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Abstract: Composite polymer electrolytes prepared by adding SiO2 nanowires into P(VDF-HFP) are described. Their electrochemical and mechanical properties were improved by 3-dimensional network interaction between the nanowires and the polymer chains. The composite polymer membrane can tolerate a maximal stress of 27.8MPa. The ionic conductivity of the prepared gelled polymer electrolyte is up to 1.08×10−3 Scm−1, the electrochemical window is 4.8V. The composite polymer electrolyte with a 1-dimensional nanofiller such as SiO2 nanowires provides a new way to polymer electrolytes with better electrochemical and mechanical performance for practical applications in lithium ion batteries. [Copyright &y& Elsevier]

An aqueous rechargeable lithium battery (ARLB) using an electroactive polymer, polypyrrole (PPy), as a negative electrode; a lithium ion intercalation compound LiCoO2 as a positive electrode; and Li2SO4 aqueous solution as an electrolyte and its working mechanism are described. The charge/discharge process is associated with the doping/un-doping of anions at the negative electrode and intercalation/deintercalation of lithium ions at the positive electrode. The average output voltage of the PPy//LiCoO2 battery is about 0.85 V. This battery exhibits excellent cycling performance. This new technology solves the major problem of poor cycling life of ARLBs and will provide a new strategy to explore advanced energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

Abstract: A new cheap asymmetric supercapacitor based on activated carbon (AC) and NaMnO2 as electrodes and aqueous Na2SO4 solution as electrolyte was assembled. It shows an energy density of 19.5Whkg−1 at a power density of 130Wkg−1 based on the total mass of the active electrode materials and an excellent cycling behavior. This asymmetric aqueous AC//NaMnO2 capacitor is promising for practical applications due to its low price, easy preparation of NaMnO2 and friendliness to environment. [Copyright &y& Elsevier]

Abstract: V2O5·0.6H2O nanoribbons were prepared and their electrochemical behaviors in K2SO4 aqueous solution were investigated. Results show for the first time that K+ ions could intercalate/deintercalate reversibly in the V2O5·0.6H2O lattice. An asymmetric supercapacitor activated carbon/0.5mol/l K2SO4/V2O5·0.6H2O was successfully assembled, which could be cycled reversibly in the voltage region of 0–1.8V. This supercapacitor presents an energy density of 29.0Wh/kg based on the total mass of the active electrode materials, a very good rate behavior with energy density of 20.3Wh/kg at power density of 2kW/kg, and also a rather good cycling performance. [Copyright &y& Elsevier]

Abstract: Electrochemical intercalation of lithium ions from a saturated LiNO3 aqueous electrolyte solution into LiV3O8 prepared by a solid-state reaction at 680°C was studied with cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Results show that there are three steps of intercalation in the presence of an aqueous electrolyte, in agreement with those previously observed with organic liquid electrolytes. In addition, variations of several parameters including the charge transfer resistance (R ct), the capacitance of the double layer (C DL), the Warburg diffusion impedance (Z w), and diffusion coefficient of lithium ions () during the intercalation process are reported. [Copyright &y& Elsevier]

Abstract: The electrochemical behavior of a commercial LiCoO2 with spherical shape in a saturated Li2SO4 aqueous solution was investigated with cyclic voltammetry and electrochemical impedance spectroscopy. Three redox couples at E SCE =0.87/0.71, 0.95/0.90 and 1.06/1.01V corresponding to those found at , 4.13/4.03 and 4.21/4.14V in organic electrolyte solutions were observed. The diffusion coefficient of lithium ions is 1.649×10−10 cm2 s−1, close to the value in organic electrolyte solutions. The results indicate that the intercalation and deintercalation behavior of lithium ions in the Li2SO4 solution is similar to that in the organic electrolyte solutions. However, due to the higher ionic conductivity of the aqueous solution, current response and reversibility of redox behavior in the aqueous solution are better than in the organic electrolyte solutions, suggesting that the aqueous solution is favorable for high rate capability. The charge transfer resistance, the exchange current and the capacitance of the double layer vary with the charge voltage during the deintercalation process. At the peak of the oxidation (0.87V), the charge transfer resistance is the lowest. These fundamental results provide a good base for exploring new safe power sources for large scale energy storage. [Copyright &y& Elsevier]

Abstract: MoO2 synthesized through reduction of MoO3 with ethanol vapor at 400°C was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Its electrochemical performance as an anode material for lithium ion battery was tested by cyclic voltammetry (CV) and capacity measurements. During the reduction process, the starting material (MoO3) collapsed into nanoparticles (∼100nm), on the nanoparticles remains a carbon layer from ethanol decomposition. Rate capacity and cycling performance of the as-prepared product is very satisfactory. It displays 318mAhg−1 in the initial charge process with capacity retention of 100% after 20 cycles in the range of 0.01–3.00V vs. lithium metal at a current density of 5.0mAcm−2, and around 85% of the retrievable capacity is in the range of 1.00–2.00V. This suggests the application of this type of MoO2 as anode material in lithium ion batteries. [Copyright &y& Elsevier]

Abstract: For the first time Cu2O particles with different morphologies are synthesized by adopting a polyol process performed at different temperatures. SEM and TEM show that the samples obtained at 140 and 160°C present a core-shell structure. XRD measurements indicate that both samples exhibit better crystallinity compared with the samples obtained at 120°C. Results from charge–discharge experiments and cyclic voltammograms (CV) reveal that morphology and crystallinity play important roles in determining the electrochemical performance of Cu2O samples. [Copyright &y& Elsevier]

Abstract: Nanosized tin powder was prepared by laser-induced vapor deposition and studied as an alternative anode material for lithium ion batteries. The nano tin particles are spherical, and their size varies from 5nm to 80nm. The prepared powder consists of two compounds: a major amount of Sn and a minor amount of SnO. Results of cyclic voltammograms (CVs) indicate that SnO is deoxidized to Sn almost completely in the first cycle. The reaction of tin with lithium proceeds in two steps. At first, a Li-deficient phase is formed, later a Li-rich phase. Reaction kinetics are controlled by a diffusion step, and the diffusion coefficient of lithium ions in the anode is calculated to be 4.15×10−8 cm2 s−1. The initial charge capacity is nearly to the theoretical reversible capacity of lithium insertion into tin, resulting in Li22Sn5. [Copyright &y& Elsevier]

Abstract: Cuprous oxide-coated graphite was synthesized by a polyol reduction process and analyzed by scanning electron microscopy, charge–discharge measurements and cyclic voltammetry. Cu2O exists at the surface of graphite in the form of nanoparticles and nanorods. The coated cuprous oxide layer acts as a protective layer separating graphite from the propylene carbonate (PC)-based electrolyte solution, and greatly suppresses PC decomposition and graphite exfoliation in PC-based electrolyte systems. [Copyright &y& Elsevier]

Abstract: Cu-coated graphite electrode foil was prepared by an improved electroless plating method. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to study the surface morphology and composition of Cu-coated graphite electrode foil. Tests of discharge and charge and cyclic voltammograms suggest that the decomposition of propylene carbonate and exfoliation of graphite are greatly suppressed, and lithium ions can reversibly intercalate into and de-intercalate from the Cu-coated graphite electrode. Results from electrochemical impedance spectroscopy show that the Cu-coated graphite electrode has lower charge-transfer resistance and higher diffusion coefficient of lithium ions in comparison with the original graphite. [Copyright &y& Elsevier]

The article evaluates the primary electrochemical performance of surface modified spherical graphite in relation to the distribution of conductive additive particles on the coated electrode material. It has been observed that the cycling behavior was influenced by the dispersion of conductive additive. The initial reversible capacity was greater than that of commercial synthetic graphite. Also, poor dispersion produced numerous white deposits.

Abstract: Since the commercialization of lithium secondary batteries in the early of 1990s, their development has been rapid. Nowadays, improving the preparation technology and electrochemical performance of their electrode materials is a major focus in research and development of the materials, power sources and chemistry. Sol–gel methods are a promising way to prepare electrode materials due to their evident advantages over traditional methods, for example, homogeneous mixing at the atomic or molecular level, lower synthesis temperature, shorter heating time, better crystallinity, uniform particle distribution and smaller particle size at nanometer level. In this paper, latest progress in the preparation of electrode materials by sol–gel methods is reviewed, including cathodic ones, e.g., lithium cobalt oxides, lithium nickel oxides, spinel and layered lithium manganese oxides, vanadium oxides and ferrous phosphates, and anodic ones, e.g., tin oxides and titanium oxides. Compared with those prepared by traditional solid-state reaction, the structure stability of the prepared electrode materials and the behavior of lithium intercalation and de-intercalation are much improved. As a result, the prepared products provide better electrochemical performance including reversible capacity, cycling behavior and rate capability. In addition, sol–gel methods can be used to prepare new kinds of electrode materials such as nanowires of LiCoO2 and nanotubes of V2O5, which cannot be easily created by the traditional methods. Further development and application of sol–gel methods will bring about new and better electrode materials, meaning a great promotion to lithium secondary batteries. [Copyright &y& Elsevier]

Since the birth of the lithium ion battery in the early 1990s a lot of methods has been tried to prepare materials with better performance and/or lower cost. In comparison with other methods, mechanochemical methods are advantageous because they are based on simple processes, show high efficiency, low energy consumption and cost They are widely applied to prepare materials for lithium ion batteries such as cathode materials, anodic ones and solid electrolytes. The latest progress on these aspects is reviewed in this paper including the effects of mechanochemical methods and mechanisms in improving electrochemical performance. In addition, some problems concerning some materials and further directions are pointed out. [Copyright &y& Elsevier]

Sensitivity of anode materials towards humidity is an important factor for the performance of lithium ion batteries. Here it is demonstrated for the first time that the sensitivity of composite anode materials prepared of metals such as copper and silver with natural graphite can be strikingly lowered. The composites are prepared by adsorbing metal ions from solutions onto the surface of natural graphite followed by heat-treatment at high temperature. Results from X-ray photoelectron spectroscopy, high resolution electron microscopy, thermogravimmetry, differential thermal analysis, and capacity measurements indicate that the deposited metals exist in two forms, viz. metallic and carbidic MxC (M=Cu and Ag), and remove/cover (i.e. deactivated) the active hydrophilic sites at the surface of graphite. As a result, in the presence of high humidity the composites absorb less water, and the obtained electrochemical performance including reversible capacity, coulombic efficiency in the first cycle and cycling behavior is markedly improved. This approach provides a potentially powerful method to manufacture lithium ion batteries under less critical conditions. [Copyright &y& Elsevier]

Modification of natural graphite has recently moved into the focus of methods to prepare anode materials for lithium ion batteries. Here we report a treatment method for the modification of a common natural graphite employing oxidative solutions. Four solutions based on H2O2, Ce(SO4)2, HNO3 and (NH4)2S2O8 were employed; their effects were investigated with X-ray photoelectron spectroscopy, thermogravimmetric and differential thermal analysis, high resolution electron microscopy and measurement of electrochemical capacity. All oxidants resulted in marked improvements of reversible capacity, columbic efficiency in the first cycle and cycling behavior due to elimination of some imperfections with high activities towards lithium such as carbon chains, edge carbon atoms and sp3-hybridized carbon atoms, creation of more micropores/nano-channels, modification of the surface of natural graphite with a coverage of a dense layer of oxides, and improvement in stability of graphite structure. Effects of the oxidative solutions on electrochemical performance of natural graphite are compared. [Copyright &y& Elsevier]

Modification of graphite has recently moved into the focus of the preparation of anode materials for lithium ion batteries. We report on an oxidative treatment by air and concentrated nitric acid solution to improve the electrochemical performance of a common natural graphite. Results from X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), thermogravimmetry (TG) and differential thermal analysis (DTA), high resolution electron microscopy (HREM), and measurements of the reversible electrochemical capacity suggest that the surface structure of natural graphite is changed and a fresh dense layer of oxides is formed. Structural imperfections are removed and the stability of the graphite structure is increased. These changes inhibit electrolyte decomposition, block intercalation of solvated lithium ions and prevent graphene planes from moving along the a-axis direction. In addition, nanochannels and micropores are introduced, and thus, lithium intercalation and deintercalation are favored and more sites are provided for lithium storage. Consequently, reversible capacity and cycling behavior of the modified natural graphite through the oxidation treatments is improved considerably. Since common natural graphite is low in cost, this method is promising for industrial application. [Copyright &y& Elsevier]

Sensitivity of anode materials to humidity is an important factor for the performance of lithium ion batteries. Here it is demonstrated for the first time that the sensitivity of composite anode materials of silver and natural graphite can be strikingly lowered. The composites are prepared by depositing silver ions onto the surface of natural graphite. After the following heat-treatment, silver ions turn into metallic silver and carbide AgxC by covering and/or removing active sites that absorb water very easily. Under high humidity condition (about 1000 ppm H2O), the composite materials absorb strikingly less water resulting in still good electrochemical performance. In comparison, natural graphite without this treatment shows fast fade in capacity under high humidity even though it is good in cycling under low humidity (<100 ppm H2O). Silver is a good matrix for lithium storage, and is assumed to contribute to reversible capacity since it enhances with the amount of deposited silver. This method can effectively lower the sensitivity of anode materials to humidity, and is promising in manufacturing lithium ion batteries under less critical conditions. [Copyright &y& Elsevier]

A concentrated nitric acid solution was used as an oxidant to modify the electrochemical performance of natural graphite as anode material for lithium ion batteries. Results of X-ray photoelectron spectroscopy, electron paramagnetic resonance, thermogravimmetry, differential thermal analysis, high resolution electron microscopy, and measurement of the reversible capacity suggest that the surface structure of natural graphite was changed, a fresh dense layer of oxides was formed. Some structural imperfections were removed, and the stability of the graphite structure increased. These changes impede decomposition of electrolyte solvent molecules, co-intercalation of solvated lithium ions and movement of graphene planes along the a-axis direction. Concomitantly, more micropores were introduced, and thus, lithium intercalation and deintercalation were favored and more sites were provided for lithium storage. Consequently, the reversible capacity and the cycling behavior of the modified natural graphite were much improved by the oxidation. Obviously, the liquid–solid oxidation is advantageous in controlling the uniformity of the products. [Copyright &y& Elsevier]

The article presents information on a study on rechargeable lithium ion batteries with nonaqueous electrolyte solutions. These batteries are used for consumer electronic devices including mobile phones and laptop computers. For the study, crystalline LiV3O8 was prepared in an appropriate molar ratio at 680 degree C and was cooled down slowly to room temperature. The combination of negative and positive electrodes of a rechargeable lithium battery in aqueous electrolytes is stated to be of importance for obtaining good electrochemical performance. It was found that the cycling performance of the aqueous rechargeable lithium battery (ARLB) system is not comparable with our other ARLB systems using positive electrodes.

Among the challenges related to rechargeable magnesium batteries (RMBs) still not resolved are positive electrode materials with sufficient charge storage and rate capability as well as stability and raw material resources. Out of the materials proposed and studied so far, vanadium oxides stand out for these requirements, but significant further improvements are expected and required. They will be based on new materials and an improved understanding of their mode of operation. This report provides a critical review focused on this material, which is embedded in a brief overview on the general subject. It starts with the main strategic ways to design layered vanadium oxides cathodes for RMBs. Taking these examples in more detail, the typical issues and challenges often missed in broader overviews and reviews are discussed. In particular, issues related to the electrochemistry of intercalation processes in layered vanadium oxides; advantageous strategies for the development of vanadium oxide composite cathodes; their mechanism in aqueous, "wet", and dry non-aqueous aprotic systems; and the possibility of co-intercalation processes involving protons and magnesium ions are considered. The perspectives for future development of vanadium oxide-based cathode materials are finally discussed and summarized.

The most prominent and highly visible advantage attributed to supercapacitors of any type and application, beyond their most notable feature of high current capability, is their high stability in terms of lifetime, number of possible charge/discharge cycles or other stability-related properties. Unfortunately, actual devices show more or less pronounced deterioration of performance parameters during time and use. Causes for this in the material and component levels, as well as on the device level, have only been addressed and discussed infrequently in published reports. The present review attempts a complete coverage on these levels; it adds in modelling approaches and provides suggestions for slowing down ag(e)ing and degradation.

Intrinsically conducting polymers ICPs can be combined with further electrochemically active materials into composites for use as active masses in supercapacitor electrodes. Typical examples are inspected with particular attention to the various roles played by the constituents of the composites and to conceivable synergistic effects. Stability of composite electrode materials, as an essential property for practical application, is addressed, taking into account the observed causes and effects of materials degradation.

Intrinsically conducting polymers may undergo significant changes of molecular structure and material properties when exposed to highly oxidizing conditions or very positive electrode potentials, commonly called overoxidation. The type and extent of the changes depend on the experimental conditions and chemical environment. They may proceed already at much lower rates at lower electrode potentials because some of the processes associated with overoxidation are closely related to more or less reversible redox processes employed in electrochemical energy conversion and electrochromism. These changes may be welcome for some applications of these polymers in sensors, extraction, and surface functionalization, but in many cases, the change of properties affects the performance of the material negatively, contributing to material and device degradation. This report presents published examples, experimental observations, and their interpretations in terms of both structural and of material property changes. Options to limit and suppress overoxidation are presented, and useful applications are described extensively.

Intrinsically conducting polymers constituting a subclass of macromolecules, as well as a still growing family of large, conjugated molecules, oligomers, and polymers, have attracted research interest for the recent decades. Closely corresponding to the fascination of these materials, combining typical properties of organic polymers and metallic materials, numerous applications have been suggested, explored, and sometimes transferred into products. In electrochemistry, they have been used in various functions beyond the initially proposed and obvious application as active masses in devices for electrochemical energy conversion and storage. This perspective contribution wraps up basic facts that are necessary to understand the behavior and properties of the oligo and polymers and their behavior in electrochemical cells for energy conversion by electrode reactions and associated energy storage. Representative examples are presented and discussed, and an overview of the state of research and development is provided. Particular attention is paid to stability and related aspects of practical importance. Future trends and perspectives are indicated.

Cyclic voltammograms and optical absorption spectra of PEDOT/WO 3 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 WO 3 and the composite PEDOT/WO 3 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.

Herein, we report the fabrication of highly oxidized silver oxide/silver/tin(IV) oxide (HOSBTO or Ag 3+ -enriched AgO/Ag/SnO 2 ) nanocomposite under a robust oxidative environment created with the use of concentrated nitric acid. Tin(IV) hydroxide nanofluid is added to the reaction mixture as a stabilizer for the Ag 3+ -enriched silver oxide in the nanocomposite. The formation of Ag nanoparticles in this nanocomposite originates from the decomposition of silver oxides during calcination at 600 °C. For comparison, poorly oxidized silver oxide/silver/tin(IV) oxide (POSBTO with formula AgO/Ag/SnO 2 ) nanocomposite has also been prepared by following the same synthetic procedures, except for the use of concentrated nitric acid. Finally, we studied in detail the anti-pathogenic capabilities of both nanocomposites against four hazardous pathogens, including pathogenic fish bacterium (Stenotrophomonas maltophilia stain EP10), oomycete (Phytophthora cactorum strain P-25), and two different strains of pathogenic strawberry fungus, BRSP08 and BRSP09 (Collectotrichum siamense). The bioassays reveal that the as-prepared HOSBTO and POSBTO nanocomposites exhibit significant inhibitory activities against the tested pathogenic bacterium, oomycete, and fungus in a dose-dependent manner. However, the degree of dose-dependent effectiveness of the two nanocomposites against each pathogen largely varies., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Suggested beneficial effects of surfactants added to the electrolyte solution of supercapacitors have been studied with the aim of improving wetting of the metal oxide electrode surface possibly enhancing material utilization and overall performance. Using representative non-ionic and anionic surfactants such improvements in terms of increased specific capacitance, capacitance retention with current density and improved stability were found. Further examination of type of surfactant and optimum surfactant concentration are recommended.

In this introductory report, composites and copolymers combining intrinsically conducting polymers and redox-active organic molecules, suggested as active masses without additional binder and conducting agents for supercapacitor electrodes, possibly using the advantageous properties of both constituents, are presented. A brief overview of the few reported examples of the use of such copolymers, composites, and comparable combinations of organic molecules and carbon supports is given. For comparison a few related reports on similar materials without intrinsically conducting polymers are included.

A new ruthenium cobalt oxide (RuCo 2 O 4 ) with a unique marigold-like nanostructure and excellent performance as an advanced electrode material has been successfully prepared by a simple electrodeposition (potentiodynamic mode) method. The RuCo 2 O 4 marigolds consist of numerous clusters of ultrathin mesoporous nanoflakes, leaving a large interspace between them to provide numerous electrochemically active sites. Strikingly, this unique marigold-like nanostructure provided excellent electrochemical performance in terms of high energy-storage capacitance (1469 F g -1 at 6 A g -1 ) with excellent rate proficiency and long-lasting operating cycling stability (ca. 91.3 % capacitance retention after 3000 cycles), confirming that the mesoporous nanoflakes participate in the ultrafast electrochemical reactions. Furthermore, an asymmetric supercapacitor was assembled using RuCo 2 O 4 (positive electrode) and activated carbon (negative electrode) with aqueous KOH electrolyte. The asymmetric design allowed an upgraded potential range of 1.4 V, which further provided a good energy density of 32.6 Wh kg -1 (1.1 mWh cm -3 ). More importantly, the cell delivered an energy density of 12.4 Wh kg -1 even at a maximum power density of 3.2 kW kg -1 , which is noticeably superior to carbon-based symmetric systems., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Correction for 'An acid-free rechargeable battery based on PbSO4 and spinel LiMn2O4' by Yu Liu et al., Chem. Commun., 2014, 50, 13714-13717.

Coulombic efficiency especially in the first cycle, cycling stability, and high-rate performance are crucial factors for commercial Li-ion batteries (LIBs). To improve them, in this work, Al2O3-coated natural graphite powder was obtained through a low-cost and facile sol-gel method. Based on a comparison of various coated amounts, 0.5 mol % Al(NO3)3 (vs mole of graphite) could bring about a smooth Al2O3 coating layer with proper thickness, which could act as a preformed solid electrolyte interface (SEI) to reduce the regeneration of SEI and lithium-ions consumption during subsequent cycling. Furthermore, we examined the advantages of Al2O3 coating by relating energy levels in LIBs using density functional theory calculations. Owing to its proper bandgap and lithium-ion conduction ability, the coating layer performs the same function as a SEI does, preventing an electron from getting to the outer electrode surface and allowing lithium-ion transport. Therefore, as a preformed SEI, the Al2O3 coating layer reduces extra cathode consumption observed in commercial LIBs.

The adsorbate formed by adsorption of thiophenol on a polycrystalline gold electrode and brought into contact with aqueous solutions of 1 M HClO4 and 0.1 M KClO4 has been studied using cyclic voltammetry and surface-enhanced Raman spectroscopy. A strong adsorption is deduced from observations made using cyclic voltammetry. From the SER spectra, interactions of thiophenol with the gold surface via a gold-sulfur bond with the aromatic ring pointing away from the surface is concluded for both electrolyte solutions.

One of the main challenges of electrical energy storage (EES) is the development of environmentally friendly battery systems with high safety and high energy density. Rechargeable Mg batteries have been long considered as one highly promising system due to the use of low cost and dendrite-free magnesium metal. The bottleneck for traditional Mg batteries is to achieve high energy density since their output voltage is below 2.0 V. Here, we report a magnesium battery using Mg in Grignard reagent-based electrolyte as the negative electrode, a lithium intercalation compound in aqueous solution as the positive electrode, and a solid electrolyte as a separator. Its average discharge voltage is 2.1 V with stable discharge platform and good cycling life. The calculated energy density based on the two electrodes is high. These findings open another door to rechargeable magnesium batteries.

Reported is the synthesis of 3D hierarchical structures based on one-dimensional MnO 2 nanobuilding blocks (nanorods, nanowires, and nanoneedles) by means of a facile and scalable coprecipitation method and their use as electrodes for the assembly of all-solid-state supercapacitors. Asymmetric devices were also assembled by using these nanostructured MnO 2 materials as the positive electrode and reduced graphene oxide (rGO) as the negative electrode with a polymeric gel electrolyte. The asymmetric cells successfully extend the working voltage windows beyond 1.4 V and allowed for a maximum voltage of 1.8 V. An asymmetric device based on hierarchical nanoneedle-like MnO 2 and rGO achieved a maximum specific capacitance of 99 F g -1 at a scan rate of 10 mV s -1 with a stable operational voltage of 1.8 V. This high value allowed for a large specific energy of 24.12 Wh kg -1 ., (Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Earnest efforts have been taken to design hybrid energy storage devices using hybrid electrodes based on capacitive (rGO) and pseudocapacitive (Ni(OH)2 and Co(OH)2) materials deposited on the skeleton of 3D macroporous (indicate sponge material) sponge support. Conducting framework was formed by coating rGO on macroporous sponge on which subsequent deposition of Ni(OH)2 and Co(OH)2 was carried out. The synergetic combination of rGO and Ni(OH)2 or Co(OH)2) provides dual charge-storing mechanisms whereas 3D framework of sponge allows excellent accessibility of electrolyte to hybrid electrodes. Moreover, to further increase the energy density, hybrid devices have been fabricated with SP@rGO@Ni or SP@rGO@Co and SP@rGO as positive and negative electrodes, respectively. These hybrid devices operate with extended operating voltage windows and achieve remarkable electrochemical supercapacitive properties which make them truly promising energy storage devices for commercial production.

An acid-free lead rechargeable battery system comprising PbSO4 as the negative electrode, LiMn2O4 as the positive electrode and a neutral Li2SO4 aqueous solution as electrolyte is reported and its electrochemical performance is very good. It shows great promise to reduce the global use of lead by 50% since it is also low cost.

Copper oxide (CuO) thin films are successfully synthesized using a surfactant assisted chemical bath deposition method for application in supercapacitors. The effect of organic surfactants such as Triton X-100 and polyvinyl alcohol (PVA) on structural, morphological, surface areas and electrochemical properties of CuO thin films is investigated. The films deposited using organic surfactants exhibit different surface morphologies. It is observed that the organic surfactants play important roles in modifying the morphology, surface area and pore size distribution. Electrochemical analysis confirms that the nanostructures of the electrode material play a vital role in supercapacitors. The cyclic voltammetry studies show a considerably improved high rate pseudocapacitance of CuO samples synthesized using organic surfactants. The maximum specific capacitance of 411 F g(-1) at 5 mV s(-1) is obtained for the CuO sample prepared using an organic surfactant (Triton X-100). Furthermore, all the CuO nanostructures exhibit high power performance, excellent rate as well as long term cycling stability. The Ragone plot ascertains better power and energy densities of CuO nanostructured samples. This is an easy and simple way to tune the morphology using surfactants which can be applied for other energy storage materials.

This study uses a "bottom-up" approach chemical method to coat nanocrystalline Ni(OH)2 onto multiwalled carbon nanotubes (MWCNTs) for flexible supercapacitor electrodes, where the higher electronic conductivity of MWCNTs permits their use as the supporting backbone onto which Ni(OH)2 can be deposited. The paper portrays the advantages of the facile successive ionic layer adsorption and reaction (SILAR) method for depositing Ni(OH)2/MWCNT thin films onto large area flexible substrates. We demonstrate that these Ni(OH)2/MWCNT films consist of a uniform coating of sponge-like Ni(OH)2 on the MWCNT network structure using scanning electron micrographs and transmission electron micrographs; this structure is promising for supercapacitor applications. Ni(OH)2/MWCNT films exhibit a specific capacitance of 1487 F g(-1) at a scan rate of 5 mV s(-1) in a 2 M KOH aqueous solution. The electrodes are generated using a simple three-beaker SILAR system at ambient conditions, thus providing an easy approach to fabricate high-power and high-energy flexible supercapacitors. Ni(OH)2/MWCNTs demonstrate a good rate capability and excellent long-term cyclic stability (96% capacity retention after 1000 cycles). Such high-performance capacitive behavior indicates that Ni(OH)2/MWCNT composites are promising electrode materials for the fabrication of supercapacitors. Thus, the method described in this paper provides a generalized route for the production of a wide range of Ni(OH)2/MWCNT-based materials for applications beyond electrochemical energy storage. These encouraging results promote interest in developing such devices, including nontoxic and greener components, compared with current organic-based devices.

New energy industry including electric vehicles and large-scale energy storage in smart grids requires energy storage systems of good safety, high reliability, high energy density and low cost. Here a coated Li metal is used as anode for an aqueous rechargeable lithium battery (ARLB) combining LiMn2O4 as cathode and 0.5 mol l(-1) Li2SO4 aqueous solution as electrolyte. Due to the "cross-over" effect of Li(+) ions in the coating, this ARLB delivers an output voltage of about 4.0 V, a big breakthrough of the theoretic stable window of water, 1.229 V. Its cycling is very excellent with Coulomb efficiency of 100% except in the first cycle. Its energy density can be 446 Wh kg(-1), about 80% higher than that for traditional lithium ion battery. Its power efficiency can be above 95%. Furthermore, its cost is low and safety is much reliable. It provides another chemistry for post lithium ion batteries.

Polypyrrole (PPy) and poly(pyrrole-2,6-dimethyl-β-cyclodextrin) [P(Py-β-DMCD)] films prepared by potential cycling in aqueous acidic solutions on indium tin oxide (ITO)-coated glass and gold electrodes were studied by in situ UV-vis and Raman spectroscopy. Characteristic UV-vis and Raman bands were identified and their dependencies on the electrode potential have been discussed. Spectroelectrochemical results reveal differences both in the position of the spectral bands and their potential dependence for PPy and P(Py-β-DMCD) films indicating interactions between polymer chains and CDs during electropolymerization process. The films were also characterized by cyclic voltammetry and FT-IR spectroscopy., (Copyright © 2009 Elsevier B.V. All rights reserved.)

Dodecylbenzenesulfonic acid (DBSA) dissolved in 2-propanol (70% solution), a surfactant and dopant, is used in the synthesis of polyaniline (PANI) colloids. The micelle-aided synthesis yields green dispersions that do not undergo macroscopic precipitation for more than a year. UV-vis studies reveal that polymerization is completed in 3 h irrespective of the feed ratio of DBSA/aniline. The polymerization yield depends on the amount of DBSA in the feed. UV-vis spectroscopy as a function of applied potential was carried out for the first time for thin layers of the dispersion. Bands corresponding to both emeraldine salt and emeraldine base were observed during cathodic potential sweeps whereas in an anodic sweep bands due to only emeraldine base were observed. Electronic absorption spectroscopy and preresonance Raman spectroscopy as a function of pH indicate emeraldine salt (metal) to emeraldine base (insulator) transformation at higher pH (pH 9-10). The high aggregation tendency of PANI particles during solvent drying yields particles with irregular shapes.

Electrochemical reduction potentials of a broad selection of nitrogen-containing molecules suitable as bridging (dipodal and tripodal) ligands in coordination and organometallic chemistry are reported and compared with results of semiempirical calculations. Trends of electrode potentials observed experimentally agree with respective calculated data, deviations can be explained by invoking peculiarities of the involved molecular orbitals and ligand-electrode surface interactions.