The PIL (denoted as “PVIm[DS]”) synthesized herein consists of poly(1-vinyl-3- ethylimidazolium) cations and dodecyl sulfate counter anions, whose molecular structures are rationally designed to enable the multiple functions described below. PVIm serves as a precursor for the carbon shell featuring continuous/conformal nanothickness surface coverage, while the DS acts as a porogen (i.e., a pore-generating agent) for realizing the mesoporous structure in the carbon shell. The nitrogen (N) of PVIm and the sulfur (S) of DS provide a dual (N and S)-doping source. The embedding of SWCNTs into the dual-doped mesoporous carbon (MC) shell further increases the electronic conductivity. During the preparation of the PVIm[DS]/SWCNT coating solution, PVIm[DS] allows homogeneous dispersion of the SWCNTs even in the absence of traditional surfactants, revealing its additional function as a polymeric dispersant. Benefiting from the structural/physicochemical uniqueness mentioned above, the SMC shell exhibits unprecedented synergistic effects as an ion/electron-conductive nanoshield (i.e., mitigating interfacial side reactions between cathode materials and liquid electrolytes while facilitating redox reaction kinetics), thereby enabling significant improvements in the electrochemical performance and thermal stability of the cathode materials.
"Earth, air, fire, water" – these were believed by the Ancient Greeks to be the basic building blocks (elements) of their World . Seen in today’s perspective, "air, fire, water" correspond to the essential material components in electro- chemical energy conversion devices now known as fuel-cells, while the fourth element "earth" (read: the mineral content of the Earth’s crust) is the source of active electrodematerials in advanced battery concepts, which are today proving so relevant to the development of next-generation sustainable transport and communication solutions. As our global population continues to grow and become more mobile, the reduction of Greenhouse Gas (GHG) emissions from the transport sector presents an ever more urgent challenge. They are currently responsible for roughly one third of the World’s total GHG emissions . The development of on-board storage of electrical energy derived from sustainable power sources in cheap, large-scale batteries is slowly emerging as a critical element of many long-term solutions. However, an efficient battery technology capable of meeting this challenge is still lacking to a large extent, mainly because of performance inadequacies in terms of energy- and power- density, safety, etc. Above all, their high cost can be seen as the major hinder holding back large- scale battery development. Although we have seen significant breakthroughs in recent years, these must be consolidated if we are to achieve commercially realistic sustainable solutions. It is already clear that rechargeable Li-ion batteries (as already used widely in mobile-phones and portable computers) are also fast becoming the battery of choice in next-generation hybrid and pure-electric (HEV, P-HEV and EV) vehicle concepts, as well as in large-scale sustainable energy storage applications. No other battery technology has yet to emerge to pose a serious challenge. As ever- larger Li-ion battery packs are developed, we will be forced to exploit significantly cheaper cathode materials – with the cost of the cathode material corresponding to more than one-third of the total material costs in a Li-ion battery. Huge savings can be made if the cost of cathode materials can be reduced; so the question arises: can significant breakthroughs be found amongst as yet
of the redox electrode is rectangular or not (capacitor-like or not), the supercapattery will always show rectangular CVs as same as a capacitor. Fig. 1 and Table 1 compare the current status of different energy storage devices in terms of their energy and power performance [10-14]. Due to the use of redox materials, especially the batteryelectrodematerials, supercapatteries with an organic electrolyte can output higher power than, and store a comparable amount of energy as Li ion batteries. In aqueous electrolytes, supercapatteries show smaller specific energy because of the smaller operational cell voltage, but they are advantageous in terms of specific power. Table 1 summarises various combinations of capacitive and faradaic electrodematerials, and lists the reported performance of the electrochemical energy storage devices, including the supercapacitors [15-20], supercapatteries [5,8,17-22] and batteries .
other metal elements such as zirconium, niobium, and magnesium . It could also be solved by coating the particles with carbon  or other Li-permeable phase . Characteristics and specifications of the aforementioned cathode materials were collected and compared for Li-ion batteries (Table 2.1). Specifically, I focus on (1) volumetric power and energy densities, (2) gravimetric power and energy densities, (3) stability, safety and environmental factors, and (4) capacity and rate-capacity. Since synthetic methods are different for the four different cathode materials, only the representative data that appeared most frequently within the past five years were chosen to ensure that data from different literature sources are comparable.
Microstructures and elemental composition of obtained materials were examined with the help of Carl Zeiss NVision 40 scanning electron microscope SEM (micrographs were obtained at an accelerating voltage of 7 kV), equipped with an Oxford Instruments X-MAX energy-dispersive X-ray (EDX) analyzer operating at an accelerating voltage of 30 kV.
storage alloy electrodes [41-44], it can be interpreted from the following several aspects, first, iron electrode is easy to corrosion in alkaline solution, because the steady potential of the iron in alkaline solution smaller than hydrogen balance potential 40~50 mV, and hydrogen and separation overpotential of hydrogen is small on the iron electrode, at the same time, oxygen ionization potential is not big ; second, adsorption of oxygen electrode surface will cause the passivation of iron, a monolayer adsorption oxygen could make the iron electrode passivation completely, stop the electronic exchange reaction [46-48]; third, the structure of the electrode material is too dense that make effective electrode surface area is too small , it is worth further study for its suitable capacity and good cycle stability. The rapid capacity fading on the BiFeO 3 electrodes could be ascribed to the formation of
of electrode was improved to increase the active site and then increase the performance of zinc bromine flow battery. Wang makes cage shaped porous carbon electrode, the bromine element can be combined with complexing agent and transpired through cage holes, improve the activity of electrode, battery efficiency in Kulun reached 98%, working at 80 mAcm -2 current density and energy efficiency reached 81%. Wang use resins, ethyl orthosilicate and block copolymers (F127), double highly ordered mesoporous carbon electrodes are fabricated at the best mass ratio, exhibit highly ordered two-dimensional six square hole and banded structure, larger surface area and highly ordered mesoporous structure provides more active sites which can short the transfer path, increase efficiency and reduce the diffusion resistance and improve the mass transfer rate, the adsorption performance is improved, finally, the voltage efficiency reached 82.9% and the energy efficiency reached 80.1% when the current density was 80 mAcm -2 , after the 200 cycle test, the performance of the battery has not been significantly attenuated, it is still very stable. The innovation of this electrode provides a practical basis for large-scale application of zinc bromide redox flow battery.
Our study is motivated by the need for development and deployment of reliable and efficient energy storage devices, such as lithium-ion batteries. However, the rate-capacity loss is the key obstacle faced by current lithium-ion battery technology, hindering many potential large-scale engineering applications, such as future transportation modalities, grid stabilization and storage systems for renewable energy. During electrochemical processes, diffusion-induced stress is an important factor causing electrode material capacity loss and failure. In this study, we present models that are capable for describing diffusion mechanisms and stress formation in LiFePO 4
The electrochemical performances of the cathode materials were evaluated by assembling into CR2032 type half-cells with a positive electrode, a metallic lithium which used as counter-electrode, a microporous polypropylene membrane (Celgard 2400) and electrolyte at room temperature (25℃). The electrolyte was 1 mol L -1 LiPF6 in ethylene carbonate (EC)/dimethyl carbonate (DEC)/ethyl methyl carbonate (EMC) (1:1:1 by volume). To prepare the positive electrode, 80 wt% active material, 10 wt% acetylene black (Super P) and 10 wt% polyvinylidene fluoride binder (PVDF) were dissolved to N-methylpyrrolidone (NMP, from Aldrich). After ultrasonic and stirring, the slurry was spread onto aluminum foil (20um thickness) by using applicator and then dried at 110 ℃ for 12h in a vacuum oven to get the electrode. The dried electrode was punched into circular disks with a diameter of 12 mm for assembling the coin half-cells, and then rolled into a film with a thickness of 32 mm. The cells were assembled in an argon-filled glove box with the contents of the water and the oxygen below 0.1ppm. After standing for 12h, the rate performance of the cells are charged by 0.2C (36 mA g -1 ), and discharged from 0.1 C to 5 C in the voltage range of 2.8-4.3V (versus Li/Li + ) by using the Neware battery testing system at room temperature. Furthermore, the cycle performance of the cells is tested at charged to 4.3V at 0.2C and discharged to 2.8V at 2C. The Cyclic voltammetry (CV) measurements at a scan rate of 0.1 mV s -1 between 2.8 and 4.3 V, and the electrochemical impedance spectroscopy (EIS) with amplitude of 5 mV at the frequency range from 0.01 Hz to 100 KHz were performed by an electrochemical workstation (CHI670D, CH Instruments).
Among the anode candidates, red phosphorus has the highest theoretical capacity of ~2600 mAh g -1 , and it has been widely investigated since it was first reported as anode material for SIBs in 2013. 1,252,289 The poor electrical conductivity and huge volume expansion (490 %) of red phosphorus, however, give it poor practical capacity and cycling stability, which are obstructing its practical application. To overcome these problems, various carbon materials, such as Super P®, 1,252 multi-walled carbon nanotubes (MWCNT), 289 single-walled carbon nanotubes (SWCNT), 2 and graphene, 3 have been introduced to prepare red phosphorus and carbon (P/C) composites, where the carbon plays the roles of both improving the electric conductivity and buffering the volume expansion. Compared with commercial red phosphorus, the cycling performance of P/Super P and P/MWCNT composites was improved to some extent, however, the capacity still gradually deteriorated. Among these P/C composites, P/SWCNT and phosphorus/graphene (P/G) composites showed improved cycling performance. 2,3 P/SWCNT composite synthesized by the vaporization-condensation method showed excellent cycling stability with no capacity decay over 200 cycles at the current density of 500 mA g -1 . 2 There is a big potential safety hazard, however, if the tube is not well sealed, because of the white phosphorus generated during the preparation process at the temperature of 600 °C, and moreover, the utilization of SWCNT can increase the cost. Song et al. reported that P/G composite prepared via simple ball milling delivered 1706 mAh g -1 capacity (on the basis of phosphorus weight) with 95% retention of the capacity in the second cycle for over 60 cycles. 3 Such good cycling performance is proposed to originate from the strong P-O-C chemical bonds between the graphene nanosheets and the phosphorus, which can stabilize the solid electrolyte interphase (SEI) to improve the cycling performance. The preparation of graphene requires tedious steps, however, such as the synthesis of graphite oxide (GO) and the reduction of GO. Moreover, the price of graphene is higher than that of natural graphite. Before, Jeon et al. reported the graphite can be exfoliated into graphene nanoplates during the ball milling process through the shear force. 290 Cui et al. demonstrated that the P-C bond can form during the ball-milling process to improve the contact between black phosphorus and carbon, giving the black phosphorus and carbon composite excellent electrochemical performance for lithium ion storage. 291
Ultra-Fast and Long-Term Cycling Anode for Sodium-Ion Batteries 99 but shifts to 0.6 V instead, indicating that part of this reaction can be reversible. The disappearance of the peak in other reports is always ascribed to the SEI layer formation only. 16 Therefore, the partly reversible peak in our case should correspond to sodium ion storage at defect sites. The second peak located at low potential (from 0.5 to 0 V) is much wider than for the previously reported hard carbon materials (from 0.2 to 0 V). 17,31 The common narrow peak only comes from sodium ion insertion into graphene layers, nanovoids, and pore-filling. 16 Thus, the peak from 0.2 to 0.5 V should correspond to the sodium ion adsorption on the carbon surface. 16 More importantly, this peak can also be reversible in the subsequent cycles. The above results indicate that the C-600 sample contains a huge number of defects, which can store sodium ion quickly and frequently, in a supercapacitor-like manner. Accordingly, the extraction of sodium ions is also different and occurs in a wide voltage range in the reverse scan, forming a rectangular-like CV shape, which is the nature of capacitive charge storage by surface adsorption/desorption of ions. 15 From the 2 nd cycle, the cathodic peaks shift to lower voltage as the unwanted side reactions such as electrolyte decomposition cease to be an issue. 17 The CV curves of C-800 and C-1000 (Figure 4.11a and 4.11b) are very different from those of C-600. The reversible peak for sodium-ion storage at defect sites has almost disappeared. This result is in good agreement with the Raman spectra and HRTEM images. With higher calcinations temperature, the D-sodium ascorbate-derived porous carbon materials acquire short-range ordering, accompanied by the disappearance of the defects. Therefore, the C-600 sample exhibits the largest integral area and strongest intensity peaks among all the samples, which demonstrates that it is the best anode for sodium storage among the tested samples. 16,31
Several methods have been extensively applied for the development of biosensor applications, like CV, amperometry and square wave voltammetry. Among these methods, DPV exhibit an excellent compatibility, high sensitivity and easily handled. Noaradrenalin (NA) and acetaminophen (AC) are electroactive compound, they can be detected by hematoxylin modified glassy carbon electrode. The electrocatalytic oxidation of NA and AC simultaneous measurement by using DPV . The recent surge of flower-like morphology of zinc oxide (ZnO) nanostructure has been synthesized by hydrothermal method. The DNA immobilizations are mainly focused on interaction of physically immobilized single stranded thiolate DNA (SS th-DNA) and the nanostructure of ZnO. The assembled immobilized electrode can quantify the target molecule of ss th-DNA . Hu et al  employed a simple and irreversible electrochemical biosensor of glucose by Cv and DPV. Fig.5.shows that the glucose oxidation concentrations increases with increasing of peak current. The development of biosensors glucose oxidation LOD value of 0.015 mM.
on a superior catalytic activity in PEMFCs and it exists good stability with respect to the conventional Pt/C catalyst. The electro-kinetic parameters of reaction order and activation energy have been determined by a steady-state of the galvanostatic polarization curve method. The observed negative activation energies of 40 kJ mol -1 and 18 kJ mol -1 were occurring at 0.9 V and 0.65 V respectively. The influencing of temperatures under high pressure (3 bar abs) operating conditions exhibited maximum power density of 934 mW cm -2 at 80° C and 990 mW cm -2 at 100° C . A novel-hybrid carbon supported binuclear-cobalt-phthalocyanine (Bi-CoPc/C) was integrated with metal oxides (NiO and CoO) to form a macro cyclic complex for the enhancement of electrocatalytic (ORR) activities. The cyclic voltammetry study showed the nickel based catalytic (Bi-CoPc/C-NiO) reduction peak potential at -0.12 V and cobalt based catalytic (Bi-CoPc/C-CoO) reduction peak potential at -0.22 V respectively. Among these tested catalysts, Bi-CoPc/C integrated metal oxide showed potential electrode material to replace the cost Pt electrode catalyst . Among the above discussed catalyst method, hydrothermal was one of the important methods for the preparation of biomass carbon supported silver-tungsten carbide nanohybrid (Ag-WC/C) catalyst for ORR in MFC under neutral (pH = Phosphate buffer) medium. Ag-WC/C catalyst has been characterized by the powder X-ray diffraction and transmission electron microscopic (Average particle size about 14 nm) methods . A novel and efficient cost effective stainless steel mesh/cobalt hydroxide (SSM/Co 3 O 4 ) electrode was
by introducing oleylamine (OLA) as surfactant. The phase of each sample was characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM), transmission electron microscope (TEM) revealed brick-liked nanomaterials were obtained, with a size of 50-200 nm long, 20-50 nm wide, about 10 nm thick. The electrochemical performance was also tested with 2025-type coin cell, and it exhibited a high initial capacity with discharge and charge capacities of 1090 mAh g -1 and 761.6 mAh g -1 respectively, although the capacity retention was insufficient. By using cyclic voltammogram (CV), ex situ XRD, the reaction mechanism of the new CuSbS 2 electrode was also examined during the first
Forming perovskite compounds to introduce oxygen anion-intercalation-type charge storage mechanism was an effective way to significantly improve the capacitance of cobalt-based oxides as electrodes for supercapacitor. A high oxygen vacancy concentration was critical to achieve high capacitance. In order to maintain stable performance, the dopant should be carefully selected to avoid the over-leaching of selective cations in alkaline solution, which may cause the collapse of perovskite structure, thus detrimentally affected the electrode performance. From this consideration, although it had high initial capacitance from the high variable oxygen vacancy concentration, BSCF was not a good candidate because of poor cycling stability. This poor stability was resulted from the significant leaching of Ba 2+ and Sr 2+ in alkaline solution during cycling, which destroyed the perovskite structure seriously. Interestingly, modest level of cation leaching can help to increase the specific surface area without affecting the perovskite phase structure; as a result, the surface reaction was promoted and the electrode performance was subsequently improved. Although the hexagonal SC was believed to have poor oxygen-ion conductivity due to the structural ordering, favourable rate performance was still achieved as electrode in supercapacitors. It implied that improved oxygen anion diffusivity was likely experienced under electrically biased condition. All above findings provided useful guidelines for the design of perovskite oxides as high-performance oxygen anion- intercalation type electrodes for supercapacitors. As a whole, SC was a promising electrode candidate for practical use in supercapacitors. Stabilizing its oxygen vacancy-disordered cubic phase through doping strategy by using dopant other than Ba 2+ could be a useful way to further improve the electrode performance of SC in the
was a large difference in the transfer coefficients and the standard rate constants between the two redox couples at the same electrode. The most noteworthy feature of the curve fitting results was that the standard rate constants of the two reductions at the glassy carbon electrodes were much larger than those at the platinum. We think this feature probably arose from the much higher affinities of sulfur to glassy carbon electrodes. Overall results indicate that the electrode reactions of sulfur are significantly affected by the electrodematerials as well as the nature of solvents.
(HPLC) has been used to detect carbamate pesticide values. The toxicity of pesticides (carbamate) may induce nausea, vomiting and coma like health effects. This type of problems could be controlled by minimizing residue levels (MRLs) of pesticides in the food samples [18, 19]. Chromatography technique can be used as versatile detection methods which are ideally suited for analyzing a wide range of compounds. Using these techniques, samples have been analyzed within 7 minutes. This is due to the high sensitivity of the diamond electrode, which allows a well defined chromatogram for 10 nM mixture of the pesticide analyte. However, HPLC is a time consuming method, uses some toxic organic reagents and require expensive equipment. Also, HPLC involves with complicated operating protocols.
Different methods are used to achieve effective colour removal of wastewaters. Physico- chemical methods are based on the dye separation from the solution, which involve a tertiary treatment to destroy the concentrated dye. In addition, adsorbents materials (active carbon [2-4], silica gel and alumina) have to be regenerated after some treatments . Filtration and the use of membranes (mainly nano-membranes [6-7]) require cleaning treatments, whereas flocculation-coagulation methods  produce sludge. The dye degradation by an enzymatic method requires further investigation in order to know which enzymatic process takes place ; also both temperature and pressure parameters have to be controlled to avoid enzyme denaturalization. Chemical oxidation methods such as ozonation [10, 11] or Fenton processes [12, 13] are quite expensive and the addition of auxiliary chemicals is necessary which can involve operational difficulties [14,15]. Biological treatments are the simplest methods but do not supply efficient decolouration results because of their chemical stability and resistance to microbiological attack . Consequently, nowadays electrochemical methods are being the focus of different research studies on wastewater decolouration treatments [9, 14, 16-19]. The advantages of these techniques are that operation at smooth conditions is possible and they use electron as a clean reagent. They also provide versatility, high energy efficiency, safety and ease for automation .
Observation of resolved in-pore resonances in the NMR spectra of supercapacitor electrodes offers a large amount of valuable information; (i) the intensities of the in-pore resonances allow the number of in-pore anions and cations to be determined, and thus the composition of the carbon pores and supercapacitor charging mechanisms can be studied, 8,9,25–27 (ii) the chemical shift difference between in- and ex-pore resonances gives information about the carbon structure, with both carbon ordering and pore size distribution affecting the shift, 33–35 and (iii) the linewidth of the in-pore resonance can offer information about the dynamics of the in-pore ions. 25 However, in some experiments it can be difficult to resolve the in-pore resonances, which can limit the information that can be obtained. Examples include; in situ NMR experiments where there are intense signals from the large amount of free electrolyte in the cell and magic angle spinning is not possible, 8–10 experiments on carbons with small ring current shifts, 30,37 and experiments on viscous electrolytes where broad in-pore resonances are observed. 25 The development of advanced NMR methods that improve spectral resolution is therefore necessary if a wide range of electrolytes and carbon materials are to be studied.
The problem of surface area may be tackled by developing synthetic methods that produce intricate nano/meso scale structure or porosity in the BTMO that results in a dramatically increased surface area per particle, keeping in mind that ions still need to be able to access the surface, i.e. there is no point in having surface structure at a scale that is too small for ion migration to the surface [13 – 16]. One way to achieve this is to add a polymer template during the initial synthesis of the material. Using polymeric materials as templates may also result in improvements in the mechanical ﬂ exibility of the electrode, more reliable mesoporosity, and the capability to introduce pore shape and volume versatility depending on the polymer template utilised [17 – 19]. Many such templating agents exist with two of the more interesting being eggshell membrane (ESM) and poly methyl methacrylate (PMMA). The former has been suggested as a useful template due to its porous structure, high temperature of decomposition (over 200 ° C), low water uptake and swelling properties . In addition use of ESM could be viewed as re-use/valorisation of a product normally considered a waste. The PMMA has a much more regular (and potentially tunable) structure .