed by multistep drop cast deposition for the formation of thin metal-polymer composite layers on glassy carbon electrode. The morphology of pristine and composite films as well as the size and distribution of Pd particles were characterized by scanning electron microscopy. The electrochemical properties of composite metal-polymer layers were examined by cyclic voltammetry and chronoamperometry in solution of 0.2 M phosphate buffer solutions (PBS) in the presence and absence of hydrazine. It was demonstrated that electrocatalytical oxidation of hydrazine takes place only on electrochemically accessible palladium particles, located on surface or near-surface layers of composite film. The proposed multi-layer electrodes exhibited a wide linear range of response towards hydrazine detection (from 0.4 to 100 μM) and low detection limit of 0.12 μM (S/N = 3). [ABSTRACT FROM AUTHOR]

Composite poly-3,4-ethylenedioxythiophene (PEDOT)/palladium (Pd) films were obtained by chemical deposition of dispersed palladium nanoparticles into PEDOT conducting polymer matrix. The amounts of palladium particles incorporated into PEDOT films were estimated by electrochemical quartz crystal microbalance measurements. It was shown that palladium loading depends on the time a PEDOT film is exposed in the solution, containing Pd(II)-ions, on the concentration of Pd(II) ions and the film thickness. X-ray photoelectron spectroscopy data have confirmed the presence of metallic palladium in the polymer. The morphology of pristine and composite films as well as the size of Pd nanoparticles and their distribution were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From SEM images, it was found that Pd particles decorated PEDOT globular structures as quasi-spherical particles, and their mean size was dependent on synthesis conditions. The nanoparticles were non-uniformly dispersed on the polymer surface. The comparison of TEM images of composite PEDOT/Pd films obtained for different times of metal loading was made. The remarkable effect of loading time on the size of particles has been established: the mean size of dominating palladium particles was close to 6-10 nm for 30 s of metal deposition, and it was getting larger with the increase of deposition time (close to 15-30 nm for 120 s). It is most likely that with prolongation of synthesis time, the deposition of palladium predominantly proceeds on the already deposited palladium clusters, resulting in the extension growth of their size. Catalytic properties of PEDOT/Pd composite films were studied in respect to hydrazine oxidation by cyclic voltammetry and voltammetry on rotating disk electrode. The obtained data allow to conclude that the process of hydrazine oxidation on PEDOT/Pd composites takes place predominantly on palladium particles, located on the surface or in the near-surface layers of the polymer. The diffusion nature of the limiting current of hydrazine oxidation on composite PEDOT/Pd film in phosphate buffer solution рН = 6.86 was confirmed, and hydrazine diffusion coefficient was calculated. The increase of the limiting currents of hydrazine oxidation with the increase of Pd deposition time was observed, resulting from the increase of the active surface area of palladium particles, acting as microelectrodes. The electroanalytical applications of these nanocomposite materials for the determination of hydrazine were demonstrated. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) are being intensively developed as potential alternative electrochemical power sources, due to their advantages such as low cost, high safety, abundance of natural zinc resources and appropriate energy density. Among currently investigated prospective cathode materials for AZIBs, vanadium oxide-based composites with intrinsically conducting polymers have shown many advantages, such as high capacity, high power density and long battery life. This review gives a focused view of the design for the boosting of zinc ion storage performance using intrinsically conducting polymers in vanadium oxide-based composites and the mechanism of intercalation processes. The main challenges in interfacial engineering of vanadium oxide-conducting polymers composite structures and the prospects for further development of such cathode materials are summarized and discussed. The review would give rise to a broad interest focusing on the advantageous strategy of the development of vanadium oxide composite cathodes with intrinsically conducting polymers (polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene)) for AZIBs with improved energy density, high-rate capability and stability. [ABSTRACT FROM AUTHOR]

Au-containing polymer films were obtained by electroless deposition of gold from diluted solutions of HAuCl into preliminarily reduced poly-3,4-ethylenedioxythiophene (PEDOT) films. Structural peculiarities of such pristine and composite films were characterized by scanning and transmission electron microscopy methods. It was established that the gold clusters forming under such deposition appear on the outer surface of polymer films and their pores. The clusters' sizes ranged between 30 and 100 nm depending on the time of exposition of a PEDOT film in solutions of Au(III) ions and the concentration of these ions. It was also observed that in contrast to pristine PEDOT films, cyclic voltammograms (CVs) of composite films in the presence of chloride ions show additional redox peaks resulting from oxidation of gold with formation of an insoluble product and followed by the product reduction under reversal of the potential scan direction. As a result of parallel electrochemical quartz crystal microbalance (EQCM) and CV measurements, it was also established that the number of chloride ions per one transferring electron in the gold oxidation process is near to unity. To elucidate the oxidation degree of gold in the presence of chloride ions, a special procedure of changing the electrode potential was used. It consisted of clamping the high anodic potential in the region of gold oxidation (0.97 V, Ag/AgCl) and subsequent gradual decrease of the electrode potential with a constant scan rate. Under these conditions, it was possible to completely oxidize all the gold particles containing in a composite film and find out the maximum amount of electricity consumed for the product particles' reduction. A comparison between such data and the results obtained in EQCM determinations of the gold content in the same film led to the conclusion that the oxidation state of gold in the complexes formed is Au(III). The effects of chloride ion concentration and scan rate of the electrode potential on current responses of PEDOT-Au films were investigated. Some primary conclusions on the kinetics of the studied processes are made. [ABSTRACT FROM AUTHOR]

Composite PEDOT/Au films were obtained by chemical deposition of dispersed gold nanoparticles into PEDOT (poly-3,4-ethylenedioxythiophene) conducting polymer matrix. Morphology of the obtained gold-containing films was studied by SEM and TEM methods. To study the kinetics of the hydrogen peroxide electroreduction that proceeds on glassy carbon electrodes modified with such films, we used phosphate buffer solutions containing addenda of hydrogen peroxide species. It was observed that the electroreduction process takes place on both the gold clusters' surface and the film surface free of metal inclusions. The rate of the process is higher in the first case and rises with increasing the gold content in modifying films, but in the limit of large gold contents it is limited only by diffusion of hydrogen peroxide species in the bathing solution. A simple theory of such parallel electroreduction is proposed, which appears to allow for quantitative treatment of the obtained results. [ABSTRACT FROM AUTHOR]

Carbon with few active sites and narrow interlayer distance as anode for potassium ion batteries (PIBs) always shows low capacity, sluggish kinetics, and low Columbic efficiency. Herein, poly(2‐aminothiazole) (P2AT) hollow nanospheres are first synthesized as a carbon source for high N, S co‐doped carbon hollow nanospheres (NS‐HCSs). The hollow P2AT nanospheres can be controllably synthesized with an Ostwald ripening process. The unique doping and structure endow the NS‐HCSs with high content of N and S dopants in carbon, mesoporous structure with enlarged interlayer distance, elevated ratio of N‐6 and N‐5 species, enhanced conductivity, abundant surface defects, and large active sites. When evaluated as an anode for PIBs, NS‐HCSs exhibit a high reversible capacity of 422 mAh g‒1 and excellent long‐term cycling performance. Using combined experiment and theoretical computation, including in situ TEM and in situ Raman, the K‐storage mechanism and dynamic evolution processes of NS‐HCSs, including low volume expansion, enhanced K‐ion adsorption, and stable composition and structure evolution during repeating potassiation/de‐potassiation processes is revealed. This quantitative design for highly durable K‐storage and large capacity in carbon can be advantageous for the rational design of anode materials of PIBs with ideal electrochemical performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic electrode materials are considered as ideal candidates for the next generation of rechargeable batteries owing to their safety, environmental friendliness, sustainability, structure designability, and low price. Among them, organosulfur compounds are promising cathodes for advanced lithium batteries due to their high theoretical capacity and working potential, and have attracted much attention. However, some intrinsic problems such as low conductivity, high solubility in electrolytes, and poor stability have seriously affected the promising perspective of organosulfur cathode materials. This review introduces the latest researches on the basic properties and reaction mechanisms of organosulfur compounds (thioether, organodisulfide, organopolysulfide, and sulfurized polyacrylonitrile) and summarizes the design strategies to improve their capacity, voltage plateau, cycling stability, and rate performance caused by intrinsic problems. In this review, significant challenges and prospects of organosulfur compounds as cathode materials of lithium batteries are investigated. The purpose of this review is to provide meaningful guidance for researchers to promote the development of organosulfur cathode materials. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) and, in particular, Zn//MnO2 rechargeable batteries have attracted great attention due to the abundant natural resources of zinc and manganese, low cost, environmental friendliness, and high operating voltage. Among the various ways to improve the electrochemical performance of MnO2-based cathodes, the development of MnO2 cathodes doped with metal ions or composites of MnO2 with conducting polymers has shown such advantages as increasing the specific capacity and cycling stability. This mini-review focuses on the strategies to improve the electrochemical performance of manganese-based cathodes of AZIBs. [ABSTRACT FROM AUTHOR]

In this work the nanocomposite of vanadium oxide with conducting polymer poly(3,4-ethylenedioxythiophene) (VO@PEDOT) was obtained by microwave-assisted hydrothermal synthesis. The detailed study of its structural and electrochemical properties as cathode of aqueous zinc-ion battery was performed by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The initial VO@PEDOT composite has layered nanosheets structure with thickness of about 30–80 nm, which are assembled into wavy agglomerated thicker layers of up to 0.3–0.6 μm. The phase composition of the samples was determined by XRD analysis which confirmed lamellar structure of vanadium oxide V10O24∙12H2O with interlayer distance of about 13.6 Å. The VO@PEDOT composite demonstrates excellent electrochemical performance, reaching specific capacities of up to 390 mA∙h∙g−1 at 0.3 A∙g−1. Moreover, the electrodes retain specific capacity of 100 mA∙h∙g−1 at a high current density of 20 A∙g−1. The phase transformations of VO@PEDOT electrodes during the cycling were studied at different degrees of charge/discharge by using ex situ XRD measurements. The results of ex situ XRD allow us to conclude that the reversible zinc ion intercalation occurs in stable zinc pyrovanadate structures formed during discharge. [ABSTRACT FROM AUTHOR]

A simple and green approach for creating a highly capacitive molybdenum disulphide (MoS2) anode material for lithium-ion batteries is proposed. The electrode composition consists of MoS2 and conductive water-based binder PEDOT:PSS/CMC (poly(3,4-ethylenedioxythiophene)/poly(styrenesulphonate)/carboxymethyl cellulose). The electrochemical performance of modified electrodes is markedly superior to those with conventional PVDF (polyvinylidene fluoride) and carbon black composition. The electrode provides initial capacity of 1090 mA h g−1 at 0.1 mA g−1, maintains 410 mA h g−1 at 2 mA g−1 and retains 78% of initial capacity after 100 charge-discharge cycles. [ABSTRACT FROM AUTHOR]

Developing transitional metal-based electrocatalysts with outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance is essential for energy-efficiency alkaline water electrolysis. Herein, a group of heterostructured electrocatalysts constructing of nickel-based hydroxide (NiX(OH) x , X = Co, Fe) nanosheets decorated on copper phosphide nanowires arrays，were fabricated. Both of the as-prepared NiCo(OH) x -CuP/CF and NiFe(OH) x -CuP/CF present outstanding HER and OER activity, with the overpotential of 79 and 202 mV to deliver 10 mA cm−2, respectively, along with considerable long-term stability. Encouragingly, the NiCo(OH) x -CuP/CF ǀǀ NiFe(OH) x -CuP/CF couple enables sustainable alkaline water electrolysis and powered by a solar-powered system. In-depth analyses elucidate that owing to the modulated heterogeneous interfacial states, both of the catalytic kinetics can be optimized targeting HER and OER, respectively. More significantly, a regulated electrode-electrolyte microenvironment induced by unique arrays nanostructure efficiently promote the electron-mass transfer capacity, thereby facilitating the catalytic activity expression. This work demonstrates the desirable catalytic performance by rationally designing of hydroxide-phosphide heterostructure, and highlights the structural features on catalytic performance promotion. • A delicate NiCo(OH) x -CuP/CF and NiFe(OH) x -CuP/CF catalysts were fabricated, in which the heterogeneous interfacial synergy effect between copper phosphide and nickel-based hydroxide enables the catalytic performance breakthrough. • The modulation of current distribution for the HER and OER optimizing the reaction kinetics, is achieved by interfacial synergy effect between Cu 3 P and nickel-based hydroxide. • The arrays nanostructure features high active area, good electrical conductivity, while also regulate the interfacial microenvironment between electrocatalysts and electrolyte that facilitates electro-mass transfer. [ABSTRACT FROM AUTHOR]

Electrochemical properties of a composite material based on PEDOT:PSS and MnO were investigated. The composite was synthesized by spontaneous redox reaction between reduced fragments of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) and permanganate ions. PEDOT:PSS/MnO composite dispersion can be drop-cast both on rigid and flexible, conducting and non-conducting substrates. Electrochemical studies of PEDOT:PSS/MnO electrodes were performed in 0.1 M LiClO aqueous electrolyte. The specific capacity values of the composite were 46 and 33 F g at 10 and 50 mV s, respectively. Capacity retention after 1000 galvanostatic charge-discharge cycles was 73 %. The morphology of the material was investigated by SEM; the oxidation state of manganese in oxide was characterized by XPS. [ABSTRACT FROM AUTHOR]

Graphical abstract A novel anode material based on Li 4 Ti 5 O 12 prepared using the combination of poly-3,4-ethylenedioxythiophene/polystyrene sulfonate and carboxymethylcellulose for the conducting polymer binder was developed. The comparative study of this material with conventional polyvinylidene fluoride and with the conductive polymer binder by the cyclic voltammetry and galvanostatic charge–discharge methods revealed that the anode material modified with the conductive binder possesses superior properties in terms of higher specific capacity (increase up to 14%), improved high-rate capability, and life cycle stability of battery. [ABSTRACT FROM AUTHOR]

Atomically dispersed iron-nitrogen-carbon catalysts offer great potential in oxygen reduction reaction (ORR), yet the poor exposure and low density of Fe-N x sites causes relatively low ORR activity. Herein, a zinc-assisted MgO template strategy is reported to construct porous carbon-supported Fe-N 4 sites (Fe-N-C). Iron atoms surrounded by zinc species are converted to abundant Fe-N 4 sites rather than Fe containing nanoparticles. Meanwhile, both the zinc species and the MgO template can effectively produce porous structure so as to increase the utilization of Fe-N 4 sites. Fe-N-C achieves superior ORR performance and stability in alkaline medium. Theoretical calculations manifest that Fe-N 4 sites can narrow the energy barrier for ORR. Moreover, finite element simulation exhibits the porous framework in Fe-N-C could significantly accelerate the diffusion of O 2. Therefore, Fe-N-C provides a high peak power density and superior discharge ability toward Zn-air batteries. [Display omitted] • Atomically dispersed Fe-N-C are prepared by zinc-assisted template strategy. • High density of Fe-N x and hierarchical porosity boost oxygen reduction reaction. • The porous framework of Fe-N-C could significantly accelerate the diffusion of O 2. • The catalyst exhibits an excellent performance in Zn-air batteries. [ABSTRACT FROM AUTHOR]

The effects of resistive switching were investigated in composite films based on multifunctional nonconjugated polymers such as poly(9-vinylcarbazole)—PVK mixed with particles of graphene (Gr) and graphene oxide (GO). The concentration of Gr and GO particles in the PVK matrix was varied in the range of 1–3 wt%, which is close to the percolation threshold in these systems. It was found that the effect of switching in structures of the form Al/PVK:Gr(GO)/ITO/PET manifests itself in a sharp change of the electrical resistance of the composite film from a low-conducting state to a relatively high-conducting state when applying a bias to Al–ITO electrodes of ∼0.2–0.4 V, which is below the threshold switching voltages for similar composites. The cyclic voltammetric measurements of PVK:Gr(GO) films were carried out. It was found that the potential of redox transition of Gr/GO belongs to the interval of redox-switching voltage of PVK:Gr(GO)/ITO/PET composite films with effect of the resistive switching. The possible mechanism of the resistive switching, which is associated with the redox processes as well as with processes of capture and accumulation of charge carriers by Gr (GO) particles introduced into the matrices of the PVK polymer due to reduction/oxidation processes is discussed. [ABSTRACT FROM AUTHOR]

Composite materials based on conducting polymers and transitional metal chalcogenides have attracted considerable attention as electrode materials for supercapacitors. Molybdenum disulfide is a layered transitional metal dichalcogenide extensively researched in energy storage and conversion applications, and poly(3,4-ethylenedioxythiophene) (PEDOT) is an intrinsically conducting polymer that can act as a conductive matrix. We propose a single-step electrochemical deposition of PEDOT/MoS 2 composite materials from the dispersion containing commercially available MoS 2 platelets and EDOT monomer. Potentiodynamic, galvanostatic, and potentiostatic modes are all suitable for synthesis of the materials with predominant content of MoS 2 , which is attached to the current collector via conducting PEDOT matrix. The materials can work in various water-based electrolytes and combine capacitor-like and redox pseudocapacitive response. The composites deposited on graphite foil in assembled asymmetric cells with Kynol carbon cloth counter-electrode deliver up to 870 mF cm−2 areal capacitance in LiClO 4 aqueous solution at a current density of 1 mA cm−2 due to combined capacitive input of both components. [Display omitted] • Multiple electrochemical modes of synthesis were explored for PEDOT/MoS 2 composite. • PEDOT/MoS 2 with exceptionally high areal capacitance of 870 mF cm−2 was obtained. • Synergistic effect between MoS 2 and PEDOT results in increased capacitance. [ABSTRACT FROM AUTHOR]

Highlights: [•] Triple associates based on (oxime)Pt(II) species, 18-crown-6, and water. [•] Discrete binuclear assemblies Pt(II)–H2O–18-crown-6–H2O–Pt(II) and one-dimensional polymeric chain with alternating sequence. [•] Electronic structures and vibrational frequencies evaluation by the DFT method. [ABSTRACT FROM AUTHOR]

[Display omitted] • GHNCNs_Urea was designed by introducing nitrogen source, increasing pore structures. • The GHNCNs_Urea electrocatalyst exhibited outstanding ORR activity. • The excellent ORR activity was attributed to ultra-high SSA and large pore volume. • The Zn-air battery exhibited a high peak power density and a long-term stability. When designing carbon-based electrocatalysts as Pt-free catalysts for the oxygen reduction reaction (ORR), pore structures is crucial, in addition to creating active sites. Here, N-doped carbon nanosheets were rationally designed by tactfully introducing nitrogen source into the carbonization process, which could increase the density of pore structures and effective active sites. Owing to the ultra-high specific surface area (2127 m2 g−1), large pore volume (5.77 cm3 g−1), and bimodal-pore structure (micropores and mesopores), the optimized catalyst exhibited an excellent ORR activity (a half-wave potential of 0.86 V), as well as outstanding durability and methanol tolerance in alkaline medium. Moreover, it provided excellent stability and high peak power density when used as ORR catalyst in Zn-air battery, exceeding that driven by Pt/C catalyst. This work brings a feasible and universal strategy for fabricating metal-free ORR catalysts. [ABSTRACT FROM AUTHOR]

Cyclic voltammograms and optical absorption spectra of PEDOT/WO3 composite films were recorded in order to identify possible interactions and modes of improved performance of the composite as compared to the single materials. Changes in the shape of redox peaks related to the W(VI)/W(V) couple in the CVs of WO3 and the composite PEDOT/WO3 films indicate electrostatic interactions between the negatively charged tungsten oxide species and the positively charged conducting polymer. Smaller peak separation suggests a more reversible redox process due to the presence of the conducting polymer matrix, accelerating electron transfer between tungsten ions. Electronic absorption spectra of the materials were analyzed with respect to changes of the shapes of the spectra and characteristic band positions. There are no noticeable changes in the position of the electronic absorption bands of the main chromophores in the electronic spectra of the composite film. Obviously, the interactions accelerating the redox performance do not show up in the optical spectra. This suggests that the existing electrostatic interactions in the composite do not significantly change the opto-electronic properties of components of the composite but resulted in the redistribution of fractions of polaron and bipolaron forms in the polymer. [ABSTRACT FROM AUTHOR]

The electrodes of lithium-ion batteries (LIBs) are multicomponent systems and their electrochemical properties are influenced by each component, therefore the composition of electrodes should be properly balanced. At the beginning of lithium-ion battery research, most attention was paid to the nature, size, and morphology peculiarities of inorganic active components as the main components which determine the functional properties of electrode materials. Over the past decade, considerable attention has been paid to development of new binders, as the binders have shown great effect on the electrochemical performance of electrodes in LIBs. The study of new conductive binders, in particular water-based binders with enhanced electronic and ionic conductivity, has become a trend in the development of new electrode materials, especially the conversion/alloying-type anodes. This mini-review provides a summary on the progress of current research of the effects of binders on the electrochemical properties of intercalation electrodes, with particular attention to the mechanisms of binder effects. The comparative analysis of effects of three different binders (PEDOT:PSS/CMC, CMC, and PVDF) for a number of oxide-based and phosphate-based positive and negative electrodes for lithium-ion batteries was performed based on literature and our own published research data. It reveals that the combined PEDOT:PSS/CMC binder can be considered as a versatile component of lithium-ion battery electrode materials (for both positive and negative electrodes), effective in the wide range of electrode potentials. [ABSTRACT FROM AUTHOR]