Ionics

The non-stoichiometry and chemical diffusion coefficient of SrFe1−xCoxO3-δ have been measured by steady state and transient thermogravimetry in the temperature range 750–1200 °C at different oxygen partial pressures. At high oxygen partial pressures, the chemical diffusion coefficient was in the range 1·10−4 – 7·10−4 cm2/s. This, combined with high concentration of disordered vacancies make these materials perhaps the fastest solid oxygen ion diffusers known at high temperatures and high oxygen partial pressures. However, due to the high concentration of defects in SrFe1−xCoxO3-δ the compound transforms from a cubic (disordered) perovskite to a brownmillerite type of structure under reduced oxygen partial pressures below approx. 900 °C. Due to this phase transition, the mobility of oxygen vacancies in SrFe1−xCoxO3-δ decreases up to about an order of magnitude at 850 °C. We also observe an ordering effect at 1000 °C, although smaller in size, and this is suggested to be due to short range ordering of four-coordinated polyhedra of Fe. For possible use as oxygen separation membranes, phase stability against sulphur and carbon containing atmospheres is also discussed with respect to the formation of carbonates and sulphates.

In the process of studying the system Tl2MoO4–In2(MoO4)3–Hf(MoO4)2, a new thallium indium hafnium molybdate was found. The crystal structure of the molybdate Tl5InHf(MoO4)6 was determined in the centrosymmetric space group R $$ \overline{3} $$ c (a = 10.63893 (5) Å, c = 38.1447(3) Å; V = 3739.04 (4) Å3, Z = 6). The structure is a three-dimensional framework consisting of alternating (Hf,In)O6-octahedra connected by МоО4-tetrahedra. Each octahedron has common vertices with tetrahedra. The atoms arranged in this way form channels extended along with the a and b axes, in which thallium atoms are located. The conductivity behavior of Tl5InHf(MoO4)6 ceramics was studied in the temperature range from 300 to 870 K. The conductivity of the heavy cations of thallium is activated with increasing temperature.

Among several materials (transition metal oxide) under development for use as a cathode in lithium-ion batteries, cubic spinel LiMn2O4 is one of the most promising cathode materials. In this study, the sea urchin-like LiMn2O4 hollow macrospheres were synthesized by using sea urchin-like α-MnO2 precursors through solid-state in situ self-sacrificing conversion route. The as-prepared LiMn2O4 was assembled by many single-crystalline “thorns” of ca.10–20 nm in diameter and ca. 400–500 nm in length. Galvanostatic battery testing showed that sea urchin-like LiMn2O4 had an initial discharge capacity of 126.8 mAh/g at the rate of 0.2 C in the potential range between 3.0 and 4.5 V. More than 96.67 % of the initial discharge capacity was maintained for over 50 cycles. The improved electrochemical properties were attributed to the reduced particle size and enhanced electrical contacts by the materials. This particular sea urchin-like structured composite conceptually provides a new strategy for designing electrodes in energy storage applications.

Synthesis of novel purpald (4-amino-5-hydrazino-1,2,4-triazole-3-thiol) containing 2,5-di(2-thienyl)pyrrole (TPTP) derivative monomer has been successfully achieved. Its functional conductive polymer (pTPTP) obtained electrochemically has been characterized and electrooptical properties have been investigated. In this way, multifunctional conductive polymer film has been formed by means of advanced functionalization of thiol and amine group on the polymeric backbone that can be applied in many fields such as metal sensor, biosensor sensor, and biochemical imaging. The potential usage of this multifunctional conductive polymer film in smart windows application has been investigated and the optical contrast value which is the most important parameter of this technology has been measured as 75%.

Overcharge performance of LiFePO4 cells is investigated through adding 2, 5-ditertbutyl 1, 4-dimethoxybenzene (DDB) as redox shuttle into electrolyte (RS electrolyte) at different charge rate. RS electrolytes with DDB works well as overcharge protection at low charge rate of less than 0.1 C. Novel charge/discharge characteristics are observed when charge rate increases in the cell with RS electrolyte. Especially, larger discharge capacities are obtained at the same discharge rate after charge rate gets higher than 0.1 C rate. Discharge capacity is larger in the cell with RS electrolyte than that in the cell without RS electrolyte at the same charge and discharge rate. At the same charge rate, cells with RS electrolyte have better cycling performances and larger discharge capacity than that with conventional electrolyte. These indicate that DDB accumulates in cathode with cycling and influences electrode–electrolyte interface reactions.

The prediction of remaining useful life (RUL) of lithium-ion batteries takes a critical effect in the battery management system, and precise prediction of RUL guarantees the secure and reliable functioning of batteries. For the difficult problem of selecting the parameter kernel of the training data set of the RUL prediction model constructed based on the support vector regression model, an intelligent gray wolf optimization algorithm is introduced for optimization, and owing to the premature stagnation and multiple susceptibility to local optimum problems of the gray wolf algorithm, a differential evolution strategy is introduced to propose a hybrid gray wolf optimization algorithm based on differential evolution to enhance the original gray wolf optimization. The variance and choice operators of differential evolution are designed to sustaining the diversity of stocks, and then their crossover operations and selection operators are made to carry out global search to enhance the prediction of the model and realize exact forecast of the remaining lifetime. Experiments on the NASA lithium-ion battery dataset demonstrate the effectiveness of the proposed RUL prediction method. Experimental results demonstrate that the maximum average absolute value error of the prediction of the fusion algorithm on the battery dataset is limited to within 1%, which reflects the high accuracy prediction capability and strong robustness.

Antimony telluride thin films were prepared on the well-cleaned glass substrates under a pressure of 10 – 5 torr by thermal evaporation method. The thicknesses of the films were measured using Multiple Beam Interferometer (MBI) technique. The structure of the sample was analyzed by X-ray diffraction technique. The film attains crystalline structure as the temperature of the substrate is increased to 373 K. The d spacing and the lattice parameters of the sample were calculated. Optical behavior of the film samples with the various thicknesses was analyzed by obtaining their transmittance spectra in the wavelength range of 400 – 800 nm. The transmittance is found to decrease with increase in film thickness and also it falls steeply with decreasing wavelength. The optical constants were estimated and the results are discussed. The optical band gap energy decreases with increase in the film thickness. The optical transition in these films is found to be indirect and allowed.

A novel three mixed metal–organic framework (TM-MOF) containing lanthanum, gadolinium and thulium metals is prepared through a simple cathodic electrodeposition strategy onto nickel foam substrate. Various techniques are used to full characterization of the as-prepared TM-MOF product. The microscopic results revealed formation of the TM-MOF nanosheets uniformly grown onto porous Ni-foam. The synergistic effects of the La/Gd/Tm-lanthanide elements within the composition of TM-MOF electrode delivered a high specific capacity of 412 C/g at a current density of 1 A/g, high-rate capability of 52.9% (at 15 A/g), and an outstanding cycling stability of 94.2% after 6000 cycles. Based on the electrochemical findings, the hierarchical sheet-like morphology of the TM-MOF was rich in active redox sites and electrolyte ions diffusion pathways. All of these characters suggested that TM-MOF electrode could be promising candidate for supercapacitors.

Graphene oxide is well known as a new kind of functional materials because of its super-high specie surface area, mechanical strength, as well as excellent amphipathicity. In this article, graphene oxide was further sulfonated via substitution reaction with diazo salt of sulfanilic in order to endow graphene oxide with better ion exchange capacity and proton conductivity. The microstructure and morphology of the obtained sulfonated graphene oxide were characterized by X-ray diffraction (XRD), Raman spectra, and TEM, while the sulfonation of graphene oxide was confirmed by energy-dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR) spectra. As expected, ion exchange capacity and proton conductivity of sulfonated graphene oxide increased by about 0.589 and 33.6 times than those of graphene oxide, respectively.

Being eco-friendly, cost-effective, easy to synthesize and handle, starch-based electrolytes have tremendous advantages for electrochemical device fabrications. Starch electrolytes synthesized by crosslinking process result in stable, flexible, free-standing films which can be molded in different shapes and sizes. Rice starch–based material, prepared using glutaraldehyde as crosslinker and NaClO4 as ion-providing salt, resulted in high conductivity (~ 0.01 S/cm) and fast-relaxing (ion relaxation time in micro seconds) electrolytes having wide electrochemical stability window (~ 3 V). Resistance of highest conducting sample, having 0.8 mm thickness and 1 × 1 cm2 area is ~ 6 Ω. The synthesized electrolyte is easily moldable in desired shape and size and hence devices may be fabricated with smaller equivalent series resistance. The estimated relaxation time is 62 μs indicating that fabricated devices will be able to deliver energy in shorter time. The approximate preparation cost of the material (1 × 1 × 0.08 cm3) is INR 20 (~ 0.3USD). The low cost, good technical parameters, and flexibility make it a promising material for electrochemical device fabrication.