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A peculiar nanostructure consisting of nitrogen-doped, carbon-encapsulated (N-C) SnO2@Sn nanoparticles grafted on three-dimensional (3D) graphene-like networks (designated as N-C@SnO2@Sn/3D-GNs) has been fabricated via a low-cost and scalable method, namely an in situ hydrolysis of Sn salts and immobilization of SnO2 nanoparticles on the surface of 3D-GNs, followed by an in situ polymerization of dopamine on the surface of the SnO2/3D-GNs, and finally a carbonization. In the composites, three-layer core-shell N-C@SnO2@Sn nanoparticles were uniformly grafted onto the surfaces of 3D-GNs, which promotes highly efficient insertion/extraction of Li(+). In addition, the outermost N-C layer with graphene-like structure of the N-C@SnO2@Sn nanoparticles can effectively buffer the large volume changes, enhance electronic conductivity, and prevent SnO2/Sn aggregation and pulverization during discharge/charge. The middle SnO2 layer can be changed into active Sn and nano-Li2O during discharge, as described by SnO2 + Li(+) → Sn + Li2O, whereas the thus-formed nano-Li2O can provide a facile environment for the alloying process and facilitate good cycling behavior, so as to further improve the cycling performance of the composite. The inner Sn layer with large theoretical capacity can guarantee high lithium storage in the composite. The 3D-GNs, with high electrical conductivity (1.50 × 10(3) S m(-1)), large surface area (1143 m(2) g(-1)), and high mechanical flexibility, tightly pin the core-shell structure of the N-C@SnO2@Sn nanoparticles and thus lead to remarkably enhanced electrical conductivity and structural integrity of the overall electrode. Consequently, this novel hybrid anode exhibits highly stable capacity of up to 901 mAh g(-1), with ∼89.3% capacity retention after 200 cycles at 0.1 A g(-1) and superior high rate performance, as well as a long lifetime of 500 cycles with 84.0% retention at 1.0 A g(-1). Importantly, this unique hybrid design is expected to be extended to other alloy-type anode materials such as silicon, germanium, etc.

A series of lithium borate added electrolyte compounds, xLi3BO3-(1−x)Li3.5Si0.5P0.5O4 (0 ≤ x ≤ 0.2), are synthesized and characterized. This so-called LISICON electrolyte system is analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), solid state nuclear magnetic resonance (ss-NMR), electrochemical impedance spectra (EIS), and direct current (DC) polarization methods. From 11B MAS NMR spectra, it is demonstrated that a small fraction of boron exists in the form of BO4, while its majority settles at grain boundaries in the form of BO3, indicating that lithium borate glasses play a role as sintering assistant. This prominently increases the relative density of samples, and is beneficial to the ionic conductivity. Further results show that the electrical conduction of lithium borate added LISICONs is dominated by Li+ ions, with a transference number of tLi+ ≥ 0.996 and a corresponding ionic conductivity of about 6.5 × 10−6 S cm−1 at room temperature, almost two times that of pristine Li3.5Si0.5P0.5O4.

Flexible lithium sulfur batteries are promising power sources for the next generation wearable electronics, due to their high energy density and low cost. Here, we demonstrate a metal current collector-free, binder-free, flexible sulfurized polyacrylonitrile film electrode with hollow tubular nanofibers (H-SPAN), which is fabricated via coaxial electrospinning and a simple heat treatment. The all-fibrous films H-SPAN not only provides three-dimensional continuous electron and ion transport paths, but also suppresses the shuttle effect, contributing to better redox kinetics, cycling performance, and flexibility. The H-SPAN film electrode delivers a high specific lithium storage capacity of 1250 mAh g−1sulfur or 514.75 mAh g−1electrode at 0.1C with stable cycling over 300 cycles. Additionally, when H-SPAN is applied as a cathode for room temperature Na–S batteries, it also exhibits superb capacity and cycling stability (717 mAh g−1sulfur or 295.2 mAh g−1electrode at 0.1C after 200 cycles). The working mechanism of H-SPAN is well elucidated by ex situ Raman spectroscopy and ex situ X-ray Photoelectron Spectroscopy (XPS). The excellent flexibility of the H-SPAN film electrode lends itself well to potential applications in wearable electronic devices.

Facile green and scalable synthesis of low-cost nonprecious metal electrocatalysts which favor a four-electron pathway for the oxygen reduction reaction (ORR) are in great need for high-performance metal-air batteries. Herein, an ultrasonication-assisted synthesis method of preparing MnO2 nanosheets anchored on carbon black (MnO2/Super P Li) ORR catalyst is proposed. Three kinds of MnO2 nanostructures can be controlled and conformably deposited on Super P Li backbone. The MnO2/Super P Li composites facilitates a four-electron ORR process and demonstrates superior stability than the benchmark catalyst Pt/C in alkaline solutions. Moreover, the Zn-air battery using one of the MnO2/Super P Li catalysts displays a specific capacity of 705mA h g−1 and the voltage platform is almost unchanged after discharge for 180 h. The high ORR activity of the hybrid catalyst can be attributed to the MnO2 nanosheets uniformly grown on the Super P Li three dimensional (3D) framework and the appropriate Mn(Ⅲ)/Mn(Ⅳ) of the MnO2/Super P Li composite which can magically catalyze the reduction of hydrogen peroxide. Due to the high ORR activity and the superior stability, low cost MnO2/Super P Li catalysts lends itself well to potential applications in renewable energy conversion devices.

Highly efficient and low-cost nonprecious metal electrocatalysts that favor a four-electron pathway for the oxygen reduction reaction (ORR) are essential for high-performance metal-air batteries. Herein, we show an ultrasonication-assisted synthesis method to prepare Mn

Rechargeable lithium metal anodes (LMAs) with long cycling life have been regarded as the "Holy Grail" for high-energy-density lithium metal secondary batteries. The skeleton plays an important role in determining the performance of LMAs. Commercially available copper foam (CF) is not normally regarded as a suitable skeleton for stable lithium storage owing to its relatively inappropriate large pore size and relatively low specific surface area. Herein, for the first time, we revisit CF and address these issues by rationally designing a highly porous copper (HPC) architecture grown on CF substrates (HPC/CF) as a three-dimensional (3D) hierarchically bicontinuous porous skeleton through a novel approach combining the self-assembly of polystyrene microspheres, electrodeposition of copper, and a thermal annealing treatment. Compared to the CF skeleton, the HPC/CF skeleton exhibits a significantly improved Li plating/stripping behavior with high Coulombic efficiency (CE) and superior Li dendrite growth suppression. The 3D HPC/CF-based LMAs can run for 620 h without short-circuiting in a symmetric Li/Li@Cu cell at 0.5 mA cm

Graphene/nickel oxide composite (G/NiO) was synthesized through a facile hydrothermal method and subsequently microwave thermal treatment by using alcohols-reduced graphene as substrate. The as-prepared G/NiO was characterized by X-ray diffraction, Raman spectra, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The results indicate that the graphene oxide has been successfully reduced to graphene, and NiO nanoparticles are homogeneous anchored on the surface of graphene, forming a globule-on-sheet structure. The loading content of NiO nanoparticles anchoring on the surface of graphene nanosheets can be controlled by adjusting the hydrothermal temperature. The G/NiO displays superior electrochemical performance with a specific capacitance of 530 F g −1 at 1 A g −1 in 2 M of NaOH. After 5000 cycles, the supercapacitor still maintains a specific capacitance of 490 F g −1 (92% retention of the initial capacity), exhibiting excellent cycling stability.

A three-dimensional lithium iron phosphate (LiFePO4)/carbon nanotubes (CNTs)/graphene composite was successfully synthesized via solid-state reaction. The LiFePO4/carbon nanotubes/graphene (LFP–CNT–G) composite used as Li-ions battery cathode material exhibits superior high-rate capability and favorable charge–discharge cycle performance under relative high current density compared with that of LiFePO4/carbon nanotubes (LFP–CNT) composite and LiFePO4/graphene (LFP–G) composite. Graphene nanosheets and CNTs construct 3D conducting networks are favor for faster electron transfer, higher Li-ions diffusion coefficient and lower resistance during the Li-ions reversible reaction. The synergistic effect of graphene nanosheets and CNTs improves the rate capability and cycling stability of LiFePO4-based cathodes. The LFP–CNT–G electrode shows reversible capacity of 168.9 mA h g−1 at 0.2 C and 115.8 mA h g−1 at 20 C. The electrochemical impedance spectroscopy demonstrate that the LFP–CNT–G electrode has the smallest charge-transfer resistance, indicating that the fast electron transfer from the electrolyte to the LFP–CNT–G active materials in the Li-ions intercalation/deintercalation reactions owing to the three-dimensional networks of graphene and carbon nanotubes.

Moxidectin is a single-component and semisynthetic macrocyclic lactone antibiotic, which has been widely used in the prevention and treatment of parasites in farm animals. In this paper, the transformation of ethanol solvate to form I of moxidectin in an ethanol–water mixture was studied. Offline methods and online instruments were used to monitor and identify the transformation process, and the influences of water content and temperature were discussed. It is noted that the transformation kinetics are highly sensitive to both the solvent composition and temperature and the transformation rate is a function of the ethanol content in aqueous ethanol mixtures. The solvent-mediated polymorphic transformation mechanism from ethanol solvate to form I was suggested, and the process is controlled by the nucleation and growth rate of the stable form. Understanding these effects can aid optimization and improve process control in the crystallization of moxidectin.

Conductive polypyrrole (PPy)-coated LiNi0.5Mn1.5O4 (LNMO) composites are applied as cathode materials in Li-ion batteries, and their electrochemical properties are explored at both room and elevated temperature. The morphology, phase evolution, and chemical properties of the as-prepared samples are analyzed by means of X-ray powder diffraction, thermogravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning and transmission electron microscopy techniques. The composite with 5 wt% polypyrrole coating shows a discharge capacity retention of 92% after 300 cycles and better rate capability than the bare LNMO electrode in the potential range of 3.5–4.9 V vs. Li/Li+ at room temperature. At the elevated temperature, the cycling performance of the electrode made from LNMO–5 wt% PPy is also remarkably stable (∼91% capacity retention after 100 cycles). It is revealed that the polypyrrole coating can suppress the dissolution of manganese in the electrolyte which occurs during cycling. The charge transfer resistance of the composite electrode is much lower than that of the bare LNMO electrode after cycling, indicating that the polypyrrole coating significantly increases the electrical conductivity of the LNMO electrode. Polypyrrole can also work as an effective protective layer to suppress the electrolyte decomposition arising from undesirable reactions between the cathode electrode and electrolyte on the surface of the active material at elevated temperature, leading to high coulombic efficiency.

A graphene/chromium-MOF(MIL-101) composite is investigated to serve as a host for sulfur immobilisation in Li–S batteries. The unique structure with a large specific area and a conductive shell ensures a high dispersion of sulfur in the composite and minimizes the loss of polysulfides to the electrolyte.

Wrought Mg-Al-Pb-RE strips of different thicknesses are synthesized via extrusion and used as the anodes in Mg-air batteries. We find that, compared to other Mg-Al-Pb-RE samples, the 5 mm-thick strip exhibits greater stability and higher discharge voltage plateaus for long time (10 h). Its anodic efficiency at 10 mA cm −2 reaches 64.1%, which is even higher than pure magnesium and AZ31 magnesium alloy. The outstanding performance of the 5 mm-thick Mg-Al-Pb-RE anode strip is attributed to its unique microstructure favourable for anodic dissolution. Furthermore, the correlations between microstructure features and electrochemical performance for the wrought Mg-Al-Pb-RE strips are also systematically defined.

Metallic lithium (Li) has been acclaimed as the most promising anode materials for lithium batteries due to its ultrahigh theoretical capacity of 3860 mA h g−1. Its practical application is impeded, however, due to the notorious problems related to dendrite growth caused by its uneven current density distribution and high Li nucleation overpotential. Here, we report a three-dimensional (3D) lithiophobic phase (Cu) and lithiophilic phase (Zn or Sn) composite architecture realized through a facile electrochemical co-deposition technology and its use as a scaffold for dendrite-free Li metal anode. It is found that the simultaneous formation of this lithiophobic-lithiophilic composite on Cu foam leads to ultrafine lithiophilic phase (20 nm) and reduced Li nucleation overpotential, as well as enhanced homogeneity, which enables a uniform electric field distribution during lithium plating/stripping, thus facilitating even and dendrite-free Li deposition. In the meanwhile, the lithiophobic component in the composite acts as a strong backbone, helping to maintain structural stability during lithium storage. Also, the as-prepared three-dimensional micro/nanoporous scaffold with large surface area can effectively reduce the local current density and suppress Li dendrite growth. The full cells with the composite architecture/Li as anode and LiFePO4 as cathode show promising electrochemical performance with over 80% capacity retention over 1600 cycles at 5 C. This work broadens the horizon of lithiophilic hosts for next-generation high-performance Li metal batteries.

A magnetoelectric hysteresis loop measurement system based on dynamic method was built under a demodulation concept with a lock-in amplifier as the high speed demodulator. A measuring speed as fast as 300 ms/point was achieved, and a complete and fluent magnetoelectric hysteresis loop could be obtained within minutes. Results show that the static magnetic phenomenon affects magnetoelectric effect significantly. This method is recommended to be the standard for magnetoelectric hysteresis loop measurement.

Spinel LiMn1.5Ni0.5O4 (LMNO) sub-micrometer-sized spheres were prepared in one step using porous MnCO3 microspheres as a self-supporting template. The LMNO spheres were characterized by XRD, SEM and TEM. The obtained LMNO was in a well-crystallized cubic phase with little impurity. It showed high rate capability and excellent cycling stability as a cathode material for lithium ion batteries. Initial discharge capacities of 122.0, 120.3, 119.5 and 112.1 mAh g−1 were found at 2, 3, 5 and 10C respectively with 1C being 146.7 mA g−1. Their capacity retentions are 92, 91, 82 and 79% respectively after 500 cycles. The as-prepared LMNO is a promising cathode material for high power and long-life lithium ion batteries. Keywords: LiMn1.5Ni0.5O4 spheres, Cathode, Self-supporting template synthesis, High capacity retention

Spherical Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 material was treated with persulfates Na 2 S 2 O 8 or (NH 4 ) 2 S 2 O 8 to extract lithium to increase the coulombic efficiency of the first cycle. The two persulfates showed different effects. Na 2 S 2 O 8 greatly improved the first cycle efficiency of the active material to nearly 100%. The rate performance was also increased to more than 200 mAh g −1 at 1C rate. The reason for the improved rate performance by the treatment of Na 2 S 2 O 8 is attributed to the formation of spinel phase on the surface of the material and the extraction of lithium and oxygen, which results in a decreased electrochemical resistance, whereas the treatment with (NH 4 ) 2 S 2 O 8 deteriorated the electrochemical performance of the Li-rich compound due to the Li + /H + exchange and the collapse of the layered structure.

Topological quantum computation has been extensively studied due to its robustness against decoherence. A conventional way to realize it is by adiabatic operations---it requires relatively long time to accomplish so that the speed of quantum computation slows down. In this work, we present a method to realize topological quantum computation by periodic driving. Compared to the adiabatic evolution, the total operation time can be regulated arbitrarily by the amplitude and frequency of the periodic driving. For the sinusoidal driving, we give an expression for the total operation time in the high-frequency limit. For the square wave driving, we derive an exact analytical expression for the evolution operator without any approximations, and show that the amplitude and frequency of driving field depend on its period and total operation time. This could provide a new direction in regulations of the operation time in topological quantum computation., 9 pages, 10 figures

In this study, sub-micrometer LiFePO4 particles with high purity and crystallinity were synthesized using supercritical hydrothermal method as the cathode material for lithium ion batteries. Experimental results show that templates and calcination time have significant impacts on the purity, particle size and morphology of LiFePO4 particles. The as-prepared LiFePO4 particles using polyvinyl pyrrolidone (PVP) template with additional one hour calcination at 700°C exhibit characteristics of good crystallinity, uniform size distribution, high capacity and cycling performance. The specific discharge capacities of 141.2 and 114.0mA·h/g were obtained at the charge/discharge rates of 0.1 and 1.0 C, respectively. It retained 96.0% of an initial capacity after 100 cycles at 1.0 C rate. The good electrochemical performance of the as-synthesized material is attributed to the synergistic factors of its reasonable particle size and surface areas and high crystallinity.

Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C for 8 h. The spherical MnCO3 precursors were obtained from the control of the crystallizing process of Mn2+ ions and NH4HCO3 in aqueous solution. The effects of the mole ratio of the raw materials, reaction time, and reaction temperature on the morphology and yield of the MnCO3 were investigated. The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Galvanostatic charge/discharge tests indicate that the spinel LiMn2O4 microspheres deliver a discharge capacity of 90 mA·h/g at 10C rate show good capacity retention capability (75% of their initial capacity after 800 cycles at 10C rate). The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.

Monodispersed hollow Fe 3 O 4 spheres with different diameters and shell thickness were synthesized by a simple solvothermal process and were investigated as anode materials for lithium ion batteries (LIBs). The shell of the hollow spheres exhibited porous structure composed of aggregated Fe 3 O 4 nanoparticles. The composition and morphology of the obtained samples were characterized by X-ray powder diffraction (XRD), Raman spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A novel formation mechanism was proposed based on the results of time-dependent reactions. The electrochemical tests of the hollow Fe 3 O 4 spheres were performed to determine the reversible capacity, rate and cycling performance as anode materials for LIBs. The Fe 3 O 4 obtained from the reaction at 200 °C for 48 h exhibited the best specific capacity and capacity retention and superior rate performance compared to other Fe 3 O 4 spheres, which is ascribed to their reasonable particle size, high crystallinity and hollow spherical structures. Different conductive additive were used to investigate the electrochemical performance of Fe 3 O 4 hollow spheres. The binary conductive additives containing acetylene black (AB) and carbon nanobutes (CNTs) improved the electrochemical performance of the Fe 3 O 4 hollow spheres obviously. The results reveal that there is a synergistic effect of the particle size, crystallinity and conductive agents on the electrochemical properties of the hollow Fe 3 O 4 spheres.

PurposeThe aim of this paper is to investigate the synergism effect between lanthanum salt (La(NO3)3) and benzotriazole (BTAH) on the corrosion inhibition of commercial brass and to further study the inhibition mechanism.Design/methodology/approachPotentiodynamic polarization curves were carried out on bare brass and brass treated with additions of optimum concentration of BTAH, La salt and La salt+BTAH to the basal deposition solutions in 3.5 wt. percent sodium chloride solution. The inhibition mechanism of the composite conversion coatings on brass obtained in optimal deposition techniques were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X‐ray diffraction (XRD), and FT‐IR reflection spectra.FindingsA “Critical La(NO3)3 content” and “Critical BTAH content” were both observed, at which the coatings prepared performs the highest protectiveness, and La(NO3)3 and BTAH had an excellent synergism effect on the corrosion inhibition of brass. The corrosion mechanisms for uncoated and coated brass are different. A remarkable enhancement of the brass's corrosion protection was obtained by the formation of composite conversion coatings consisted of Cu(I)BTA and La coordinate thing except for Cu2O and La2O3, which acted as a barrier avoiding the release of metal ions and inhibited the diffusion of the oxygen.Originality/valueThe results from this paper showed that La(NO3)3 and BTAH could be used together to prepare the novel composited conversion coatings on commercial brass for the good corrosion inhibition.

Unique hollow Fe 3 O 4 /C spheres are prepared by a simple one-pot solvothermal method, with spinel structure and 750 nm in diameter identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The hollow Fe 3 O 4 /C spheres exhibit excellent cycling and rate performance as anode material for lithium ion batteries, delivering reversible specific capacities of 984 mAh g −1 even after 70 cycles at 0.2 C, 620 mAh g −1 at 2 C, and 460 mAh g −1 at 5 C, respectively. Lithium insertion mechanisms are also proposed in terms of the ex situ XRD analysis of the electrodes after discharged and charged to certain voltages together with cyclic voltammetry (CV) and voltage profile.

Self-assembled monolayers (SAMs) of 3-mercaptopropyltrimethoxysilane (PropS-SH), dodecyltrimethoxysilane (DTMS), 3-aminopropyl(trimethoxy)silane (APS), and chloropropyl(trimethoxy)silane (CPTMS) were investigated to evaluate the influence of the silane molecule structure towards brass corrosion protection. The results indicated that SAMs of PropS-SH, CPTMS and DTMS inhibited the corrosion of brass in 0.2 M NaCl showing a mixed type behavior, while APS was not a good inhibitor. The inhibitive action of the PropS-SH and DTMS can be explained by chemisorption which obeys the Langmuir adsorption isotherm. The thiolate bond allows a better anchorage of the silane layer to the brass surface than the oxane bond.

The La2O3 nanoparticles incorporation and electrodeposition were used together to prepare the La-conversion coatings on brass surface in a basal solution containing rare earth salt and benzotriazole. The results showed that both of these techniques can improve the coatings formation and their protectiveness. A critical nanoparticulate La2O3 content and a critical deposition potential were observed, under which the conversion coatings had the highest protective properties. The composite La-conversion coatings could provide important protection against brass corrosion for considerable immersion periods in 3.5% NaCl solution because it ennobled the corrosion potential and decreased the anodic current.

The La2O3 nanoparticles incorporation and electrodeposition were used together to prepare the La-conversion coatings on α-brass surface in a basal solution containing rare earth salt. The results showed that both techniques can improve the protective properties of coatings. A ‘critical nano-La2O3 content’ and a ‘critical deposition potential’ were observed, under which the conversion coatings had the highest protective properties. Increased electrodeposition time improve the quality of conversion coatings. The La-conversion coatings could provide important protection against α-brass corrosion for considerable immersion periods in 3.5 wt% sodium chloride solution because it ennobled the corrosion potential and decreased the anodic current.

Conversion coatings on commercial brass were prepared with lanthanum salt (La(NO3)3) and benzotriazole (BTAH) as reagents. A “Critical La(NO3)3 content” and “Critical BTAH content” were both observed, at which the coatings prepared performs the highest protectiveness.The results showed that La(NO3)3 and BTAH had an excellent synergism effect on the corrosion inhibition of brass. A remarkable enhancement of the brass’s corrosion protection was obtained by the formation of conversion coatings consisted of Cu2O, La2O3, Cu(I)BTA and La-complex, which acted as a barrier avoiding the release of metal ions and inhibited the diffusion of the oxygen.

A new oxide-salt composite electrolyte, YSZ–K3PO4–Ca3(PO4)2, shows proton conductivity in the order of 10−2 S/cm at 700 °C. The proton transport number, determined using a hydrogen concentration cell, rises from more than 93% at 550 °C to 99% at 700 °C. The composite electrolyte is chemically stable in H2S containing atmosphere, and so is a good candidate electrolyte material for H2S solid oxide fuel cells applications.

Mesoporous FePO 4 could deliver enhanced specific capacity of 160 mAh g −1 at first discharge process, 90% of theoretical capacity of pure FePO 4 , and 135 mAh g −1 in the following cycles at 0.1 C rate. At 1 and 3 C rates, the capacities are 110 and 85 mAh g −1 , respectively, which is much higher than that of previously reported for modified FePO 4 materials. Electrochemical impedance spectroscopy (EIS) tests proved that mesoporous structure in FePO 4 materials enhanced the lithium ion intercalation/deintercalation kinetics as indicated by smaller charge transfer resistance ( R ct ) of these materials. These results revealed that this mesoporous electrode material can be a potential candidate for high-power energy conversion devices.

Yttrium-doped barium cerate, BaCe0.85Y0.15O3−α (BCY15), membranes are proton-conducting electrolytes for intermediate-temperature protonic ceramic fuel cells (IT-PCFC), useful for, among other processes, co-production of power and ethylene by dehydrogenation of ethane. BCY15 membranes showed good conductivity at intermediate temperatures, 15 and 20 mS cm−1 at 700 and 750 °C, respectively. Maximum power density was 174 mW cm−2 at 700 °C, with a corresponding current density of 320 mA cm−2, using a C2H6,Pt/BCY15/Pt,O2 fuel cell, with a ca. 0.5 mm thick membrane, producing 34% ethane conversion with 96% ethylene selectivity Comparison of performances using vertical and horizontal set-ups showed that horizontal set-ups are subject to torsional strain, causing reduced cell performance resulting from even minor leakage at the glass seal.

Mesoporous titanium pyrophosphates have been synthesized by a sol–gel template method with further calcinations at or below the temperature of 700 °C. When calcined at 800 °C, crystalline TiP2O7 will be formed accompanied with the break down of meso-structure in the precursor. Mesoporous TiP2O7 shows a similar lithium ion intercalation behavior to that of solid solution in the electrochemical tests. When cycled at high charge/discharge rate, mesoporous TiP2O7 calcined at 700 °C delivers a higher specific discharge capacity than that of crystalline TiP2O7, indicating that mesoporous structure is beneficial for improving the transportation and intercalation/deintercalation behavior of lithium ions in the materials, thus improving the charge/discharge performance of the materials at high charge/discharge rate.

Nano-Germanium/polypyrrole composite has been synthesized by chemical reduction method in aqueous solution. The Ge nanoparticles were directly coated on the surface of the polypyrrole. The morphology and structural properties of samples were determined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis was carried out to determine the polypyrrole content. The electrochemical properties of the samples have been investigated and their suitability as anode materials for the lithium-ion battery was examined. The discharge capacity of the Ge nanoparticles calculated in the Ge-polypyrrole composite is 1014 mAh g(-1) after 50 cycles at 0.2 C rate, which is much higher than that of pristine germanium (439 mAh g(-1)). The composite also demonstrates high specific discharge capacities at different current rates (1318, 1032, 661, and 460 mAh g(-1) at 0.5, 1.0, 2.0, and 4.0 C, respectively). The superior electrochemical performance of Ge-polypyrrole composite could be attributed to the polypyrrole core, which provides an efficient transport pathway for electrons. SEM images of the electrodes have demonstrated that polypyrrole can also act as a conductive binder and alleviate the pulverization of electrode caused by the huge volume changes of the nanosized germanium particles during Li(+) intercalation/de-intercalation.

Lithium iron phosphate has become the subject of great interest as storage cathodes for rechargeable lithium-ion batteries. Unfortunately, its intrinsic low electronic conductivity and low energy density still prevent it from practical commercialization [1]. In the past decade, Padhi et al [2] pioneered interest in the LiFe1-yMnyPO4 olivine system, showing the occupation of some percentage of octahedral 4c sites of LiFePO4 by Mn combines the advantages of the low toxicity of LiFePO4 and the relatively high operating voltage of LiMnPO4 (~4.1 V). This ability to increase the energy density of conventional LiFePO4 has been the driving force for extensive research on LiFe1-XMnxPO4 [3]. Nevertheless, besides the fundamentally low electronic conductivity of olivine, the Mn3+ doping may lead to another drawback, which is Mn3+ dissolution. It is generally accepted that Mn3+ causes serious mechanical stress and its disproportionation results in Mn2+dissolution from the surface by Jahn-Teller distortion [4]. Therefore, there have been many efforts to overcome these obstacles, for instance by decreasing the crystallite size and changing the morphology or providing a conductive matrix (e.g. carbon). In this work, we present the application of a composite LiMn0.15Fe0.85PO4 coated with conductive polypyrrole (PPy) as cathode electrode for the Li-ion battery. The effects of the PPy coating on the physicochemical and electrochemical properties have been extensively studied. SEM and TEM images show that the PPy is uniformly coated on the surface of LiMn0.15Fe0.85PO4. The LiMn0.15Fe0.85PO4 electrode with 9 wt. % PPy coating exhibits a high discharge capacity and good cycle life at room temperature. This electrode delivers a discharge capacity of 135 mAh/g at 1/2 C, and after 100 cycles, the discharge capacity still reaches 126 mAh/g. In contrast, the discharge capacity of the pristine LiMn0.15Fe0.85PO4 is only around 128 mAh/g under the same conditions, and 114 mAh/g remains after 100 cycles, as shown in Fig. 1a. Electrochemical impedance spectroscopy verified the improved electrochemical conductivity of LiMn0.15Fe0.85PO4/PPy electrode. In addition, analysis of the counter electrode (Li film) confirmed that the PPy coating can protect the electrode from HF attack, and thus lead to reduction of Mn3+ dissolution in the LiMn0.15Fe0.85PO4-PPy electrode (Fig. 1b). [1] A. Yamada, S. C. Chung, K. Hinokuma, Journal of the Electrochemical Society, 148 (2001) A224-A229. [2] A. K. Padhi, K. S. Nanjundaswamy, J. B. Goodenough, Journal of the Electrochemical Society, 144 (1997) 1188-1194. [3] S. Y. Chung, J. T. Bloking, Y. M. Chiang, Nat. Mater., 1 (2002) 123-128. [4] R. Von Hagen, H. Lorrmann, K. C. Möller, S. Mathur, Advanced Energy Materials, 2 (2012) 553-559.

Relatively uniform sized graphene-encapsulated sulphur (GES) composites with a core (S)–shell (graphene) structure were synthesized in one pot based on a solution-chemical reaction–deposition method. These novel GES particles were characterized by XRD, Raman spectrometry, SEM, TGA, EDS and TEM. The electrochemical tests showed that the present GES composites exhibit high specific capacity, good discharge capacity retention and superior rate capability when they were employed as cathodes in rechargeable Li–S cells. A high sulphur content (83.3 wt%) was obtained in the GES composites. Stable discharge capacities of about 900, 650, 540 and 480 mA h g−1 were achieved at 0.75, 2.0, 3.0 and 6.0 C, respectively. The good electrochemical performance is attributed to the high electrical conductivity of the graphene, the reasonable particle size of sulphur particles, and the core–shell structures that have synergistic effects on facilitating good transport of electrons from the poorly conducting sulphur, preserving fast transport of lithium ions to the encapsulated sulphur particles, and alleviating the polysulfide shuttle phenomenon. The present finding may provide a significant contribution to the enhancement of cathodes for the lithium–sulphur battery technology.

Porous LiMn2O4 microspheres, which are constructed with nanometer-sized primary particles, have been synthesized by a facile method using porous MnCO3 microspheres as a self-supporting template. The LiMn2O4 microspheres were characterized by XRD, SEM and HR-TEM. The as-synthesized porous LiMn2O4 microspheres exhibit high rate capability and long-term cyclability as cathode materials for lithium ion batteries, with the specific discharge capacity of 119, 107 and 98 mA h g−1 and the corresponding capacity retention of 82, 91 and 80% for up to 500 cycles at 2, 10 and 20 C, respectively. The high rate performance and good cyclability are believed to result from the porous structure, reasonable primary particle size and high crystallinity of the obtained material, which favor fast Li intercalation/deintercalation kinetics by allowing electrolyte insertion through the nanoparticles and high structural stability during the reversible electrochemical process. The high level of Mn4+ concentration on the surface of the sample can alleviate the Jahn–Teller transition, which was triggered normally by the equal amounts of Mn4+/Mn3+ concentration on the surface of the LiMn2O4 cathode material. This good example offering extended cycle life at 20 C rate for the LiMn2O4 microspheres indicates their promising application as cathode materials for high performance LIBs.

A facile one pot hydrothermal method has been developed to synthesize laminate-structured graphene sheet–Fe3O4 nanocomposites (GNS–Fe3O4). Fe3O4 nanoparticles were decorated densely and homogeneously in the graphene matrix. Galvanostatic charge–discharge cycling of the GNS–Fe3O4 nanocomposites exhibited a reversible specific capacity over 1200 mAh g−1 at 100 mA g−1 without palpable fading for 50 cycles in the voltage range 0.01–3.0 V. A cell for the rate capacity test indicated a high current density of 946 mAh g−1 at a cycling rate of 1000 mA g−1, which could be fully recovered to 1359 mAh g−1 at 100 mA g−1 after 50 cycles. The superior electrochemical performance of the nanocomposites can be attributed to the following factors: (i) the thermal expanded graphene oxide (TEGO) under atmosphere could attach more oxygen functional groups than the hydrogen reduced graphene, which benefited the adsorption and fastness of the nano-sized Fe3O4; (ii) annealing of TEGO–Fe3O4 nanocomposites further improved the conductivity of the graphene matrix, providing a high electron transport rate at the electrode–electrolyte interface; (iii) the laminated structure of nanocomposites could prevent the agglomeration of Fe3O4 nanoparticles and the restacking of graphene sheets, and effectively release the strain caused by the volume expansion of the Fe3O4 nanoparticles, facilitating ion/electron transportation within the electrode and at the electrode–electrolyte interface.

Porous Mn2O3 microspheres have been synthesized by morphology-controlled decomposition of spherical MnCO3 precursors at 600 °C. The porous Mn2O3 microspheres show a good rate capability and a high specific capacity of 796 mA h g−1 after 50 cycles.

Three nanomaterials, namely, titanium carbide (TiC), tungsten oxide (WO2), and vanadium nitride (VN), are introduced into dye-sensitized solar cells (DSCs) as counter electrode (CE) catalysts to replace the expensive Pt CE. Three kinds of substrates of bare glass (BG), Ti foil, and polyimide (PI) film are applied as F-doped tin oxide (FTO)-free substrates for rigid and flexible DSCs; thus realizing FTO-free and Pt-free CEs simultaneously in the DSC system. A carbon layer is used as an electron collector to replace the expensive FTO conductive layer in the insulative BG and PI film. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization curves are performed to compare the catalytic activities of these CEs for the reduction of triiodide to iodide. The results demonstrate that the DSCs that use TiC, WO2, and VN as CEs on Ti foil have better photovoltaic performance than those that use CEs on traditional FTO glass. Moreover, the TiC, WO2, and VN on the BG substrates show excellent catalytic activities that can match the performance of the CEs on FTO glasses.

ZnFe(2)O(4)/C hollow spheres have been synthesized via a facile solvothermal route using low cost raw materials. The resulting composite showed a very high specific capacity of 841 mAh g(-1) after 30 cycles and good rate capability.

Agglomerated pure spinel ZnMn2O4 nanoparticles with flake-shaped structure have been synthesized viacalcination of an agglomerated Zn–Mn citrate complex precursor, which was prepared with high yield by a convenient, environmentally benign and low temperature route. The composition, morphology and thermal decomposition of the Zn–Mn citrate complex were studied by C&H elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The resulting ZnMn2O4 nanoparticles obtained from the precursor calcination at 700 °C were systematically characterized by XRD, FTIR, N2Adsorption/Desorption, SEM, TEM, HRTEM and selected area electron diffraction (SAED). The results show that the ZnMn2O4 material was agglomerated to form a porous texture in pure phase. The electrochemical properties of the agglomerated ZnMn2O4 material were investigated to determine its reversible capacity, rate and cycling performance as the anode material for lithium ion batteries (LIBs). This ZnMn2O4 material exhibited promising capacity retention of over 200 cycles at varying discharge rates. The electrode also exhibited attractive rate capabilities yielding capacity of 330 mAh g−1 after more than 35 cycles at 600 mA g−1.The ameliorated electrochemical performance can be ascribed to the high crystallinity and porous texture of the ZnMn2O4 material which provided short diffusion paths for lithium ions. Ex situXRD analysis of the electrodes after discharging and charging to the selected voltage was conducted and the possible lithium insertion mechanisms are discussed. This study suggests that the ZnMn2O4 material synthesized via the single source precursor route is a promising anode material for LIBs.

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Electrical Vehicles (EVs) are very important in reducing fossil oil consumption and carbon emission in cities. Spinel LiNi 0.5 Mn 1.5 O 4 is one promising cathode material for lithium ion batteries used in EVs owing to its high power density. Here AlF 3 coated LiNi 0.5 Mn 1.5 O 4 is prepared through an newly developed method. The spinel oxide sintered at 900 C presents the best electrochemical performance with a specific discharge capacity of 132.4 mAh/g at 0.5 C. 81.0% of the initial specific capacity can be retained after 50 cycles. AlF 3 coating can further improve the electrochemical performance. The initial specific capacity at 10 C is enhanced from 104.6 to 109.1 mAh g -1 with the capacities retention increasing from 80.6 to 92.1% after 100 cycles.