Thermal properties of 15-mol% gadolinia doped ceria thin films prepared by pulsed laser ablation

Thermal properties of 15-mol% gadolinia doped ceria thin films (Ce_0.85Gd_0.15 O_1.925) prepared by pulsed laser ablation on silicon substrates in the temperature range 473–973 K are presented. Thermal diffusivities and thermal conductivities were evaluated using photoacoustic spectroscopy. The influence of grain size on thermal properties of the films as a function of deposition temperature is studied. It is observed that the thermal diffusivity and the conductivity of these films decreases up to 873 K and then increases with substrate temperatures. The thermal properties obtained in these films are discussed on the basis of influence of grain size on phonon scattering.     

Study of pristine and carbon-coated LiCoPO<Subscript>4</Subscript> olivine material synthesized by modified sol–gel method

LiCoPO₄ and LiCoPO₄/C electrode active material was synthesized by a simple single-step protocol namely citric acid-assisted, isopropanol-added sol–gel method. Structural and morphology studies reveal the formation of single-phase products of pristine as well as in situ carbon-coated nano-sized grains of genuine purple-colored product of LiCoPO₄ and black-colored LiCoPO₄/C due to uniform carbon coatings, respectively. In situ carbon coating was confirmed by scanning transmission electron microscopy imaging which exhibits the in situ nanocarbon coating networks. The electrode active characteristics of the synthesized products confirmed by resolved cyclic voltammograms corresponding to cobalt redox couple (Co²⁺/Co³⁺) confirm the lithium extraction/insertion reversible processes. Carbon coating ensures better resolved near symmetric redox peaks with increased current profile indicative of enhanced rate capability (Li⁺ extraction/insertion), presumably due to the enhanced electrode conductivity of the host matrix by means of carbon coating.     

A new type of electrochemical cell based on the configuration NaI |PEG| I2

Different operating conditions of a new electrochemical cell based on sodium iodide and polyethylene glycol (PEG) polymer as separator as well as conducting electrolyte is reported. Five types of cells were fabricated using pure NaI, PC+NaI, water+NaI dil. HCl+NaI and dil. H₂SO₄+NaI in the cell configuration NaI |PEG| I₂ and NaI |PEG|s I₂+C. Their discharge characteristics were studied at room temperature (33 °C). From the cell parameters, it is found that the open circuit voltage ranges from 648 mV to 1023 mV and the short circuit current ranges from 29 μA to 4.8 mA.     

Mesoporous MnCo2O4 spinel oxide nanostructure synthesized by solvothermal technique for supercapacitor

A manganese cobaltite spinel oxide was synthesized successfully via d-glucose-assisted solvothermal process. The structure and morphology of the sample heat treated at 300 and 400 °C for 6 h has been studied with X-ray diffraction, scanning electron microscope, and transmission electron microscope. Cyclic voltammograms at different scan rate have demonstrated that an excellent capacitance feature of MnCo₂O₄ spinel oxide electrode. Pseudotype-capacitive behavior of the sample was further corroborated by the charge–discharge measurements at various current densities. The estimated specific capacitance of spinel oxides with two calcination temperature was found to be 189 and 346 F g^?1 at a constant current density of 1 A g^?1. Observed specific capacitance and excellent cyclic stability of MnCo₂O₄ spinel oxide has ascribed to their high surface area and mesoporous microstructure. This facilitates to easy electrolyte ion intercalation and deintercalation at electrode/electrolyte interface. In this study, we suggest that the MnCo₂O₄ spinel nanostructure with high surface area and desired cation distribution could be a promising electrode material for next-generation high-performance supercapacitor.     

Ionic conductivity and battery characteristic studies on PEO+NaClO3 polymer electrolyte

Solid polymer electrolyte films based on poly (ethylene oxide) PEO complexed with NaClO₃ have been prepared by a solution-cast technique. The solvation of Na⁺ ion with PEO is confirmed by XRD and IR studies. Measurements of the a.c. conductivity in the temperature range 308 – 378 K and the transference numbers have been carried out to investigate the charge transport in this polymer electrolyte system. Transport number data show that the charge transport in this polymer electrolyte system is predominantly due to ions. The highest conductivity (2.12.10⁻⁴ S/cm) has been observed for the 70:30 composition. Using the polymer electrolyte solid state electrochemical cells have been fabricated. The various cell parameters are evaluated and reported.