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Doped Tin (IV) Oxide has excellent potential in high-temperature thermoelectrics because of its large bandgap. It has been thoroughly experimentally studied for high-temperature thermoelectric application. Low electron mobility limits the thermoelectric performance of oxides. Understanding the temperature dependence of mobility help increase thermoelectric performance. This is rarely performed. In this work, we study antimony doped tin dioxide. Combining the calculated transport properties and the existing experimental results, we obtain other transport properties. Unlike in bulk materials, the grain boundary scattering competes against the acoustic phonon scattering. The grain size, temperature, and carrier concentration determine the mobility. The small grain, low carrier concentration, and high temperature are beneficial to the mobility. Antimony doping also causes the Fermi level into the conduction band as deep as 0.59 eV, making the large bandgap SnO2 metallic. Furthermore, the conductivity effective mass demonstrates the doping effect. These findings might help design new oxide thermoelectric materials by decrease the grain size.

This work is focused on the mechanism study of nanoscale Co3O4 powders prepared by an enhanced solid-state reaction method. The as-prepared powders are characterized by thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with the powders ball milled for different times as the control. The results show that ball milling can accelerate the thermal decomposition process by approximately 18.2%. Moreover, the apparent thermal decomposition activation energy of CoCO3 powders pretreated by the enhanced solid-state method declined by 33.2%. To elucidate this,the thermal decomposition kinetic equations of CoCO3 powders, with and without ball milling, are calculated. And the thermal decomposition kinetic equation of the ball-milled powders is dα/dt = (2.42E6~2.19E7) exp [(8.74E3~9.96E3)/T] 4/3(1-α) [-ln(1-α)]1/4; while that of the powders lack of ball milling is dα/dt = (1.08E10–1.07E11) exp [(1.43E4~1.51E4)/T] 2/3α−1/2, respectively. The reaction process at different time points can be forecasted by the obtained equations.

Enhanced thermal decomposition of carbonates is developed to improve the traditional solid state reaction for the synthesis of ultrafine LiNi1/3Co1/3Mn1/3O2 powders. Controllable activation is obtained by optimizing the mechano-chemical treatment time, which is found to affect lattice structure, morphology and electrochemical properties of the as-synthesized ultrafine LiNi1/3Co1/3Mn1/3O2 powders. The optimal mechano-chemical activation time of 10 h results in more stable and integrated structured ultrafine LiNi1/3Co1/3Mn1/3O2 powders with average diameter of 200–500 nm, leading to a high reversible capacity of 114.3 and 140.9 mAh g−1 at 6 C (1620 mA g−1) in the voltage range of 2.5–4.3 and 2.5–4.5 V, respectively. Moreover, the particles exhibit capacity retentions of 80.8% (2.5–4.3 V) and 83.3% (2.5–4.5 V) at 270 mA g−1 after 200 cycles. Importantly, it is revealed that ball-milling has a positive impact on the calcination process, and the decomposition efficiency is about 35.7% higher compared to ball-milling-free process. The LiNi1/3Co1/3Mn1/3O2 powders prepared by enhancing thermal decomposition show a remarkable high temperature electrochemical property. For optimum performance, the time of mechano-chemical activation should be neither too long nor too short. In addition, the calcination process is further studied in order to understand the transformation regularities of the electrode materials.

Half-Heusler compounds have distinguished themselves as outstanding thermoelectric materials on account of high temperature stability and large thermopower. However, the dimensionless figure of merit of traditional half-Heusler alloys remains low. In this study, we investigate the thermoelectric performance of novel ZrXPb (X= Ni, Pd, and Pt) ternary compounds by semi-classical Boltzmann transport theory combining with deformation potential. The n-type ZrNiPb and ZrPtPb exhibits obviously largeZTvalues of 1.71 around 650 K and 1.75 around 1200 K, with 1.17 × 1020 cm-3and 3.43 × 1020 cm-3, respectively. The electron and phonon structure calculations demonstrate that for the n-type ZrXPb (X= Ni, Pd, and Pt) compounds, doping at Pb site can not only modify the carrier concentrations but also significantly decrease the lattice thermal conductivity. These investigations are expected to be beneficial to the exploration of novel highZTthermoelectric materials.

Ultrafine LiCoO 2 powders were directly synthesized by enhancing thermal decomposition of Cobalt and Lithium carbonates through a mechanochemical activation treatment to intensify the solid state diffusion reaction. Effects of activation treatment time on particle size and structure of the LiCoO 2 compound were investigated. In the present study, the optimum mechano-chemical activation time was found to be 10 h. In this study, the ultrafine LiCoO 2 powders (particle size in the range from 200 nm to 400 nm) show good structural stability and higher structural integrity. X-ray photoelectron spectroscopy (XPS) results indicate that most of Co cations exist as Co 3+ , which contributes to the improvement of the electrochemical performance. Cyclic voltammetry (CV) curves of different cycles display almost a complete overlap, which can be regarded as another evidence of the excellent cycle performance. The LiCoO 2 powders exhibit a high initial discharge specific capacity of 175.2 mAh/g at 0.1 C (274 mA/g at 1 C) and a remarkable cycle stability from 167.5 mAh/g to 146.2 mAh/g at 0.5 C and from 147.5 mAh/g to 115.2 mAh/g at 3 C after 100 cycles in the range of 3.3–4.3 V. The apparent activation energy and the frequency factor of the decomposition of CoCO 3 are 69.83 kJ/mol and 1.369×10 6 , respectively, indicating that the ultrafine in-process product of Co 3 O 4 can be quickly prepared at a low temperature.

The composite of porous carbon obtained from MOFs loading sulfur has been regard as promising candidate for lithium-sulfur batteries cathode material due to the large specific surface area, high porosity, diversity of types, and designable structures large specific surface area, high porosity, diversity of types, and designable structures. However, the production processes of MOFs materials play a pivotal role on the lithium-sulfur batteries performance. Herein, the effect of key process parameters such as heat treatment temperature, heat treatment time, and heat treatment atmosphere on the electrochemical performance of lithium-sulfur batteries were systematically studied. The results show that at a heating rate of 5 ℃·min−1, heat preservation at 900 ℃ for 3 h, and treatment with CO2 airflow for 1 h, the composite material has the best electrochemical performance. The first discharge specific capacity of the lithium-sulfur battery reached 1060.32 mAh·g−1, and after 50 cycles it reached 614.29 mAh·g−1. This heat treatment research method based on MOFs-derived materials can be used as a reference for related research in other energy storage and conversion fields.

First, we solve a semi-classical electronic Boltzmann transport equation and acquire the thermoelectric coefficients for a pure unit cell using the rigid-band approximation. Then, combined with the existing experimental results, we not only reproduce the Seebeck coefficients and electrical conductivity but also yield the carrier concentrations and relaxation time, which cannot be obtained by either experiments or theories alone. Our results are in good agreement with the experiment for all doping samples. Furthermore, we show that Wiedemann-Franz law fails to connect the electronic thermal conductivity with the electrical conductivity. We also show that the Hall effect fails to measure carrier concentration in this study. We attribute these failures to the breakdown of the parabolic band. We think that our approach can be extended to other alloy or compound thermoelectric materials that utilize electronic transport property because they all have problems identifying relaxation time and carrier concentrations.

In order to improve the properties of the nickel—zinc battery and study the effects of the additives on performance of zinc electrode, 3 levels and 4 factors (acetylene black, Bi 2 O 3 , PbO, Ca[Zn(OH) 3 ] 2 ·2H 2 O coated by La(OH) 3 ) that affect the zinc electrode were tested with orthogonal design experiments. The charge—discharge experiments of zinc electrode made up of only zinc oxide were done in 20% KOH solution to investigate the function of the additive. In order to better understand the discharge capability attenuation of electrode, the ratios of zinc to calcium in the worst sample and the best sample of the orthogonal design test were analyzed. The samples were characterized by charge—discharge cycling, phase structure analysis, cyclic voltammetry and X-ray diffraction. Experimental evidences indicate that the optimum ratio of electrode additive is as follows: 0.02 g acetylene black, 0.5 g Bi 2 O 3 , 0.3 g PbO and 0.2 g Ca[Zn(OH) 3 ] 2 ·2H 2 O coated with La(OH) 3 in 5 g sample.

In this paper, ZrO2-coated LiNi1/3Mn1/3Co1/3O2 is successfully prepared by the microwave pyrolysis method. The structure and electrochemical properties of the ZrO2-coated LiNi1/3Co1/3Mn1/3O2 are investigated using x-ray diffraction, AC impedance, and charge/discharge tests, indicating that the lattice structure of LiNi1/3Co1/3Mn1/3O2 is unchanged after the coating but the cycling stability is improved. As the coating amount is 2 wt.%, initial capacity of the coated LiNi1/3Co1/3Mn1/3O2 decreases slightly. However, the cycling stability increases remarkably over the cut-off voltages of 2.75~4.3 V and the capacity retention reaches 93.1% after 50 cycles. Electrochemical impedance spectra results show that the increase of charge transfer resistance during cycling is suppressed significantly by coating with ZrO2.

In this paper, La0.4Ca0.6CoO3-coated LiNi1/3Mn1/3Co1/3O2 is successfully prepared by the sol–gel method associated with microwave pyrolysis method. The structure and electrochemical properties of the La0.4Ca0.6CoO3-coated LiNi1/3Co1/3Mn1/3O2 are investigated by using X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. XRD analyses show that the La0.4Ca0.6CoO3 coating does not change the structure of LiNi1/3Co1/3Mn1/3O2. The electrochemical performance studies demonstrate that 2 wt.% La0.4Ca0.6CoO3-coated LiNi1/3Co1/3Mn1/3O2 powders exhibit the best electrochemical properties, with an initial discharge capacity of 156.9 mAh g–1 and capacity retention of 98.9 % after 50 cycles when cycled at a current density of 0.2 C between 2.75 and 4.3 V. La0.4Ca0.6CoO3 coating can improve the rate performance because of the enhancement of the surface electronic/ionic transportation by the coating layer. EIS results suggest that the coating La0.4Ca0.6CoO3 plays an important role in suppressing the increase of cell impedance with cycling especially for the increase of charge-transfer resistance.

Au@Pt core-shell nanoparticles were synthesized by a simple one-step ultraviolet irradiation method and were then assembled on functionalized multiwalled carbon nanotubes (MWCNTs) surface. This new type of Au@Pt/MWCNTs composite catalysts was characterized by UV–vis spectrometry, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning TEM, HRTEM, and electrochemical techniques. The results revealed that the Au@Pt nanoparticles with an average diameter less than 5 nm were well coated on the MWCNTs surface. As compared with commercial Pt/C catalysts, the Au@Pt/MWCNTs prepared using Au/Pt atomic ratio of 1:1 exhibited distinctly higher activity and better stability toward methanol oxidation in alkaline media.

AAO/Ni composite membranes were prepared by AC(alternative current) electrochemical deposition of Ni in the ordered porous anodic alumina oxide(AAO). The structure was characterized by XRD, SEM and UV—visible absorption spectroscopy. The XRD analysis indicated Ni in the pores of AAO membranes was in face-centered cubic structure after heat treatment. EDX showed that the relative amounts of Ni was 2.65%wt. UV—visible absorption spectroscopy showed that deposition of Ni had significant effect on ultraviolet-visible light absorption properties of AAO membranes and made UV absorptivity decreased. With increasing thickness of membrane, the UV absorptivity decreased remarkably.